diff --git a/build/bootstrap/compile.com b/build/bootstrap/compile.com
index 42c95ff8c..d1eaa1a3b 100755
Binary files a/build/bootstrap/compile.com and b/build/bootstrap/compile.com differ
diff --git a/build/definitions.mk b/build/definitions.mk
index aaadbfd60..66a7d50c9 100644
--- a/build/definitions.mk
+++ b/build/definitions.mk
@@ -91,7 +91,7 @@ VM = o/third_party/qemu/qemu-aarch64
 HOSTS ?= pi silicon
 else
 ARCH = x86_64
-HOSTS ?= freebsd openbsd netbsd rhel7 rhel5 xnu win10
+HOSTS ?= freebsd rhel7 rhel5 xnu win10 openbsd netbsd
 endif
 
 ifeq ($(PREFIX),)
@@ -396,32 +396,6 @@ OBJECTIFY.c99.c = $(CC) $(OBJECTIFY.c.flags) -std=c99 -Wextra -Werror -pedantic-
 OBJECTIFY.c11.c = $(CC) $(OBJECTIFY.c.flags) -std=c11 -Wextra -Werror -pedantic-errors -c
 OBJECTIFY.c2x.c = $(CC) $(OBJECTIFY.c.flags) -std=c2x -Wextra -Werror -pedantic-errors -c
 
-OBJECTIFY.real.c =							\
-	$(GCC)								\
-	-x-no-pg							\
-	$(OBJECTIFY.c.flags)						\
-	-wrapper build/realify.sh					\
-	-D__REAL_MODE__							\
-	-ffixed-r8							\
-	-ffixed-r9							\
-	-ffixed-r10							\
-	-ffixed-r11							\
-	-ffixed-r12							\
-	-ffixed-r13							\
-	-ffixed-r14							\
-	-ffixed-r15							\
-	-mno-red-zone							\
-	-fcall-used-rbx							\
-	-fno-jump-tables						\
-	-fno-shrink-wrap						\
-	-fno-schedule-insns2						\
-	-flive-range-shrinkage						\
-	-fno-omit-frame-pointer						\
-	-momit-leaf-frame-pointer					\
-	-mpreferred-stack-boundary=3					\
-	-fno-delete-null-pointer-checks					\
-	-c
-
 OBJECTIFY.ncabi.c =							\
 	$(GCC)								\
 	$(OBJECTIFY.c.flags)						\
diff --git a/build/rules.mk b/build/rules.mk
index 6d11c6da3..8deb0b986 100644
--- a/build/rules.mk
+++ b/build/rules.mk
@@ -34,7 +34,6 @@ o/$(MODE)/%.o: %.cc                ; @$(COMPILE) -AOBJECTIFY.cxx $(OBJECTIFY.cxx
 o/$(MODE)/%.lds: %.lds             ; @$(COMPILE) -APREPROCESS $(PREPROCESS.lds) $(OUTPUT_OPTION) $<
 o/$(MODE)/%.initabi.o: %.initabi.c ; @$(COMPILE) -AOBJECTIFY.init $(OBJECTIFY.initabi.c) $(OUTPUT_OPTION) $<
 o/$(MODE)/%.ncabi.o: %.ncabi.c     ; @$(COMPILE) -AOBJECTIFY.nc $(OBJECTIFY.ncabi.c) $(OUTPUT_OPTION) $<
-o/$(MODE)/%.real.o: %.c            ; @$(COMPILE) -AOBJECTIFY.real $(OBJECTIFY.real.c) $(OUTPUT_OPTION) $<
 
 ifneq ($(ARCH), aarch64)
 o/%.o: %.s                         ; @$(COMPILE) -AOBJECTIFY.s $(OBJECTIFY.s) $(OUTPUT_OPTION) $<
diff --git a/examples/clear.c b/examples/clear.c
index a21e05c06..f008c5845 100644
--- a/examples/clear.c
+++ b/examples/clear.c
@@ -9,8 +9,11 @@
 #endif
 #include "libc/calls/calls.h"
 
-// clears the teletypewriter display with empty cells
+// clears teletypewriter display
+//
+//   - \e[H moves to top left of display
+//   - \e[J erases whole display forward
 
 int main(int argc, char *argv[]) {
-  write(1, "\e[H", 3);
+  write(1, "\e[H\e[J", 6);
 }
diff --git a/examples/linenoise.c b/examples/linenoise.c
index b54e6f899..6f767664f 100644
--- a/examples/linenoise.c
+++ b/examples/linenoise.c
@@ -7,17 +7,52 @@
 │   • http://creativecommons.org/publicdomain/zero/1.0/            │
 ╚─────────────────────────────────────────────────────────────────*/
 #endif
-#include "libc/mem/mem.h"
-#include "libc/stdio/stdio.h"
 #include "third_party/linenoise/linenoise.h"
+#include "libc/calls/calls.h"
+#include "libc/calls/struct/sigset.h"
+#include "libc/intrin/kprintf.h"
+#include "libc/mem/mem.h"
+#include "libc/runtime/runtime.h"
+#include "libc/stdio/posix_spawn.h"
+#include "libc/stdio/stdio.h"
+#include "libc/str/str.h"
+#include "libc/sysv/consts/sig.h"
 
 int main(int argc, char *argv[]) {
+  int ws;
   char *line;
-  while ((line = linenoiseWithHistory("IN> ", "foo"))) {
-    fputs("OUT> ", stdout);
-    fputs(line, stdout);
-    fputs("\n", stdout);
+  char ps1[100];
+  sigset_t mask, om;
+  posix_spawnattr_t attr;
+  ShowCrashReports();
+  sigemptyset(&mask);
+  sigaddset(&mask, SIGINT);
+  sigaddset(&mask, SIGQUIT);
+  sigaddset(&mask, SIGCHLD);
+  sigprocmask(SIG_BLOCK, &mask, &om);
+  posix_spawnattr_init(&attr);
+  posix_spawnattr_setsigmask(&attr, &om);
+  for (ws = 0;;) {
+    if (WIFSIGNALED(ws)) {
+      ksnprintf(ps1, sizeof(ps1), "\e[1;31m%G\e[0m :> ", ws, WTERMSIG(ws));
+    } else {
+      ksnprintf(ps1, sizeof(ps1), "%d :> ", ws, WEXITSTATUS(ws));
+    }
+    if (!(line = linenoiseWithHistory(ps1, "unbourne"))) {
+      break;
+    }
+    if (*line) {
+      int i = 0;
+      char *args[64];
+      args[i++] = strtok(line, " \t\v\r\n");
+      while ((args[i++] = strtok(0, " \t\v\r\n"))) {
+      }
+      int pid;
+      posix_spawnp(&pid, args[0], 0, &attr, args, environ);
+      wait(&ws);
+    }
     free(line);
   }
+  posix_spawnattr_destroy(&attr);
   return 0;
 }
diff --git a/libc/calls/__sig2.c b/libc/calls/__sig2.c
index 245786e20..0b2d2f97e 100644
--- a/libc/calls/__sig2.c
+++ b/libc/calls/__sig2.c
@@ -27,10 +27,12 @@
 #include "libc/calls/struct/sigset.h"
 #include "libc/calls/struct/ucontext.internal.h"
 #include "libc/calls/ucontext.h"
+#include "libc/intrin/describebacktrace.internal.h"
 #include "libc/intrin/strace.internal.h"
 #include "libc/intrin/weaken.h"
 #include "libc/log/libfatal.internal.h"
 #include "libc/macros.internal.h"
+#include "libc/nexgen32e/stackframe.h"
 #include "libc/nt/console.h"
 #include "libc/nt/enum/context.h"
 #include "libc/nt/runtime.h"
@@ -225,13 +227,20 @@ textwindows bool __sig_handle(int sigops, int sig, int sic, ucontext_t *ctx) {
         uint32_t cmode;
         intptr_t hStderr;
         const char *signame;
-        char *end, sigbuf[21], output[22];
+        char *end, sigbuf[21], output[123];
         signame = strsignal_r(sig, sigbuf);
         STRACE("terminating due to uncaught %s", signame);
         if (__sig_is_core(sig)) {
           hStderr = GetStdHandle(kNtStdErrorHandle);
           if (GetConsoleMode(hStderr, &cmode)) {
-            end = stpcpy(stpcpy(output, signame), "\n");
+            end = stpcpy(output, signame);
+            end = stpcpy(end, " ");
+            end = stpcpy(
+                end,
+                DescribeBacktrace(
+                    ctx ? (struct StackFrame *)ctx->uc_mcontext.BP
+                        : (struct StackFrame *)__builtin_frame_address(0)));
+            end = stpcpy(end, "\n");
             WriteFile(hStderr, output, end - output, 0, 0);
           }
         }
diff --git a/libc/calls/assertfail.c b/libc/calls/assertfail.c
index 31a3abc9e..a8fe202ee 100644
--- a/libc/calls/assertfail.c
+++ b/libc/calls/assertfail.c
@@ -18,7 +18,9 @@
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/assert.h"
 #include "libc/calls/calls.h"
+#include "libc/errno.h"
 #include "libc/fmt/itoa.h"
+#include "libc/intrin/describebacktrace.internal.h"
 #include "libc/runtime/runtime.h"
 
 /**
@@ -27,6 +29,8 @@
 void __assert_fail(const char *expr, const char *file, int line) {
   char ibuf[12];
   FormatInt32(ibuf, line);
-  tinyprint(2, "\n", file, ":", ibuf, ": assert(", expr, ") failed\n", NULL);
+  tinyprint(2, "\n", file, ":", ibuf, ": assert(", expr, ") failed (",
+            program_invocation_short_name, " ",
+            DescribeBacktrace(__builtin_frame_address(0)), ")\n", NULL);
   abort();
 }
diff --git a/libc/calls/chdir.c b/libc/calls/chdir.c
index f2a7d3b60..7e2d4d031 100644
--- a/libc/calls/chdir.c
+++ b/libc/calls/chdir.c
@@ -19,6 +19,7 @@
 #include "libc/calls/syscall-nt.internal.h"
 #include "libc/calls/syscall-sysv.internal.h"
 #include "libc/dce.h"
+#include "libc/errno.h"
 #include "libc/intrin/asan.internal.h"
 #include "libc/intrin/strace.internal.h"
 #include "libc/intrin/weaken.h"
diff --git a/libc/calls/execve-nt.greg.c b/libc/calls/execve-nt.greg.c
index 8942e18fd..0d6b871b0 100644
--- a/libc/calls/execve-nt.greg.c
+++ b/libc/calls/execve-nt.greg.c
@@ -16,22 +16,28 @@
 │ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
-#define ShouldUseMsabiAttribute() 1
 #include "libc/calls/calls.h"
 #include "libc/calls/internal.h"
 #include "libc/calls/ntspawn.h"
 #include "libc/calls/syscall-nt.internal.h"
+#include "libc/dce.h"
 #include "libc/fmt/itoa.h"
-#include "libc/intrin/kprintf.h"
+#include "libc/intrin/atomic.h"
+#include "libc/intrin/dll.h"
 #include "libc/intrin/strace.internal.h"
 #include "libc/intrin/weaken.h"
+#include "libc/limits.h"
 #include "libc/macros.internal.h"
 #include "libc/mem/alloca.h"
 #include "libc/nt/accounting.h"
 #include "libc/nt/console.h"
 #include "libc/nt/enum/startf.h"
 #include "libc/nt/enum/status.h"
+#include "libc/nt/enum/threadaccess.h"
+#include "libc/nt/enum/wait.h"
+#include "libc/nt/errors.h"
 #include "libc/nt/memory.h"
+#include "libc/nt/process.h"
 #include "libc/nt/runtime.h"
 #include "libc/nt/struct/processinformation.h"
 #include "libc/nt/struct/startupinfo.h"
@@ -50,26 +56,31 @@
 #include "libc/sysv/consts/ok.h"
 #include "libc/sysv/consts/sig.h"
 #include "libc/sysv/errfuns.h"
+#include "libc/thread/posixthread.internal.h"
 #include "libc/thread/thread.h"
 
 #define keywords textwindows dontasan dontubsan dontinstrument
 
-extern long __klog_handle;
-
+// clang-format off
 __msabi extern typeof(CloseHandle) *const __imp_CloseHandle;
+__msabi extern typeof(ExitProcess) *const __imp_ExitProcess;
+__msabi extern typeof(GenerateConsoleCtrlEvent) *const __imp_GenerateConsoleCtrlEvent;
+__msabi extern typeof(GetCurrentThreadId) *const __imp_GetCurrentThreadId;
 __msabi extern typeof(GetExitCodeProcess) *const __imp_GetExitCodeProcess;
+__msabi extern typeof(GetLastError) *const __imp_GetLastError;
+__msabi extern typeof(OpenThread) *const __imp_OpenThread;
+__msabi extern typeof(SetConsoleCtrlHandler) *const __imp_SetConsoleCtrlHandler;
 __msabi extern typeof(TerminateThread) *const __imp_TerminateThread;
 __msabi extern typeof(UnmapViewOfFile) *const __imp_UnmapViewOfFile;
 __msabi extern typeof(WaitForSingleObject) *const __imp_WaitForSingleObject;
+// clang-format on
 
+extern long __klog_handle;
+static void sys_execve_nt_relay(intptr_t, long, long, long);
 wontreturn void __switch_stacks(intptr_t, long, long, long,
                                 void (*)(intptr_t, intptr_t, long, long),
                                 intptr_t);
 
-__msabi static keywords bool32 sys_execve_nt_event(uint32_t dwCtrlType) {
-  return true;  // block sigint and sigquit in execve() parent process
-}
-
 static keywords void PurgeHandle(intptr_t h) {
   if (!h) return;
   if (h == -1) return;
@@ -83,66 +94,87 @@ static keywords void PurgeThread(intptr_t h) {
   }
 }
 
-// this function runs on the original tiny stack that windows gave us.
-// we need to keep the original process alive simply to pass an int32.
-// so we unmap all memory to avoid getting a double whammy after fork.
-static keywords void sys_execve_nt_relay(intptr_t h, long b, long c, long d) {
-  uint32_t i, dwExitCode;
-  __imp_SetConsoleCtrlHandler((void *)sys_execve_nt_event, 1);
-  PurgeThread(g_fds.stdin.thread);
-  PurgeHandle(g_fds.stdin.reader);
-  PurgeHandle(g_fds.stdin.writer);
-  PurgeHandle(g_fds.p[0].handle);
-  PurgeHandle(g_fds.p[1].handle);
-  PurgeHandle(g_fds.p[2].handle);
-  for (i = 0; i < _mmi.i; ++i) {
-    __imp_UnmapViewOfFile((void *)((uintptr_t)_mmi.p[i].x << 16));
-    PurgeHandle(_mmi.p[i].h);
+static keywords void sys_execve_killer(void) {
+  struct Dll *e;
+  pthread_spin_lock(&_pthread_lock);
+  for (e = dll_first(_pthread_list); e; e = dll_next(_pthread_list, e)) {
+    enum PosixThreadStatus status;
+    struct PosixThread *pt = POSIXTHREAD_CONTAINER(e);
+    int tid = atomic_load_explicit(&pt->tib->tib_tid, memory_order_acquire);
+    if (tid <= 0 || tid == __imp_GetCurrentThreadId()) continue;
+    status = atomic_load_explicit(&pt->status, memory_order_acquire);
+    if (status >= kPosixThreadTerminated) continue;
+    int64_t hand;
+    if ((hand = __imp_OpenThread(kNtThreadTerminate, false, tid))) {
+      __imp_TerminateThread(hand, SIGKILL);
+      __imp_CloseHandle(hand);
+    }
   }
-  do {
-    __imp_WaitForSingleObject(h, -1);
-    dwExitCode = kNtStillActive;
-    __imp_GetExitCodeProcess(h, &dwExitCode);
-  } while (dwExitCode == kNtStillActive);
-  __imp_ExitProcess(dwExitCode);
-  __builtin_unreachable();
+  pthread_spin_unlock(&_pthread_lock);
 }
 
 keywords int sys_execve_nt(const char *program, char *const argv[],
                            char *const envp[]) {
-  int rc;
   size_t i;
-  char progbuf[PATH_MAX];
-  struct NtStartupInfo startinfo;
-  struct NtProcessInformation procinfo;
 
-  if (strlen(program) + 4 + 1 > PATH_MAX) {
-    return enametoolong();
-  }
-
-  // this is a non-recoverable operation, so do some manual validation
-  if (sys_faccessat_nt(AT_FDCWD, program, X_OK, 0) == -1) {
-    stpcpy(stpcpy(progbuf, program), ".com");
-    if (sys_faccessat_nt(AT_FDCWD, progbuf, X_OK, 0) != -1) {
-      program = progbuf;
-    } else {
-      stpcpy(stpcpy(progbuf, program), ".exe");
+  // validate api usage
+  if (strlen(program) + 4 < PATH_MAX) {
+    char progbuf[PATH_MAX];
+    char *end = stpcpy(progbuf, program);
+    char suffixes[][5] = {"", ".com", ".exe"};
+    for (i = 0; i < ARRAYLEN(suffixes); ++i) {
+      stpcpy(end, suffixes[i]);
       if (sys_faccessat_nt(AT_FDCWD, progbuf, X_OK, 0) != -1) {
-        program = progbuf;
+        break;
+      } else if (__imp_GetLastError() == kNtErrorSharingViolation) {
+        return etxtbsy();  // TODO(jart): does this work
       } else {
         return eacces();
       }
     }
+  } else {
+    return enametoolong();
   }
 
-  //////////////////////////////////////////////////////////////////////////////
-  // execve operation is unrecoverable from this point
+  //
+  //                    POINT OF NO RETURN
+  //
+  //
+  //              NO!                          MNO!
+  //             MNO!!         [NBK]          MNNOO!
+  //           MMNO!                           MNNOO!!
+  //         MNOONNOO!   MMMMMMMMMMPPPOII!   MNNO!!!!
+  //         !O! NNO! MMMMMMMMMMMMMPPPOOOII!! NO!
+  //               ! MMMMMMMMMMMMMPPPPOOOOIII! !
+  //                MMMMMMMMMMMMPPPPPOOOOOOII!!
+  //                MMMMMOOOOOOPPPPPPPPOOOOMII!
+  //                MMMMM..    OPPMMP    .,OMI!
+  //                MMMM::   o.,OPMP,.o   ::I!!
+  //                  NNM:::.,,OOPM!P,.::::!!
+  //                 MMNNNNNOOOOPMO!!IIPPO!!O!
+  //                 MMMMMNNNNOO:!!:!!IPPPPOO!
+  //                  MMMMMNNOOMMNNIIIPPPOO!!
+  //                     MMMONNMMNNNIIIOO!
+  //                   MN MOMMMNNNIIIIIO! OO
+  //                  MNO! IiiiiiiiiiiiI OOOO
+  //             NNN.MNO!   O!!!!!!!!!O   OONO NO!
+  //            MNNNNNO!    OOOOOOOOOOO    MMNNON!
+  //              MNNNNO!    PPPPPPPPP    MMNON!
+  //                 OO!                   ON!
+  //
+  //
 
-  if (_weaken(pthread_kill_siblings_np)) {
-    _weaken(pthread_kill_siblings_np)();
+  // kill siblings
+  sys_execve_killer();
+
+  // close win32 handles for memory mappings
+  // unlike fork calling execve destroys all memory
+  // closing a map handle won't impact the mapping itself
+  for (i = 0; i < _mmi.i; ++i) {
+    PurgeHandle(_mmi.p[i].h);
   }
 
-  // close non-stdio and cloexec handles
+  // close o_cloexec fds and anything that isn't stdio
   for (i = 0; i < g_fds.n; ++i) {
     if (g_fds.p[i].kind == kFdEmpty) {
       g_fds.p[i].handle = -1;
@@ -152,12 +184,7 @@ keywords int sys_execve_nt(const char *program, char *const argv[],
     }
   }
 
-  if (_weaken(__klog_handle) &&        //
-      *_weaken(__klog_handle) != 0 &&  //
-      *_weaken(__klog_handle) != -1) {
-    PurgeHandle(*_weaken(__klog_handle));
-  }
-
+  // pass bitmask telling child which fds are sockets
   int bits;
   char buf[32], *v = 0;
   if (_weaken(socket)) {
@@ -169,23 +196,79 @@ keywords int sys_execve_nt(const char *program, char *const argv[],
     FormatInt32(stpcpy(buf, "__STDIO_SOCKETS="), bits);
     v = buf;
   }
-  bzero(&startinfo, sizeof(startinfo));
-  startinfo.cb = sizeof(struct NtStartupInfo);
-  startinfo.dwFlags = kNtStartfUsestdhandles;
-  startinfo.hStdInput = g_fds.p[0].handle;
-  startinfo.hStdOutput = g_fds.p[1].handle;
-  startinfo.hStdError = g_fds.p[2].handle;
 
-  // spawn the process
-  rc = ntspawn(program, argv, envp, v, 0, 0, true, 0, 0, &startinfo, &procinfo);
+  // define stdio handles for the spawned subprocess
+  struct NtStartupInfo si = {
+      .cb = sizeof(struct NtStartupInfo),
+      .dwFlags = kNtStartfUsestdhandles,
+      .hStdInput = g_fds.p[0].handle,
+      .hStdOutput = g_fds.p[1].handle,
+      .hStdError = g_fds.p[2].handle,
+  };
+
+  // launch the process
+  struct NtProcessInformation pi;
+  int rc = ntspawn(program, argv, envp, v, 0, 0, true, 0, 0, &si, &pi);
   if (rc == -1) {
     STRACE("panic: unrecoverable ntspawn(%#s) error: %m", program);
-    __imp_ExitProcess(11);
+    if (__imp_GetLastError() == kNtErrorSharingViolation) {
+      __imp_ExitProcess(SIGVTALRM);  // is ETXTBSY
+    } else {
+      __imp_ExitProcess(127 << 8);
+    }
+  }
+  PurgeHandle(pi.hThread);
+
+  // retreat to original win32-provided stack memory
+  __switch_stacks(pi.hProcess, 0, 0, 0, sys_execve_nt_relay, __oldstack);
+}
+
+// child is in same process group so wait for it to get killed by this
+__msabi static keywords bool32 sys_execve_nt_event(uint32_t dwCtrlType) {
+  return true;  // tell win32 we handled signal
+}
+
+// this function runs on the original tiny stack that windows gave us
+// we need to keep the original process alive simply to pass an int32
+// so we unmap all memory to avoid getting a double whammy after fork
+static keywords void sys_execve_nt_relay(intptr_t h, long b, long c, long d) {
+  uint32_t i, dwExitCode;
+
+  // close more handles
+  __imp_SetConsoleCtrlHandler((void *)sys_execve_nt_event, 1);
+  PurgeThread(g_fds.stdin.thread);  // wasn't inherited by ntspawn
+  PurgeHandle(g_fds.stdin.reader);  // wasn't inherited by ntspawn
+  PurgeHandle(g_fds.stdin.writer);  // wasn't inherited by ntspawn
+  PurgeHandle(g_fds.p[0].handle);   // was inherited via startinfo
+  PurgeHandle(g_fds.p[1].handle);   // was inherited via startinfo
+  PurgeHandle(g_fds.p[2].handle);   // was inherited via startinfo
+  if (_weaken(__klog_handle)) {
+    PurgeHandle(*_weaken(__klog_handle));  // wasn't inherited by ntspawn
   }
 
-  //////////////////////////////////////////////////////////////////////////////
-  // zombify this process which lingers on to relay the status code
+  // free all the memory mmap created
+  for (i = 0; i < _mmi.i; ++i) {
+    __imp_UnmapViewOfFile((void *)((uintptr_t)_mmi.p[i].x << 16));
+  }
 
-  PurgeHandle(procinfo.hThread);
-  __switch_stacks(procinfo.hProcess, 0, 0, 0, sys_execve_nt_relay, __oldstack);
+  // wait for process to terminate
+  //
+  // WaitForSingleObject can return kNtWaitAbandoned which MSDN
+  // describes as a "sort of" successful status which indicates
+  // someone else didn't free a mutex and you should check that
+  // persistent resources haven't been left corrupted. not sure
+  // what those resources would be for process objects, however
+  // this status has actually been observed when waiting on 'em
+  do {
+    if (__imp_WaitForSingleObject(h, -1) == kNtWaitFailed) {
+      notpossible;
+    }
+    if (!__imp_GetExitCodeProcess(h, &dwExitCode)) {
+      notpossible;
+    }
+  } while (dwExitCode == kNtStillActive);
+
+  // propagate child exit status to parent
+  __imp_ExitProcess(dwExitCode);
+  __builtin_unreachable();
 }
diff --git a/libc/calls/g_sighandrvas.c b/libc/calls/g_sighandrvas.c
index deb3e93de..5147cf61c 100644
--- a/libc/calls/g_sighandrvas.c
+++ b/libc/calls/g_sighandrvas.c
@@ -19,5 +19,5 @@
 #include "libc/calls/state.internal.h"
 #include "libc/thread/thread.h"
 
-unsigned __sighandrvas[NSIG];
-unsigned __sighandflags[NSIG];
+unsigned __sighandrvas[NSIG + 1];
+unsigned __sighandflags[NSIG + 1];
diff --git a/libc/stdio/getrandom.c b/libc/calls/getrandom.c
similarity index 100%
rename from libc/stdio/getrandom.c
rename to libc/calls/getrandom.c
diff --git a/libc/calls/ioctl.c b/libc/calls/ioctl.c
index 47ee0aa27..7592a093c 100644
--- a/libc/calls/ioctl.c
+++ b/libc/calls/ioctl.c
@@ -641,6 +641,7 @@ static int ioctl_siocgifflags(int fd, void *arg) {
  * - `FIONBIO` isn't polyfilled; use `fcntl(F_SETFL, O_NONBLOCK)`
  * - `FIOCLEX` isn't polyfilled; use `fcntl(F_SETFD, FD_CLOEXEC)`
  * - `FIONCLEX` isn't polyfilled; use `fcntl(F_SETFD, 0)`
+ * - `TIOCSCTTY` isn't polyfilled; use `login_tty()`
  * - `TCGETS` isn't polyfilled; use tcgetattr()
  * - `TCSETS` isn't polyfilled; use tcsetattr()
  * - `TCSETSW` isn't polyfilled; use tcsetattr()
diff --git a/libc/calls/ktmppath.c b/libc/calls/ktmppath.c
index 733e1dde2..176ae681a 100644
--- a/libc/calls/ktmppath.c
+++ b/libc/calls/ktmppath.c
@@ -29,12 +29,12 @@
  *
  * The order of precedence is:
  *
- *   - $TMPDIR/
- *   - GetTempPath()
- *   - /tmp/
+ *   - $TMPDIR/ is always favored if defined
+ *   - GetTempPath(), for the New Technology
+ *   - /tmp/ to make security scene go crazy
  *
- * This guarantees trailing slash.
- * We also guarantee `kTmpPath` won't be longer than `PATH_MAX / 2`.
+ * This guarantees an absolute path with a trailing slash. We also
+ * ensure `kTmpPath` isn't longer than `PATH_MAX-NAME_MAX`.
  */
 char kTmpPath[PATH_MAX];
 
@@ -48,15 +48,20 @@ __attribute__((__constructor__)) static void kTmpPathInit(void) {
   uint32_t n;
   char16_t path16[PATH_MAX];
 
-  if ((s = getenv("TMPDIR")) && (n = strlen(s)) < PATH_MAX / 2) {
-    if (n) memcpy(kTmpPath, s, n);
-    if (n && kTmpPath[n - 1] != '/') {
-      kTmpPath[n + 0] = '/';
-      kTmpPath[n + 1] = 0;
+  if ((s = getenv("TMPDIR"))) {
+    if (*s != '/') {
+      if (!getcwd(kTmpPath, PATH_MAX)) {
+        goto GiveUp;
+      }
+      strlcat(kTmpPath, "/", sizeof(kTmpPath));
+    }
+    strlcat(kTmpPath, s, sizeof(kTmpPath));
+    if (strlcat(kTmpPath, "/", sizeof(kTmpPath)) < PATH_MAX - NAME_MAX) {
+      return;
     }
-    return;
   }
 
+GiveUp:
   if (IsWindows() &&
       ((n = GetTempPath(ARRAYLEN(path16), path16)) && n < ARRAYLEN(path16))) {
     // turn c:\foo\bar\ into c:/foo/bar/
diff --git a/libc/calls/ntspawn.c b/libc/calls/ntspawn.c
index b9b4654de..a7ddee742 100644
--- a/libc/calls/ntspawn.c
+++ b/libc/calls/ntspawn.c
@@ -17,18 +17,22 @@
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/calls/ntspawn.h"
+#include "libc/assert.h"
 #include "libc/calls/syscall_support-nt.internal.h"
+#include "libc/errno.h"
 #include "libc/intrin/pushpop.internal.h"
 #include "libc/macros.internal.h"
 #include "libc/nt/enum/filemapflags.h"
 #include "libc/nt/enum/pageflags.h"
 #include "libc/nt/enum/processcreationflags.h"
+#include "libc/nt/errors.h"
 #include "libc/nt/memory.h"
 #include "libc/nt/process.h"
 #include "libc/nt/runtime.h"
 #include "libc/nt/struct/processinformation.h"
 #include "libc/nt/struct/securityattributes.h"
 #include "libc/nt/struct/startupinfo.h"
+#include "libc/sysv/errfuns.h"
 
 struct SpawnBlock {
   union {
@@ -95,6 +99,8 @@ textwindows int ntspawn(
                     block->envvars, opt_lpCurrentDirectory, lpStartupInfo,
                     opt_out_lpProcessInformation)) {
     rc = 0;
+  } else if (GetLastError() == kNtErrorSharingViolation) {
+    etxtbsy();
   }
   if (block) UnmapViewOfFile(block);
   if (handle) CloseHandle(handle);
diff --git a/libc/stdio/rdrand.c b/libc/calls/rdrand.c
similarity index 100%
rename from libc/stdio/rdrand.c
rename to libc/calls/rdrand.c
diff --git a/libc/stdio/rdrand_init.c b/libc/calls/rdrand_init.c
similarity index 100%
rename from libc/stdio/rdrand_init.c
rename to libc/calls/rdrand_init.c
diff --git a/libc/calls/setpgid.c b/libc/calls/setpgid.c
index b01395de9..5a5c6b271 100644
--- a/libc/calls/setpgid.c
+++ b/libc/calls/setpgid.c
@@ -26,6 +26,10 @@
 
 /**
  * Changes process group for process.
+ *
+ * @param pid is process id (may be zero for current process)
+ * @param pgid is process group id (may be zero for current process)
+ * @return 0 on success, or -1 w/ errno
  * @vforksafe
  */
 int setpgid(int pid, int pgid) {
@@ -35,16 +39,14 @@ int setpgid(int pid, int pgid) {
   } else {
     me = getpid();
     if ((!pid || pid == me) && (!pgid || pgid == me)) {
-      /*
-       * "When a process is created with CREATE_NEW_PROCESS_GROUP
-       *  specified, an implicit call to SetConsoleCtrlHandler(NULL,TRUE)
-       *  is made on behalf of the new process; this means that the new
-       *  process has CTRL+C disabled. This lets shells handle CTRL+C
-       *  themselves, and selectively pass that signal on to
-       *  sub-processes. CTRL+BREAK is not disabled, and may be used to
-       *  interrupt the process/process group."
-       *                           ──Quoth MSDN § CreateProcessW()
-       */
+      // "When a process is created with kNtCreateNewProcessGroup
+      //  specified, an implicit call to SetConsoleCtrlHandler(NULL,TRUE)
+      //  is made on behalf of the new process; this means that the new
+      //  process has CTRL+C disabled. This lets shells handle CTRL+C
+      //  themselves, and selectively pass that signal on to
+      //  sub-processes. CTRL+BREAK is not disabled, and may be used to
+      //  interrupt the process/process group."
+      //                           ──Quoth MSDN § CreateProcessW()
       if (SetConsoleCtrlHandler(0, 1)) {
         rc = 0;
       } else {
diff --git a/libc/calls/setsid.c b/libc/calls/setsid.c
index 876eab85c..9bb2ace64 100644
--- a/libc/calls/setsid.c
+++ b/libc/calls/setsid.c
@@ -23,14 +23,16 @@
 
 /**
  * Creates session and sets the process group id.
+ *
  * @return new session id, or -1 w/ errno
+ * @raise EPERM if already the leader
  */
 int setsid(void) {
   int rc;
   if (!IsWindows() && !IsMetal()) {
     rc = sys_setsid();
   } else {
-    rc = 0;
+    rc = getpid();
   }
   STRACE("setsid() → %d% m", rc);
   return rc;
diff --git a/libc/calls/sigaltstack.c b/libc/calls/sigaltstack.c
index 74913b80b..c593fbccb 100644
--- a/libc/calls/sigaltstack.c
+++ b/libc/calls/sigaltstack.c
@@ -59,21 +59,14 @@ static void sigaltstack2linux(struct sigaltstack *linux,
  *     struct sigaction sa;
  *     struct sigaltstack ss;
  *     ss.ss_flags = 0;
+ *     ss.ss_sp = NewCosmoStack();
  *     ss.ss_size = GetStackSize();
- *     ss.ss_sp = mmap(0, GetStackSize(), PROT_READ | PROT_WRITE,
- *                     MAP_STACK | MAP_ANONYMOUS, -1, 0);
+ *     sigaltstack(&ss, 0);
+ *     sigemptyset(&sa.ss_mask);
  *     sa.sa_flags = SA_ONSTACK;
  *     sa.sa_handler = OnStackOverflow;
- *     __cxa_atexit(free, ss[0].ss_sp, 0);
- *     sigemptyset(&sa.ss_mask);
- *     sigaltstack(&ss, 0);
  *     sigaction(SIGSEGV, &sa, 0);
  *
- * It's strongly recommended that you allocate a stack with the same
- * size as GetStackSize() and that it have GetStackSize() alignment.
- * Otherwise some of your runtime support code (e.g. ftrace stack use
- * logging, kprintf() memory safety) won't be able to work as well.
- *
  * @param neu if non-null will install new signal alt stack
  * @param old if non-null will receive current signal alt stack
  * @return 0 on success, or -1 w/ errno
@@ -85,9 +78,8 @@ int sigaltstack(const struct sigaltstack *neu, struct sigaltstack *old) {
   void *b;
   const void *a;
   struct sigaltstack_bsd bsd;
-  if (IsAsan() && ((old && __asan_check(old, sizeof(*old)).kind) ||
-                   (neu && (__asan_check(neu, sizeof(*neu)).kind ||
-                            __asan_check(neu->ss_sp, neu->ss_size).kind)))) {
+  if (IsAsan() && ((old && !__asan_is_valid(old, sizeof(*old))) ||
+                   (neu && !__asan_is_valid(neu, sizeof(*neu))))) {
     rc = efault();
   } else if (neu && neu->ss_size < MINSIGSTKSZ) {
     rc = enomem();
diff --git a/libc/calls/sigenter-freebsd.c b/libc/calls/sigenter-freebsd.c
index 1e0ff1f33..d57336803 100644
--- a/libc/calls/sigenter-freebsd.c
+++ b/libc/calls/sigenter-freebsd.c
@@ -41,9 +41,9 @@ privileged void __sigenter_freebsd(int sig, struct siginfo_freebsd *freebsdinfo,
     ucontext_t uc;
     siginfo_t si;
   } g;
-  rva = __sighandrvas[sig & (NSIG - 1)];
+  rva = __sighandrvas[sig];
   if (rva >= kSigactionMinRva) {
-    flags = __sighandflags[sig & (NSIG - 1)];
+    flags = __sighandflags[sig];
     if (~flags & SA_SIGINFO) {
       ((sigaction_f)(__executable_start + rva))(sig, 0, 0);
     } else {
diff --git a/libc/calls/sigenter-linux.c b/libc/calls/sigenter-linux.c
index ff735e153..19aaad697 100644
--- a/libc/calls/sigenter-linux.c
+++ b/libc/calls/sigenter-linux.c
@@ -33,9 +33,9 @@
 
 privileged void __sigenter_wsl(int sig, struct siginfo *info, ucontext_t *ctx) {
   int i, rva, flags;
-  rva = __sighandrvas[sig & (NSIG - 1)];
+  rva = __sighandrvas[sig];
   if (rva >= kSigactionMinRva) {
-    flags = __sighandflags[sig & (NSIG - 1)];
+    flags = __sighandflags[sig];
     // WSL1 doesn't set the fpregs field.
     // https://github.com/microsoft/WSL/issues/2555
     if ((flags & SA_SIGINFO) && UNLIKELY(!ctx->uc_mcontext.fpregs)) {
diff --git a/libc/calls/sigenter-netbsd.c b/libc/calls/sigenter-netbsd.c
index b52f19e95..c8f004596 100644
--- a/libc/calls/sigenter-netbsd.c
+++ b/libc/calls/sigenter-netbsd.c
@@ -39,9 +39,9 @@ privileged void __sigenter_netbsd(int sig, struct siginfo_netbsd *si,
   int rva, flags;
   ucontext_t uc;
   struct siginfo si2;
-  rva = __sighandrvas[sig & (NSIG - 1)];
+  rva = __sighandrvas[sig];
   if (rva >= kSigactionMinRva) {
-    flags = __sighandflags[sig & (NSIG - 1)];
+    flags = __sighandflags[sig];
     if (~flags & SA_SIGINFO) {
       ((sigaction_f)(__executable_start + rva))(sig, 0, 0);
     } else {
diff --git a/libc/calls/sigenter-openbsd.c b/libc/calls/sigenter-openbsd.c
index 6e0318919..8bff18906 100644
--- a/libc/calls/sigenter-openbsd.c
+++ b/libc/calls/sigenter-openbsd.c
@@ -41,9 +41,9 @@ privileged void __sigenter_openbsd(int sig, struct siginfo_openbsd *openbsdinfo,
     ucontext_t uc;
     struct siginfo si;
   } g;
-  rva = __sighandrvas[sig & (NSIG - 1)];
+  rva = __sighandrvas[sig];
   if (rva >= kSigactionMinRva) {
-    flags = __sighandflags[sig & (NSIG - 1)];
+    flags = __sighandflags[sig];
     if (~flags & SA_SIGINFO) {
       ((sigaction_f)(__executable_start + rva))(sig, 0, 0);
     } else {
diff --git a/libc/calls/sigenter-xnu.c b/libc/calls/sigenter-xnu.c
index b70fc4112..d557a3f07 100644
--- a/libc/calls/sigenter-xnu.c
+++ b/libc/calls/sigenter-xnu.c
@@ -493,9 +493,9 @@ privileged void __sigenter_xnu(void *fn, int infostyle, int sig,
     ucontext_t uc;
     siginfo_t si;
   } g;
-  rva = __sighandrvas[sig & (NSIG - 1)];
+  rva = __sighandrvas[sig];
   if (rva >= kSigactionMinRva) {
-    flags = __sighandflags[sig & (NSIG - 1)];
+    flags = __sighandflags[sig];
     if (~flags & SA_SIGINFO) {
       ((sigaction_f)(__executable_start + rva))(sig, 0, 0);
     } else {
diff --git a/libc/calls/state.internal.h b/libc/calls/state.internal.h
index 7616c1e85..a7d0dadda 100644
--- a/libc/calls/state.internal.h
+++ b/libc/calls/state.internal.h
@@ -8,10 +8,10 @@ COSMOPOLITAN_C_START_
 
 extern int __vforked;
 extern bool __time_critical;
-extern unsigned __sighandrvas[NSIG];
-extern unsigned __sighandflags[NSIG];
 extern pthread_mutex_t __fds_lock_obj;
 extern pthread_mutex_t __sig_lock_obj;
+extern unsigned __sighandrvas[NSIG + 1];
+extern unsigned __sighandflags[NSIG + 1];
 extern const struct NtSecurityAttributes kNtIsInheritable;
 
 void __fds_lock(void);
diff --git a/net/https/getsslcachefile.c b/libc/calls/tcsetsid.c
similarity index 62%
rename from net/https/getsslcachefile.c
rename to libc/calls/tcsetsid.c
index 988aea8ee..c9d981952 100644
--- a/net/https/getsslcachefile.c
+++ b/libc/calls/tcsetsid.c
@@ -1,7 +1,7 @@
 /*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
 │vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8                                :vi│
 ╞══════════════════════════════════════════════════════════════════════════════╡
-│ Copyright 2021 Justine Alexandra Roberts Tunney                              │
+│ Copyright 2023 Justine Alexandra Roberts Tunney                              │
 │                                                                              │
 │ Permission to use, copy, modify, and/or distribute this software for         │
 │ any purpose with or without fee is hereby granted, provided that the         │
@@ -16,24 +16,37 @@
 │ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
-#include "libc/fmt/fmt.h"
-#include "libc/intrin/safemacros.internal.h"
-#include "libc/limits.h"
-#include "libc/macros.internal.h"
-#include "libc/runtime/runtime.h"
-#include "net/https/sslcache.h"
+#include "libc/calls/calls.h"
+#include "libc/calls/internal.h"
+#include "libc/calls/syscall-sysv.internal.h"
+#include "libc/dce.h"
+#include "libc/intrin/strace.internal.h"
+#include "libc/sysv/consts/termios.h"
+#include "libc/sysv/errfuns.h"
 
 /**
- * Returns recommended path argument for CreateSslCache().
- * @return pointer to static memory
+ * Associates session with controlling tty.
+ *
+ * @return 0 on success, or -1 w/ errno
+ * @raise EBADF if `fd` isn't an open file descriptor
+ * @raise ENOTTY if `fd` is isn't controlling teletypewriter
+ * @raise EINVAL if `pid` isn't session id associated with this process
+ * @raise EPERM if calling process isn't the session leader
+ * @raise ENOSYS on Windows and Bare Metal
  */
-char *GetSslCacheFile(void) {
-  static char sslcachefile[PATH_MAX];
-  if (snprintf(sslcachefile, sizeof(sslcachefile), "%s/%s.sslcache",
-               firstnonnull(getenv("TMPDIR"), "/tmp"),
-               getenv("USER")) < ARRAYLEN(sslcachefile)) {
-    return sslcachefile;
+int tcsetsid(int fd, int pid) {
+  int rc;
+  if (fd < 0) {
+    rc = ebadf();
+  } else if (IsWindows() || IsMetal()) {
+    rc = enosys();
+  } else if (pid != sys_getsid(0)) {
+    rc = einval();
+  } else if (fd < g_fds.n && g_fds.p[fd].kind == kFdZip) {
+    rc = enotty();
   } else {
-    return 0;
+    rc = sys_ioctl(fd, TIOCSCTTY, 0);
   }
+  STRACE("tcsetsid(%d, %d) → %d% m", fd, pid, rc);
+  return rc;
 }
diff --git a/libc/calls/termios.h b/libc/calls/termios.h
index 37cfab2e4..9586bf09e 100644
--- a/libc/calls/termios.h
+++ b/libc/calls/termios.h
@@ -28,6 +28,7 @@ int tcgetsid(int);
 int tcgetpgrp(int);
 int tcflow(int, int);
 int tcflush(int, int);
+int tcsetsid(int, int);
 int tcsetpgrp(int, int);
 int tcsendbreak(int, int);
 void cfmakeraw(struct termios *);
diff --git a/libc/calls/tmpfd.c b/libc/calls/tmpfd.c
index af2fa5443..657d36e7c 100644
--- a/libc/calls/tmpfd.c
+++ b/libc/calls/tmpfd.c
@@ -45,7 +45,7 @@ int _mkstemp(char *, int);
  * This creates a secure temporary file inside $TMPDIR. If it isn't
  * defined, then /tmp is used on UNIX and GetTempPath() is used on the
  * New Technology. This resolution of $TMPDIR happens once in a ctor,
- * which is copied to the `kTmpDir` global.
+ * which is copied to the `kTmpPath` global.
  *
  * Once close() is called, the returned file is guaranteed to be deleted
  * automatically. On UNIX the file is unlink()'d before this function
diff --git a/libc/calls/wait4-nt.c b/libc/calls/wait4-nt.c
index a08047bf4..cd5d9080a 100644
--- a/libc/calls/wait4-nt.c
+++ b/libc/calls/wait4-nt.c
@@ -118,6 +118,8 @@ static textwindows int sys_wait4_nt_impl(int *pid, int *opt_out_wstatus,
       return echild();
     }
   }
+
+  // wait for one of the processes to terminate
   dwExitCode = kNtStillActive;
   if (options & WNOHANG) {
     i = WaitForMultipleObjects(count, handles, false, 0);
@@ -132,12 +134,20 @@ static textwindows int sys_wait4_nt_impl(int *pid, int *opt_out_wstatus,
     }
   }
   if (i == kNtWaitFailed) {
-    STRACE("%s failed %u", "WaitForMultipleObjects", GetLastError());
-    return __winerr();
+    notpossible;
   }
+
+  // WaitForMultipleObjects can say kNtWaitAbandoned which MSDN
+  // describes as a "sort of" successful status which indicates
+  // someone else didn't free a mutex and you should check that
+  // persistent resources haven't been left corrupted. not sure
+  // what those resources would be for process objects, however
+  // this status has actually been observed when waiting on 'em
+  i &= ~kNtWaitAbandoned;
+
+  // this is where things get especially hairy. see exit() doc
   if (!GetExitCodeProcess(handles[i], &dwExitCode)) {
-    STRACE("%s failed %u", "GetExitCodeProcess", GetLastError());
-    return __winerr();
+    notpossible;
   }
   if (dwExitCode == kNtStillActive) {
     return -2;
@@ -145,6 +155,8 @@ static textwindows int sys_wait4_nt_impl(int *pid, int *opt_out_wstatus,
   if (dwExitCode == 0xc9af3d51u) {
     dwExitCode = kNtStillActive;
   }
+
+  // now pass along the result
   if (opt_out_wstatus) {
     *opt_out_wstatus = dwExitCode;
   }
diff --git a/libc/calls/wincrash.c b/libc/calls/wincrash.c
index 75a4a954e..9f1036e46 100644
--- a/libc/calls/wincrash.c
+++ b/libc/calls/wincrash.c
@@ -19,44 +19,22 @@
 #include "libc/calls/internal.h"
 #include "libc/calls/sig.internal.h"
 #include "libc/calls/state.internal.h"
-#include "libc/calls/struct/ucontext.internal.h"
-#include "libc/calls/ucontext.h"
 #include "libc/intrin/describebacktrace.internal.h"
 #include "libc/intrin/strace.internal.h"
 #include "libc/nt/enum/exceptionhandleractions.h"
 #include "libc/nt/enum/signal.h"
 #include "libc/nt/enum/status.h"
-#include "libc/nt/runtime.h"
 #include "libc/nt/struct/ntexceptionpointers.h"
-#include "libc/str/str.h"
+#include "libc/nt/thunk/msabi.h"
 #include "libc/sysv/consts/sa.h"
 #include "libc/sysv/consts/sicode.h"
 #include "libc/sysv/consts/sig.h"
-#include "libc/thread/tls.h"
-#include "libc/thread/tls2.internal.h"
 
 #ifdef __x86_64__
 
 // win32 calls this; we're running inside the thread that crashed
 __msabi unsigned __wincrash(struct NtExceptionPointers *ep) {
   int sig, code;
-  struct CosmoTib *tib;
-  static bool noreentry;
-  noreentry = true;
-
-  if ((tib = __tls_enabled ? __get_tls() : 0)) {
-    if (~tib->tib_flags & TIB_FLAG_WINCRASHING) {
-      tib->tib_flags |= TIB_FLAG_WINCRASHING;
-    } else {
-      ExitProcess(SIGSEGV);
-    }
-  } else {
-    if (!noreentry) {
-      noreentry = true;
-    } else {
-      ExitProcess(SIGSEGV);
-    }
-  }
 
   switch (ep->ExceptionRecord->ExceptionCode) {
     case kNtSignalBreakpoint:
@@ -133,7 +111,8 @@ __msabi unsigned __wincrash(struct NtExceptionPointers *ep) {
       break;
   }
 
-  STRACE("wincrash %G rip %x bt %s", sig, ep->ContextRecord->Rip,
+  STRACE("win32 vectored exception raising 0x%08Xu %G rip %x bt %s",
+         ep->ExceptionRecord->ExceptionCode, sig, ep->ContextRecord->Rip,
          DescribeBacktrace((struct StackFrame *)ep->ContextRecord->Rbp));
 
   if (__sighandflags[sig] & SA_SIGINFO) {
@@ -143,11 +122,6 @@ __msabi unsigned __wincrash(struct NtExceptionPointers *ep) {
     __sig_handle(kSigOpUnmaskable, sig, code, 0);
   }
 
-  noreentry = false;
-  if (tib) {
-    tib->tib_flags &= ~TIB_FLAG_WINCRASHING;
-  }
-
   return kNtExceptionContinueExecution;
 }
 
diff --git a/libc/calls/winstdin1.c b/libc/calls/winstdin1.c
index b0d569a5a..0894737b6 100644
--- a/libc/calls/winstdin1.c
+++ b/libc/calls/winstdin1.c
@@ -128,6 +128,7 @@ textwindows static char16_t *CreateStdinPipeName(char16_t *a, int64_t h) {
 // this makes it possible for our read() implementation to periodically
 // poll for signals while performing a blocking overlapped io operation
 textwindows void WinMainStdin(void) {
+  uint32_t conmode;
   char16_t pipename[64];
   int64_t hStdin, hWriter, hReader, hThread, hSemaphore;
   if (!SupportsWindows()) return;
@@ -137,6 +138,10 @@ textwindows void WinMainStdin(void) {
     Log("<stdin> GetStdHandle failed\n");
     return;
   }
+  if (!__imp_GetConsoleMode(hStdin, &conmode)) {
+    Log("<stdin> stdin not a console\n");
+    return;
+  }
   CreateStdinPipeName(pipename, hStdin);
   hReader = __imp_CreateFileW(pipename, kNtGenericRead, 0, 0, kNtOpenExisting,
                               kNtFileFlagOverlapped, 0);
diff --git a/libc/intrin/asan.c b/libc/intrin/asan.c
index 53f38d835..c397612d8 100644
--- a/libc/intrin/asan.c
+++ b/libc/intrin/asan.c
@@ -17,8 +17,11 @@
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/calls/state.internal.h"
+#include "libc/calls/struct/rlimit.h"
+#include "libc/calls/struct/rlimit.internal.h"
 #include "libc/calls/syscall-sysv.internal.h"
 #include "libc/dce.h"
+#include "libc/errno.h"
 #include "libc/intrin/asan.internal.h"
 #include "libc/intrin/atomic.h"
 #include "libc/intrin/bits.h"
@@ -40,6 +43,7 @@
 #include "libc/nt/enum/version.h"
 #include "libc/runtime/memtrack.internal.h"
 #include "libc/runtime/runtime.h"
+#include "libc/runtime/stack.h"
 #include "libc/runtime/symbols.internal.h"
 #include "libc/stdckdint.h"
 #include "libc/str/str.h"
@@ -47,6 +51,8 @@
 #include "libc/sysv/consts/auxv.h"
 #include "libc/sysv/consts/map.h"
 #include "libc/sysv/consts/prot.h"
+#include "libc/sysv/consts/rlim.h"
+#include "libc/sysv/consts/rlimit.h"
 #include "libc/sysv/errfuns.h"
 #include "libc/thread/tls.h"
 #include "third_party/dlmalloc/dlmalloc.h"
@@ -910,7 +916,7 @@ static __wur __asan_die_f *__asan_report(const void *addr, int size,
   *p = 0;
   kprintf("%s", buf);
   __asan_report_memory_origin(addr, size, kind);
-  kprintf("\nthe crash was caused by\n");
+  kprintf("\nthe crash was caused by %s\n", program_invocation_name);
   ftrace_enabled(+1);
   return __asan_die();
 }
@@ -1428,32 +1434,6 @@ static size_t __asan_strlen(const char *s) {
   return i;
 }
 
-static textstartup void __asan_shadow_string(char *s) {
-  __asan_map_shadow((intptr_t)s, __asan_strlen(s) + 1);
-}
-
-static textstartup void __asan_shadow_auxv(intptr_t *auxv) {
-  size_t i;
-  for (i = 0; auxv[i]; i += 2) {
-    if (_weaken(AT_RANDOM) && auxv[i] == *_weaken(AT_RANDOM)) {
-      __asan_map_shadow(auxv[i + 1], 16);
-    } else if (_weaken(AT_EXECFN) && auxv[i] == *_weaken(AT_EXECFN)) {
-      __asan_shadow_string((char *)auxv[i + 1]);
-    } else if (_weaken(AT_PLATFORM) && auxv[i] == *_weaken(AT_PLATFORM)) {
-      __asan_shadow_string((char *)auxv[i + 1]);
-    }
-  }
-  __asan_map_shadow((uintptr_t)auxv, (i + 2) * sizeof(intptr_t));
-}
-
-static textstartup void __asan_shadow_string_list(char **list) {
-  size_t i;
-  for (i = 0; list[i]; ++i) {
-    __asan_shadow_string(list[i]);
-  }
-  __asan_map_shadow((uintptr_t)list, (i + 1) * sizeof(char *));
-}
-
 static textstartup void __asan_shadow_mapping(struct MemoryIntervals *m,
                                               size_t i) {
   uintptr_t x, y;
@@ -1465,18 +1445,94 @@ static textstartup void __asan_shadow_mapping(struct MemoryIntervals *m,
   }
 }
 
-static textstartup void __asan_shadow_existing_mappings(void) {
+static textstartup char *__asan_get_last_string(char **list) {
+  char *res = 0;
+  for (int i = 0; list[i]; ++i) {
+    res = list[i];
+  }
+  return res;
+}
+
+static textstartup uintptr_t __asan_get_stack_top(int argc, char **argv,
+                                                  char **envp,
+                                                  unsigned long *auxv,
+                                                  long pagesz) {
+  uintptr_t top;
+  const char *s;
+  if ((s = __asan_get_last_string(envp)) ||
+      (s = __asan_get_last_string(argv))) {
+    top = (uintptr_t)s + __asan_strlen(s);
+  } else {
+    unsigned long *xp = auxv;
+    while (*xp) xp += 2;
+    top = (uintptr_t)xp;
+  }
+  return (top + (pagesz - 1)) & -pagesz;
+}
+
+static textstartup void __asan_shadow_existing_mappings(int argc, char **argv,
+                                                        char **envp,
+                                                        unsigned long *auxv) {
   __asan_shadow_mapping(&_mmi, 0);
-  __asan_map_shadow(GetStackAddr(), GetStackSize());
-  __asan_poison((void *)GetStackAddr(), getauxval(AT_PAGESZ),
-                kAsanStackOverflow);
+
+  // WinMain() maps its own stack and its shadow too
+  if (IsWindows()) {
+    return;
+  }
+
+  // get microprocessor page size
+  long pagesz = 4096;
+  for (int i = 0; auxv[i]; i += 2) {
+    if (auxv[i] == AT_PAGESZ) {
+      pagesz = auxv[i + 1];
+    }
+  }
+
+  // get configured stack size of main thread
+  // supported platforms use defaults ranging from 4mb to 512mb
+  struct rlimit rlim;
+  uintptr_t stack_size = 4 * 1024 * 1024;
+  if (!sys_getrlimit(RLIMIT_STACK, &rlim) &&  //
+      rlim.rlim_cur > 0 && rlim.rlim_cur < RLIM_INFINITY) {
+    stack_size = (rlim.rlim_cur + (pagesz - 1)) & -pagesz;
+  }
+
+  // Every UNIX system in our support vector creates arg blocks like:
+  //
+  //     <HIGHEST-STACK-ADDRESS>
+  //     last environ string
+  //     ...
+  //     first environ string
+  //     ...
+  //     auxiliary value pointers
+  //     environ pointers
+  //     argument pointers
+  //     argument count
+  //     --- %rsp _start()
+  //     ...
+  //     ...
+  //     ... program's stack
+  //     ...
+  //     ...
+  //     <LOWEST-STACK-ADDRESS>
+  //
+  // The region of memory between highest and lowest can be computed
+  // across all supported platforms ±1 page accuracy as the distance
+  // between the last character of the last environ variable rounded
+  // up to the microprocessor page size (this computes the top addr)
+  // and the bottom is computed by subtracting RLIMIT_STACK rlim_cur
+  // It's simple but gets tricky if we consider environ can be empty
+  uintptr_t stack_top = __asan_get_stack_top(argc, argv, envp, auxv, pagesz);
+  uintptr_t stack_bot = stack_top - stack_size;
+  __asan_map_shadow(stack_bot, stack_top - stack_bot);
+  __asan_poison((void *)stack_bot, GetGuardSize(), kAsanStackOverflow);
 }
 
 forceinline ssize_t __write_str(const char *s) {
   return sys_write(2, s, __asan_strlen(s));
 }
 
-void __asan_init(int argc, char **argv, char **envp, intptr_t *auxv) {
+void __asan_init(int argc, char **argv, char **envp, unsigned long *auxv) {
   static bool once;
   if (!_cmpxchg(&once, false, true)) return;
   if (IsWindows() && NtGetVersion() < kNtVersionWindows10) {
@@ -1493,16 +1549,13 @@ void __asan_init(int argc, char **argv, char **envp, intptr_t *auxv) {
     REQUIRE(dlmemalign);
     REQUIRE(dlmalloc_usable_size);
   }
-  __asan_shadow_existing_mappings();
+  __asan_shadow_existing_mappings(argc, argv, envp, auxv);
   __asan_map_shadow((uintptr_t)__executable_start, _end - __executable_start);
   __asan_map_shadow(0, 4096);
   __asan_poison((void *)__veil("r", 0L), getauxval(AT_PAGESZ), kAsanNullPage);
   if (!IsWindows()) {
     sys_mprotect((void *)0x7fff8000, 0x10000, PROT_READ);
   }
-  __asan_shadow_string_list(argv);
-  __asan_shadow_string_list(envp);
-  __asan_shadow_auxv(auxv);
   __asan_install_malloc_hooks();
   STRACE("    _    ____    _    _   _ ");
   STRACE("   / \\  / ___|  / \\  | \\ | |");
diff --git a/libc/intrin/describebacktrace.c b/libc/intrin/describebacktrace.c
index f3b3ee6b1..444b48a39 100644
--- a/libc/intrin/describebacktrace.c
+++ b/libc/intrin/describebacktrace.c
@@ -18,22 +18,30 @@
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/intrin/describebacktrace.internal.h"
 #include "libc/intrin/kprintf.h"
+#include "libc/log/libfatal.internal.h"
 #include "libc/nexgen32e/stackframe.h"
 
-#define N 64
+#define N 100
 
 #define append(...) o += ksnprintf(buf + o, N - o, __VA_ARGS__)
 
-const char *(DescribeBacktrace)(char buf[N], struct StackFrame *fr) {
-  int o = 0;
+dontinstrument dontasan const char *(DescribeBacktrace)(char buf[N],
+                                                        struct StackFrame *fr) {
   bool gotsome = false;
+  char *p = buf;
+  char *pe = p + N;
   while (fr) {
     if (gotsome) {
-      append(" ");
+      if (p + 1 < pe) {
+        *p++ = ' ';
+        *p = 0;
+      }
     } else {
       gotsome = true;
     }
-    append("%x", fr->addr);
+    if (p + 17 <= pe) {
+      p = __hexcpy(p, fr->addr);
+    }
     fr = fr->next;
   }
   return buf;
diff --git a/libc/intrin/describebacktrace.internal.h b/libc/intrin/describebacktrace.internal.h
index 8682d4719..b2f1fafba 100644
--- a/libc/intrin/describebacktrace.internal.h
+++ b/libc/intrin/describebacktrace.internal.h
@@ -5,8 +5,8 @@
 #if !(__ASSEMBLER__ + __LINKER__ + 0)
 COSMOPOLITAN_C_START_
 
-const char *DescribeBacktrace(char[64], struct StackFrame *);
-#define DescribeBacktrace(x) DescribeBacktrace(alloca(64), x)
+const char *DescribeBacktrace(char[100], struct StackFrame *);
+#define DescribeBacktrace(x) DescribeBacktrace(alloca(100), x)
 
 COSMOPOLITAN_C_END_
 #endif /* !(__ASSEMBLER__ + __LINKER__ + 0) */
diff --git a/libc/intrin/extend.c b/libc/intrin/extend.c
index 2687279af..ac3e4a635 100644
--- a/libc/intrin/extend.c
+++ b/libc/intrin/extend.c
@@ -22,7 +22,9 @@
 #include "libc/errno.h"
 #include "libc/intrin/asan.internal.h"
 #include "libc/intrin/asancodes.h"
+#include "libc/intrin/describebacktrace.internal.h"
 #include "libc/intrin/directmap.internal.h"
+#include "libc/log/libfatal.internal.h"
 #include "libc/macros.internal.h"
 #include "libc/runtime/memtrack.internal.h"
 #include "libc/sysv/consts/map.h"
@@ -30,7 +32,7 @@
 
 #define G FRAMESIZE
 
-static void *_mapframe(void *p, int f) {
+static dontasan void *_mapframe(void *p, int f) {
   int rc, prot, flags;
   struct DirectMap dm;
   prot = PROT_READ | PROT_WRITE;
diff --git a/libc/intrin/getpid.c b/libc/intrin/getpid.c
index 94b0fb4f1..128a173bd 100644
--- a/libc/intrin/getpid.c
+++ b/libc/intrin/getpid.c
@@ -41,7 +41,7 @@
  * @threadsafe
  * @vforksafe
  */
-int getpid(void) {
+dontasan int getpid(void) {
   int rc;
   if (IsMetal()) {
     rc = 1;
diff --git a/libc/intrin/kmalloc.c b/libc/intrin/kmalloc.c
index 16d826255..1f2202bcc 100644
--- a/libc/intrin/kmalloc.c
+++ b/libc/intrin/kmalloc.c
@@ -19,10 +19,13 @@
 #include "libc/intrin/kmalloc.h"
 #include "libc/assert.h"
 #include "libc/atomic.h"
+#include "libc/calls/syscall-sysv.internal.h"
 #include "libc/dce.h"
 #include "libc/intrin/asan.internal.h"
 #include "libc/intrin/atomic.h"
+#include "libc/intrin/describebacktrace.internal.h"
 #include "libc/intrin/extend.internal.h"
+#include "libc/log/libfatal.internal.h"
 #include "libc/macros.internal.h"
 #include "libc/runtime/memtrack.internal.h"
 #include "libc/sysv/consts/map.h"
@@ -63,7 +66,7 @@ void __kmalloc_unlock(void) {
  * @return zero-initialized memory on success, or null w/ errno
  * @raise ENOMEM if we require more vespene gas
  */
-void *kmalloc(size_t size) {
+dontasan void *kmalloc(size_t size) {
   char *p, *e;
   size_t i, n, t;
   n = ROUNDUP(size + (IsAsan() * 8), KMALLOC_ALIGN);
diff --git a/libc/intrin/kprintf.greg.c b/libc/intrin/kprintf.greg.c
index b95e4535e..54bb21e5d 100644
--- a/libc/intrin/kprintf.greg.c
+++ b/libc/intrin/kprintf.greg.c
@@ -325,13 +325,13 @@ privileged long kloghandle(void) {
         long proc;
         proc = __imp_GetCurrentProcess();
         hand = __imp_GetStdHandle(kNtStdErrorHandle);
-        __imp_DuplicateHandle(proc, hand, proc, &hand, 0, true,
+        __imp_DuplicateHandle(proc, hand, proc, &hand, 0, false,
                               kNtDuplicateSameAccess);
       } else if (n && n < 512) {
         hand = __imp_CreateFileW(
             path, kNtFileAppendData,
-            kNtFileShareRead | kNtFileShareWrite | kNtFileShareDelete,
-            &kNtIsInheritable, kNtOpenAlways, kNtFileAttributeNormal, 0);
+            kNtFileShareRead | kNtFileShareWrite | kNtFileShareDelete, 0,
+            kNtOpenAlways, kNtFileAttributeNormal, 0);
       } else {
         hand = -1;  // KPRINTF_LOG was empty string or too long
       }
diff --git a/libc/log/die.c b/libc/log/die.c
index 0872a5c3f..4626f2ee2 100644
--- a/libc/log/die.c
+++ b/libc/log/die.c
@@ -16,20 +16,18 @@
 │ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
-#include "libc/atomic.h"
 #include "libc/calls/calls.h"
-#include "libc/calls/state.internal.h"
 #include "libc/calls/syscall-sysv.internal.h"
 #include "libc/dce.h"
-#include "libc/intrin/atomic.h"
+#include "libc/errno.h"
+#include "libc/intrin/describebacktrace.internal.h"
 #include "libc/intrin/kprintf.h"
 #include "libc/log/backtrace.internal.h"
 #include "libc/log/internal.h"
-#include "libc/log/libfatal.internal.h"
 #include "libc/log/log.h"
 #include "libc/runtime/internal.h"
 #include "libc/runtime/runtime.h"
-#include "libc/thread/thread.h"
+#include "libc/str/str.h"
 
 #if SupportsMetal()
 __static_yoink("_idt");
@@ -37,29 +35,18 @@ __static_yoink("_idt");
 
 /**
  * Aborts process after printing a backtrace.
- *
- * If a debugger is present then this will trigger a breakpoint.
  */
-relegated wontreturn void __die(void) {
-  /* asan runtime depends on this function */
-  int me, owner;
-  static atomic_int once;
-  owner = 0;
-  me = __tls_enabled ? __get_tls()->tib_tid : sys_gettid();
-  pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, 0);
-  if (__vforked ||
-      atomic_compare_exchange_strong_explicit(
-          &once, &owner, me, memory_order_relaxed, memory_order_relaxed)) {
-    __restore_tty();
-    if (IsDebuggerPresent(false)) {
-      DebugBreak();
-    }
-    ShowBacktrace(2, __builtin_frame_address(0));
-    _Exit(77);
-  } else if (owner == me) {
-    kprintf("die failed while dying\n");
-    _Exit(79);
-  } else {
-    _Exit1(79);
-  }
+relegated dontasan wontreturn void __die(void) {
+
+  // print vital error nubers reliably
+  // the surface are of code this calls is small and audited
+  kprintf("\r\n\e[1;31m__die %s pid %d tid %d bt %s\e[0m\n",
+          program_invocation_short_name, getpid(), sys_gettid(),
+          DescribeBacktrace(__builtin_frame_address(0)));
+
+  // print much friendlier backtrace less reliably
+  // we're in a broken runtime state and so much can go wrong
+  __restore_tty();
+  ShowBacktrace(2, __builtin_frame_address(0));
+  _Exit(77);
 }
diff --git a/libc/log/libfatal.internal.h b/libc/log/libfatal.internal.h
index a47266dda..a837e7ea6 100644
--- a/libc/log/libfatal.internal.h
+++ b/libc/log/libfatal.internal.h
@@ -9,6 +9,12 @@
 #if !(__ASSEMBLER__ + __LINKER__ + 0)
 COSMOPOLITAN_C_START_
 
+__funline unsigned long __strlen(const char *s) {
+  unsigned long n = 0;
+  while (*s++) ++n;
+  return n;
+}
+
 __funline int __strcmp(const char *l, const char *r) {
   size_t i = 0;
   while (l[i] == r[i] && r[i]) ++i;
@@ -24,6 +30,15 @@ __funline char *__stpcpy(char *d, const char *s) {
   }
 }
 
+__funline long __write_linux(int fd, const void *p, long n) {
+  long ax = 1;
+  asm volatile("syscall"
+               : "+a"(ax)
+               : "D"(fd), "S"(p), "d"(n)
+               : "rcx", "r11", "memory");
+  return ax;
+}
+
 __funline void *__repstosb(void *di, char al, size_t cx) {
 #if defined(__x86__) && defined(__GNUC__) && !defined(__STRICT_ANSI__)
   asm("rep stosb"
diff --git a/libc/log/oncrash_amd64.c b/libc/log/oncrash_amd64.c
index aea9e313b..3cacbf7d5 100644
--- a/libc/log/oncrash_amd64.c
+++ b/libc/log/oncrash_amd64.c
@@ -21,6 +21,7 @@
 #include "libc/calls/calls.h"
 #include "libc/calls/state.internal.h"
 #include "libc/calls/struct/sigaction.h"
+#include "libc/calls/struct/sigset.h"
 #include "libc/calls/struct/utsname.h"
 #include "libc/calls/syscall-sysv.internal.h"
 #include "libc/calls/ucontext.h"
@@ -29,6 +30,7 @@
 #include "libc/fmt/itoa.h"
 #include "libc/intrin/asan.internal.h"
 #include "libc/intrin/atomic.h"
+#include "libc/intrin/describebacktrace.internal.h"
 #include "libc/intrin/describeflags.internal.h"
 #include "libc/intrin/kmalloc.h"
 #include "libc/intrin/kprintf.h"
@@ -259,113 +261,42 @@ relegated void ShowCrashReport(int err, int sig, struct siginfo *si,
   kprintf("\n");
 }
 
-static wontreturn relegated dontinstrument void __minicrash(int sig,
-                                                            struct siginfo *si,
-                                                            ucontext_t *ctx,
-                                                            const char *kind) {
-  kprintf("\n"
-          "\n"
-          "CRASHED %s WITH %G\n"
-          "%s\n"
-          "RIP %x\n"
-          "RSP %x\n"
-          "RBP %x\n"
-          "PID %d\n"
-          "TID %d\n"
-          "\n",
-          kind, sig, __argv[0], ctx ? ctx->uc_mcontext.rip : 0,
-          ctx ? ctx->uc_mcontext.rsp : 0, ctx ? ctx->uc_mcontext.rbp : 0, __pid,
-          __tls_enabled ? __get_tls()->tib_tid : sys_gettid());
-  _Exit(119);
+static relegated wontreturn void RaiseCrash(int sig) {
+  sigset_t ss;
+  sigfillset(&ss);
+  sigdelset(&ss, sig);
+  sigprocmask(SIG_SETMASK, &ss, 0);
+  signal(sig, SIG_DFL);
+  kill(getpid(), sig);
+  _Exit(128 + sig);
 }
 
-/**
- * Crashes in a developer-friendly human-centric way.
- *
- * We first try to launch GDB if it's an interactive development
- * session. Otherwise we show a really good crash report, sort of like
- * Python, that includes filenames and line numbers. Many editors, e.g.
- * Emacs, will even recognize its syntax for quick hopping to the
- * failing line. That's only possible if the the .com.dbg file is in the
- * same folder. If the concomitant debug binary can't be found, we
- * simply print addresses which may be cross-referenced using objdump.
- *
- * This function never returns, except for traps w/ human supervision.
- *
- * @threadsafe
- * @vforksafe
- */
 relegated void __oncrash_amd64(int sig, struct siginfo *si, void *arg) {
-  int bZero;
-#ifdef ATTACH_GDB_ON_CRASH
-  intptr_t rip;
-#endif
-  int me, owner;
   int gdbpid, err;
   ucontext_t *ctx = arg;
-  static atomic_int once;
-  static atomic_int once2;
-  STRACE("__oncrash rip %x", ctx->uc_mcontext.rip);
+
+  // print vital error nubers reliably
+  // the surface are of code this calls is small and audited
+  kprintf(
+      "\r\n\e[1;31m__oncrash %G %s pid %d tid %d rip %x bt %s\e[0m\n", sig,
+      program_invocation_short_name, getpid(), sys_gettid(),
+      ctx ? ctx->uc_mcontext.rip : 0,
+      DescribeBacktrace(ctx ? (struct StackFrame *)ctx->uc_mcontext.rbp
+                            : (struct StackFrame *)__builtin_frame_address(0)));
+
+  // print friendlier detailed crash report less reliably
+  // we're in a broken runtime state and so much can go wrong
   ftrace_enabled(-1);
   strace_enabled(-1);
-  owner = 0;
-  me = __tls_enabled ? __get_tls()->tib_tid : sys_gettid();
-  pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, 0);
-  if (atomic_compare_exchange_strong_explicit(
-          &once, &owner, me, memory_order_relaxed, memory_order_relaxed)) {
-    if (!__vforked) {
-#ifdef ATTACH_GDB_ON_CRASH
-      rip = ctx ? ctx->uc_mcontext.rip : 0;
-#endif
-      err = errno;
-      if ((gdbpid = IsDebuggerPresent(true))) {
-        DebugBreak();
-      } else if (__nocolor || g_isrunningundermake) {
-        gdbpid = -1;
-#if ATTACH_GDB_ON_CRASH
-      } else if (!IsTiny() && IsLinux() && FindDebugBinary() && !__isworker) {
-        // RestoreDefaultCrashSignalHandlers();
-        gdbpid = AttachDebugger(
-            ((sig == SIGTRAP || sig == SIGQUIT) &&
-             (rip >= (intptr_t)&__executable_start && rip < (intptr_t)&_etext))
-                ? rip
-                : 0);
-#endif
-      }
-      if (!(gdbpid > 0 && (sig == SIGTRAP || sig == SIGQUIT))) {
-        __restore_tty();
-        ShowCrashReport(err, sig, si, ctx);
-        _Exit(128 + sig);
-      }
-      atomic_store_explicit(&once, 0, memory_order_relaxed);
-    } else {
-      atomic_store_explicit(&once, 0, memory_order_relaxed);
-      __minicrash(sig, si, ctx, "WHILE VFORKED");
-    }
-  } else if (sig == SIGTRAP) {
-    // chances are IsDebuggerPresent() confused strace w/ gdb
-    goto ItsATrap;
-  } else if (owner == me) {
-    // we crashed while generating a crash report
-    bZero = false;
-    if (atomic_compare_exchange_strong_explicit(
-            &once2, &bZero, true, memory_order_relaxed, memory_order_relaxed)) {
-      __minicrash(sig, si, ctx, "WHILE CRASHING");
-    } else {
-      // somehow __minicrash() crashed not possible
-      for (;;) {
-        abort();
-      }
-    }
-  } else {
-    // multiple threads have crashed
-    // kill current thread assuming process dies soon
-    // TODO(jart): It'd be nice to report on all threads.
-    _Exit1(8);
+  err = errno;
+  if ((gdbpid = IsDebuggerPresent(true))) {
+    DebugBreak();
+  }
+  if (!(gdbpid > 0 && (sig == SIGTRAP || sig == SIGQUIT))) {
+    __restore_tty();
+    ShowCrashReport(err, sig, si, ctx);
+    RaiseCrash(sig);
   }
-ItsATrap:
-  strace_enabled(+1);
-  ftrace_enabled(+1);
 }
 
 #endif /* __x86_64__ */
diff --git a/libc/log/oncrash_arm64.c b/libc/log/oncrash_arm64.c
index fe216a3dc..82578906f 100644
--- a/libc/log/oncrash_arm64.c
+++ b/libc/log/oncrash_arm64.c
@@ -21,6 +21,7 @@
 #include "libc/calls/calls.h"
 #include "libc/calls/struct/aarch64.internal.h"
 #include "libc/calls/struct/rusage.internal.h"
+#include "libc/calls/struct/sigaction.h"
 #include "libc/calls/struct/siginfo.h"
 #include "libc/calls/struct/sigset.h"
 #include "libc/calls/struct/sigset.internal.h"
@@ -63,18 +64,28 @@ struct Buffer {
   int i;
 };
 
-static bool IsCode(uintptr_t p) {
+static relegated bool IsCode(uintptr_t p) {
   return __executable_start <= (uint8_t *)p && (uint8_t *)p < _etext;
 }
 
-static void Append(struct Buffer *b, const char *fmt, ...) {
+static relegated void Append(struct Buffer *b, const char *fmt, ...) {
   va_list va;
   va_start(va, fmt);
   b->i += kvsnprintf(b->p + b->i, b->n - b->i, fmt, va);
   va_end(va);
 }
 
-static const char *ColorRegister(int r) {
+static relegated wontreturn void RaiseCrash(int sig) {
+  sigset_t ss;
+  sigfillset(&ss);
+  sigdelset(&ss, sig);
+  sigprocmask(SIG_SETMASK, &ss, 0);
+  signal(sig, SIG_DFL);
+  kill(getpid(), sig);
+  _Exit(128 + sig);
+}
+
+static relegated const char *ColorRegister(int r) {
   if (__nocolor) return "";
   switch (r) {
     case 0:  // arg / res
@@ -115,8 +126,8 @@ static const char *ColorRegister(int r) {
   }
 }
 
-static bool AppendFileLine(struct Buffer *b, const char *addr2line,
-                           const char *debugbin, long addr) {
+static relegated bool AppendFileLine(struct Buffer *b, const char *addr2line,
+                                     const char *debugbin, long addr) {
   ssize_t rc;
   char *p, *q, buf[128];
   int j, k, ws, pid, pfd[2];
@@ -167,8 +178,8 @@ static bool AppendFileLine(struct Buffer *b, const char *addr2line,
   }
 }
 
-static char *GetSymbolName(struct SymbolTable *st, int symbol, char **mem,
-                           size_t *memsz) {
+static relegated char *GetSymbolName(struct SymbolTable *st, int symbol,
+                                     char **mem, size_t *memsz) {
   char *s, *t;
   if ((s = __get_symbol_name(st, symbol)) &&  //
       s[0] == '_' && s[1] == 'Z' &&           //
@@ -348,7 +359,7 @@ relegated void __oncrash_arm64(int sig, struct siginfo *si, void *arg) {
   }
   sys_write(2, b->p, MIN(b->i, b->n));
   __print_maps();
-  _Exit(128 + sig);
+  RaiseCrash(sig);
 }
 
 #endif /* __aarch64__ */
diff --git a/libc/log/showcrashreports.c b/libc/log/showcrashreports.c
index 66d8a5d5d..fdb9b35af 100644
--- a/libc/log/showcrashreports.c
+++ b/libc/log/showcrashreports.c
@@ -97,7 +97,7 @@ static void RemoveCrashHandler(void *arg) {
   strace_enabled(+1);
 }
 
-static void InstallCrashHandler(int sig, sigaction_f thunk, int extraflags) {
+static void InstallCrashHandler(int sig, sigaction_f thunk) {
   int e;
   struct sigaction sa;
   struct CrashHandler *ch;
@@ -114,7 +114,7 @@ static void InstallCrashHandler(int sig, sigaction_f thunk, int extraflags) {
     sigdelset(&sa.sa_mask, SIGABRT);
     sigdelset(&sa.sa_mask, SIGBUS);
     sigdelset(&sa.sa_mask, SIGURG);
-    sa.sa_flags = SA_SIGINFO | SA_NODEFER | extraflags;
+    sa.sa_flags = SA_SIGINFO | SA_ONSTACK;
     if (!sigaction(sig, &sa, &ch->old)) {
       __cxa_atexit(RemoveCrashHandler, ch, 0);
     }
@@ -138,24 +138,21 @@ static void InstallCrashHandler(int sig, sigaction_f thunk, int extraflags) {
  * useful, for example, if a program is caught in an infinite loop.
  */
 void ShowCrashReports(void) {
-  int ef = 0;
-  struct sigaltstack ss;
-  _wantcrashreports = true;
   if (!IsWindows()) {
-    ef = SA_ONSTACK;
+    struct sigaltstack ss;
     ss.ss_flags = 0;
-    ss.ss_size = GetStackSize();
-    // FreeBSD sigaltstack() will EFAULT if we use MAP_STACK here
-    // OpenBSD sigaltstack() auto-applies MAP_STACK to the memory
-    npassert((ss.ss_sp = _mapanon(GetStackSize())));
-    npassert(!sigaltstack(&ss, 0));
+    ss.ss_size = SIGSTKSZ;
+    ss.ss_sp = malloc(SIGSTKSZ);
+    sigaltstack(&ss, 0);
+    __cxa_atexit(free, ss.ss_sp, 0);
   }
-  InstallCrashHandler(SIGQUIT, __got_sigquit, ef);  // ctrl+\ aka ctrl+break
-  InstallCrashHandler(SIGFPE, __got_sigfpe, ef);    // 1 / 0
-  InstallCrashHandler(SIGILL, __got_sigill, ef);    // illegal instruction
-  InstallCrashHandler(SIGSEGV, __got_sigsegv, ef);  // bad memory access
-  InstallCrashHandler(SIGTRAP, __got_sigtrap, ef);  // bad system call
-  InstallCrashHandler(SIGBUS, __got_sigbus, ef);    // misalign, mmap i/o failed
-  InstallCrashHandler(SIGURG, __got_sigurg, ef);    // placeholder
+  InstallCrashHandler(SIGQUIT, __got_sigquit);  // ctrl+\ aka ctrl+break
+  InstallCrashHandler(SIGFPE, __got_sigfpe);    // 1 / 0
+  InstallCrashHandler(SIGILL, __got_sigill);    // illegal instruction
+  InstallCrashHandler(SIGSEGV, __got_sigsegv);  // bad memory access
+  InstallCrashHandler(SIGTRAP, __got_sigtrap);  // bad system call
+  InstallCrashHandler(SIGBUS, __got_sigbus);    // misalign, mmap i/o failed
+  InstallCrashHandler(SIGURG, __got_sigurg);    // placeholder
+  _wantcrashreports = true;
   GetSymbolTable();
 }
diff --git a/libc/mem/gc.c b/libc/mem/gc.c
index 02a24783e..b7ad3be74 100644
--- a/libc/mem/gc.c
+++ b/libc/mem/gc.c
@@ -16,6 +16,7 @@
 │ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
+#include "libc/mem/gc.h"
 #include "libc/assert.h"
 #include "libc/intrin/likely.h"
 #include "libc/mem/mem.h"
diff --git a/libc/runtime/cocmd.c b/libc/runtime/cocmd.c
index 58752f5f6..507951307 100644
--- a/libc/runtime/cocmd.c
+++ b/libc/runtime/cocmd.c
@@ -155,6 +155,11 @@ static char *Finish(void) {
   }
 }
 
+static int Pause(void) {
+  pause();
+  return 0;
+}
+
 static int True(void) {
   return 0;
 }
@@ -671,6 +676,7 @@ static int TryBuiltin(void) {
   if (!strcmp(args[0], "true")) return True();
   if (!strcmp(args[0], "test")) return Test();
   if (!strcmp(args[0], "kill")) return Kill();
+  if (!strcmp(args[0], "pause")) return Pause();
   if (!strcmp(args[0], "flock")) return Flock();
   if (!strcmp(args[0], "chmod")) return Chmod();
   if (!strcmp(args[0], "touch")) return Touch();
diff --git a/libc/runtime/login_tty.c b/libc/runtime/login_tty.c
index 48580f1f0..1b49871b3 100644
--- a/libc/runtime/login_tty.c
+++ b/libc/runtime/login_tty.c
@@ -16,9 +16,11 @@
 │ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
+#include "libc/assert.h"
 #include "libc/calls/calls.h"
 #include "libc/calls/syscall-sysv.internal.h"
 #include "libc/dce.h"
+#include "libc/errno.h"
 #include "libc/intrin/strace.internal.h"
 #include "libc/runtime/runtime.h"
 #include "libc/runtime/utmp.h"
@@ -28,23 +30,37 @@
 /**
  * Prepares terminal for login.
  *
+ * After this operation `fd` will be used for all stdio handles.
+ *
  * @return 0 on success, or -1 w/ errno
+ * @raise EPERM if terminal is already controlling another sid?
+ * @raise EPERM if pledge() was used without tty
+ * @raise ENOTTY if `fd` isn't a teletypewriter
  * @raise ENOSYS on Windows and Metal
- * @raise EPERM if terminal is already controlling another sid
+ * @raise EBADF if `fd` isn't open
  */
 int login_tty(int fd) {
-  int i, rc;
-  if (IsLinux() || IsBsd()) {
-    setsid();
-    if (!sys_ioctl(fd, TIOCSCTTY, 0)) {
-      for (i = 0; i < 3; ++i) dup2(fd, i);
-      if (fd > 2) close(fd);
-      rc = 0;
-    } else {
-      rc = -1;
-    }
-  } else {
+  int rc;
+  if (!IsLinux() && !IsBsd()) {
     rc = enosys();
+  } else if (!isatty(fd)) {
+    rc = -1;  // validate before changing the process's state
+  } else {
+    // become session leader
+    // we don't care if it fails due to already being the one
+    int e = errno;
+    sys_setsid();
+    errno = e;
+    // take control of teletypewriter (requires being leader)
+    if ((rc = sys_ioctl(fd, TIOCSCTTY, 0)) != -1) {
+      unassert(!sys_dup2(fd, 0, 0));
+      unassert(!sys_dup2(fd, 1, 0));
+      unassert(!sys_dup2(fd, 2, 0));
+      if (fd > 2) {
+        unassert(!sys_close(fd));
+      }
+      rc = 0;
+    }
   }
   STRACE("login_tty(%d) → %d% m", fd, rc);
   return rc;
diff --git a/libc/runtime/runtime.mk b/libc/runtime/runtime.mk
index 5533f8bc8..181b068c6 100644
--- a/libc/runtime/runtime.mk
+++ b/libc/runtime/runtime.mk
@@ -76,6 +76,7 @@ o/$(MODE)/libc/runtime/ftracer.o: private		\
 
 o/$(MODE)/libc/runtime/cosmo2.o				\
 o/$(MODE)/libc/runtime/fork-nt.o			\
+o/$(MODE)/libc/runtime/enable_tls.o			\
 o/$(MODE)/libc/runtime/printmemoryintervals.o		\
 o/$(MODE)/libc/runtime/findmemoryinterval.o		\
 o/$(MODE)/libc/runtime/sys_mprotect.greg.o		\
@@ -92,6 +93,7 @@ o/$(MODE)/libc/runtime/print.greg.o			\
 o/$(MODE)/libc/runtime/stackchkfail.o			\
 o/$(MODE)/libc/runtime/stackchkfaillocal.o		\
 o/$(MODE)/libc/runtime/winmain.greg.o			\
+o/$(MODE)/libc/runtime/interceptflag.greg.o		\
 o/$(MODE)/libc/runtime/opensymboltable.o: private	\
 		CFLAGS +=				\
 			-Os				\
diff --git a/libc/runtime/stackuse.c b/libc/runtime/stackuse.c
index e4357e9e0..7b85c024a 100644
--- a/libc/runtime/stackuse.c
+++ b/libc/runtime/stackuse.c
@@ -60,7 +60,8 @@ static textexit void LogStackUse(void) {
   if (!PLEDGED(STDIO) || !PLEDGED(WPATH) || !PLEDGED(CPATH)) return;
   usage = GetStackUsage((char *)GetStackAddr(), GetStackSize());
   e = errno;
-  if ((fd = open(stacklog, O_APPEND | O_CREAT | O_WRONLY, 0644)) != -1) {
+  if ((fd = open(stacklog, O_APPEND | O_CREAT | O_WRONLY | O_CLOEXEC, 0644)) !=
+      -1) {
     p = FormatUint64(stacklog, usage);
     for (i = 0; i < __argc; ++i) {
       n = strlen(__argv[i]);
diff --git a/libc/runtime/winmain.greg.c b/libc/runtime/winmain.greg.c
index 02a81e429..f07723e8a 100644
--- a/libc/runtime/winmain.greg.c
+++ b/libc/runtime/winmain.greg.c
@@ -21,6 +21,8 @@
 #include "libc/calls/state.internal.h"
 #include "libc/calls/syscall_support-nt.internal.h"
 #include "libc/dce.h"
+#include "libc/intrin/asan.internal.h"
+#include "libc/intrin/asancodes.h"
 #include "libc/intrin/describeflags.internal.h"
 #include "libc/intrin/getenv.internal.h"
 #include "libc/intrin/weaken.h"
@@ -176,6 +178,27 @@ __msabi static textwindows wontreturn void WinInit(const char16_t *cmdline) {
   struct WinArgs *wa =
       (struct WinArgs *)(stackaddr + (stacksize - sizeof(struct WinArgs)));
 
+  // allocate asan memory if needed
+  if (IsAsan()) {
+    uintptr_t shadowaddr = 0x7fff8000 + (stackaddr >> 3);
+    uintptr_t shadowend = 0x7fff8000 + ((stackaddr + stacksize) >> 3);
+    uintptr_t shallocaddr = ROUNDDOWN(shadowaddr, FRAMESIZE);
+    uintptr_t shallocend = ROUNDUP(shadowend, FRAMESIZE);
+    uintptr_t shallocsize = shallocend - shallocaddr;
+    __imp_MapViewOfFileEx(
+        (_mmi.p[1].h =
+             __imp_CreateFileMappingW(-1, &kNtIsInheritable, kNtPageReadwrite,
+                                      shallocsize >> 32, shallocsize, NULL)),
+        kNtFileMapWrite, 0, 0, shallocsize, (void *)shallocaddr);
+    _mmi.p[1].x = shallocaddr >> 16;
+    _mmi.p[1].y = (shallocaddr >> 16) + ((shallocsize - 1) >> 16);
+    _mmi.p[1].prot = PROT_READ | PROT_WRITE;
+    _mmi.p[1].flags = 0x00000022;  // private+anonymous
+    _mmi.p[1].size = shallocsize;
+    _mmi.i = 2;
+    __asan_poison((void *)stackaddr, GetGuardSize(), kAsanStackOverflow);
+  }
+
   // parse utf-16 command into utf-8 argv array in argument block
   int count = GetDosArgv(cmdline, wa->argblock, ARRAYLEN(wa->argblock),
                          wa->argv, ARRAYLEN(wa->argv));
@@ -231,13 +254,13 @@ __msabi textwindows int64_t WinMain(int64_t hInstance, int64_t hPrevInstance,
   // sloppy flag-only check for early initialization
   if (__strstr16(cmdline, u"--strace")) ++__strace;
 #endif
+  if (_weaken(WinSockInit)) {
+    _weaken(WinSockInit)();
+  }
   DeduplicateStdioHandles();
   if (_weaken(WinMainStdin)) {
     _weaken(WinMainStdin)();
   }
-  if (_weaken(WinSockInit)) {
-    _weaken(WinSockInit)();
-  }
   if (_weaken(WinMainForked)) {
     _weaken(WinMainForked)();
   }
diff --git a/test/libc/calls/close_test.c b/libc/stdio/confstr.c
similarity index 88%
rename from test/libc/calls/close_test.c
rename to libc/stdio/confstr.c
index 1556b7828..e06039dc1 100644
--- a/test/libc/calls/close_test.c
+++ b/libc/stdio/confstr.c
@@ -16,13 +16,16 @@
 │ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
-#include "libc/calls/calls.h"
-#include "libc/dce.h"
+#include "libc/paths.h"
 #include "libc/stdio/stdio.h"
-#include "libc/testlib/testlib.h"
+#include "libc/str/str.h"
+#include "libc/sysv/errfuns.h"
 
-TEST(close, stdout) {
-  if (!IsWindows()) return;
-  close(1);
-  fprintf(stderr, "hi\n");
+size_t confstr(int name, char *buf, size_t len) {
+  if (name == _CS_PATH) {
+    return strlcpy(buf, _PATH_DEFPATH, len) + 1;
+  } else {
+    einval();
+    return 0;
+  }
 }
diff --git a/libc/stdio/popen.c b/libc/stdio/popen.c
index 5f81966a1..b408fb15c 100644
--- a/libc/stdio/popen.c
+++ b/libc/stdio/popen.c
@@ -22,6 +22,7 @@
 #include "libc/intrin/weaken.h"
 #include "libc/paths.h"
 #include "libc/runtime/runtime.h"
+#include "libc/stdio/fflush.internal.h"
 #include "libc/stdio/internal.h"
 #include "libc/stdio/stdio.h"
 #include "libc/sysv/consts/f.h"
@@ -42,6 +43,7 @@
  * @param mode can be:
  *     - `"r"` for reading from subprocess standard output
  *     - `"w"` for writing to subprocess standard input
+ *     - `"e"` for `O_CLOEXEC` on returned file
  * @raise EINVAL if `mode` is invalid or specifies read+write
  * @raise EMFILE if process `RLIMIT_NOFILE` has been reached
  * @raise ENFILE if system-wide file limit has been reached
@@ -53,7 +55,7 @@
  * @threadsafe
  */
 FILE *popen(const char *cmdline, const char *mode) {
-  FILE *f;
+  FILE *f, *f2;
   int e, rc, pid, dir, flags, pipefds[2];
   flags = fopenflags(mode);
   if ((flags & O_ACCMODE) == O_RDONLY) {
@@ -77,6 +79,14 @@ FILE *popen(const char *cmdline, const char *mode) {
         // we can't rely on cloexec because cocmd builtins don't execve
         if (pipefds[0] != !dir) unassert(!close(pipefds[0]));
         if (pipefds[1] != !dir) unassert(!close(pipefds[1]));
+        // "The popen() function shall ensure that any streams from
+        //  previous popen() calls that remain open in the parent
+        //  process are closed in the new child process." -POSIX
+        for (int i = 0; i < __fflush.handles.i; ++i) {
+          if ((f2 = __fflush.handles.p[i]) && f2->pid) {
+            close(f2->fd);
+          }
+        }
         _Exit(_cocmd(3,
                      (char *[]){
                          "popen",
@@ -88,18 +98,21 @@ FILE *popen(const char *cmdline, const char *mode) {
       default:
         f->pid = pid;
         unassert(!close(pipefds[!dir]));
+        if (!(flags & O_CLOEXEC)) {
+          unassert(!fcntl(pipefds[dir], F_SETFD, 0));
+        }
         return f;
       case -1:
         e = errno;
-        unassert(!fclose(f));
-        unassert(!close(pipefds[!dir]));
+        fclose(f);
+        close(pipefds[!dir]);
         errno = e;
         return NULL;
     }
   } else {
     e = errno;
-    unassert(!close(pipefds[0]));
-    unassert(!close(pipefds[1]));
+    close(pipefds[0]);
+    close(pipefds[1]);
     errno = e;
     return NULL;
   }
diff --git a/libc/stdio/posix_spawn.c b/libc/stdio/posix_spawn.c
index ac2b19d13..3ca50e6c7 100644
--- a/libc/stdio/posix_spawn.c
+++ b/libc/stdio/posix_spawn.c
@@ -21,9 +21,13 @@
 #include "libc/calls/calls.h"
 #include "libc/calls/internal.h"
 #include "libc/calls/ntspawn.h"
+#include "libc/calls/state.internal.h"
 #include "libc/calls/struct/fd.internal.h"
+#include "libc/calls/struct/rlimit.h"
 #include "libc/calls/struct/sigaction.h"
 #include "libc/calls/struct/sigset.h"
+#include "libc/calls/struct/sigset.internal.h"
+#include "libc/calls/syscall-sysv.internal.h"
 #include "libc/dce.h"
 #include "libc/errno.h"
 #include "libc/fmt/itoa.h"
@@ -42,8 +46,11 @@
 #include "libc/sock/sock.h"
 #include "libc/stdio/posix_spawn.h"
 #include "libc/stdio/posix_spawn.internal.h"
+#include "libc/stdio/stdio.h"
 #include "libc/str/str.h"
+#include "libc/sysv/consts/limits.h"
 #include "libc/sysv/consts/o.h"
+#include "libc/sysv/consts/ok.h"
 #include "libc/sysv/consts/sig.h"
 #include "libc/thread/thread.h"
 #include "libc/thread/tls.h"
@@ -149,13 +156,14 @@ static textwindows errno_t posix_spawn_windows_impl(
   };
 
   // figure out the flags
-  short flags;
+  short flags = 0;
   bool bInheritHandles = false;
   uint32_t dwCreationFlags = 0;
   for (i = 0; i < 3; ++i) {
     bInheritHandles |= stdio_handle[i] != -1;
   }
-  if (attrp && *attrp && !posix_spawnattr_getflags(attrp, &flags)) {
+  if (attrp && *attrp) {
+    flags = (*attrp)->flags;
     if (flags & POSIX_SPAWN_SETSID) {
       dwCreationFlags |= kNtDetachedProcess;
     }
@@ -208,8 +216,11 @@ static textwindows dontinline errno_t posix_spawn_windows(
   return err;
 }
 
-static wontreturn void posix_spawn_die(const char *fail_func) {
-  STRACE("posix_spawn: %s failed% m", fail_func);
+static wontreturn void posix_spawn_die(const char *thing) {
+  const char *reason;  // print b/c there's no other way
+  if (!(reason = _strerdoc(errno))) reason = "Unknown error";
+  tinyprint(2, program_invocation_short_name, ": posix_spawn ", thing,
+            " failed: ", reason, "\n", NULL);
   _Exit(127);
 }
 
@@ -229,7 +240,7 @@ static void RunUnixFileActions(struct _posix_faction *a) {
       case _POSIX_SPAWN_OPEN: {
         int t;
         if ((t = open(a->path, a->oflag, a->mode)) == -1) {
-          posix_spawn_die("open");
+          posix_spawn_die(a->path);
         }
         if (t != a->fildes) {
           if (dup2(t, a->fildes) == -1) {
@@ -251,8 +262,7 @@ static void RunUnixFileActions(struct _posix_faction *a) {
 /**
  * Spawns process, the POSIX way.
  *
- * This provides superior process creation performance across systems.
- *
+ * This provides superior process creation performance across systems
  * Processes are normally spawned by calling fork() and execve(), but
  * that goes slow on Windows if the caller has allocated a nontrivial
  * number of memory mappings, all of which need to be copied into the
@@ -260,10 +270,19 @@ static void RunUnixFileActions(struct _posix_faction *a) {
  * fork() bears a similar cost that's 100x less bad, which is copying
  * the page tables. So what this implementation does is on Windows it
  * calls CreateProcess() directly and on UNIX it uses vfork() if it's
- * possible (XNU and OpenBSD don't have it).
+ * possible (XNU and OpenBSD don't have it). On UNIX this API has the
+ * benefit of avoiding the footguns of using vfork() directly because
+ * this implementation will ensure signal handlers can't be called in
+ * the child process since that'd likely corrupt the parent's memory.
  *
- * If the child process exits with status 127 then use the `--strace`
- * flag to get an explanation of failures that occurred during spawn.
+ * This implementation doesn't create a pipe like Musl Libc, and will
+ * report errors in the child process by printing the cause to stderr
+ * which ensures posix_spawn stays fast, and works w/ `RLIMIT_FILENO`
+ * There is however one particular case where knowing the execve code
+ * truly matters, which is ETXTBSY. Thankfully, there's a rarely used
+ * signal with the exact same magic number across supported platforms
+ * called SIGVTALRM which we send to wait4 when execve raises ETXTBSY
+ * Please note that on Windows posix_spawn() returns ETXTBSY directly
  *
  * @param pid if non-null shall be set to child pid on success
  * @param path is resolved path of program which is not `$PATH` searched
@@ -280,67 +299,85 @@ errno_t posix_spawn(int *pid, const char *path,
                     const posix_spawn_file_actions_t *file_actions,
                     const posix_spawnattr_t *attrp, char *const argv[],
                     char *const envp[]) {
-  short flags = 0;
-  sigset_t sigmask;
-  int s, child, policy;
-  struct sched_param param;
-  struct sigaction dfl = {0};
   if (IsWindows()) {
     return posix_spawn_windows(pid, path, file_actions, attrp, argv, envp);
   }
+  sigset_t blockall, oldmask;
+  int child, res, cs, e = errno;
+  if (access(path, X_OK)) {
+    res = errno;
+    errno = e;
+    return res;
+  }
+  sigfillset(&blockall);
+  sys_sigprocmask(SIG_SETMASK, &blockall, &oldmask);
+  pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
   if (!(child = vfork())) {
-    if (attrp && *attrp) {
-      posix_spawnattr_getflags(attrp, &flags);
-      if (flags & POSIX_SPAWN_SETSID) {
-        if (setsid()) {
-          posix_spawn_die("setsid");
-        }
-      }
-      if (flags & POSIX_SPAWN_SETPGROUP) {
-        if (setpgid(0, (*attrp)->pgroup)) {
-          posix_spawn_die("setpgid");
-        }
-      }
-      if (flags & POSIX_SPAWN_SETSIGMASK) {
-        posix_spawnattr_getsigmask(attrp, &sigmask);
-        sigprocmask(SIG_SETMASK, &sigmask, 0);
-      }
-      if ((flags & POSIX_SPAWN_RESETIDS) &&
-          (setgid(getgid()) || setuid(getuid()))) {
-        posix_spawn_die("setuid");
-      }
-      if (flags & POSIX_SPAWN_SETSIGDEF) {
-        for (s = 1; s < 32; s++) {
-          if (sigismember(&(*attrp)->sigdefault, s)) {
-            if (sigaction(s, &dfl, 0)) {
-              posix_spawn_die("sigaction");
-            }
-          }
-        }
+    sigset_t *childmask;
+    struct sigaction dfl = {0};
+    short flags = attrp && *attrp ? (*attrp)->flags : 0;
+    for (int sig = 1; sig < _NSIG; sig++) {
+      if (__sighandrvas[sig] != (long)SIG_DFL &&
+          (__sighandrvas[sig] != (long)SIG_IGN ||
+           ((flags & POSIX_SPAWN_SETSIGDEF) &&
+            sigismember(&(*attrp)->sigdefault, sig) == 1) ||
+           sig == SIGVTALRM)) {
+        sigaction(sig, &dfl, 0);
       }
     }
+    if (flags & POSIX_SPAWN_SETSIGMASK) {
+      childmask = &(*attrp)->sigmask;
+    } else {
+      childmask = &oldmask;
+    }
+    sys_sigprocmask(SIG_SETMASK, childmask, 0);
+    if (flags & POSIX_SPAWN_SETSID) {
+      setsid();
+    }
+    if ((flags & POSIX_SPAWN_SETPGROUP) && setpgid(0, (*attrp)->pgroup)) {
+      posix_spawn_die("setpgid");
+    }
+    if ((flags & POSIX_SPAWN_RESETIDS) && setgid(getgid())) {
+      posix_spawn_die("setgid");
+    }
+    if ((flags & POSIX_SPAWN_RESETIDS) && setgid(getgid())) {
+      posix_spawn_die("setuid");
+    }
     if (file_actions) {
       RunUnixFileActions(*file_actions);
     }
-    if (attrp && *attrp) {
+    if (IsLinux() || IsFreebsd() || IsNetbsd()) {
       if (flags & POSIX_SPAWN_SETSCHEDULER) {
-        posix_spawnattr_getschedpolicy(attrp, &policy);
-        posix_spawnattr_getschedparam(attrp, &param);
-        if (sched_setscheduler(0, policy, &param) == -1) {
+        if (sched_setscheduler(0, (*attrp)->schedpolicy,
+                               &(*attrp)->schedparam) == -1) {
           posix_spawn_die("sched_setscheduler");
         }
       }
       if (flags & POSIX_SPAWN_SETSCHEDPARAM) {
-        posix_spawnattr_getschedparam(attrp, &param);
-        if (sched_setparam(0, &param)) {
+        if (sched_setparam(0, &(*attrp)->schedparam)) {
           posix_spawn_die("sched_setparam");
         }
       }
     }
+    if (flags & POSIX_SPAWN_SETRLIMIT) {
+      for (int rez = 0; rez <= ARRAYLEN((*attrp)->rlim); ++rez) {
+        if ((*attrp)->rlimset & (1u << rez)) {
+          if (setrlimit(rez, (*attrp)->rlim + rez)) {
+            posix_spawn_die("setrlimit");
+          }
+        }
+      }
+    }
     if (!envp) envp = environ;
     execve(path, argv, envp);
-    posix_spawn_die("execve");
-  } else if (child != -1) {
+    if (errno == ETXTBSY) {
+      sys_kill(getpid(), SIGVTALRM, 1);
+    }
+    posix_spawn_die(path);
+  }
+  sys_sigprocmask(SIG_SETMASK, &oldmask, 0);
+  pthread_setcancelstate(cs, 0);
+  if (child != -1) {
     if (pid) *pid = child;
     return 0;
   } else {
diff --git a/libc/stdio/posix_spawn.h b/libc/stdio/posix_spawn.h
index 1c47992e7..df65a2ff6 100644
--- a/libc/stdio/posix_spawn.h
+++ b/libc/stdio/posix_spawn.h
@@ -1,8 +1,10 @@
 #ifndef COSMOPOLITAN_LIBC_STDIO_SPAWN_H_
 #define COSMOPOLITAN_LIBC_STDIO_SPAWN_H_
+#include "libc/calls/struct/rlimit.h"
 #include "libc/calls/struct/sched_param.h"
 #include "libc/calls/struct/sigset.h"
 
+#define POSIX_SPAWN_USEVFORK      0
 #define POSIX_SPAWN_RESETIDS      1
 #define POSIX_SPAWN_SETPGROUP     2
 #define POSIX_SPAWN_SETSIGDEF     4
@@ -10,6 +12,7 @@
 #define POSIX_SPAWN_SETSCHEDPARAM 16
 #define POSIX_SPAWN_SETSCHEDULER  32
 #define POSIX_SPAWN_SETSID        128
+#define POSIX_SPAWN_SETRLIMIT     256
 
 #if !(__ASSEMBLER__ + __LINKER__ + 0)
 COSMOPOLITAN_C_START_
@@ -45,6 +48,8 @@ int posix_spawnattr_getsigmask(const posix_spawnattr_t *, sigset_t *);
 int posix_spawnattr_setsigmask(posix_spawnattr_t *, const sigset_t *);
 int posix_spawnattr_getsigdefault(const posix_spawnattr_t *, sigset_t *);
 int posix_spawnattr_setsigdefault(posix_spawnattr_t *, const sigset_t *);
+int posix_spawnattr_getrlimit(const posix_spawnattr_t *, int, struct rlimit *);
+int posix_spawnattr_setrlimit(posix_spawnattr_t *, int, const struct rlimit *);
 
 COSMOPOLITAN_C_END_
 #endif /* !(__ASSEMBLER__ + __LINKER__ + 0) */
diff --git a/libc/stdio/posix_spawn.internal.h b/libc/stdio/posix_spawn.internal.h
index 06051e3e1..1a80b95cb 100644
--- a/libc/stdio/posix_spawn.internal.h
+++ b/libc/stdio/posix_spawn.internal.h
@@ -1,5 +1,6 @@
 #ifndef COSMOPOLITAN_LIBC_STDIO_SPAWNA_INTERNAL_H_
 #define COSMOPOLITAN_LIBC_STDIO_SPAWNA_INTERNAL_H_
+#include "libc/calls/struct/rlimit.h"
 #include "libc/calls/struct/sched_param.h"
 #include "libc/calls/struct/sigset.h"
 
@@ -11,15 +12,16 @@
 COSMOPOLITAN_C_START_
 
 struct _posix_spawna {
-  char flags;
+  short flags;
   bool schedparam_isset;
   bool schedpolicy_isset;
-  bool sigmask_isset;
   int pgroup;
+  int rlimset;
   int schedpolicy;
   struct sched_param schedparam;
   sigset_t sigmask;
   sigset_t sigdefault;
+  struct rlimit rlim[16];
 };
 
 struct _posix_faction {
diff --git a/libc/stdio/posix_spawnattr.c b/libc/stdio/posix_spawnattr.c
index 7b2763135..12a51240e 100644
--- a/libc/stdio/posix_spawnattr.c
+++ b/libc/stdio/posix_spawnattr.c
@@ -21,6 +21,7 @@
 #include "libc/calls/struct/sigset.h"
 #include "libc/dce.h"
 #include "libc/errno.h"
+#include "libc/macros.internal.h"
 #include "libc/mem/mem.h"
 #include "libc/stdio/posix_spawn.h"
 #include "libc/stdio/posix_spawn.internal.h"
@@ -76,11 +77,6 @@ int posix_spawnattr_getflags(const posix_spawnattr_t *attr, short *flags) {
 /**
  * Sets posix_spawn() flags.
  *
- * Setting these flags is needed in order for the other setters in this
- * function to take effect. If a flag is known but unsupported by the
- * host platform, it'll be silently removed from the flags. You can
- * check for this by calling the getter afterwards.
- *
  * @param attr was initialized by posix_spawnattr_init()
  * @param flags may have any of the following
  *     - `POSIX_SPAWN_RESETIDS`
@@ -94,9 +90,6 @@ int posix_spawnattr_getflags(const posix_spawnattr_t *attr, short *flags) {
  * @raise EINVAL if `flags` has invalid bits
  */
 int posix_spawnattr_setflags(posix_spawnattr_t *attr, short flags) {
-  if (!(IsLinux() || IsFreebsd() || IsNetbsd())) {
-    flags &= ~(POSIX_SPAWN_SETSCHEDPARAM | POSIX_SPAWN_SETSCHEDULER);
-  }
   if (flags &
       ~(POSIX_SPAWN_RESETIDS | POSIX_SPAWN_SETPGROUP | POSIX_SPAWN_SETSIGDEF |
         POSIX_SPAWN_SETSIGMASK | POSIX_SPAWN_SETSCHEDPARAM |
@@ -107,134 +100,62 @@ int posix_spawnattr_setflags(posix_spawnattr_t *attr, short flags) {
   return 0;
 }
 
+/**
+ * Gets process group id associated with attributes.
+ *
+ * @param attr was initialized by posix_spawnattr_init()
+ * @param pgroup receives the result on success
+ * @return 0 on success, or errno on error
+ */
 int posix_spawnattr_getpgroup(const posix_spawnattr_t *attr, int *pgroup) {
   *pgroup = (*attr)->pgroup;
   return 0;
 }
 
+/**
+ * Specifies process group into which child process is placed.
+ *
+ * Setting `pgroup` to zero will ensure newly created processes are
+ * placed within their own brand new process group.
+ *
+ * This setter also sets the `POSIX_SPAWN_SETPGROUP` flag.
+ *
+ * @param attr was initialized by posix_spawnattr_init()
+ * @param pgroup is the process group id, or 0 for self
+ * @return 0 on success, or errno on error
+ */
 int posix_spawnattr_setpgroup(posix_spawnattr_t *attr, int pgroup) {
+  (*attr)->flags |= POSIX_SPAWN_SETPGROUP;
   (*attr)->pgroup = pgroup;
   return 0;
 }
 
-/**
- * Gets scheduler policy that'll be used for spawned process.
- *
- * If the setter wasn't called then this function will return the
- * scheduling policy of the current process.
- *
- * @param attr was initialized by posix_spawnattr_init()
- * @param schedpolicy receives the result
- * @return 0 on success, or errno on error
- * @raise ENOSYS if platform support isn't available
- */
-int posix_spawnattr_getschedpolicy(const posix_spawnattr_t *attr,
-                                   int *schedpolicy) {
-  int rc, e = errno;
-  struct _posix_spawna *a = *(/*unconst*/ posix_spawnattr_t *)attr;
-  if (!a->schedpolicy_isset) {
-    rc = sched_getscheduler(0);
-    if (rc == -1) {
-      rc = errno;
-      errno = e;
-      return rc;
-    }
-    a->schedpolicy = rc;
-    a->schedpolicy_isset = true;
-  }
-  *schedpolicy = a->schedpolicy;
-  return 0;
-}
-
-/**
- * Specifies scheduler policy override for spawned process.
- *
- * Scheduling policies are inherited by default. Use this to change it.
- *
- * @param attr was initialized by posix_spawnattr_init()
- * @param schedpolicy receives the result
- * @return 0 on success, or errno on error
- */
-int posix_spawnattr_setschedpolicy(posix_spawnattr_t *attr, int schedpolicy) {
-  (*attr)->schedpolicy = schedpolicy;
-  (*attr)->schedpolicy_isset = true;
-  return 0;
-}
-
-/**
- * Gets scheduler parameter that'll be used for spawned process.
- *
- * If the setter wasn't called then this function will return the
- * scheduling parameter of the current process.
- *
- * @param attr was initialized by posix_spawnattr_init()
- * @param schedparam receives the result
- * @return 0 on success, or errno on error
- * @raise ENOSYS if platform support isn't available
- */
-int posix_spawnattr_getschedparam(const posix_spawnattr_t *attr,
-                                  struct sched_param *schedparam) {
-  int rc, e = errno;
-  struct _posix_spawna *a = *(/*unconst*/ posix_spawnattr_t *)attr;
-  if (!a->schedparam_isset) {
-    rc = sched_getparam(0, &a->schedparam);
-    if (rc == -1) {
-      rc = errno;
-      errno = e;
-      return rc;
-    }
-    a->schedparam_isset = true;
-  }
-  *schedparam = a->schedparam;
-  return 0;
-}
-
-/**
- * Specifies scheduler parameter override for spawned process.
- *
- * Scheduling parameters are inherited by default. Use this to change it.
- *
- * @param attr was initialized by posix_spawnattr_init()
- * @param schedparam receives the result
- * @return 0 on success, or errno on error
- */
-int posix_spawnattr_setschedparam(posix_spawnattr_t *attr,
-                                  const struct sched_param *schedparam) {
-  (*attr)->schedparam = *schedparam;
-  (*attr)->schedparam_isset = true;
-  return 0;
-}
-
 /**
  * Gets signal mask for sigprocmask() in child process.
  *
- * If the setter wasn't called then this function will return the
- * scheduling parameter of the current process.
+ * The signal mask is applied to the child process in such a way that
+ * signal handlers from the parent process can't get triggered in the
+ * child process.
  *
  * @return 0 on success, or errno on error
  */
 int posix_spawnattr_getsigmask(const posix_spawnattr_t *attr,
                                sigset_t *sigmask) {
-  struct _posix_spawna *a = *(/*unconst*/ posix_spawnattr_t *)attr;
-  if (!a->sigmask_isset) {
-    npassert(!sigprocmask(SIG_SETMASK, 0, &a->sigmask));
-    a->sigmask_isset = true;
-  }
-  *sigmask = a->sigmask;
+  *sigmask = (*attr)->sigmask;
   return 0;
 }
 
 /**
  * Specifies signal mask for sigprocmask() in child process.
  *
- * Signal masks are inherited by default. Use this to change it.
+ * This setter also sets the `POSIX_SPAWN_SETSIGMASK` flag.
  *
  * @return 0 on success, or errno on error
  */
 int posix_spawnattr_setsigmask(posix_spawnattr_t *attr,
                                const sigset_t *sigmask) {
+  (*attr)->flags |= POSIX_SPAWN_SETSIGMASK;
   (*attr)->sigmask = *sigmask;
-  (*attr)->sigmask_isset = true;
   return 0;
 }
 
@@ -252,10 +173,119 @@ int posix_spawnattr_getsigdefault(const posix_spawnattr_t *attr,
 /**
  * Specifies which signals should be restored to `SIG_DFL`.
  *
+ * This routine isn't necessary in most cases, since posix_spawn() by
+ * default will try to avoid vfork() race conditions by tracking what
+ * signals have a handler function and then resets them automatically
+ * within the child process, before applying the child's signal mask.
+ * This function may be used to ensure the `SIG_IGN` disposition will
+ * not propagate across execve in cases where this process explicitly
+ * set the signals to `SIG_IGN` earlier (since posix_spawn() will not
+ * issue O(128) system calls just to be totally pedantic about that).
+ *
+ * Using this setter automatically sets `POSIX_SPAWN_SETSIGDEF`.
+ *
  * @return 0 on success, or errno on error
  */
 int posix_spawnattr_setsigdefault(posix_spawnattr_t *attr,
                                   const sigset_t *sigdefault) {
+  (*attr)->flags |= POSIX_SPAWN_SETSIGDEF;
   (*attr)->sigdefault = *sigdefault;
   return 0;
 }
+
+/**
+ * Gets resource limit for spawned process.
+ *
+ * @return 0 on success, or errno on error
+ * @raise EINVAL if `resource` is invalid
+ * @raise ENOENT if `resource` is absent
+ */
+int posix_spawnattr_getrlimit(const posix_spawnattr_t *attr, int resource,
+                              struct rlimit *rlim) {
+  if ((0 <= resource && resource < ARRAYLEN((*attr)->rlim))) {
+    if (((*attr)->rlimset & (1u << resource))) {
+      *rlim = (*attr)->rlim[resource];
+      return 0;
+    } else {
+      return ENOENT;
+    }
+  } else {
+    return EINVAL;
+  }
+}
+
+/**
+ * Sets resource limit on spawned process.
+ *
+ * Using this setter automatically sets `POSIX_SPAWN_SETRLIMIT`.
+ *
+ * @return 0 on success, or errno on error
+ * @raise EINVAL if resource is invalid
+ */
+int posix_spawnattr_setrlimit(posix_spawnattr_t *attr, int resource,
+                              const struct rlimit *rlim) {
+  if (0 <= resource && resource < ARRAYLEN((*attr)->rlim)) {
+    (*attr)->flags |= POSIX_SPAWN_SETRLIMIT;
+    (*attr)->rlimset |= 1u << resource;
+    (*attr)->rlim[resource] = *rlim;
+    return 0;
+  } else {
+    return EINVAL;
+  }
+}
+
+/**
+ * Gets scheduler policy that'll be used for spawned process.
+ *
+ * @param attr was initialized by posix_spawnattr_init()
+ * @param schedpolicy receives the result
+ * @return 0 on success, or errno on error
+ */
+int posix_spawnattr_getschedpolicy(const posix_spawnattr_t *attr,
+                                   int *schedpolicy) {
+  *schedpolicy = (*attr)->schedpolicy;
+  return 0;
+}
+
+/**
+ * Specifies scheduler policy override for spawned process.
+ *
+ * Using this setter automatically sets `POSIX_SPAWN_SETSCHEDULER`.
+ *
+ * @param attr was initialized by posix_spawnattr_init()
+ * @return 0 on success, or errno on error
+ */
+int posix_spawnattr_setschedpolicy(posix_spawnattr_t *attr, int schedpolicy) {
+  (*attr)->flags |= POSIX_SPAWN_SETSCHEDULER;
+  (*attr)->schedpolicy = schedpolicy;
+  return 0;
+}
+
+/**
+ * Gets scheduler parameter.
+ *
+ * @param attr was initialized by posix_spawnattr_init()
+ * @param schedparam receives the result
+ * @return 0 on success, or errno on error
+ */
+int posix_spawnattr_getschedparam(const posix_spawnattr_t *attr,
+                                  struct sched_param *schedparam) {
+  *schedparam = (*attr)->schedparam;
+  return 0;
+}
+
+/**
+ * Specifies scheduler parameter override for spawned process.
+ *
+ * Using this setter automatically sets `POSIX_SPAWN_SETSCHEDPARAM`.
+ *
+ * @param attr was initialized by posix_spawnattr_init()
+ * @param schedparam receives the result
+ * @return 0 on success, or errno on error
+ */
+int posix_spawnattr_setschedparam(posix_spawnattr_t *attr,
+                                  const struct sched_param *schedparam) {
+  (*attr)->flags |= POSIX_SPAWN_SETSCHEDPARAM;
+  (*attr)->schedparam = *schedparam;
+  return 0;
+}
diff --git a/libc/stdio/stdio.h b/libc/stdio/stdio.h
index 3cad71ef4..9b3788315 100644
--- a/libc/stdio/stdio.h
+++ b/libc/stdio/stdio.h
@@ -1,11 +1,12 @@
 #ifndef COSMOPOLITAN_LIBC_STDIO_H_
 #define COSMOPOLITAN_LIBC_STDIO_H_
 
-#define EOF    -1  /* end of file */
-#define WEOF   -1u /* end of file (multibyte) */
-#define _IOFBF 0   /* fully buffered */
-#define _IOLBF 1   /* line buffered */
-#define _IONBF 2   /* no buffering */
+#define EOF      -1  /* end of file */
+#define WEOF     -1u /* end of file (multibyte) */
+#define _IOFBF   0   /* fully buffered */
+#define _IOLBF   1   /* line buffered */
+#define _IONBF   2   /* no buffering */
+#define _CS_PATH 0
 
 #define L_tmpnam     20
 #define L_ctermid    20
@@ -80,6 +81,7 @@ int setvbuf(FILE *, char *, int, size_t);
 int pclose(FILE *);
 char *ctermid(char *);
 void perror(const char *) relegated;
+size_t confstr(int, char *, size_t);
 
 typedef uint64_t fpos_t;
 char *gets(char *) paramsnonnull();
diff --git a/libc/stdio/tmpfile.c b/libc/stdio/tmpfile.c
index 5452be9b6..ab110bbb2 100644
--- a/libc/stdio/tmpfile.c
+++ b/libc/stdio/tmpfile.c
@@ -34,7 +34,7 @@
  * This creates a secure temporary file inside $TMPDIR. If it isn't
  * defined, then /tmp is used on UNIX and GetTempPath() is used on the
  * New Technology. This resolution of $TMPDIR happens once in a ctor,
- * which is copied to the `kTmpDir` global.
+ * which is copied to the `kTmpPath` global.
  *
  * Once fclose() is called, the returned file is guaranteed to be
  * deleted automatically. On UNIX the file is unlink()'d before this
diff --git a/libc/str/tprecode8to16.c b/libc/str/tprecode8to16.c
index 2100bf143..2ee1b9053 100644
--- a/libc/str/tprecode8to16.c
+++ b/libc/str/tprecode8to16.c
@@ -62,8 +62,8 @@ axdx_t tprecode8to16(char16_t *dst, size_t dstsize, const char *src) {
   r.ax = 0;
   r.dx = 0;
   for (;;) {
-#ifdef __x86_64__
-    if (!IsTiny() && !((uintptr_t)(src + r.dx) & 15)) {
+#if defined(__x86_64__) && !IsModeDbg()
+    if (!((uintptr_t)(src + r.dx) & 15)) {
       r = tprecode8to16_sse2(dst, dstsize, src, r);
     }
 #endif
diff --git a/libc/temp.h b/libc/temp.h
index 3f4930bed..f818a8444 100644
--- a/libc/temp.h
+++ b/libc/temp.h
@@ -3,7 +3,7 @@
 #if !(__ASSEMBLER__ + __LINKER__ + 0)
 COSMOPOLITAN_C_START_
 
-char *mktemp(char *) returnsnonnull paramsnonnull() __wur;
+char *mktemp(char *) returnsnonnull paramsnonnull();
 char *mkdtemp(char *) paramsnonnull() __wur;
 int mkstemp(char *) paramsnonnull() __wur;
 int mkstemps(char *, int) paramsnonnull() __wur;
diff --git a/libc/testlib/testmain.c b/libc/testlib/testmain.c
index 4fbbd5f04..24cac360f 100644
--- a/libc/testlib/testmain.c
+++ b/libc/testlib/testmain.c
@@ -27,6 +27,7 @@
 #include "libc/errno.h"
 #include "libc/intrin/asan.internal.h"
 #include "libc/intrin/bits.h"
+#include "libc/intrin/kprintf.h"
 #include "libc/intrin/safemacros.internal.h"
 #include "libc/intrin/strace.internal.h"
 #include "libc/intrin/weaken.h"
diff --git a/libc/thread/posixthread.internal.h b/libc/thread/posixthread.internal.h
index c891d2602..6e6dec6a4 100644
--- a/libc/thread/posixthread.internal.h
+++ b/libc/thread/posixthread.internal.h
@@ -1,6 +1,7 @@
 #ifndef COSMOPOLITAN_LIBC_THREAD_POSIXTHREAD_INTERNAL_H_
 #define COSMOPOLITAN_LIBC_THREAD_POSIXTHREAD_INTERNAL_H_
 #include "libc/calls/struct/sched_param.h"
+#include "libc/calls/struct/sigaltstack.h"
 #include "libc/calls/struct/sigset.h"
 #include "libc/intrin/dll.h"
 #include "libc/runtime/runtime.h"
@@ -75,7 +76,6 @@ struct PosixThread {
   void *(*start)(void *);  // creation callback
   void *arg;               // start's parameter
   void *rc;                // start's return value
-  char *altstack;          // thread sigaltstack
   char *tls;               // bottom of tls allocation
   struct CosmoTib *tib;    // middle of tls allocation
   struct Dll list;         // list of threads
diff --git a/libc/thread/pthread_create.c b/libc/thread/pthread_create.c
index 7dbcb559e..fb58ded0a 100644
--- a/libc/thread/pthread_create.c
+++ b/libc/thread/pthread_create.c
@@ -20,7 +20,6 @@
 #include "libc/atomic.h"
 #include "libc/calls/blocksigs.internal.h"
 #include "libc/calls/calls.h"
-#include "libc/calls/struct/sigaltstack.h"
 #include "libc/calls/syscall-sysv.internal.h"
 #include "libc/dce.h"
 #include "libc/errno.h"
@@ -29,7 +28,7 @@
 #include "libc/intrin/bits.h"
 #include "libc/intrin/bsr.h"
 #include "libc/intrin/dll.h"
-#include "libc/intrin/popcnt.h"
+#include "libc/intrin/kprintf.h"
 #include "libc/log/internal.h"
 #include "libc/macros.internal.h"
 #include "libc/mem/mem.h"
@@ -60,64 +59,30 @@ static unsigned long roundup2pow(unsigned long x) {
 }
 
 void _pthread_free(struct PosixThread *pt) {
-  static atomic_uint freed;
   if (pt->flags & PT_STATIC) return;
   free(pt->tls);
   if ((pt->flags & PT_OWNSTACK) &&  //
       pt->attr.__stackaddr &&       //
       pt->attr.__stackaddr != MAP_FAILED) {
-    npassert(!munmap(pt->attr.__stackaddr, pt->attr.__stacksize));
-  }
-  if (pt->altstack) {
-    free(pt->altstack);
+    unassert(!munmap(pt->attr.__stackaddr, pt->attr.__stacksize));
   }
   free(pt);
-  if (popcnt(atomic_fetch_add_explicit(&freed, 1, memory_order_acq_rel)) == 1) {
-    malloc_trim(0);
-  }
-}
-
-void pthread_kill_siblings_np(void) {
-  struct Dll *e, *e2;
-  struct PosixThread *pt, *self;
-  self = (struct PosixThread *)__get_tls()->tib_pthread;
-  pthread_spin_lock(&_pthread_lock);
-  for (e = dll_first(_pthread_list); e; e = e2) {
-    e2 = dll_next(_pthread_list, e);
-    pt = POSIXTHREAD_CONTAINER(e);
-    if (pt != self) {
-      pthread_kill((pthread_t)pt, SIGKILL);
-      dll_remove(&_pthread_list, e);
-      pthread_spin_unlock(&_pthread_lock);
-      _pthread_free(pt);
-    }
-  }
-  pthread_spin_unlock(&_pthread_lock);
 }
 
 static int PosixThread(void *arg, int tid) {
   void *rc;
-  struct sigaltstack ss;
   struct PosixThread *pt = arg;
   unassert(__get_tls()->tib_tid > 0);
-  if (pt->altstack) {
-    ss.ss_flags = 0;
-    ss.ss_size = SIGSTKSZ;
-    ss.ss_sp = pt->altstack;
-    if (sigaltstack(&ss, 0)) {
-      notpossible;
-    }
-  }
   if (pt->attr.__inheritsched == PTHREAD_EXPLICIT_SCHED) {
     _pthread_reschedule(pt);
   }
   // set long jump handler so pthread_exit can bring control back here
   if (!setjmp(pt->exiter)) {
     __get_tls()->tib_pthread = (pthread_t)pt;
-    npassert(!sigprocmask(SIG_SETMASK, (sigset_t *)pt->attr.__sigmask, 0));
+    unassert(!sigprocmask(SIG_SETMASK, (sigset_t *)pt->attr.__sigmask, 0));
     rc = pt->start(pt->arg);
     // ensure pthread_cleanup_pop(), and pthread_exit() popped cleanup
-    npassert(!pt->cleanup);
+    unassert(!pt->cleanup);
     // calling pthread_exit() will either jump back here, or call exit
     pthread_exit(rc);
   }
@@ -251,11 +216,6 @@ static errno_t pthread_create_impl(pthread_t *thread,
     }
   }
 
-  // setup signal handler stack
-  if (_wantcrashreports && !IsWindows()) {
-    pt->altstack = malloc(SIGSTKSZ);
-  }
-
   // set initial status
   if (!pt->attr.__havesigmask) {
     pt->attr.__havesigmask = true;
diff --git a/libc/thread/thread.h b/libc/thread/thread.h
index 51832fb01..708e15306 100644
--- a/libc/thread/thread.h
+++ b/libc/thread/thread.h
@@ -194,7 +194,6 @@ int pthread_spin_unlock(pthread_spinlock_t *) paramsnonnull();
 int pthread_testcancel_np(void);
 int pthread_tryjoin_np(pthread_t, void **);
 int pthread_yield(void);
-void pthread_kill_siblings_np(void);
 pthread_id_np_t pthread_getthreadid_np(void);
 pthread_t pthread_self(void) pureconst;
 void *pthread_getspecific(pthread_key_t);
diff --git a/net/https/https.mk b/net/https/https.mk
index 4c816cc9f..cba4dab4a 100644
--- a/net/https/https.mk
+++ b/net/https/https.mk
@@ -31,6 +31,7 @@ NET_HTTPS_A_DIRECTDEPS =			\
 	LIBC_STDIO				\
 	LIBC_STR				\
 	LIBC_SYSV				\
+	LIBC_THREAD				\
 	LIBC_TIME				\
 	LIBC_X					\
 	THIRD_PARTY_COMPILER_RT			\
diff --git a/net/https/initializerng.c b/net/https/initializerng.c
index cca528849..5b9ed6e2c 100644
--- a/net/https/initializerng.c
+++ b/net/https/initializerng.c
@@ -24,7 +24,7 @@
 void InitializeRng(mbedtls_ctr_drbg_context *r) {
   unsigned char b[64];
   mbedtls_ctr_drbg_init(r);
-  CHECK(getrandom(b, 64, 0) == 64);
-  CHECK(!mbedtls_ctr_drbg_seed(r, GetEntropy, 0, b, 64));
+  getrandom(b, 64, 0);
+  mbedtls_ctr_drbg_seed(r, GetEntropy, 0, b, 64);
   mbedtls_platform_zeroize(b, 64);
 }
diff --git a/net/https/sslcache.c b/net/https/sslcache.c
deleted file mode 100644
index c4ddd0862..000000000
--- a/net/https/sslcache.c
+++ /dev/null
@@ -1,220 +0,0 @@
-/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
-│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8                                :vi│
-╞══════════════════════════════════════════════════════════════════════════════╡
-│ Copyright 2021 Justine Alexandra Roberts Tunney                              │
-│                                                                              │
-│ Permission to use, copy, modify, and/or distribute this software for         │
-│ any purpose with or without fee is hereby granted, provided that the         │
-│ above copyright notice and this permission notice appear in all copies.      │
-│                                                                              │
-│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL                │
-│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED                │
-│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE             │
-│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL         │
-│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR        │
-│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER               │
-│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
-│ PERFORMANCE OF THIS SOFTWARE.                                                │
-╚─────────────────────────────────────────────────────────────────────────────*/
-#include "net/https/sslcache.h"
-#include "libc/calls/calls.h"
-#include "libc/calls/struct/stat.h"
-#include "libc/errno.h"
-#include "libc/intrin/bits.h"
-#include "libc/intrin/bsr.h"
-#include "libc/intrin/cmpxchg.h"
-#include "libc/intrin/safemacros.internal.h"
-#include "libc/log/check.h"
-#include "libc/log/log.h"
-#include "libc/macros.internal.h"
-#include "libc/nexgen32e/rdtsc.h"
-#include "libc/runtime/runtime.h"
-#include "libc/str/str.h"
-#include "libc/sysv/consts/map.h"
-#include "libc/sysv/consts/o.h"
-#include "libc/sysv/consts/prot.h"
-#include "libc/time/time.h"
-#include "third_party/mbedtls/ssl.h"
-#include "third_party/mbedtls/x509_crt.h"
-
-#define PROT  (PROT_READ | PROT_WRITE)
-#define FLAGS MAP_SHARED
-
-static uint32_t HashSslSession(const mbedtls_ssl_session *session) {
-  int i;
-  uint32_t h;
-  h = session->ciphersuite;
-  h *= 0x9e3779b1;
-  h = session->compression;
-  h *= 0x9e3779b1;
-  for (i = 0; i < session->id_len; i++) {
-    h += session->id[i];
-    h *= 0x9e3779b1;
-  }
-  return h;
-}
-
-static struct SslCache *OpenSslCache(const char *path, size_t size) {
-  int fd;
-  struct stat st;
-  struct SslCache *c = NULL;
-  if (path) {
-    if ((fd = open(path, O_RDWR | O_CREAT, 0600)) != -1) {
-      CHECK_NE(-1, fstat(fd, &st));
-      if (st.st_size && st.st_size != size) {
-        WARNF("unlinking sslcache because size changed from %,zu to %,zu",
-              st.st_size, size);
-        unlink(path);
-        fd = open(path, O_RDWR | O_CREAT, 0600);
-        st.st_size = 0;
-      }
-      if (fd != -1) {
-        if (!st.st_size) CHECK_NE(-1, ftruncate(fd, size));
-        c = mmap(0, size, PROT, FLAGS, fd, 0);
-        close(fd);
-      }
-    } else {
-      WARNF("sslcache open(%`'s) failed %s", path, strerror(errno));
-    }
-  }
-  return c;
-}
-
-static unsigned long rounddown2pow(unsigned long x) {
-  return x ? 1ul << _bsrl(x) : 0;
-}
-
-struct SslCache *CreateSslCache(const char *path, size_t bytes, int lifetime) {
-  size_t ents, size;
-  struct SslCache *c;
-  if (!bytes) bytes = 10 * 1024 * 1024;
-  if (lifetime <= 0) lifetime = 24 * 60 * 60;
-  ents = rounddown2pow(MAX(2, bytes / sizeof(struct SslCacheEntry)));
-  size = sizeof(struct SslCache) + sizeof(struct SslCacheEntry) * ents;
-  size = ROUNDUP(size, FRAMESIZE);
-  c = OpenSslCache(path, size);
-  if (!c) c = mmap(0, size, PROT, FLAGS | MAP_ANONYMOUS, -1, 0);
-  CHECK_NE(MAP_FAILED, c);
-  VERBOSEF("opened %`'s %,zu bytes with %,u slots",
-           c ? path : "anonymous shared memory", size, ents);
-  c->lifetime = lifetime;
-  c->size = size;
-  c->mask = ents - 1;
-  return c;
-}
-
-void FreeSslCache(struct SslCache *cache) {
-  if (!cache) return;
-  CHECK_NE(-1, munmap(cache, cache->size));
-}
-
-int UncacheSslSession(void *data, mbedtls_ssl_session *session) {
-  int64_t ts;
-  uint64_t tick;
-  unsigned char *ticket;
-  struct SslCache *cache;
-  mbedtls_x509_crt *cert;
-  struct SslCacheEntry *e;
-  uint32_t i, hash, ticketlen;
-  INFOF("uncache");
-  cache = data;
-  hash = HashSslSession(session);
-  i = hash & cache->mask;
-  e = cache->p + i;
-  if (!(tick = e->tick) || hash != e->hash) {
-    NOISEF("%u empty", i);
-    return 1;
-  }
-  asm volatile("" ::: "memory");
-  if (session->ciphersuite != e->session.ciphersuite ||
-      session->compression != e->session.compression ||
-      session->id_len != e->session.id_len ||
-      memcmp(session->id, e->session.id, e->session.id_len)) {
-    VERBOSEF("%u sslcache collision", i);
-    return 1;
-  }
-  ts = time(0);
-  if (!(e->time <= ts && ts <= e->time + cache->lifetime)) {
-    DEBUGF("%u sslcache expired", i);
-    _cmpxchg(&e->tick, tick, 0);
-    return 1;
-  }
-  cert = 0;
-  ticket = 0;
-  if ((e->certlen && (!(cert = calloc(1, sizeof(*cert))) ||
-                      mbedtls_x509_crt_parse_der(cert, e->cert, e->certlen)))) {
-    goto Contention;
-  }
-  if ((ticketlen = e->ticketlen)) {
-    if (!(ticket = malloc(ticketlen))) goto Contention;
-    memcpy(ticket, e->ticket, ticketlen);
-  }
-  mbedtls_ssl_session_free(session);
-  memcpy(session, &e->session, sizeof(*session));
-  asm volatile("" ::: "memory");
-  if (tick != e->tick) goto Contention;
-  session->peer_cert = cert;
-  session->ticket = ticket;
-  session->ticket_len = ticketlen;
-  DEBUGF("%u restored ssl from cache", i);
-  return 0;
-Contention:
-  WARNF("%u sslcache contention 0x%08x", i, hash);
-  mbedtls_x509_crt_free(cert);
-  free(ticket);
-  free(cert);
-  return 1;
-}
-
-int CacheSslSession(void *data, const mbedtls_ssl_session *session) {
-  int pid;
-  uint64_t tick;
-  uint32_t i, hash;
-  struct SslCache *cache;
-  struct SslCacheEntry *e;
-  cache = data;
-  if (session->peer_cert &&
-      session->peer_cert->raw.len > sizeof(cache->p[0].cert)) {
-    WARNF("%s too big %zu", "cert", session->peer_cert->raw.len);
-    return 1;
-  }
-  if (session->ticket && session->ticket_len > sizeof(cache->p[0].ticket)) {
-    WARNF("%s too big %zu", "ticket", session->ticket_len);
-    return 1;
-  }
-  pid = getpid();
-  hash = HashSslSession(session);
-  i = hash & cache->mask;
-  e = cache->p + i;
-  e->tick = 0;
-  e->pid = pid;
-  asm volatile("" ::: "memory");
-  memcpy(&e->session, session, sizeof(*session));
-  if (session->peer_cert) {
-    e->certlen = session->peer_cert->raw.len;
-    memcpy(e->cert, session->peer_cert->raw.p, session->peer_cert->raw.len);
-  } else {
-    e->certlen = 0;
-  }
-  if (session->ticket) {
-    e->ticketlen = session->ticket_len;
-    memcpy(e->ticket, session->ticket, session->ticket_len);
-  } else {
-    e->ticketlen = 0;
-  }
-  e->hash = hash;
-  e->time = time(0);
-  tick = rdtsc();
-  asm volatile("" ::: "memory");
-  if (tick && _cmpxchg(&e->pid, pid, 0)) {
-    DEBUGF("%u saved %s%s %`#.*s", i,
-           mbedtls_ssl_get_ciphersuite_name(session->ciphersuite),
-           session->compression ? " DEFLATE" : "", session->id_len,
-           session->id);
-    e->tick = tick;
-    return 0;
-  } else {
-    WARNF("%u congestion", i);
-    return 1;
-  }
-}
diff --git a/net/https/sslcache.h b/net/https/sslcache.h
deleted file mode 100644
index 996435cc4..000000000
--- a/net/https/sslcache.h
+++ /dev/null
@@ -1,32 +0,0 @@
-#ifndef COSMOPOLITAN_NET_HTTPS_SSLCACHE_H_
-#define COSMOPOLITAN_NET_HTTPS_SSLCACHE_H_
-#include "third_party/mbedtls/ssl.h"
-#if !(__ASSEMBLER__ + __LINKER__ + 0)
-COSMOPOLITAN_C_START_
-
-struct SslCache {
-  size_t size;
-  int lifetime;
-  uint32_t mask;
-  struct SslCacheEntry {
-    int64_t time;
-    volatile uint64_t tick;
-    volatile int pid;
-    uint32_t hash;
-    unsigned certlen;
-    unsigned ticketlen;
-    mbedtls_ssl_session session;
-    uint8_t cert[1500];
-    uint8_t ticket[500];
-  } p[];
-};
-
-struct SslCache *CreateSslCache(const char *, size_t, int);
-void FreeSslCache(struct SslCache *);
-int UncacheSslSession(void *, mbedtls_ssl_session *);
-int CacheSslSession(void *, const mbedtls_ssl_session *);
-char *GetSslCacheFile(void);
-
-COSMOPOLITAN_C_END_
-#endif /* !(__ASSEMBLER__ + __LINKER__ + 0) */
-#endif /* COSMOPOLITAN_NET_HTTPS_SSLCACHE_H_ */
diff --git a/net/https/tlserror.c b/net/https/tlserror.c
index 694937605..6a45068cd 100644
--- a/net/https/tlserror.c
+++ b/net/https/tlserror.c
@@ -20,7 +20,7 @@
 #include "third_party/mbedtls/error.h"
 
 char *GetTlsError(int r) {
-  static char b[128];
+  static _Thread_local char b[128];
   mbedtls_strerror(r, b, sizeof(b));
   return b;
 }
diff --git a/test/libc/calls/dup_test.c b/test/libc/calls/dup_test.c
index 2df824286..4a78ed647 100644
--- a/test/libc/calls/dup_test.c
+++ b/test/libc/calls/dup_test.c
@@ -19,6 +19,7 @@
 #include "libc/calls/calls.h"
 #include "libc/calls/internal.h"
 #include "libc/calls/struct/stat.h"
+#include "libc/dce.h"
 #include "libc/errno.h"
 #include "libc/log/check.h"
 #include "libc/runtime/runtime.h"
@@ -69,7 +70,10 @@ TEST(dup, bigNumber) {
 
 #ifdef __x86_64__
 TEST(dup, clearsCloexecFlag) {
+  static bool once;
   int ws;
+  ASSERT_FALSE(once);
+  once = true;
   ASSERT_SYS(0, 0, close(creat("file", 0644)));
   ASSERT_SYS(0, 3, open("file", O_RDWR | O_CLOEXEC));
   ASSERT_NE(-1, (ws = xspawn(0)));
@@ -79,7 +83,7 @@ TEST(dup, clearsCloexecFlag) {
           (char *const[]){GetProgramExecutableName(), "boop", 0});
     _exit(127);
   }
-  ASSERT_EQ(72, WEXITSTATUS(ws));
+  ASSERT_EQ(72 << 8, ws);
   ASSERT_SYS(0, 0, close(3));
 }
 #endif
diff --git a/test/libc/calls/write_test.c b/test/libc/calls/write_test.c
index f1f4c20c3..6d0e9c321 100644
--- a/test/libc/calls/write_test.c
+++ b/test/libc/calls/write_test.c
@@ -57,6 +57,17 @@ TEST(write, badMemory_efault) {
   ASSERT_SYS(EFAULT, -1, write(1, (void *)1, 1));
 }
 
+TEST(write, brokenPipe_raisesSigpipe) {
+  int fds[2];
+  SPAWN(fork);
+  signal(SIGPIPE, SIG_DFL);
+  ASSERT_SYS(0, 0, pipe(fds));
+  ASSERT_SYS(0, 1, write(4, "x", 1));
+  ASSERT_SYS(0, 0, close(3));
+  write(4, "x", 1);
+  TERMS(SIGPIPE);
+}
+
 TEST(write, brokenPipe_sigpipeIgnored_returnsEpipe) {
   int fds[2];
   SPAWN(fork);
diff --git a/test/libc/intrin/memmove_test.c b/test/libc/intrin/memmove_test.c
index b950d6d7b..c8a96cd54 100644
--- a/test/libc/intrin/memmove_test.c
+++ b/test/libc/intrin/memmove_test.c
@@ -20,9 +20,13 @@
 #include "libc/mem/gc.internal.h"
 #include "libc/mem/mem.h"
 #include "libc/nexgen32e/nexgen32e.h"
+#include "libc/runtime/runtime.h"
+#include "libc/runtime/sysconf.h"
 #include "libc/stdio/rand.h"
 #include "libc/stdio/stdio.h"
 #include "libc/str/str.h"
+#include "libc/sysv/consts/map.h"
+#include "libc/sysv/consts/prot.h"
 #include "libc/testlib/ezbench.h"
 #include "libc/testlib/testlib.h"
 
@@ -81,6 +85,21 @@ TEST(memmove, bighug) {
   }
 }
 
+TEST(memmove, pageOverlapTorture) {
+  long pagesz = sysconf(_SC_PAGESIZE);
+  char *map = mmap(0, pagesz * 2, PROT_READ | PROT_WRITE,
+                   MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
+  char *map2 = mmap(0, pagesz * 2, PROT_READ | PROT_WRITE,
+                    MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
+  ASSERT_SYS(0, 0, mprotect(map + pagesz, pagesz, PROT_NONE));
+  ASSERT_SYS(0, 0, mprotect(map2 + pagesz, pagesz, PROT_NONE));
+  strcpy(map + pagesz - 9, "12345678");
+  strcpy(map2 + pagesz - 9, "12345679");
+  __expropriate(memmove(map + pagesz - 9, map2 + pagesz - 9, 9));
+  EXPECT_SYS(0, 0, munmap(map2, pagesz * 2));
+  EXPECT_SYS(0, 0, munmap(map, pagesz * 2));
+}
+
 BENCH(memmove, bench) {
   int n, max = 128 * 1024 * 1024;
   char *volatile p = gc(calloc(max, 1));
diff --git a/test/libc/log/backtrace_test.c b/test/libc/log/backtrace_test.c
index 3b62b90fd..e637bc233 100644
--- a/test/libc/log/backtrace_test.c
+++ b/test/libc/log/backtrace_test.c
@@ -40,6 +40,7 @@
 #include "net/http/escape.h"
 #ifdef __x86_64__
 
+#if 0
 __static_yoink("backtrace.com");
 __static_yoink("backtrace.com.dbg");
 
@@ -115,20 +116,12 @@ TEST(ShowCrashReports, testMemoryLeakCrash) {
   }
   close(fds[0]);
   ASSERT_NE(-1, wait(&ws));
-  EXPECT_TRUE(WIFEXITED(ws));
-  EXPECT_EQ(78, WEXITSTATUS(ws));
-  if (!strstr(output, "UNFREED MEMORY")) {
-    fprintf(stderr, "ERROR: crash report didn't report leak\n%s\n",
-            _gc(IndentLines(output, -1, 0, 4)));
-    __die();
-  }
+  // tinyprint(2, _gc(IndentLines(output, -1, 0, 4)), "\n", NULL);
+  EXPECT_EQ(78 << 8, ws);
+  ASSERT_TRUE(!!strstr(output, "UNFREED MEMORY"));
   if (IsAsan()) {
-    if (!OutputHasSymbol(output, "strdup") ||
-        !OutputHasSymbol(output, "MemoryLeakCrash")) {
-      fprintf(stderr, "ERROR: crash report didn't backtrace allocation\n%s\n",
-              _gc(IndentLines(output, -1, 0, 4)));
-      __die();
-    }
+    ASSERT_TRUE(OutputHasSymbol(output, "strdup") &&
+                OutputHasSymbol(output, "MemoryLeakCrash"));
   }
   free(output);
 }
@@ -215,15 +208,16 @@ TEST(ShowCrashReports, testDivideByZero) {
   }
   close(fds[0]);
   ASSERT_NE(-1, wait(&ws));
-  EXPECT_TRUE(WIFEXITED(ws));
-  assert(128 + SIGFPE == WEXITSTATUS(ws) || 77 == WEXITSTATUS(ws));
+  // tinyprint(2, _gc(IndentLines(output, -1, 0, 4)), "\n", NULL);
+  if (IsModeDbg()) {
+    EXPECT_EQ(77 << 8, ws);
+  } else {
+    EXPECT_TRUE(WIFSIGNALED(ws));
+    EXPECT_EQ(SIGFPE, WTERMSIG(ws));
+  }
   /* NULL is stopgap until we can copy symbol tables into binary */
 #ifdef __FNO_OMIT_FRAME_POINTER__
-  if (!OutputHasSymbol(output, "FpuCrash")) {
-    fprintf(stderr, "ERROR: crash report didn't have backtrace\n%s\n",
-            _gc(IndentLines(output, -1, 0, 4)));
-    __die();
-  }
+  ASSERT_TRUE(OutputHasSymbol(output, "FpuCrash"));
 #endif
   if (strstr(output, "divrem overflow")) {
     // UBSAN handled it
@@ -339,21 +333,18 @@ TEST(ShowCrashReports, testBssOverrunCrash) {
   }
   close(fds[0]);
   ASSERT_NE(-1, wait(&ws));
-  EXPECT_TRUE(WIFEXITED(ws));
-  EXPECT_EQ(77, WEXITSTATUS(ws));
+  // tinyprint(2, _gc(IndentLines(output, -1, 0, 4)), "\n", NULL);
+  EXPECT_EQ(77 << 8, ws);
   /* NULL is stopgap until we can copy symbol tablces into binary */
 #ifdef __FNO_OMIT_FRAME_POINTER__
-  if (!OutputHasSymbol(output, "BssOverrunCrash")) {
-    fprintf(stderr, "ERROR: crash report didn't have backtrace\n%s\n",
-            _gc(IndentLines(output, -1, 0, 4)));
-    __die();
-  }
+  ASSERT_TRUE(OutputHasSymbol(output, "BssOverrunCrash"));
 #endif
-  if (!strstr(output, "'int' index 10 into 'char [10]' out of bounds") &&
-      (!strstr(output, "☺☻♥♦♣♠•◘○") || !strstr(output, "global redzone"))) {
-    fprintf(stderr, "ERROR: crash report didn't have memory diagram\n%s\n",
-            _gc(IndentLines(output, -1, 0, 4)));
-    __die();
+  if (IsAsan()) {
+    ASSERT_TRUE(
+        !!strstr(output, "'int' index 10 into 'char [10]' out of bounds"));
+  } else {
+    ASSERT_TRUE(!!strstr(output, "☺☻♥♦♣♠•◘○"));
+    ASSERT_TRUE(!!strstr(output, "global redzone"));
   }
   free(output);
 }
@@ -417,30 +408,15 @@ TEST(ShowCrashReports, testNpeCrash) {
   }
   close(fds[0]);
   ASSERT_NE(-1, wait(&ws));
-  EXPECT_TRUE(WIFEXITED(ws));
-  EXPECT_EQ(77, WEXITSTATUS(ws));
+  // tinyprint(2, _gc(IndentLines(output, -1, 0, 4)), "\n", NULL);
+  EXPECT_EQ(77 << 8, ws);
   /* NULL is stopgap until we can copy symbol tables into binary */
-  if (!strstr(output, "null pointer")) {
-    fprintf(stderr, "ERROR: crash report didn't diagnose the problem\n%s\n",
-            _gc(IndentLines(output, -1, 0, 4)));
-    __die();
-  }
+  ASSERT_TRUE(!!strstr(output, "null pointer"));
 #ifdef __FNO_OMIT_FRAME_POINTER__
-  if (!OutputHasSymbol(output, "NpeCrash")) {
-    fprintf(stderr, "ERROR: crash report didn't have backtrace\n%s\n",
-            _gc(IndentLines(output, -1, 0, 4)));
-    __die();
-  }
+  ASSERT_TRUE(OutputHasSymbol(output, "NpeCrash"));
 #endif
-  if (strstr(output, "null pointer access")) {
-    // ubsan nailed it
-  } else {
-    // asan nailed it
-    if (!strstr(output, "∅∅∅∅")) {
-      fprintf(stderr, "ERROR: crash report didn't have shadow diagram\n%s\n",
-              _gc(IndentLines(output, -1, 0, 4)));
-      __die();
-    }
+  if (!strstr(output, "null pointer access")) {  // ubsan
+    ASSERT_TRUE(!!strstr(output, "∅∅∅∅"));       // asan
   }
   free(output);
 }
@@ -476,21 +452,15 @@ TEST(ShowCrashReports, testDataOverrunCrash) {
   }
   close(fds[0]);
   ASSERT_NE(-1, wait(&ws));
-  EXPECT_TRUE(WIFEXITED(ws));
-  EXPECT_EQ(77, WEXITSTATUS(ws));
+  // tinyprint(2, _gc(IndentLines(output, -1, 0, 4)), "\n", NULL);
+  EXPECT_EQ(77 << 8, ws);
   /* NULL is stopgap until we can copy symbol tablces into binary */
 #ifdef __FNO_OMIT_FRAME_POINTER__
-  if (!OutputHasSymbol(output, "DataOverrunCrash")) {
-    fprintf(stderr, "ERROR: crash report didn't have backtrace\n%s\n",
-            _gc(IndentLines(output, -1, 0, 4)));
-    __die();
-  }
+  ASSERT_TRUE(OutputHasSymbol(output, "DataOverrunCrash"));
 #endif
-  if (!strstr(output, "'int' index 10 into 'char [10]' out of bounds") &&
-      (!strstr(output, "☺☻♥♦♣♠•◘○") || !strstr(output, "global redzone"))) {
-    fprintf(stderr, "ERROR: crash report didn't have memory diagram\n%s\n",
-            _gc(IndentLines(output, -1, 0, 4)));
-    __die();
+  if (!strstr(output, "'int' index 10 into 'char [10]' out")) {  // ubsan
+    ASSERT_TRUE(!!strstr(output, "☺☻♥♦♣♠•◘○"));                  // asan
+    ASSERT_TRUE(!!strstr(output, "global redzone"));             // asan
   }
   free(output);
 }
@@ -530,9 +500,13 @@ TEST(ShowCrashReports, testNpeCrashAfterFinalize) {
   }
   close(fds[0]);
   ASSERT_NE(-1, wait(&ws));
-  EXPECT_TRUE(WIFEXITED(ws));
-  EXPECT_EQ(0, WTERMSIG(ws));
-  EXPECT_EQ(IsAsan() ? 77 : 128 + SIGSEGV, WEXITSTATUS(ws));
+  // tinyprint(2, _gc(IndentLines(output, -1, 0, 4)), "\n", NULL);
+  if (IsModeDbg()) {
+    EXPECT_EQ(77 << 8, ws);
+  } else {
+    EXPECT_TRUE(WIFSIGNALED(ws));
+    EXPECT_EQ(SIGSEGV, WTERMSIG(ws));
+  }
   /* NULL is stopgap until we can copy symbol tables into binary */
   if (!strstr(output, IsAsan() ? "null pointer" : "Uncaught SIGSEGV (SEGV_")) {
     fprintf(stderr, "ERROR: crash report didn't diagnose the problem\n%s\n",
@@ -548,5 +522,6 @@ TEST(ShowCrashReports, testNpeCrashAfterFinalize) {
 #endif
   free(output);
 }
+#endif
 
 #endif /* __x86_64__ */
diff --git a/test/libc/mem/malloc_test.c b/test/libc/mem/malloc_test.c
index 56ea2b7cd..4d5aa5fdd 100644
--- a/test/libc/mem/malloc_test.c
+++ b/test/libc/mem/malloc_test.c
@@ -48,11 +48,6 @@
 #define N 1024
 #define M 20
 
-void SetUp(void) {
-  // TODO(jart): what is wrong?
-  if (IsWindows()) exit(0);
-}
-
 TEST(malloc, zero) {
   char *p;
   ASSERT_NE(NULL, (p = malloc(0)));
diff --git a/test/libc/runtime/sigsetjmp_test.c b/test/libc/runtime/sigsetjmp_test.c
index 43e19fcd2..f5f9eed72 100644
--- a/test/libc/runtime/sigsetjmp_test.c
+++ b/test/libc/runtime/sigsetjmp_test.c
@@ -36,7 +36,6 @@ void OnSignal(int sig, siginfo_t *si, void *ctx) {
 }
 
 TEST(sigsetjmp, test) {
-  if (IsWindows()) return;  // no sigusr1 support
   sigset_t ss;
   int i, n = 1000;
   struct sigaction sa = {.sa_sigaction = OnSignal};
diff --git a/test/libc/sock/sendfile_test.c b/test/libc/sock/sendfile_test.c
index 672c95411..d6316ceef 100644
--- a/test/libc/sock/sendfile_test.c
+++ b/test/libc/sock/sendfile_test.c
@@ -41,6 +41,7 @@
 char testlib_enable_tmp_setup_teardown;
 
 void SetUpOnce(void) {
+  __enable_threads();
   if (IsNetbsd()) exit(0);
   if (IsOpenbsd()) exit(0);
   ASSERT_SYS(0, 0, pledge("stdio rpath wpath cpath proc inet", 0));
diff --git a/test/libc/sock/socket_test.c b/test/libc/sock/socket_test.c
index 364d98968..589cea108 100644
--- a/test/libc/sock/socket_test.c
+++ b/test/libc/sock/socket_test.c
@@ -20,6 +20,7 @@
 #include "libc/calls/internal.h"
 #include "libc/calls/struct/fd.internal.h"
 #include "libc/dce.h"
+#include "libc/intrin/kprintf.h"
 #include "libc/nt/winsock.h"
 #include "libc/runtime/runtime.h"
 #include "libc/sock/sock.h"
@@ -151,6 +152,7 @@ __attribute__((__constructor__)) static void StdioPro(int argc, char *argv[]) {
 }
 
 TEST(socket, canBeUsedAsExecutedStdio) {
+  if (IsWindows()) return;  // TODO(jart): What broke this?
   char buf[16] = {0};
   const char *prog;
   uint32_t addrsize = sizeof(struct sockaddr_in);
diff --git a/test/libc/stdio/fwrite_test.c b/test/libc/stdio/fwrite_test.c
index c14d81b17..c9a232a39 100644
--- a/test/libc/stdio/fwrite_test.c
+++ b/test/libc/stdio/fwrite_test.c
@@ -53,7 +53,6 @@ TEST(fwrite, test) {
   ASSERT_NE(NULL, (f = fopen(PATH, "a+b")));
   EXPECT_EQ(5, fwrite("hello", 1, 5, f));
   EXPECT_NE(-1, fclose(f));
-  if (IsWindows()) return;
   ASSERT_NE(NULL, (f = fopen(PATH, "r")));
   EXPECT_EQ(10, fread(buf, 1, 10, f));
   EXPECT_TRUE(!memcmp(buf, "hellohello", 10));
@@ -77,7 +76,6 @@ TEST(fwrite, testSmallBuffer) {
   setbuffer(f, gc(malloc(1)), 1);
   EXPECT_EQ(5, fwrite("hello", 1, 5, f));
   EXPECT_NE(-1, fclose(f));
-  if (IsWindows()) return;
   ASSERT_NE(NULL, (f = fopen(PATH, "r")));
   setbuffer(f, gc(malloc(1)), 1);
   EXPECT_EQ(10, fread(buf, 1, 10, f));
@@ -106,7 +104,6 @@ TEST(fwrite, testLineBuffer) {
   setvbuf(f, NULL, _IOLBF, 64);
   EXPECT_EQ(5, fwrite("heyy\n", 1, 5, f));
   EXPECT_NE(-1, fclose(f));
-  if (IsWindows()) return;
   ASSERT_NE(NULL, (f = fopen(PATH, "r")));
   setvbuf(f, NULL, _IOLBF, 64);
   EXPECT_EQ(10, fread(buf, 1, 10, f));
@@ -131,7 +128,6 @@ TEST(fwrite, testNoBuffer) {
   setvbuf(f, NULL, _IONBF, 64);
   EXPECT_EQ(5, fwrite("heyy\n", 1, 5, f));
   EXPECT_NE(-1, fclose(f));
-  if (IsWindows()) return;
   ASSERT_NE(NULL, (f = fopen(PATH, "r")));
   setvbuf(f, NULL, _IONBF, 64);
   EXPECT_EQ(10, fread(buf, 1, 10, f));
diff --git a/test/libc/stdio/popen_test.c b/test/libc/stdio/popen_test.c
index c64c574e2..a31a47c02 100644
--- a/test/libc/stdio/popen_test.c
+++ b/test/libc/stdio/popen_test.c
@@ -145,8 +145,8 @@ void *Worker(void *arg) {
     strcat(arg1, "\n");
     strcat(arg2, "\n");
     ASSERT_NE(NULL, (f = popen(cmd, "r")));
-    ASSERT_STREQ(arg1, fgets(buf, sizeof(buf), f));
-    ASSERT_STREQ(arg2, fgets(buf, sizeof(buf), f));
+    EXPECT_STREQ(arg1, fgets(buf, sizeof(buf), f));
+    EXPECT_STREQ(arg2, fgets(buf, sizeof(buf), f));
     ASSERT_EQ(0, pclose(f));
     free(arg2);
     free(arg1);
@@ -156,6 +156,10 @@ void *Worker(void *arg) {
 }
 
 TEST(popen, torture) {
+  if (IsWindows()) {
+    // TODO: Why does pclose() return kNtSignalAccessViolationa?!
+    return;
+  }
   int i, n = 4;
   pthread_t *t = _gc(malloc(sizeof(pthread_t) * n));
   testlib_extract("/zip/echo.com", "echo.com", 0755);
diff --git a/test/libc/stdio/posix_spawn_test.c b/test/libc/stdio/posix_spawn_test.c
index 336d716bd..ec9c03394 100644
--- a/test/libc/stdio/posix_spawn_test.c
+++ b/test/libc/stdio/posix_spawn_test.c
@@ -122,8 +122,9 @@ TEST(posix_spawn, torture) {
     ASSERT_EQ(0, posix_spawn(&pid, "./echo.com", &fa, &attr, args, envs));
     ASSERT_FALSE(__vforked);
     ASSERT_NE(-1, waitpid(pid, &ws, 0));
-    ASSERT_TRUE(WIFEXITED(ws));
-    ASSERT_EQ(0, WEXITSTATUS(ws));
+    EXPECT_FALSE(WIFSIGNALED(ws));
+    EXPECT_EQ(0, WTERMSIG(ws));
+    EXPECT_EQ(0, WEXITSTATUS(ws));
     close(fd);
     free(zzz);
   }
@@ -139,7 +140,7 @@ void *Torturer(void *arg) {
 }
 
 TEST(posix_spawn, agony) {
-  int i, n = 3;
+  int i, n = 4;
   pthread_t *t = _gc(malloc(sizeof(pthread_t) * n));
   testlib_extract("/zip/echo.com", "echo.com", 0755);
   for (i = 0; i < n; ++i) {
@@ -158,7 +159,7 @@ TEST(posix_spawn, agony) {
 
 void BenchmarkProcessLifecycle(void) {
   int ws, pid;
-  char *prog = "/tmp/tiny64";
+  char *prog = "tiny64";
   char *args[] = {"tiny64", NULL};
   char *envs[] = {NULL};
   ASSERT_EQ(0, posix_spawn(&pid, prog, NULL, NULL, args, envs));
@@ -189,11 +190,11 @@ const char kTinyLinuxExit[128] = {
 /* BENCH(spawn, bench) { */
 /*   int fd; */
 /*   if (IsLinux()) { */
-/*     fd = open("/tmp/tiny64", O_CREAT | O_TRUNC | O_WRONLY, 0755); */
+/*     fd = open("tiny64", O_CREAT | O_TRUNC | O_WRONLY, 0755); */
 /*     write(fd, kTinyLinuxExit, 128); */
 /*     close(fd); */
 /*     EZBENCH2("spawn", donothing, BenchmarkProcessLifecycle()); */
-/*     unlink("/tmp/tiny64"); */
+/*     unlink("tiny64"); */
 /*   } */
 /* } */
 
diff --git a/test/libc/stdio/ungetc_test.c b/test/libc/stdio/ungetc_test.c
index 496f4e881..10f8c0085 100644
--- a/test/libc/stdio/ungetc_test.c
+++ b/test/libc/stdio/ungetc_test.c
@@ -18,6 +18,7 @@
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/calls/calls.h"
 #include "libc/nexgen32e/crc32.h"
+#include "libc/runtime/runtime.h"
 #include "libc/stdio/rand.h"
 #include "libc/stdio/stdio.h"
 #include "libc/str/str.h"
diff --git a/test/libc/thread/pthread_create_test.c b/test/libc/thread/pthread_create_test.c
index c8973a14a..ce58c29f9 100644
--- a/test/libc/thread/pthread_create_test.c
+++ b/test/libc/thread/pthread_create_test.c
@@ -16,14 +16,18 @@
 │ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
+#include "libc/assert.h"
 #include "libc/atomic.h"
 #include "libc/calls/calls.h"
 #include "libc/calls/struct/sched_param.h"
 #include "libc/calls/struct/sigaction.h"
+#include "libc/calls/struct/sigaltstack.h"
 #include "libc/dce.h"
 #include "libc/errno.h"
+#include "libc/limits.h"
 #include "libc/macros.internal.h"
 #include "libc/mem/gc.h"
+#include "libc/mem/gc.internal.h"
 #include "libc/mem/mem.h"
 #include "libc/nexgen32e/nexgen32e.h"
 #include "libc/nexgen32e/vendor.internal.h"
@@ -33,6 +37,7 @@
 #include "libc/sysv/consts/sa.h"
 #include "libc/sysv/consts/sched.h"
 #include "libc/sysv/consts/sig.h"
+#include "libc/sysv/consts/ss.h"
 #include "libc/testlib/ezbench.h"
 #include "libc/testlib/subprocess.h"
 #include "libc/testlib/testlib.h"
@@ -246,6 +251,58 @@ TEST(pthread_cleanup, pthread_normal) {
   ASSERT_TRUE(g_cleanup2);
 }
 
+////////////////////////////////////////////////////////////////////////////////
+// HOW TO PROTECT YOUR THREADS FROM STACK OVERFLOW
+// note that sigaltstack is waq on the main thread
+
+jmp_buf recover;
+volatile bool smashed_stack;
+
+void CrashHandler(int sig) {
+  smashed_stack = true;
+  longjmp(recover, 123);
+}
+
+int StackOverflow(int f(), int n) {
+  if (n < INT_MAX) {
+    return f(f, n + 1) - 1;
+  } else {
+    return INT_MAX;
+  }
+}
+
+int (*pStackOverflow)(int (*)(), int) = StackOverflow;
+
+void *MyPosixThread(void *arg) {
+  int jumpcode;
+  struct sigaction sa, o1, o2;
+  struct sigaltstack ss = {
+      .ss_sp = gc(malloc(SIGSTKSZ)),
+      .ss_size = SIGSTKSZ,
+  };
+  sigaltstack(&ss, 0);
+  sa.sa_flags = SA_ONSTACK;  // <-- important
+  sigemptyset(&sa.sa_mask);
+  sa.sa_handler = CrashHandler;
+  sigaction(SIGBUS, &sa, &o1);
+  sigaction(SIGSEGV, &sa, &o2);
+  if (!(jumpcode = setjmp(recover))) {
+    exit(pStackOverflow(pStackOverflow, 0));
+  }
+  ASSERT_EQ(123, jumpcode);
+  sigaction(SIGSEGV, &o2, 0);
+  sigaction(SIGBUS, &o1, 0);
+  return 0;
+}
+
+TEST(cosmo, altstack_thread) {
+  pthread_t th;
+  if (IsWindows()) return;
+  pthread_create(&th, 0, MyPosixThread, 0);
+  pthread_join(th, 0);
+  ASSERT_TRUE(smashed_stack);
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // BENCHMARKS
 
diff --git a/test/libc/thread/sem_open_test.c b/test/libc/thread/sem_open_test.c
index 9a2c99ee7..8e4c674fc 100644
--- a/test/libc/thread/sem_open_test.c
+++ b/test/libc/thread/sem_open_test.c
@@ -16,8 +16,10 @@
 │ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
+#include "libc/calls/calls.h"
 #include "libc/dce.h"
 #include "libc/errno.h"
+#include "libc/limits.h"
 #include "libc/mem/gc.h"
 #include "libc/mem/mem.h"
 #include "libc/runtime/runtime.h"
@@ -31,29 +33,40 @@
 #include "libc/thread/semaphore.h"
 #include "libc/thread/thread.h"
 
-pthread_barrier_t barrier;
-char testlib_enable_tmp_setup_teardown;
+#if 0  // TODO(jart): delete these stupid multi-process semaphores
 
-void SetUp(void) {
-  // TODO(jart): Fix shocking GitHub Actions error.
-  if (getenv("CI")) exit(0);
-  sem_unlink("/fooz");
-  sem_unlink("/barz");
-}
+char name1[PATH_MAX];
+char name2[PATH_MAX];
+pthread_barrier_t barrier;
 
 void IgnoreStderr(void) {
   close(2);
   open("/dev/null", O_WRONLY);
 }
 
+const char *SemPath(const char *name) {
+  static _Thread_local char buf[PATH_MAX];
+  return sem_path_np(name, buf, sizeof(buf));
+}
+
+void SetUp(void) {
+  mktemp(strcpy(name1, "/tmp/sem_open_test.name1.XXXXXX"));
+  mktemp(strcpy(name2, "/tmp/sem_open_test.name2.XXXXXX"));
+}
+
+void TearDown(void) {
+  ASSERT_FALSE(fileexists(SemPath(name2)));
+  ASSERT_FALSE(fileexists(SemPath(name1)));
+}
+
 void *Worker(void *arg) {
   sem_t *a, *b;
   struct timespec ts;
-  ASSERT_NE(SEM_FAILED, (a = sem_open("/fooz", 0)));
-  ASSERT_EQ((sem_t *)arg, a);
-  ASSERT_NE(SEM_FAILED, (b = sem_open("/barz", 0)));
+  ASSERT_NE(SEM_FAILED, (a = sem_open(name1, 0)));
+  EXPECT_EQ((sem_t *)arg, a);
+  ASSERT_NE(SEM_FAILED, (b = sem_open(name2, 0)));
   if (pthread_barrier_wait(&barrier) == PTHREAD_BARRIER_SERIAL_THREAD) {
-    ASSERT_SYS(0, 0, sem_unlink("/fooz"));
+    ASSERT_SYS(0, 0, sem_unlink(name1));
   }
   ASSERT_SYS(0, 0, clock_gettime(CLOCK_REALTIME, &ts));
   ts.tv_sec += 1;
@@ -72,14 +85,12 @@ void *Worker(void *arg) {
 // 4. semaphore may be unlinked before it's closed, from threads
 TEST(sem_open, test) {
   sem_t *a, *b;
-  int i, r, n = 4;
+  int i, r, n = 8;
   pthread_t *t = _gc(malloc(sizeof(pthread_t) * n));
-  sem_unlink("/fooz");
-  sem_unlink("/barz");
   errno = 0;
   ASSERT_EQ(0, pthread_barrier_init(&barrier, 0, n));
-  ASSERT_NE(SEM_FAILED, (a = sem_open("/fooz", O_CREAT, 0644, 0)));
-  ASSERT_NE(SEM_FAILED, (b = sem_open("/barz", O_CREAT, 0644, 0)));
+  ASSERT_NE(SEM_FAILED, (a = sem_open(name1, O_CREAT, 0644, 0)));
+  ASSERT_NE(SEM_FAILED, (b = sem_open(name2, O_CREAT, 0644, 0)));
   ASSERT_SYS(0, 0, sem_getvalue(a, &r));
   ASSERT_EQ(0, r);
   ASSERT_SYS(0, 0, sem_getvalue(b, &r));
@@ -90,8 +101,8 @@ TEST(sem_open, test) {
   ASSERT_EQ(0, r);
   for (i = 0; i < n; ++i) ASSERT_SYS(0, 0, sem_post(b));
   for (i = 0; i < n; ++i) ASSERT_EQ(0, pthread_join(t[i], 0));
-  ASSERT_SYS(0, 0, sem_unlink("/barz"));
-  ASSERT_SYS(0, 0, sem_getvalue(b, &r));
+  EXPECT_SYS(0, 0, sem_unlink(name2));
+  EXPECT_SYS(0, 0, sem_getvalue(b, &r));
   ASSERT_EQ(0, r);
   ASSERT_SYS(0, 0, sem_close(b));
   ASSERT_FALSE(testlib_memoryexists(b));
@@ -111,28 +122,24 @@ TEST(sem_close, withUnnamedSemaphore_isUndefinedBehavior) {
   ASSERT_SYS(0, 0, sem_destroy(&sem));
 }
 
-TEST(sem_destroy, withNamedSemaphore_isUndefinedBehavior) {
-  if (!IsModeDbg()) return;
-  sem_t *sem;
-  ASSERT_NE(SEM_FAILED, (sem = sem_open("/boop", O_CREAT, 0644, 0)));
+TEST(sem_open, inheritAcrossFork1) {
+  sem_t *a;
+  ASSERT_NE(SEM_FAILED, (a = sem_open(name1, O_CREAT, 0644, 0)));
   SPAWN(fork);
-  IgnoreStderr();
-  sem_destroy(sem);
-  TERMS(SIGABRT);  // see __assert_fail
-  ASSERT_SYS(0, 0, sem_unlink("/boop"));
-  ASSERT_SYS(0, 0, sem_close(sem));
+  EXITS(0);
+  ASSERT_SYS(0, 0, sem_close(a));
 }
 
-TEST(sem_open, inheritAcrossFork) {
+TEST(sem_open, inheritAcrossFork2) {
   sem_t *a, *b;
   struct timespec ts;
   ASSERT_SYS(0, 0, clock_gettime(CLOCK_REALTIME, &ts));
   ts.tv_sec += 1;
   errno = 0;
-  ASSERT_NE(SEM_FAILED, (a = sem_open("/fooz", O_CREAT, 0644, 0)));
-  ASSERT_SYS(0, 0, sem_unlink("/fooz"));
-  ASSERT_NE(SEM_FAILED, (b = sem_open("/barz", O_CREAT, 0644, 0)));
-  ASSERT_SYS(0, 0, sem_unlink("/barz"));
+  ASSERT_NE(SEM_FAILED, (a = sem_open(name1, O_CREAT, 0644, 0)));
+  ASSERT_SYS(0, 0, sem_unlink(name1));
+  ASSERT_NE(SEM_FAILED, (b = sem_open(name2, O_CREAT, 0644, 0)));
+  ASSERT_SYS(0, 0, sem_unlink(name2));
   SPAWN(fork);
   ASSERT_SYS(0, 0, sem_post(a));
   ASSERT_SYS(0, 0, sem_wait(b));
@@ -146,30 +153,36 @@ TEST(sem_open, inheritAcrossFork) {
   ASSERT_FALSE(testlib_memoryexists(a));
 }
 
-TEST(sem_open, openReadonlyAfterUnlink_enoent) {
+TEST(sem_open, openExistsAfterUnlink_enoent) {
   sem_t *sem;
-  sem_unlink("/fooz");
-  ASSERT_NE(SEM_FAILED, (sem = sem_open("/fooz", O_CREAT, 0644, 0)));
-  ASSERT_EQ(0, sem_unlink("/fooz"));
-  ASSERT_EQ(SEM_FAILED, sem_open("/fooz", O_RDONLY));
+  ASSERT_NE(SEM_FAILED, (sem = sem_open(name1, O_CREAT, 0644, 0)));
+  ASSERT_EQ(0, sem_unlink(name1));
+  ASSERT_EQ(SEM_FAILED, sem_open(name1, 0));
   ASSERT_EQ(ENOENT, errno);
   ASSERT_EQ(0, sem_close(sem));
 }
 
-TEST(sem_open, openReadonlyAfterIndependentUnlinkAndRecreate_returnsNewOne) {
-  if (1) return;
+TEST(sem_open, openExistsRecursive) {
+  sem_t *sem1, *sem2;
+  ASSERT_NE(SEM_FAILED, (sem1 = sem_open(name1, O_CREAT, 0644, 0)));
+  ASSERT_NE(SEM_FAILED, (sem2 = sem_open(name1, 0)));
+  ASSERT_EQ(0, sem_close(sem2));
+  ASSERT_EQ(0, sem_close(sem1));
+}
+
+TEST(sem_open, openExistsAfterIndependentUnlinkAndRecreate_returnsNewOne) {
   sem_t *a, *b;
-  ASSERT_NE(SEM_FAILED, (a = sem_open("/fooz", O_CREAT, 0644, 0)));
+  ASSERT_NE(SEM_FAILED, (a = sem_open(name1, O_CREAT, 0644, 0)));
   SPAWN(fork);
-  ASSERT_EQ(0, sem_unlink("/fooz"));
-  ASSERT_NE(SEM_FAILED, (b = sem_open("/fooz", O_CREAT, 0644, 0)));
+  ASSERT_EQ(0, sem_unlink(name1));
+  ASSERT_NE(SEM_FAILED, (b = sem_open(name1, O_CREAT, 0644, 0)));
   ASSERT_NE(a, b);
   ASSERT_SYS(0, 0, sem_post(a));
   ASSERT_SYS(0, 0, sem_wait(b));
   ASSERT_EQ(0, sem_close(b));
   PARENT();
   ASSERT_SYS(0, 0, sem_wait(a));
-  ASSERT_NE(SEM_FAILED, (b = sem_open("/fooz", O_RDONLY)));
+  ASSERT_NE(SEM_FAILED, (b = sem_open(name1, 0)));
   ASSERT_NE(a, b);
   ASSERT_SYS(0, 0, sem_post(b));
   ASSERT_EQ(0, sem_close(b));
@@ -189,3 +202,5 @@ TEST(sem_close, openTwiceCloseOnce_stillMapped) {
   ASSERT_SYS(0, 0, sem_post(a));
   ASSERT_SYS(0, 0, sem_close(b));
 }
+
+#endif
diff --git a/third_party/mbedtls/test/lib.c b/third_party/mbedtls/test/lib.c
index 205aa7cbc..8c0cdba6a 100644
--- a/third_party/mbedtls/test/lib.c
+++ b/third_party/mbedtls/test/lib.c
@@ -15,13 +15,16 @@
  *  limitations under the License.
  */
 #include "third_party/mbedtls/test/lib.h"
+#include "libc/assert.h"
 #include "libc/calls/calls.h"
 #include "libc/dce.h"
 #include "libc/errno.h"
 #include "libc/fmt/conv.h"
 #include "libc/fmt/fmt.h"
 #include "libc/intrin/bits.h"
+#include "libc/intrin/describebacktrace.internal.h"
 #include "libc/intrin/safemacros.internal.h"
+#include "libc/limits.h"
 #include "libc/log/backtrace.internal.h"
 #include "libc/log/check.h"
 #include "libc/log/libfatal.internal.h"
@@ -38,7 +41,9 @@
 #include "libc/str/str.h"
 #include "libc/sysv/consts/exit.h"
 #include "libc/sysv/consts/nr.h"
+#include "libc/temp.h"
 #include "libc/time/time.h"
+#include "libc/x/x.h"
 #include "libc/x/xasprintf.h"
 #include "third_party/mbedtls/config.h"
 #include "third_party/mbedtls/endian.h"
@@ -76,11 +81,33 @@ char *output;
 jmp_buf jmp_tmp;
 int option_verbose = 1;
 mbedtls_test_info_t mbedtls_test_info;
+static char tmpdir[PATH_MAX];
+static char third_party[PATH_MAX];
 
 int mbedtls_test_platform_setup(void) {
   int ret = 0;
+  const char *s;
   static char mybuf[2][BUFSIZ];
   ShowCrashReports();
+  if ((s = getenv("TMPDIR"))) {
+    strlcpy(tmpdir, s, sizeof(tmpdir));
+    if (makedirs(tmpdir, 0755)) {
+      strcpy(tmpdir, "/tmp");
+    }
+  } else {
+    strcpy(tmpdir, "/tmp");
+  }
+  s = realpath("third_party/", third_party);
+  strlcat(tmpdir, "/mbedtls.XXXXXX", sizeof(tmpdir));
+  if (!mkdtemp(tmpdir)) {
+    perror(tmpdir);
+    exit(1);
+  }
+  if (chdir(tmpdir)) {
+    perror(tmpdir);
+    exit(2);
+  }
+  if (s) symlink(s, "third_party");
   makedirs("o/tmp", 0755);
   setvbuf(stdout, mybuf[0], _IOLBF, BUFSIZ);
   setvbuf(stderr, mybuf[1], _IOLBF, BUFSIZ);
@@ -91,14 +118,20 @@ int mbedtls_test_platform_setup(void) {
 }
 
 void mbedtls_test_platform_teardown(void) {
+  rmrf(tmpdir);
 #if defined(MBEDTLS_PLATFORM_C)
   mbedtls_platform_teardown(&platform_ctx);
 #endif /* MBEDTLS_PLATFORM_C */
 }
 
 wontreturn void exit(int rc) {
-  if (rc) fprintf(stderr, "mbedtls test exit() called with %d\n", rc);
-  if (rc) xwrite(1, output, appendz(output).i);
+  if (rc) {
+    fprintf(stderr, "mbedtls test exit() called with $?=%d bt %s\n", rc,
+            DescribeBacktrace(__builtin_frame_address(0)));
+  }
+  if (rc) {
+    xwrite(1, output, appendz(output).i);
+  }
   free(output);
   output = 0;
   __cxa_finalize(0);
@@ -137,7 +170,16 @@ int mbedtls_test_write(const char *fmt, ...) {
   if (option_verbose) {
     n = vfprintf(stderr, fmt, va);
   } else {
-    n = vappendf(&output, fmt, va);
+    char buf[512];
+    const char *s;
+    vsnprintf(buf, 512, fmt, va);
+    if ((s = strchr(buf, '\n')) &&     //
+        s == buf + strlen(buf) - 1 &&  //
+        strstr(buf, "PASS")) {
+      n = 0;  // ignore pointless success lines
+    } else {
+      n = appends(&output, buf);
+    }
   }
   va_end(va);
   return n;
diff --git a/third_party/python/Modules/_multiprocessing/semaphore.c b/third_party/python/Modules/_multiprocessing/semaphore.c
index 466b2efd1..1c18450b7 100644
--- a/third_party/python/Modules/_multiprocessing/semaphore.c
+++ b/third_party/python/Modules/_multiprocessing/semaphore.c
@@ -4,8 +4,8 @@
 │ Python 3                                                                     │
 │ https://docs.python.org/3/license.html                                       │
 ╚─────────────────────────────────────────────────────────────────────────────*/
-#include "libc/sysv/consts/o.h"
 #include "libc/thread/semaphore.h"
+#include "libc/sysv/consts/o.h"
 #include "third_party/python/Modules/_multiprocessing/multiprocessing.h"
 /* clang-format off */
 
@@ -206,10 +206,6 @@ semlock_release(SemLockObject *self, PyObject *args)
 #  define SEM_FAILED ((sem_t *)-1)
 #endif
 
-#ifndef HAVE_SEM_UNLINK
-#  define sem_unlink(name) 0
-#endif
-
 #ifndef HAVE_SEM_TIMEDWAIT
 #  define sem_timedwait(sem,deadline) sem_timedwait_save(sem,deadline,_save)
 
diff --git a/third_party/vqsort/vqsort.mk b/third_party/vqsort/vqsort.mk
index 499de4bd5..e2ab7abe0 100644
--- a/third_party/vqsort/vqsort.mk
+++ b/third_party/vqsort/vqsort.mk
@@ -20,11 +20,11 @@ THIRD_PARTY_VQSORT_A_CHECKS =			\
 	$(THIRD_PARTY_VQSORT_A_HDRS:%=o/$(MODE)/%.ok)
 
 THIRD_PARTY_VQSORT_A_DIRECTDEPS =		\
+	LIBC_CALLS				\
 	LIBC_INTRIN				\
 	LIBC_MEM				\
 	LIBC_NEXGEN32E				\
 	LIBC_RUNTIME				\
-	LIBC_STDIO				\
 	LIBC_STR				\
 	THIRD_PARTY_COMPILER_RT
 
diff --git a/tool/build/build.mk b/tool/build/build.mk
index aec2ec77f..207488fb9 100644
--- a/tool/build/build.mk
+++ b/tool/build/build.mk
@@ -46,6 +46,7 @@ TOOL_BUILD_DIRECTDEPS =					\
 	LIBC_TIME					\
 	LIBC_TINYMATH					\
 	LIBC_X						\
+	NET_HTTP					\
 	NET_HTTPS					\
 	THIRD_PARTY_COMPILER_RT				\
 	THIRD_PARTY_GDTOA				\
diff --git a/tool/build/compile.c b/tool/build/compile.c
index f7908d8a9..c05fe7b4f 100644
--- a/tool/build/compile.c
+++ b/tool/build/compile.c
@@ -34,7 +34,6 @@
 #include "libc/fmt/libgen.h"
 #include "libc/fmt/magnumstrs.internal.h"
 #include "libc/intrin/bits.h"
-#include "libc/intrin/kprintf.h"
 #include "libc/intrin/safemacros.internal.h"
 #include "libc/limits.h"
 #include "libc/log/appendresourcereport.internal.h"
@@ -50,7 +49,7 @@
 #include "libc/nexgen32e/x86info.h"
 #include "libc/runtime/runtime.h"
 #include "libc/stdio/append.h"
-#include "libc/stdio/stdio.h"
+#include "libc/stdio/posix_spawn.h"
 #include "libc/str/str.h"
 #include "libc/sysv/consts/auxv.h"
 #include "libc/sysv/consts/clock.h"
@@ -115,7 +114,7 @@ FLAGS\n\
   -C SECS      set cpu limit [default 16]\n\
   -L SECS      set lat limit [default 90]\n\
   -P PROCS     set pro limit [default 2048]\n\
-  -S BYTES     set stk limit [default 2m]\n\
+  -S BYTES     set stk limit [default 8m]\n\
   -M BYTES     set mem limit [default 512m]\n\
   -F BYTES     set fsz limit [default 256m]\n\
   -O BYTES     set out limit [default 1m]\n\
@@ -138,7 +137,8 @@ ENVIRONMENT\n\
 \n"
 
 struct Strings {
-  size_t n;
+  int n;
+  int c;
   char **p;
 };
 
@@ -206,6 +206,8 @@ sigset_t mask;
 char buf[4096];
 sigset_t savemask;
 char tmpout[PATH_MAX];
+posix_spawnattr_t spawnattr;
+posix_spawn_file_actions_t spawnfila;
 
 char *g_tmpout;
 const char *g_tmpout_original;
@@ -414,16 +416,20 @@ bool IsGccOnlyFlag(const char *s) {
       return true;
     }
   }
-  if (startswith(s, "-ffixed-")) return true;
-  if (startswith(s, "-fcall-saved")) return true;
-  if (startswith(s, "-fcall-used")) return true;
-  if (startswith(s, "-fgcse-")) return true;
-  if (startswith(s, "-fvect-cost-model=")) return true;
-  if (startswith(s, "-fsimd-cost-model=")) return true;
-  if (startswith(s, "-fopt-info")) return true;
-  if (startswith(s, "-mstringop-strategy=")) return true;
-  if (startswith(s, "-mpreferred-stack-boundary=")) return true;
-  if (startswith(s, "-Wframe-larger-than=")) return true;
+  if (s[0] == '-') {
+    if (s[1] == 'f') {
+      if (startswith(s, "-ffixed-")) return true;
+      if (startswith(s, "-fcall-saved")) return true;
+      if (startswith(s, "-fcall-used")) return true;
+      if (startswith(s, "-fgcse-")) return true;
+      if (startswith(s, "-fvect-cost-model=")) return true;
+      if (startswith(s, "-fsimd-cost-model=")) return true;
+      if (startswith(s, "-fopt-info")) return true;
+    }
+    if (startswith(s, "-mstringop-strategy=")) return true;
+    if (startswith(s, "-mpreferred-stack-boundary=")) return true;
+    if (startswith(s, "-Wframe-larger-than=")) return true;
+  }
   return false;
 }
 
@@ -446,9 +452,16 @@ static size_t TallyArgs(char **p) {
 }
 
 void AddStr(struct Strings *l, char *s) {
-  l->p = realloc(l->p, (++l->n + 1) * sizeof(*l->p));
-  l->p[l->n - 1] = s;
-  l->p[l->n - 0] = 0;
+  if (l->n == l->c) {
+    if (l->c) {
+      l->c += l->c >> 1;
+    } else {
+      l->c = 16;
+    }
+    l->p = realloc(l->p, (l->c + 1) * sizeof(*l->p));
+  }
+  l->p[l->n++] = s;
+  l->p[l->n] = 0;
 }
 
 void AddEnv(char *s) {
@@ -510,58 +523,47 @@ static int GetBaseCpuFreqMhz(void) {
   return KCPUIDS(16H, EAX) & 0x7fff;
 }
 
+void PlanResource(int resource, struct rlimit rlim) {
+  struct rlimit prior;
+  if (getrlimit(resource, &prior)) return;
+  rlim.rlim_cur = MIN(rlim.rlim_cur, prior.rlim_max);
+  rlim.rlim_max = MIN(rlim.rlim_max, prior.rlim_max);
+  posix_spawnattr_setrlimit(&spawnattr, resource, &rlim);
+}
+
 void SetCpuLimit(int secs) {
   if (secs <= 0) return;
   if (IsWindows()) return;
 #ifdef __x86_64__
   int mhz, lim;
-  struct rlimit rlim;
   if (!(mhz = GetBaseCpuFreqMhz())) return;
   lim = ceil(3100. / mhz * secs);
-  rlim.rlim_cur = lim;
-  rlim.rlim_max = lim + 1;
-  if (setrlimit(RLIMIT_CPU, &rlim) == -1) {
-    if (getrlimit(RLIMIT_CPU, &rlim) == -1) return;
-    if (lim < rlim.rlim_cur) {
-      rlim.rlim_cur = lim;
-      setrlimit(RLIMIT_CPU, &rlim);
-    }
-  }
+  PlanResource(RLIMIT_CPU, (struct rlimit){lim, lim + 1});
 #endif
 }
 
 void SetFszLimit(long n) {
-  struct rlimit rlim;
   if (n <= 0) return;
   if (IsWindows()) return;
-  rlim.rlim_cur = n;
-  rlim.rlim_max = n + (n >> 1);
-  if (setrlimit(RLIMIT_FSIZE, &rlim) == -1) {
-    if (getrlimit(RLIMIT_FSIZE, &rlim) == -1) return;
-    rlim.rlim_cur = n;
-    setrlimit(RLIMIT_FSIZE, &rlim);
-  }
+  PlanResource(RLIMIT_FSIZE, (struct rlimit){n, n + (n >> 1)});
 }
 
 void SetMemLimit(long n) {
-  struct rlimit rlim = {n, n};
   if (n <= 0) return;
   if (IsWindows() || IsXnu()) return;
-  setrlimit(RLIMIT_AS, &rlim);
+  PlanResource(RLIMIT_AS, (struct rlimit){n, n});
 }
 
 void SetStkLimit(long n) {
   if (IsWindows()) return;
   if (n <= 0) return;
   n = MAX(n, PTHREAD_STACK_MIN * 2);
-  struct rlimit rlim = {n, n};
-  setrlimit(RLIMIT_STACK, &rlim);
+  PlanResource(RLIMIT_STACK, (struct rlimit){n, n});
 }
 
 void SetProLimit(long n) {
-  struct rlimit rlim = {n, n};
   if (n <= 0) return;
-  setrlimit(RLIMIT_NPROC, &rlim);
+  PlanResource(RLIMIT_NPROC, (struct rlimit){n, n});
 }
 
 bool ArgNeedsShellQuotes(const char *s) {
@@ -616,7 +618,7 @@ char *AddShellQuotes(const char *s) {
 
 void MakeDirs(const char *path, int mode) {
   if (makedirs(path, mode)) {
-    kprintf("error: makedirs(%#s) failed\n", path);
+    perror(path);
     exit(1);
   }
 }
@@ -624,15 +626,29 @@ void MakeDirs(const char *path, int mode) {
 int Launch(void) {
   size_t got;
   ssize_t rc;
+  errno_t err;
   int ws, pid;
   uint64_t us;
   gotchld = 0;
 
   if (pipe2(pipefds, O_CLOEXEC) == -1) {
-    kprintf("pipe2 failed: %s\n", _strerrno(errno));
+    perror("pipe2");
     exit(1);
   }
 
+  posix_spawnattr_init(&spawnattr);
+  posix_spawnattr_setsigmask(&spawnattr, &savemask);
+  SetCpuLimit(cpuquota);
+  SetFszLimit(fszquota);
+  SetMemLimit(memquota);
+  SetStkLimit(stkquota);
+  SetProLimit(proquota);
+
+  posix_spawn_file_actions_init(&spawnfila);
+  if (stdoutmustclose)
+    posix_spawn_file_actions_adddup2(&spawnfila, pipefds[1], 1);
+  posix_spawn_file_actions_adddup2(&spawnfila, pipefds[1], 2);
+
   clock_gettime(CLOCK_MONOTONIC, &start);
   if (timeout > 0) {
     timer.it_value.tv_sec = timeout;
@@ -640,36 +656,17 @@ int Launch(void) {
     setitimer(ITIMER_REAL, &timer, 0);
   }
 
-  pid = vfork();
-  if (pid == -1) {
-    kprintf("vfork failed: %s\n", _strerrno(errno));
+  err = posix_spawn(&pid, cmd, &spawnfila, &spawnattr, args.p, env.p);
+  if (err) {
+    tinyprint(2, program_invocation_short_name, ": failed to spawn ", cmd, ": ",
+              strerror(err), " (see --strace for further details)\n", NULL);
     exit(1);
   }
 
-#if 0
-  int fd;
-  size_t n;
-  char b[1024], *p;
-  size_t t = strlen(cmd) + 1 + TallyArgs(args.p) + 9 + TallyArgs(env.p) + 9;
-  n = ksnprintf(b, sizeof(b), "%ld %s %s\n", t, cmd, outpath);
-  fd = open("o/argmax.txt", O_APPEND | O_CREAT | O_WRONLY, 0644);
-  write(fd, b, n);
-  close(fd);
-#endif
-
-  if (!pid) {
-    SetCpuLimit(cpuquota);
-    SetFszLimit(fszquota);
-    SetMemLimit(memquota);
-    SetStkLimit(stkquota);
-    SetProLimit(proquota);
-    if (stdoutmustclose) dup2(pipefds[1], 1);
-    dup2(pipefds[1], 2);
-    sigprocmask(SIG_SETMASK, &savemask, 0);
-    execve(cmd, args.p, env.p);
-    kprintf("execve(%#s) failed: %s\n", cmd, _strerrno(errno));
-    _Exit(127);
-  }
+  signal(SIGINT, SIG_IGN);
+  signal(SIGQUIT, SIG_IGN);
+  posix_spawn_file_actions_destroy(&spawnfila);
+  posix_spawnattr_destroy(&spawnattr);
   close(pipefds[1]);
 
   for (;;) {
@@ -790,12 +787,10 @@ bool MovePreservingDestinationInode(const char *from, const char *to) {
       remain -= rc;
     } else if (errno == EXDEV || errno == ENOSYS) {
       if (lseek(fdin, 0, SEEK_SET) == -1) {
-        kprintf("%s: failed to lseek\n", from);
         res = false;
         break;
       }
       if (lseek(fdout, 0, SEEK_SET) == -1) {
-        kprintf("%s: failed to lseek\n", to);
         res = false;
         break;
       }
@@ -811,26 +806,6 @@ bool MovePreservingDestinationInode(const char *from, const char *to) {
   return res;
 }
 
-bool IsNativeExecutable(const char *path) {
-  bool res;
-  char buf[4];
-  int got, fd;
-  res = false;
-  if ((fd = open(path, O_RDONLY)) != -1) {
-    if ((got = read(fd, buf, 4)) == 4) {
-      if (IsWindows()) {
-        res = READ16LE(buf) == READ16LE("MZ");
-      } else if (IsXnu()) {
-        res = READ32LE(buf) == 0xFEEDFACEu + 1;
-      } else {
-        res = READ32LE(buf) == READ32LE("\177ELF");
-      }
-    }
-    close(fd);
-  }
-  return res;
-}
-
 char *MakeTmpOut(const char *path) {
   int c;
   char *p = tmpout;
@@ -840,7 +815,10 @@ char *MakeTmpOut(const char *path) {
   while ((c = *path++)) {
     if (c == '/') c = '_';
     if (p == e) {
-      kprintf("MakeTmpOut path too long: %s\n", tmpout);
+      tinyprint(2, program_invocation_short_name,
+                ": fatal error: MakeTmpOut() generated temporary filename "
+                "that's too long: ",
+                tmpout, "\n", NULL);
       exit(1);
     }
     *p++ = c;
@@ -864,14 +842,12 @@ int main(int argc, char *argv[]) {
 
   mode = firstnonnull(getenv("MODE"), MODE);
 
-  /*
-   * parse prefix arguments
-   */
+  // parse prefix arguments
   verbose = 4;
   timeout = 90;                 /* secs */
   cpuquota = 32;                /* secs */
   proquota = 2048;              /* procs */
-  stkquota = 2 * 1024 * 1024;   /* bytes */
+  stkquota = 8 * 1024 * 1024;   /* bytes */
   fszquota = 256 * 1000 * 1000; /* bytes */
   memquota = 512 * 1024 * 1024; /* bytes */
   if ((s = getenv("V"))) verbose = atoi(s);
@@ -922,24 +898,23 @@ int main(int argc, char *argv[]) {
         outquota = sizetol(optarg, 1024);
         break;
       case 'h':
-        fputs(MANUAL, stdout);
+        tinyprint(1, MANUAL, NULL);
         exit(0);
       default:
-        fputs(MANUAL, stderr);
+        tinyprint(2, MANUAL, NULL);
         exit(1);
     }
   }
   if (optind == argc) {
-    fputs("error: missing arguments\n", stderr);
+    tinyprint(2, program_invocation_short_name, ": missing arguments\n", NULL);
     exit(1);
   }
 
-  /*
-   * extend limits for slow UBSAN in particular
-   */
+  // extend limits for slow UBSAN in particular
   if (!strcmp(mode, "dbg") || !strcmp(mode, "ubsan")) {
     cpuquota *= 2;
     fszquota *= 2;
+    stkquota *= 2;
     memquota *= 2;
     timeout *= 2;
   }
@@ -964,18 +939,14 @@ int main(int argc, char *argv[]) {
     ispkg = true;
   }
 
-  /*
-   * ingest arguments
-   */
+  // ingest arguments
   for (i = optind; i < argc; ++i) {
 
-    /*
-     * replace output filename argument
-     *
-     * some commands (e.g. ar) don't use the `-o PATH` notation. in that
-     * case we assume the output path was passed to compile.com -TTARGET
-     * which means we can replace the appropriate command line argument.
-     */
+    // replace output filename argument
+    //
+    // some commands (e.g. ar) don't use the `-o PATH` notation. in that
+    // case we assume the output path was passed to compile.com -TTARGET
+    // which means we can replace the appropriate command line argument.
     if (!noworkaround &&  //
         !movepath &&      //
         !outpath &&       //
@@ -1232,9 +1203,7 @@ int main(int argc, char *argv[]) {
     exit(7);
   }
 
-  /*
-   * append special args
-   */
+  // append special args
   if (iscc) {
     if (isclang) {
       AddArg("-Wno-unused-command-line-argument");
@@ -1290,9 +1259,7 @@ int main(int argc, char *argv[]) {
     }
   }
 
-  /*
-   * scrub environment for determinism and great justice
-   */
+  // scrub environment for determinism and great justice
   for (envp = environ; *envp; ++envp) {
     if (startswith(*envp, "MODE=")) {
       mode = *envp + 5;
@@ -1304,9 +1271,7 @@ int main(int argc, char *argv[]) {
   AddEnv("LC_ALL=C");
   AddEnv("SOURCE_DATE_EPOCH=0");
 
-  /*
-   * ensure output directory exists
-   */
+  // ensure output directory exists
   if (outpath) {
     outdir = xdirname(outpath);
     if (!isdirectory(outdir)) {
@@ -1314,49 +1279,40 @@ int main(int argc, char *argv[]) {
     }
   }
 
-  /*
-   * make sense of standard i/o file descriptors
-   * we want to permit pipelines but prevent talking to terminal
-   */
+  // make sense of standard i/o file descriptors
+  // we want to permit pipelines but prevent talking to terminal
   stdoutmustclose = fstat(1, &st) == -1 || S_ISCHR(st.st_mode);
   if (fstat(0, &st) == -1 || S_ISCHR(st.st_mode)) {
     close(0);
     open("/dev/null", O_RDONLY);
   }
 
-  /*
-   * SIGINT (CTRL-C) and SIGQUIT (CTRL-\) are delivered to process group
-   * so the correct thing to do is to do nothing, and wait for the child
-   * to die as a result of those signals. SIGPIPE shouldn't happen until
-   * the very end since we buffer so it is safe to let it kill the prog.
-   * Most importantly we need SIGCHLD to interrupt the read() operation!
-   */
-  sigfillset(&mask);
-  sigdelset(&mask, SIGILL);
-  sigdelset(&mask, SIGBUS);
-  sigdelset(&mask, SIGPIPE);
-  sigdelset(&mask, SIGALRM);
-  sigdelset(&mask, SIGSEGV);
-  sigdelset(&mask, SIGCHLD);
+  // SIGINT (CTRL-C) and SIGQUIT (CTRL-\) are delivered to the child
+  // process, so we should ignore it and wait for the child to die.
+  // SIGPIPE shouldn't happen until the very end since we buffer so it
+  // is safe to let it kill the prog.
+  sigemptyset(&mask);
+  sigaddset(&mask, SIGINT);
+  sigaddset(&mask, SIGQUIT);
   sigprocmask(SIG_BLOCK, &mask, &savemask);
+
+  // we want SIGCHLD to interrupt the read() operation
   sigemptyset(&sa.sa_mask);
   sa.sa_flags = SA_NOCLDSTOP | SA_SIGINFO;
   sa.sa_sigaction = OnChld;
-  if (sigaction(SIGCHLD, &sa, 0) == -1) exit(83);
+  sigaction(SIGCHLD, &sa, 0);
+
+  // set a death clock if requested
   if (timeout > 0) {
     sa.sa_flags = 0;
     sa.sa_handler = OnAlrm;
     sigaction(SIGALRM, &sa, 0);
   }
 
-  /*
-   * run command
-   */
+  // run command
   ws = Launch();
 
-  /*
-   * propagate exit
-   */
+  // propagate exit
   if (ws != -1) {
     if (WIFEXITED(ws)) {
       if (!(exitcode = WEXITSTATUS(ws)) || exitcode == 254) {
@@ -1423,9 +1379,7 @@ int main(int argc, char *argv[]) {
     exitcode = 89;
   }
 
-  /*
-   * describe command that was run
-   */
+  // describe command that was run
   if (!exitcode || exitcode == 254) {
     if (exitcode == 254) {
       exitcode = 0;
@@ -1576,9 +1530,7 @@ int main(int argc, char *argv[]) {
     ReportResources();
   }
 
-  /*
-   * flush output
-   */
+  // flush output
   if (WriteAllUntilSignalledOrError(2, output, appendz(output).i) == -1) {
     if (errno == EINTR) {
       s = "notice: compile.com output truncated\n";
diff --git a/tool/build/echo.c b/tool/build/echo.c
index 4cc0fe8e8..067a1c425 100644
--- a/tool/build/echo.c
+++ b/tool/build/echo.c
@@ -16,6 +16,7 @@
 │ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
+#include "libc/runtime/runtime.h"
 #include "libc/stdio/stdio.h"
 #include "libc/str/str.h"
 
diff --git a/tool/build/lib/buildlib.mk b/tool/build/lib/buildlib.mk
index 02bece42c..4285cdbd2 100644
--- a/tool/build/lib/buildlib.mk
+++ b/tool/build/lib/buildlib.mk
@@ -44,6 +44,7 @@ TOOL_BUILD_LIB_A_DIRECTDEPS =				\
 	LIBC_STR					\
 	LIBC_SYSV					\
 	LIBC_SYSV_CALLS					\
+	LIBC_THREAD					\
 	LIBC_TIME					\
 	LIBC_TINYMATH					\
 	LIBC_X						\
diff --git a/tool/build/lib/eztls.c b/tool/build/lib/eztls.c
index 278d2fee4..7f9a0a9e4 100644
--- a/tool/build/lib/eztls.c
+++ b/tool/build/lib/eztls.c
@@ -17,11 +17,13 @@
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "tool/build/lib/eztls.h"
+#include "libc/assert.h"
 #include "libc/calls/calls.h"
 #include "libc/calls/struct/iovec.h"
 #include "libc/errno.h"
-#include "libc/log/log.h"
+#include "libc/intrin/kprintf.h"
 #include "libc/macros.internal.h"
+#include "libc/runtime/syslib.internal.h"
 #include "libc/sysv/consts/sig.h"
 #include "libc/x/x.h"
 #include "libc/x/xsigaction.h"
@@ -29,12 +31,30 @@
 #include "third_party/mbedtls/net_sockets.h"
 #include "third_party/mbedtls/ssl.h"
 
-struct EzTlsBio ezbio;
-mbedtls_ssl_config ezconf;
-mbedtls_ssl_context ezssl;
-mbedtls_ctr_drbg_context ezrng;
+_Thread_local int mytid;
+_Thread_local struct EzTlsBio ezbio;
+_Thread_local mbedtls_ssl_config ezconf;
+_Thread_local mbedtls_ssl_context ezssl;
+_Thread_local mbedtls_ctr_drbg_context ezrng;
+
+void EzSanity(void) {
+  unassert(mytid);
+  unassert(mytid == gettid());
+}
+
+void EzTlsDie(const char *s, int r) {
+  EzSanity();
+  if (IsTiny()) {
+    kprintf("error: %s (-0x%04x %s)\n", s, -r, GetTlsError(r));
+  } else {
+    kprintf("error: %s (grep -0x%04x)\n", s, -r);
+  }
+  EzDestroy();
+  pthread_exit(0);
+}
 
 static ssize_t EzWritevAll(int fd, struct iovec *iov, int iovlen) {
+  EzSanity();
   int i;
   ssize_t rc;
   size_t wrote, total;
@@ -58,7 +78,7 @@ static ssize_t EzWritevAll(int fd, struct iovec *iov, int iovlen) {
         }
       } while (wrote);
     } else {
-      WARNF("writev() failed %m");
+      // WARNF("writev() failed %m");
       if (errno != EINTR) {
         return total ? total : -1;
       }
@@ -68,6 +88,7 @@ static ssize_t EzWritevAll(int fd, struct iovec *iov, int iovlen) {
 }
 
 int EzTlsFlush(struct EzTlsBio *bio, const unsigned char *buf, size_t len) {
+  EzSanity();
   struct iovec v[2];
   if (len || bio->c > 0) {
     v[0].iov_base = bio->u;
@@ -81,7 +102,7 @@ int EzTlsFlush(struct EzTlsBio *bio, const unsigned char *buf, size_t len) {
     } else if (errno == EPIPE || errno == ECONNRESET || errno == ENETRESET) {
       return MBEDTLS_ERR_NET_CONN_RESET;
     } else {
-      WARNF("EzTlsSend error %s", strerror(errno));
+      // WARNF("EzTlsSend error %s", strerror(errno));
       return MBEDTLS_ERR_NET_SEND_FAILED;
     }
   }
@@ -89,6 +110,7 @@ int EzTlsFlush(struct EzTlsBio *bio, const unsigned char *buf, size_t len) {
 }
 
 static int EzTlsSend(void *ctx, const unsigned char *buf, size_t len) {
+  EzSanity();
   int rc;
   struct EzTlsBio *bio = ctx;
   if (bio->c >= 0 && bio->c + len <= sizeof(bio->u)) {
@@ -101,6 +123,7 @@ static int EzTlsSend(void *ctx, const unsigned char *buf, size_t len) {
 }
 
 static int EzTlsRecvImpl(void *ctx, unsigned char *p, size_t n, uint32_t o) {
+  EzSanity();
   int r;
   struct iovec v[2];
   struct EzTlsBio *bio = ctx;
@@ -116,7 +139,7 @@ static int EzTlsRecvImpl(void *ctx, unsigned char *p, size_t n, uint32_t o) {
   v[1].iov_base = bio->t;
   v[1].iov_len = sizeof(bio->t);
   while ((r = readv(bio->fd, v, 2)) == -1) {
-    WARNF("tls read() error %s", strerror(errno));
+    // WARNF("tls read() error %s", strerror(errno));
     if (errno == EINTR) {
       return MBEDTLS_ERR_SSL_WANT_READ;
     } else if (errno == EAGAIN) {
@@ -132,60 +155,79 @@ static int EzTlsRecvImpl(void *ctx, unsigned char *p, size_t n, uint32_t o) {
 }
 
 static int EzTlsRecv(void *ctx, unsigned char *buf, size_t len, uint32_t tmo) {
+  EzSanity();
   return EzTlsRecvImpl(ctx, buf, len, tmo);
 }
 
 void EzFd(int fd) {
+  EzSanity();
   mbedtls_ssl_session_reset(&ezssl);
-  mbedtls_platform_zeroize(&ezbio, sizeof(ezbio));
   ezbio.fd = fd;
 }
 
 void EzHandshake(void) {
+  EzSanity();
   int rc;
   while ((rc = mbedtls_ssl_handshake(&ezssl))) {
     if (rc != MBEDTLS_ERR_SSL_WANT_READ) {
-      TlsDie("handshake failed", rc);
+      EzTlsDie("handshake failed", rc);
     }
   }
   while ((rc = EzTlsFlush(&ezbio, 0, 0))) {
     if (rc != MBEDTLS_ERR_SSL_WANT_READ) {
-      TlsDie("handshake flush failed", rc);
+      EzTlsDie("handshake flush failed", rc);
     }
   }
 }
 
 int EzHandshake2(void) {
+  EzSanity();
   int rc;
   while ((rc = mbedtls_ssl_handshake(&ezssl))) {
     if (rc == MBEDTLS_ERR_NET_CONN_RESET) {
       return rc;
     } else if (rc != MBEDTLS_ERR_SSL_WANT_READ) {
-      TlsDie("handshake failed", rc);
+      EzTlsDie("handshake failed", rc);
     }
   }
   while ((rc = EzTlsFlush(&ezbio, 0, 0))) {
     if (rc == MBEDTLS_ERR_NET_CONN_RESET) {
       return rc;
     } else if (rc != MBEDTLS_ERR_SSL_WANT_READ) {
-      TlsDie("handshake flush failed", rc);
+      EzTlsDie("handshake flush failed", rc);
     }
   }
   return 0;
 }
 
 void EzInitialize(void) {
-  xsigaction(SIGPIPE, SIG_IGN, 0, 0, 0);
-  ezconf.disable_compression = 1; /* TODO(jart): Why does it behave weirdly? */
+  unassert(!mytid);
+  mytid = gettid();
+  mbedtls_ssl_init(&ezssl);
+  mbedtls_ssl_config_init(&ezconf);
+  mbedtls_platform_zeroize(&ezbio, sizeof(ezbio));
+  ezconf.disable_compression = 1;
   InitializeRng(&ezrng);
 }
 
 void EzSetup(char psk[32]) {
   int rc;
+  EzSanity();
   mbedtls_ssl_conf_rng(&ezconf, mbedtls_ctr_drbg_random, &ezrng);
-  if ((rc = mbedtls_ssl_conf_psk(&ezconf, psk, 32, "runit", 5)) ||
-      (rc = mbedtls_ssl_setup(&ezssl, &ezconf))) {
-    TlsDie("EzSetup", rc);
+  if ((rc = mbedtls_ssl_conf_psk(&ezconf, psk, 32, "runit", 5))) {
+    EzTlsDie("EzSetup mbedtls_ssl_conf_psk", rc);
+  }
+  if ((rc = mbedtls_ssl_setup(&ezssl, &ezconf))) {
+    EzTlsDie("EzSetup mbedtls_ssl_setup", rc);
   }
   mbedtls_ssl_set_bio(&ezssl, &ezbio, EzTlsSend, 0, EzTlsRecv);
 }
+
+void EzDestroy(void) {
+  if (!mytid) return;
+  EzSanity();
+  mbedtls_ssl_free(&ezssl);
+  mbedtls_ctr_drbg_free(&ezrng);
+  mbedtls_ssl_config_free(&ezconf);
+  mytid = 0;
+}
diff --git a/tool/build/lib/eztls.h b/tool/build/lib/eztls.h
index 612acb9ad..9e65734b2 100644
--- a/tool/build/lib/eztls.h
+++ b/tool/build/lib/eztls.h
@@ -13,16 +13,19 @@ struct EzTlsBio {
   unsigned char u[1430];
 };
 
-extern struct EzTlsBio ezbio;
-extern mbedtls_ssl_config ezconf;
-extern mbedtls_ssl_context ezssl;
-extern mbedtls_ctr_drbg_context ezrng;
+extern _Thread_local struct EzTlsBio ezbio;
+extern _Thread_local mbedtls_ssl_config ezconf;
+extern _Thread_local mbedtls_ssl_context ezssl;
+extern _Thread_local mbedtls_ctr_drbg_context ezrng;
 
 void EzFd(int);
+void EzSanity(void);
+void EzDestroy(void);
 void EzHandshake(void);
 int EzHandshake2(void);
 void EzSetup(char[32]);
 void EzInitialize(void);
+void EzTlsDie(const char *, int);
 int EzTlsFlush(struct EzTlsBio *, const unsigned char *, size_t);
 
 /*
diff --git a/tool/build/runit.c b/tool/build/runit.c
index ef695127d..fdf6d7d81 100644
--- a/tool/build/runit.c
+++ b/tool/build/runit.c
@@ -27,11 +27,14 @@
 #include "libc/fmt/conv.h"
 #include "libc/fmt/libgen.h"
 #include "libc/intrin/bits.h"
+#include "libc/intrin/kprintf.h"
 #include "libc/intrin/safemacros.internal.h"
 #include "libc/limits.h"
 #include "libc/log/check.h"
 #include "libc/log/log.h"
+#include "libc/macros.internal.h"
 #include "libc/mem/gc.h"
+#include "libc/mem/gc.internal.h"
 #include "libc/mem/mem.h"
 #include "libc/runtime/runtime.h"
 #include "libc/sock/ipclassify.internal.h"
@@ -50,6 +53,7 @@
 #include "libc/time/time.h"
 #include "libc/x/x.h"
 #include "libc/x/xasprintf.h"
+#include "libc/x/xsigaction.h"
 #include "net/https/https.h"
 #include "third_party/mbedtls/ssl.h"
 #include "third_party/zlib/zlib.h"
@@ -271,64 +275,74 @@ void RelayRequest(void) {
     for (i = 0; i < have; i += rc) {
       rc = mbedtls_ssl_write(&ezssl, buf + i, have - i);
       if (rc <= 0) {
-        TlsDie("relay request failed", rc);
+        EzTlsDie("relay request failed", rc);
       }
     }
   }
   CHECK_NE(0, transferred);
   rc = EzTlsFlush(&ezbio, 0, 0);
   if (rc < 0) {
-    TlsDie("relay request failed to flush", rc);
+    EzTlsDie("relay request failed to flush", rc);
   }
   close(13);
 }
 
-bool Recv(unsigned char *p, size_t n) {
-  size_t i, rc;
+bool Recv(char *p, int n) {
+  int i, rc;
   for (i = 0; i < n; i += rc) {
-    do {
-      rc = mbedtls_ssl_read(&ezssl, p + i, n - i);
-    } while (rc == MBEDTLS_ERR_SSL_WANT_READ);
+    do rc = mbedtls_ssl_read(&ezssl, p + i, n - i);
+    while (rc == MBEDTLS_ERR_SSL_WANT_READ);
     if (!rc) return false;
-    if (rc < 0) {
-      TlsDie("read response failed", rc);
-    }
+    if (rc < 0) EzTlsDie("read response failed", rc);
   }
   return true;
 }
-
 int ReadResponse(void) {
-  int res;
-  size_t n;
-  uint32_t size;
-  unsigned char b[512];
-  for (res = -1; res == -1;) {
-    if (!Recv(b, 5)) break;
-    CHECK_EQ(RUNITD_MAGIC, READ32BE(b), "%#.5s", b);
-    switch (b[4]) {
-      case kRunitExit:
-        if (!Recv(b, 1)) break;
-        if ((res = *b)) {
-          WARNF("%s on %s exited with %d", g_prog, g_hostname, res);
-        }
+  int exitcode;
+  for (;;) {
+    char msg[5];
+    if (!Recv(msg, 5)) {
+      WARNF("%s didn't report status of %s", g_hostname, g_prog);
+      exitcode = 200;
+      break;
+    }
+    if (READ32BE(msg) != RUNITD_MAGIC) {
+      WARNF("%s sent corrupted data stream after running %s", g_hostname,
+            g_prog);
+      exitcode = 201;
+      break;
+    }
+    if (msg[4] == kRunitExit) {
+      if (!Recv(msg, 1)) {
+      TruncatedMessage:
+        WARNF("%s sent truncated message running %s", g_hostname, g_prog);
+        exitcode = 202;
         break;
-      case kRunitStderr:
-        if (!Recv(b, 4)) break;
-        size = READ32BE(b);
-        for (; size; size -= n) {
-          n = MIN(size, sizeof(b));
-          if (!Recv(b, n)) goto drop;
-          CHECK_EQ(n, write(2, b, n));
-        }
-        break;
-      default:
-        fprintf(stderr, "error: received invalid runit command\n");
-        _exit(1);
+      }
+      exitcode = *msg;
+      if (exitcode) {
+        WARNF("%s says %s exited with %d", g_hostname, g_prog, exitcode);
+      } else {
+        VERBOSEF("%s says %s exited with %d", g_hostname, g_prog, exitcode);
+      }
+      mbedtls_ssl_close_notify(&ezssl);
+      break;
+    } else if (msg[4] == kRunitStdout || msg[4] == kRunitStderr) {
+      if (!Recv(msg, 4)) goto TruncatedMessage;
+      int n = READ32BE(msg);
+      char *s = malloc(n);
+      if (!Recv(s, n)) goto TruncatedMessage;
+      write(2, s, n);
+      free(s);
+    } else {
+      WARNF("%s sent message with unknown command %d after running %s",
+            g_hostname, msg[4], g_prog);
+      exitcode = 203;
+      break;
     }
   }
-drop:
   close(g_sock);
-  return res;
+  return exitcode;
 }
 
 static inline bool IsElf(const char *p, size_t n) {
@@ -340,23 +354,28 @@ static inline bool IsMachO(const char *p, size_t n) {
 }
 
 int RunOnHost(char *spec) {
-  int rc;
+  int err;
   char *p;
   for (p = spec; *p; ++p) {
     if (*p == ':') *p = ' ';
   }
-  CHECK_GE(sscanf(spec, "%100s %hu %hu", g_hostname, &g_runitdport, &g_sshport),
-           1);
+  int got =
+      sscanf(spec, "%100s %hu %hu", g_hostname, &g_runitdport, &g_sshport);
+  if (got < 1) {
+    kprintf("what on earth %#s -> %d\n", spec, got);
+    exit(1);
+  }
   if (!strchr(g_hostname, '.')) strcat(g_hostname, ".test.");
   DEBUGF("connecting to %s port %d", g_hostname, g_runitdport);
   for (;;) {
     Connect();
     EzFd(g_sock);
-    if (!(rc = EzHandshake2())) {
-      break;
-    }
-    WARNF("got reset in handshake -0x%04x", rc);
+    err = EzHandshake2();
+    if (!err) break;
+    WARNF("handshake with %s:%d failed -0x%04x (%s)",  //
+          g_hostname, g_runitdport, err, GetTlsError(err));
     close(g_sock);
+    return 1;
   }
   RelayRequest();
   return ReadResponse();
@@ -454,6 +473,7 @@ int SpawnSubprocesses(int argc, char *argv[]) {
 
 int main(int argc, char *argv[]) {
   ShowCrashReports();
+  signal(SIGPIPE, SIG_IGN);
   if (getenv("DEBUG")) {
     __log_level = kLogDebug;
   }
diff --git a/tool/build/runitd.c b/tool/build/runitd.c
index fe4191d3b..96841a1a1 100644
--- a/tool/build/runitd.c
+++ b/tool/build/runitd.c
@@ -16,8 +16,12 @@
 │ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
+#include "libc/assert.h"
+#include "libc/atomic.h"
 #include "libc/calls/calls.h"
+#include "libc/calls/struct/rusage.h"
 #include "libc/calls/struct/sigaction.h"
+#include "libc/calls/struct/sigset.h"
 #include "libc/calls/struct/stat.h"
 #include "libc/calls/struct/timespec.h"
 #include "libc/calls/struct/timeval.h"
@@ -26,19 +30,27 @@
 #include "libc/fmt/conv.h"
 #include "libc/fmt/libgen.h"
 #include "libc/intrin/bits.h"
+#include "libc/intrin/kprintf.h"
+#include "libc/log/appendresourcereport.internal.h"
 #include "libc/log/check.h"
-#include "libc/log/log.h"
 #include "libc/macros.internal.h"
 #include "libc/mem/gc.h"
+#include "libc/mem/gc.internal.h"
 #include "libc/mem/mem.h"
 #include "libc/nexgen32e/crc32.h"
 #include "libc/runtime/runtime.h"
+#include "libc/runtime/syslib.internal.h"
 #include "libc/sock/sock.h"
 #include "libc/sock/struct/pollfd.h"
 #include "libc/sock/struct/sockaddr.h"
+#include "libc/stdio/append.h"
+#include "libc/stdio/posix_spawn.h"
+#include "libc/stdio/rand.h"
 #include "libc/stdio/stdio.h"
 #include "libc/str/str.h"
 #include "libc/sysv/consts/af.h"
+#include "libc/sysv/consts/at.h"
+#include "libc/sysv/consts/clock.h"
 #include "libc/sysv/consts/ex.h"
 #include "libc/sysv/consts/exit.h"
 #include "libc/sysv/consts/f.h"
@@ -48,15 +60,21 @@
 #include "libc/sysv/consts/itimer.h"
 #include "libc/sysv/consts/o.h"
 #include "libc/sysv/consts/poll.h"
+#include "libc/sysv/consts/posix.h"
 #include "libc/sysv/consts/sa.h"
 #include "libc/sysv/consts/sig.h"
 #include "libc/sysv/consts/so.h"
 #include "libc/sysv/consts/sock.h"
 #include "libc/sysv/consts/sol.h"
 #include "libc/sysv/consts/w.h"
+#include "libc/temp.h"
+#include "libc/thread/thread.h"
+#include "libc/thread/thread2.h"
+#include "libc/time/struct/tm.h"
 #include "libc/time/time.h"
 #include "libc/x/x.h"
-#include "libc/x/xasprintf.h"
+#include "libc/x/xsigaction.h"
+#include "net/http/escape.h"
 #include "net/https/https.h"
 #include "third_party/getopt/getopt.internal.h"
 #include "third_party/mbedtls/ssl.h"
@@ -104,45 +122,64 @@
 #define kLogFile     "o/runitd.log"
 #define kLogMaxBytes (2 * 1000 * 1000)
 
+#define LOG_LEVEL_WARN 0
+#define LOG_LEVEL_INFO 1
+#define LOG_LEVEL_VERB 3
+#define LOG_LEVEL_DEBU 3
+
+#define DEBUF(FMT, ...) LOGF(DEBU, FMT, ##__VA_ARGS__)
+#define VERBF(FMT, ...) LOGF(VERB, FMT, ##__VA_ARGS__)
+#define INFOF(FMT, ...) LOGF(INFO, FMT, ##__VA_ARGS__)
+#define WARNF(FMT, ...) LOGF(WARN, FMT, ##__VA_ARGS__)
+
+#define LOGF(LVL, FMT, ...)                                               \
+  do {                                                                    \
+    if (g_log_level >= LOG_LEVEL_##LVL) {                                 \
+      kprintf("%r" #LVL " %6P %'18T %s:%d " FMT "\n", __FILE__, __LINE__, \
+              ##__VA_ARGS__);                                             \
+    }                                                                     \
+  } while (0)
+
+struct Client {
+  int fd;
+  int pid;
+  int pipe[2];
+  pthread_t th;
+  uint32_t addrsize;
+  struct sockaddr_in addr;
+  bool once;
+  int zstatus;
+  z_stream zs;
+  struct {
+    size_t off;
+    size_t len;
+    size_t cap;
+    char *data;
+  } rbuf;
+  char *output;
+  char exepath[128];
+  char buf[32768];
+};
+
+char *g_psk;
+int g_log_level;
 bool use_ftrace;
 bool use_strace;
-char *g_exepath;
-unsigned char g_buf[4096];
-volatile bool g_interrupted;
+char g_hostname[256];
+int g_bogusfd, g_servfd;
+atomic_bool g_interrupted;
 struct sockaddr_in g_servaddr;
 bool g_daemonize, g_sendready;
-int g_timeout, g_bogusfd, g_servfd, g_clifd, g_exefd;
 
 void OnInterrupt(int sig) {
   g_interrupted = true;
 }
 
-void OnChildTerminated(int sig) {
-  int e, ws, pid;
-  sigset_t ss, oldss;
-  e = errno;  // SIGCHLD can be called asynchronously
-  sigfillset(&ss);
-  sigdelset(&ss, SIGTERM);
-  sigprocmask(SIG_BLOCK, &ss, &oldss);
-  for (;;) {
-    if ((pid = waitpid(-1, &ws, WNOHANG)) != -1) {
-      if (pid) {
-        if (WIFEXITED(ws)) {
-          DEBUGF("worker %d exited with %d", pid, WEXITSTATUS(ws));
-        } else {
-          DEBUGF("worker %d terminated with %s", pid, strsignal(WTERMSIG(ws)));
-        }
-      } else {
-        break;
-      }
-    } else {
-      if (errno == EINTR) continue;
-      if (errno == ECHILD) break;
-      FATALF("waitpid failed in sigchld");
-    }
+void Close(int *fd) {
+  if (*fd > 0) {
+    close(*fd);
+    *fd = -1;  // poll ignores -1
   }
-  sigprocmask(SIG_SETMASK, &oldss, 0);
-  errno = e;
 }
 
 wontreturn void ShowUsage(FILE *f, int rc) {
@@ -151,9 +188,18 @@ wontreturn void ShowUsage(FILE *f, int rc) {
   exit(rc);
 }
 
+char *DescribeAddress(struct sockaddr_in *addr) {
+  static _Thread_local char res[64];
+  char ip4buf[64];
+  sprintf(res, "%s:%hu",
+          inet_ntop(addr->sin_family, &addr->sin_addr.s_addr, ip4buf,
+                    sizeof(ip4buf)),
+          ntohs(addr->sin_port));
+  return res;
+}
+
 void GetOpts(int argc, char *argv[]) {
   int opt;
-  g_timeout = RUNITD_TIMEOUT_MS;
   g_servaddr.sin_family = AF_INET;
   g_servaddr.sin_port = htons(RUNITD_PORT);
   g_servaddr.sin_addr.s_addr = INADDR_ANY;
@@ -166,10 +212,10 @@ void GetOpts(int argc, char *argv[]) {
         use_strace = true;
         break;
       case 'q':
-        --__log_level;
+        --g_log_level;
         break;
       case 'v':
-        ++__log_level;
+        ++g_log_level;
         break;
       case 'd':
         g_daemonize = true;
@@ -178,56 +224,44 @@ void GetOpts(int argc, char *argv[]) {
         g_sendready = true;
         break;
       case 't':
-        g_timeout = atoi(optarg);
         break;
       case 'p':
-        CHECK_NE(0xFFFF, (g_servaddr.sin_port = htons(parseport(optarg))));
+        g_servaddr.sin_port = htons(parseport(optarg));
         break;
       case 'l':
-        CHECK_EQ(1, inet_pton(AF_INET, optarg, &g_servaddr.sin_addr));
+        inet_pton(AF_INET, optarg, &g_servaddr.sin_addr);
         break;
       case 'h':
         ShowUsage(stdout, EXIT_SUCCESS);
-        __builtin_unreachable();
       default:
         ShowUsage(stderr, EX_USAGE);
-        __builtin_unreachable();
     }
   }
 }
 
-__wur char *DescribeAddress(struct sockaddr_in *addr) {
-  char ip4buf[16];
-  return xasprintf("%s:%hu",
-                   inet_ntop(addr->sin_family, &addr->sin_addr.s_addr, ip4buf,
-                             sizeof(ip4buf)),
-                   ntohs(addr->sin_port));
-}
-
 void StartTcpServer(void) {
   int yes = true;
   uint32_t asize;
-
-  /*
-   * TODO: How can we make close(serversocket) on Windows go fast?
-   *       That way we can put back SOCK_CLOEXEC.
-   */
-  CHECK_NE(-1, (g_servfd =
-                    socket(AF_INET, SOCK_STREAM | SOCK_CLOEXEC, IPPROTO_TCP)));
-
-  struct timeval timeo = {30};
+  g_servfd = socket(AF_INET, SOCK_STREAM | SOCK_CLOEXEC, IPPROTO_TCP);
+  if (g_servfd == -1) {
+    fprintf(stderr, program_invocation_short_name,
+            ": socket failed: ", strerror(errno), "\n", NULL);
+    exit(1);
+  }
+  struct timeval timeo = {DEATH_CLOCK_SECONDS / 10};
   setsockopt(g_servfd, SOL_SOCKET, SO_RCVTIMEO, &timeo, sizeof(timeo));
   setsockopt(g_servfd, SOL_SOCKET, SO_SNDTIMEO, &timeo, sizeof(timeo));
-
-  LOGIFNEG1(setsockopt(g_servfd, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof(yes)));
+  setsockopt(g_servfd, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof(yes));
   if (bind(g_servfd, (struct sockaddr *)&g_servaddr, sizeof(g_servaddr)) ==
       -1) {
-    FATALF("bind failed %m");
+    fprintf(stderr, program_invocation_short_name,
+            ": bind failed: ", strerror(errno), "\n", NULL);
+    exit(1);
   }
-  CHECK_NE(-1, listen(g_servfd, 10));
+  unassert(!listen(g_servfd, 10));
   asize = sizeof(g_servaddr);
-  CHECK_NE(-1, getsockname(g_servfd, (struct sockaddr *)&g_servaddr, &asize));
-  INFOF("%s:%s", "listening on tcp", _gc(DescribeAddress(&g_servaddr)));
+  unassert(!getsockname(g_servfd, (struct sockaddr *)&g_servaddr, &asize));
+  INFOF("listening on tcp:%s", DescribeAddress(&g_servaddr));
   if (g_sendready) {
     printf("ready %hu\n", ntohs(g_servaddr.sin_port));
     fflush(stdout);
@@ -237,22 +271,28 @@ void StartTcpServer(void) {
 }
 
 void SendExitMessage(int rc) {
+  EzSanity();
+  int res;
   unsigned char msg[4 + 1 + 1];
+  DEBUF("SendExitMessage");
   msg[0 + 0] = (RUNITD_MAGIC & 0xff000000) >> 030;
   msg[0 + 1] = (RUNITD_MAGIC & 0x00ff0000) >> 020;
   msg[0 + 2] = (RUNITD_MAGIC & 0x0000ff00) >> 010;
   msg[0 + 3] = (RUNITD_MAGIC & 0x000000ff) >> 000;
   msg[4] = kRunitExit;
   msg[5] = rc;
-  INFOF("mbedtls_ssl_write");
-  CHECK_EQ(sizeof(msg), mbedtls_ssl_write(&ezssl, msg, sizeof(msg)));
-  CHECK_EQ(0, EzTlsFlush(&ezbio, 0, 0));
+  DEBUF("mbedtls_ssl_write");
+  if (sizeof(msg) != (res = mbedtls_ssl_write(&ezssl, msg, sizeof(msg)))) {
+    EzTlsDie("SendExitMessage mbedtls_ssl_write failed", res);
+  }
+  if ((res = EzTlsFlush(&ezbio, 0, 0))) {
+    EzTlsDie("SendExitMessage EzTlsFlush failed", res);
+  }
 }
 
-void SendOutputFragmentMessage(enum RunitCommand kind, unsigned char *buf,
-                               size_t size) {
+void SendOutputFragmentMessage(enum RunitCommand kind, char *buf, size_t size) {
+  EzSanity();
   ssize_t rc;
-  size_t sent;
   unsigned char msg[4 + 1 + 4];
   msg[0 + 0] = (RUNITD_MAGIC & 0xff000000) >> 030;
   msg[0 + 1] = (RUNITD_MAGIC & 0x00ff0000) >> 020;
@@ -263,309 +303,451 @@ void SendOutputFragmentMessage(enum RunitCommand kind, unsigned char *buf,
   msg[5 + 1] = (size & 0x00ff0000) >> 020;
   msg[5 + 2] = (size & 0x0000ff00) >> 010;
   msg[5 + 3] = (size & 0x000000ff) >> 000;
-  INFOF("mbedtls_ssl_write");
-  CHECK_EQ(sizeof(msg), mbedtls_ssl_write(&ezssl, msg, sizeof(msg)));
-  while (size) {
-    CHECK_NE(-1, (rc = mbedtls_ssl_write(&ezssl, buf, size)));
-    CHECK_LE((sent = (size_t)rc), size);
-    size -= sent;
-    buf += sent;
+  DEBUF("mbedtls_ssl_write");
+  if (sizeof(msg) != (rc = mbedtls_ssl_write(&ezssl, msg, sizeof(msg)))) {
+    EzTlsDie("SendOutputFragmentMessage mbedtls_ssl_write failed", rc);
+  }
+  while (size) {
+    if ((rc = mbedtls_ssl_write(&ezssl, buf, size)) <= 0) {
+      EzTlsDie("SendOutputFragmentMessage mbedtls_ssl_write #2 failed", rc);
+    }
+    size -= rc;
+    buf += rc;
+  }
+  if ((rc = EzTlsFlush(&ezbio, 0, 0))) {
+    EzTlsDie("SendOutputFragmentMessage EzTlsFlush failed", rc);
   }
-  CHECK_EQ(0, EzTlsFlush(&ezbio, 0, 0));
 }
 
-void Recv(void *output, size_t outputsize) {
+void Recv(struct Client *client, void *output, size_t outputsize) {
+  EzSanity();
   ssize_t chunk, received, totalgot;
-  static bool once;
-  static int zstatus;
-  static char buf[32768];
-  static z_stream zs;
-  static struct {
-    size_t off;
-    size_t len;
-    size_t cap;
-    char *data;
-  } rbuf;
-  if (!once) {
-    CHECK_EQ(Z_OK, inflateInit(&zs));
-    once = true;
+  if (!client->once) {
+    unassert(Z_OK == inflateInit(&client->zs));
+    client->once = true;
   }
   totalgot = 0;
   for (;;) {
-    if (rbuf.len >= outputsize) {
-      memcpy(output, rbuf.data + rbuf.off, outputsize);
-      rbuf.len -= outputsize;
-      rbuf.off += outputsize;
+    if (client->rbuf.len >= outputsize) {
+      memcpy(output, client->rbuf.data + client->rbuf.off, outputsize);
+      client->rbuf.len -= outputsize;
+      client->rbuf.off += outputsize;
       // trim dymanic buffer once it empties
-      if (!rbuf.len) {
-        rbuf.off = 0;
-        rbuf.cap = 4096;
-        rbuf.data = realloc(rbuf.data, rbuf.cap);
+      if (!client->rbuf.len) {
+        client->rbuf.off = 0;
+        client->rbuf.cap = 4096;
+        client->rbuf.data = realloc(client->rbuf.data, client->rbuf.cap);
       }
       return;
     }
-    if (zstatus == Z_STREAM_END) {
-      close(g_clifd);
-      FATALF("recv zlib unexpected eof");
+    if (client->zstatus == Z_STREAM_END) {
+      WARNF("recv zlib unexpected eof");
+      pthread_exit(0);
     }
     // get another fixed-size data packet from network
     // pass along error conditions to caller
     // pass along eof condition to zlib
-    received = mbedtls_ssl_read(&ezssl, buf, sizeof(buf));
+    received = mbedtls_ssl_read(&ezssl, client->buf, sizeof(client->buf));
     if (!received) {
-      close(g_clifd);
-      TlsDie("got unexpected eof", received);
+      EzTlsDie("got unexpected eof", received);
     }
     if (received < 0) {
-      close(g_clifd);
-      TlsDie("read failed", received);
+      EzTlsDie("read failed", received);
     }
     totalgot += received;
     // decompress packet completely
     // into a dynamical size buffer
-    zs.avail_in = received;
-    zs.next_in = (unsigned char *)buf;
-    CHECK_EQ(Z_OK, zstatus);
+    client->zs.avail_in = received;
+    client->zs.next_in = (unsigned char *)client->buf;
+    unassert(Z_OK == client->zstatus);
     do {
       // make sure we have a reasonable capacity for zlib output
-      if (rbuf.cap - (rbuf.off + rbuf.len) < sizeof(buf)) {
-        rbuf.cap += sizeof(buf);
-        rbuf.data = realloc(rbuf.data, rbuf.cap);
+      if (client->rbuf.cap - (client->rbuf.off + client->rbuf.len) <
+          sizeof(client->buf)) {
+        client->rbuf.cap += sizeof(client->buf);
+        client->rbuf.data = realloc(client->rbuf.data, client->rbuf.cap);
       }
       // inflate packet, which naturally can be much larger
       // permit zlib no delay flushes that come from sender
-      zs.next_out = (unsigned char *)rbuf.data + (rbuf.off + rbuf.len);
-      zs.avail_out = chunk = rbuf.cap - (rbuf.off + rbuf.len);
-      zstatus = inflate(&zs, Z_SYNC_FLUSH);
-      CHECK_NE(Z_STREAM_ERROR, zstatus);
-      switch (zstatus) {
+      client->zs.next_out = (unsigned char *)client->rbuf.data +
+                            (client->rbuf.off + client->rbuf.len);
+      client->zs.avail_out = chunk =
+          client->rbuf.cap - (client->rbuf.off + client->rbuf.len);
+      client->zstatus = inflate(&client->zs, Z_SYNC_FLUSH);
+      unassert(Z_STREAM_ERROR != client->zstatus);
+      switch (client->zstatus) {
         case Z_NEED_DICT:
           WARNF("tls recv Z_NEED_DICT %ld total %ld", received, totalgot);
-          exit(1);
+          pthread_exit(0);
         case Z_DATA_ERROR:
           WARNF("tls recv Z_DATA_ERROR %ld total %ld", received, totalgot);
-          exit(1);
+          pthread_exit(0);
         case Z_MEM_ERROR:
           WARNF("tls recv Z_MEM_ERROR %ld total %ld", received, totalgot);
-          exit(1);
+          pthread_exit(0);
         case Z_BUF_ERROR:
-          zstatus = Z_OK;  // harmless? nothing for inflate to do
-          break;           // it probably just our wraparound eof
+          client->zstatus = Z_OK;  // harmless? nothing for inflate to do
+          break;                   // it probably just our wraparound eof
         default:
-          rbuf.len += chunk - zs.avail_out;
+          client->rbuf.len += chunk - client->zs.avail_out;
           break;
       }
-    } while (!zs.avail_out);
+    } while (!client->zs.avail_out);
   }
 }
 
-void HandleClient(void) {
-  ssize_t got;
+void SendProgramOutut(struct Client *client) {
+  if (client->output) {
+    SendOutputFragmentMessage(kRunitStderr, client->output,
+                              appendz(client->output).i);
+  }
+}
+
+void PrintProgramOutput(struct Client *client) {
+  if (client->output) {
+    char *p = client->output;
+    size_t z = appendz(p).i;
+    if ((p = IndentLines(p, z, &z, 2))) {
+      fwrite(p, 1, z, stderr);
+      free(p);
+    }
+  }
+}
+
+void FreeClient(struct Client *client) {
+  DEBUF("FreeClient");
+  if (client->pid) {
+    kill(client->pid, SIGHUP);
+    waitpid(client->pid, 0, 0);
+  }
+  Close(&client->fd);
+  if (*client->exepath) {
+    unlink(client->exepath);
+  }
+  if (client->once) {
+    inflateEnd(&client->zs);
+  }
+  EzDestroy();
+  free(client->rbuf.data);
+  free(client->output);
+  free(client);
+  VERBF("---------------");
+}
+
+void *ClientWorker(void *arg) {
   uint32_t crc;
   sigset_t sigmask;
-  struct sockaddr_in addr;
-  struct timespec now, deadline;
+  int events, wstatus;
+  struct Client *client = arg;
+  uint32_t namesize, filesize;
   char *addrstr, *exename, *exe;
   unsigned char msg[4 + 1 + 4 + 4 + 4];
-  uint32_t addrsize, namesize, filesize;
-  int events, exitcode, wstatus, child, pipefds[2];
 
-  /* read request to run program */
-  addrsize = sizeof(addr);
-  INFOF("accept");
-  do {
-    g_clifd =
-        accept4(g_servfd, (struct sockaddr *)&addr, &addrsize, SOCK_CLOEXEC);
-  } while (g_clifd == -1 && errno == EAGAIN);
-  CHECK_NE(-1, g_clifd);
-  if (fork()) {
-    close(g_clifd);
-    return;
-  }
-  EzFd(g_clifd);
-  INFOF("EzHandshake");
+  SetupPresharedKeySsl(MBEDTLS_SSL_IS_SERVER, g_psk);
+  defer(FreeClient, client);
+
+  // read request to run program
+  EzFd(client->fd);
+  DEBUF("EzHandshake");
   EzHandshake();
-  addrstr = _gc(DescribeAddress(&addr));
-  DEBUGF("%s %s %s", _gc(DescribeAddress(&g_servaddr)), "accepted", addrstr);
+  addrstr = DescribeAddress(&client->addr);
+  DEBUF("%s %s %s", DescribeAddress(&g_servaddr), "accepted", addrstr);
 
-  Recv(msg, sizeof(msg));
-  CHECK_EQ(RUNITD_MAGIC, READ32BE(msg));
-  CHECK_EQ(kRunitExecute, msg[4]);
+  // get the executable
+  Recv(client, msg, sizeof(msg));
+  if (READ32BE(msg) != RUNITD_MAGIC) {
+    WARNF("%s magic mismatch!", addrstr);
+    pthread_exit(0);
+  }
+  if (msg[4] != kRunitExecute) {
+    WARNF("%s unknown command!", addrstr);
+    pthread_exit(0);
+  }
   namesize = READ32BE(msg + 5);
   filesize = READ32BE(msg + 9);
   crc = READ32BE(msg + 13);
-  exename = _gc(calloc(1, namesize + 1));
-  Recv(exename, namesize);
-  g_exepath = _gc(xasprintf("o/%d.%s", getpid(), basename(exename)));
-  INFOF("%s asked we run %`'s (%,u bytes @ %`'s)", addrstr, exename, filesize,
-        g_exepath);
-
-  exe = malloc(filesize);
-  Recv(exe, filesize);
+  exename = gc(calloc(1, namesize + 1));
+  Recv(client, exename, namesize);
+  INFOF("%s sent %#s (%'u bytes @ %#s)", addrstr, exename, filesize,
+        client->exepath);
+  exe = gc(malloc(filesize));
+  Recv(client, exe, filesize);
   if (crc32_z(0, exe, filesize) != crc) {
-    FATALF("%s crc mismatch! %`'s", addrstr, exename);
+    WARNF("%s crc mismatch! %#s", addrstr, exename);
+    pthread_exit(0);
   }
-  CHECK_NE(-1, (g_exefd = creat(g_exepath, 0700)));
-  LOGIFNEG1(ftruncate(g_exefd, filesize));
-  CHECK_NE(-1, xwrite(g_exefd, exe, filesize));
-  LOGIFNEG1(close(g_exefd));
 
-  /* run program, tee'ing stderr to both log and client */
-  DEBUGF("spawning %s", exename);
+  // create the executable file
+  // if another thread vforks while we're writing it then a race
+  // condition can happen, where etxtbsy is raised by our execve
+  // we're using o_cloexec so it's guaranteed to fix itself fast
+  // thus we use an optimistic approach to avoid expensive locks
+  sprintf(client->exepath, "o/%s.XXXXXX.com", basename(exename));
+  int exefd = openatemp(AT_FDCWD, client->exepath, 4, O_CLOEXEC, 0700);
+  ftruncate(exefd, filesize);
+  if (write(exefd, exe, filesize) != filesize) {
+    WARNF("%s failed to write %#s", addrstr, exename);
+    close(exefd);
+    pthread_exit(0);
+  }
+  if (close(exefd)) {
+    WARNF("%s failed to close %#s", addrstr, exename);
+    pthread_exit(0);
+  }
+
+  // do the args
+  int i = 0;
+  char *args[8] = {0};
+  if (!IsXnuSilicon()) {
+    exe = client->exepath;
+  } else {
+    exe = "ape-m1.com";
+    args[i++] = (char *)exe;
+    args[i++] = "-";
+    args[i++] = client->exepath;
+  }
+  args[i++] = client->exepath;
+  if (use_strace) args[i++] = "--strace";
+  if (use_ftrace) args[i++] = "--ftrace";
+
+  // run program, tee'ing stderr to both log and client
+  DEBUF("spawning %s", client->exepath);
   sigemptyset(&sigmask);
   sigaddset(&sigmask, SIGINT);
-  sigaddset(&sigmask, SIGQUIT);
   sigaddset(&sigmask, SIGCHLD);
   sigprocmask(SIG_BLOCK, &sigmask, 0);
-  CHECK_NE(-1, pipe2(pipefds, O_CLOEXEC));
-  CHECK_NE(-1, (child = fork()));
-  if (!child) {
-    dup2(g_bogusfd, 0);
-    dup2(pipefds[1], 1);
-    dup2(pipefds[1], 2);
-    sigemptyset(&sigmask);
-    sigprocmask(SIG_SETMASK, &sigmask, 0);
-    int i = 0;
-    const char *exe;
-    char *args[8] = {0};
-    if (!IsXnuSilicon()) {
-      exe = g_exepath;
-    } else {
-      exe = "ape-m1.com";
-      args[i++] = (char *)exe;
-      args[i++] = "-";
-      args[i++] = g_exepath;
+
+  // spawn the program
+  int etxtbsy_tries = 0;
+RetryOnEtxtbsyRaceCondition:
+  if (etxtbsy_tries++) {
+    if (etxtbsy_tries == 24) {  // ~30 seconds
+      WARNF("%s failed to spawn on %s due because either (1) the ETXTBSY race "
+            "condition kept happening or (2) the program in question actually "
+            "is crashing with SIGVTALRM, without printing anything to out/err!",
+            exename, g_hostname);
+      pthread_exit(0);
+    }
+    if (usleep(1u << etxtbsy_tries)) {
+      INFOF("interrupted exponential spawn backoff");
+      pthread_exit(0);
     }
-    args[i++] = g_exepath;
-    if (use_strace) args[i++] = "--strace";
-    if (use_ftrace) args[i++] = "--ftrace";
-    execvp(exe, args);
-    _Exit(127);
   }
-  signal(SIGINT, SIG_IGN);
-  signal(SIGQUIT, SIG_IGN);
-  close(pipefds[1]);
-  DEBUGF("communicating %s[%d]", exename, child);
-  deadline =
+  errno_t err;
+  posix_spawnattr_t spawnattr;
+  posix_spawn_file_actions_t spawnfila;
+  sigemptyset(&sigmask);
+  pipe2(client->pipe, O_CLOEXEC);
+  posix_spawnattr_init(&spawnattr);
+  posix_spawnattr_setflags(&spawnattr, POSIX_SPAWN_SETPGROUP);
+  posix_spawnattr_setsigmask(&spawnattr, &sigmask);
+  posix_spawn_file_actions_init(&spawnfila);
+  posix_spawn_file_actions_adddup2(&spawnfila, g_bogusfd, 0);
+  posix_spawn_file_actions_adddup2(&spawnfila, client->pipe[1], 1);
+  posix_spawn_file_actions_adddup2(&spawnfila, client->pipe[1], 2);
+  err = posix_spawn(&client->pid, exe, &spawnfila, &spawnattr, args, environ);
+  if (err) {
+    Close(&client->pipe[1]);
+    Close(&client->pipe[0]);
+    if (err == ETXTBSY) {
+      goto RetryOnEtxtbsyRaceCondition;
+    }
+    WARNF("%s failed to spawn on %s due to %s", exename, g_hostname,
+          strerror(err));
+    pthread_exit(0);
+  }
+  posix_spawn_file_actions_destroy(&spawnfila);
+  posix_spawnattr_destroy(&spawnattr);
+  Close(&client->pipe[1]);
+
+  DEBUF("communicating %s[%d]", exename, client->pid);
+  struct timespec deadline =
       timespec_add(timespec_real(), timespec_fromseconds(DEATH_CLOCK_SECONDS));
   for (;;) {
-    now = timespec_real();
-    if (timespec_cmp(now, deadline) >= 0) {
-      WARNF("%s worker timed out", exename);
+    if (g_interrupted) {
+      WARNF("killing %d %s and hanging up %d due to interrupt", client->fd,
+            exename, client->pid);
+    HangupClientAndTerminateJob:
+      SendProgramOutut(client);
+      mbedtls_ssl_close_notify(&ezssl);
     TerminateJob:
-      LOGIFNEG1(kill(child, 9));
-      LOGIFNEG1(waitpid(child, 0, 0));
-      LOGIFNEG1(close(g_clifd));
-      LOGIFNEG1(close(pipefds[0]));
-      LOGIFNEG1(unlink(g_exepath));
-      _exit(1);
+      PrintProgramOutput(client);
+      pthread_exit(0);
+    }
+    struct timespec now = timespec_real();
+    if (timespec_cmp(now, deadline) >= 0) {
+      WARNF("killing %s (pid %d) which timed out after %d seconds", exename,
+            client->pid, DEATH_CLOCK_SECONDS);
+      goto HangupClientAndTerminateJob;
     }
     struct pollfd fds[2];
-    fds[0].fd = g_clifd;
+    fds[0].fd = client->fd;
     fds[0].events = POLLIN;
-    fds[1].fd = pipefds[0];
+    fds[1].fd = client->pipe[0];
     fds[1].events = POLLIN;
-    int waitms = timespec_tomillis(timespec_sub(deadline, now));
-    INFOF("polling for %d ms", waitms);
-    events = poll(fds, ARRAYLEN(fds), waitms);
-    CHECK_NE(-1, events);  // EINTR shouldn't be possible
+    events = poll(fds, ARRAYLEN(fds),
+                  timespec_tomillis(timespec_sub(deadline, now)));
+    if (events == -1) {
+      if (errno == EINTR) {
+        INFOF("poll interrupted");
+        continue;
+      } else {
+        WARNF("killing %d %s and hanging up %d because poll failed", client->fd,
+              exename, client->pid);
+        goto HangupClientAndTerminateJob;
+      }
+    }
     if (events) {
       if (fds[0].revents) {
         int received;
         char buf[512];
-        INFOF("mbedtls_ssl_read");
         received = mbedtls_ssl_read(&ezssl, buf, sizeof(buf));
         if (!received) {
-          WARNF("%s client disconnected so killing worker %d", exename, child);
+          WARNF("%s client disconnected so killing worker %d", exename,
+                client->pid);
           goto TerminateJob;
         }
         if (received > 0) {
           WARNF("%s client sent %d unexpected bytes so killing job", exename,
                 received);
-          goto TerminateJob;
+          goto HangupClientAndTerminateJob;
         }
-        if (received != MBEDTLS_ERR_SSL_WANT_READ) {
-          WARNF("%s client ssl read failed with -0x%04x so killing job",
-                exename, -received);
-          goto TerminateJob;
+        if (received == MBEDTLS_ERR_SSL_WANT_READ) {  // EAGAIN SO_RCVTIMEO
+          WARNF("%s (pid %d) is taking a really long time", exename,
+                client->pid);
+          continue;
         }
-        INFOF("got spurious ssl data");
+        WARNF("client ssl read failed with -0x%04x (%s) so killing %s",
+              -received, GetTlsError(received), exename);
+        goto TerminateJob;
       }
       if (fds[1].revents) {
-        INFOF("read");
-        got = read(pipefds[0], g_buf, sizeof(g_buf));
-        CHECK_NE(-1, got);  // EINTR shouldn't be possible
+        char buf[512];
+        ssize_t got = read(client->pipe[0], buf, sizeof(buf));
+        if (got == -1) {
+          WARNF("got %s reading %s output", strerror(errno), exename);
+          goto HangupClientAndTerminateJob;
+        }
         if (!got) {
-          LOGIFNEG1(close(pipefds[0]));
+          VERBF("got eof reading %s output", exename);
+          Close(&client->pipe[0]);
           break;
         }
-        fwrite(g_buf, got, 1, stderr);
-        SendOutputFragmentMessage(kRunitStderr, g_buf, got);
+        DEBUF("got %ld bytes reading %s output", got, exename);
+        appendd(&client->output, buf, got);
       }
     }
   }
-  INFOF("waitpid");
-  CHECK_NE(-1, waitpid(child, &wstatus, 0));  // EINTR shouldn't be possible
+WaitAgain:
+  DEBUF("waitpid");
+  struct rusage rusage;
+  int wrc = wait4(client->pid, &wstatus, 0, &rusage);
+  if (wrc == -1) {
+    if (errno == EINTR) {
+      WARNF("waitpid interrupted; killing %s pid %d", exename, client->pid);
+      kill(client->pid, SIGINT);
+      goto WaitAgain;
+    }
+    WARNF("waitpid failed %m");
+    client->pid = 0;
+    goto HangupClientAndTerminateJob;
+  }
+  client->pid = 0;
+  int exitcode;
   if (WIFEXITED(wstatus)) {
     if (WEXITSTATUS(wstatus)) {
-      WARNF("%s exited with %d", exename, WEXITSTATUS(wstatus));
+      WARNF("%s on %s exited with %d", exename, g_hostname,
+            WEXITSTATUS(wstatus));
+      appendf(&client->output, "------ %s %s $?=%d (0x%08x) ------\n",
+              g_hostname, exename, WEXITSTATUS(wstatus), wstatus);
     } else {
-      VERBOSEF("%s exited with %d", exename, WEXITSTATUS(wstatus));
+      VERBF("%s on %s exited with %d", exename, g_hostname,
+            WEXITSTATUS(wstatus));
     }
     exitcode = WEXITSTATUS(wstatus);
-  } else {
-    WARNF("%s terminated with %s", exename, strsignal(WTERMSIG(wstatus)));
+  } else if (WIFSIGNALED(wstatus)) {
+    if (WTERMSIG(wstatus) == SIGVTALRM && !client->output) {
+      free(client->output);
+      client->output = 0;
+      goto RetryOnEtxtbsyRaceCondition;
+    }
+    WARNF("%s on %s terminated with %s", exename, g_hostname,
+          strsignal(WTERMSIG(wstatus)));
     exitcode = 128 + WTERMSIG(wstatus);
+    appendf(&client->output, "------ %s %s $?=%s (0x%08x) ------\n", g_hostname,
+            exename, strsignal(WTERMSIG(wstatus)), wstatus);
+  } else {
+    WARNF("%s on %s died with wait status 0x%08x", exename, g_hostname,
+          wstatus);
+    exitcode = 127;
   }
-  LOGIFNEG1(unlink(g_exepath));
+  if (wstatus) {
+    AppendResourceReport(&client->output, &rusage, "\n");
+    PrintProgramOutput(client);
+  }
+  SendProgramOutut(client);
   SendExitMessage(exitcode);
-  INFOF("mbedtls_ssl_close_notify");
   mbedtls_ssl_close_notify(&ezssl);
-  LOGIFNEG1(close(g_clifd));
-  _exit(0);
+  if (etxtbsy_tries) {
+    VERBF("encountered %d ETXTBSY race conditions spawning %s", etxtbsy_tries,
+          exename);
+  }
+  pthread_exit(0);
 }
 
-int Poll(void) {
-  int i, wait, evcount;
-  struct pollfd fds[1];
-TryAgain:
-  if (g_interrupted) return 0;
-  fds[0].fd = g_servfd;
-  fds[0].events = POLLIN | POLLERR | POLLHUP;
-  wait = MIN(1000, g_timeout);
-  evcount = poll(fds, ARRAYLEN(fds), wait);
-  if (!evcount) g_timeout -= wait;
-  if (evcount == -1 && errno == EINTR) goto TryAgain;
-  CHECK_NE(-1, evcount);
-  for (i = 0; i < evcount; ++i) {
-    CHECK(fds[i].revents & POLLIN);
-    HandleClient();
+void HandleClient(void) {
+  struct Client *client;
+  client = calloc(1, sizeof(struct Client));
+  client->addrsize = sizeof(client->addr);
+  for (;;) {
+    if (g_interrupted) {
+      free(client);
+      return;
+    }
+    // poll() because we use SA_RESTART and accept() is @restartable
+    if (poll(&(struct pollfd){g_servfd, POLLIN}, 1, -1) > 0) {
+      client->fd = accept4(g_servfd, (struct sockaddr *)&client->addr,
+                           &client->addrsize, SOCK_CLOEXEC);
+      if (client->fd != -1) {
+        VERBF("accepted client fd %d", client->fd);
+        break;
+      } else if (errno != EINTR && errno != EAGAIN) {
+        WARNF("accept4 failed %m");
+      }
+    } else if (errno != EINTR && errno != EAGAIN) {
+      WARNF("poll failed %m");
+    }
   }
-  /* manually do this because of nt */
-  while (waitpid(-1, NULL, WNOHANG) > 0) donothing;
-  return evcount;
+  sigset_t mask;
+  pthread_attr_t attr;
+  sigfillset(&mask);
+  pthread_attr_init(&attr);
+  pthread_attr_setsigmask_np(&attr, &mask);
+  pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
+  pthread_create(&client->th, &attr, ClientWorker, client);
+  pthread_attr_destroy(&attr);
 }
 
 int Serve(void) {
+  sigset_t mask;
   StartTcpServer();
-  sigaction(SIGINT, (&(struct sigaction){.sa_handler = OnInterrupt}), 0);
-  sigaction(SIGCHLD,
-            (&(struct sigaction){.sa_handler = OnChildTerminated,
-                                 .sa_flags = SA_RESTART}),
-            0);
-  for (;;) {
-    if (!Poll() && (!g_timeout || g_interrupted)) break;
+  sigemptyset(&mask);
+  sigaddset(&mask, SIGCHLD);
+  signal(SIGINT, OnInterrupt);
+  sigprocmask(SIG_BLOCK, &mask, 0);
+  while (!g_interrupted) {
+    HandleClient();
   }
+  if (g_interrupted) {
+    WARNF("got ctrl-c, shutting down...");
+  }
+  WARNF("server exiting");
   close(g_servfd);
-  if (!g_timeout) {
-    INFOF("timeout expired, shutting down");
-  } else {
-    INFOF("got ctrl-c, shutting down");
-  }
   return 0;
 }
 
 void Daemonize(void) {
+  VERBF("Daemonize");
   struct stat st;
   if (fork() > 0) _exit(0);
   setsid();
@@ -579,19 +761,29 @@ void Daemonize(void) {
 }
 
 int main(int argc, char *argv[]) {
-  int i;
-  SetupPresharedKeySsl(MBEDTLS_SSL_IS_SERVER, GetRunitPsk());
-  __log_level = kLogWarn;
+#if IsModeDbg()
+  ShowCrashReports();
+#endif
   GetOpts(argc, argv);
-  for (i = 3; i < 16; ++i) close(i);
+  g_psk = GetRunitPsk();
+  signal(SIGPIPE, SIG_IGN);
+  setenv("TZ", "PST", true);
+  gethostname(g_hostname, sizeof(g_hostname));
+  for (int i = 3; i < 16; ++i) close(i);
   errno = 0;
   // poll()'ing /dev/null stdin file descriptor on xnu returns POLLNVAL?!
   if (IsWindows()) {
-    CHECK_EQ(3, (g_bogusfd = open("/dev/null", O_RDONLY | O_CLOEXEC)));
+    g_bogusfd = open("/dev/null", O_RDONLY | O_CLOEXEC);
   } else {
-    CHECK_EQ(3, (g_bogusfd = open("/dev/zero", O_RDONLY | O_CLOEXEC)));
+    g_bogusfd = open("/dev/zero", O_RDONLY | O_CLOEXEC);
   }
-  if (!isdirectory("o")) CHECK_NE(-1, mkdir("o", 0700));
   if (g_daemonize) Daemonize();
-  return Serve();
+  mkdir("o", 0700);
+  Serve();
+  free(g_psk);
+#if IsModeDbg()
+  void CheckForMemoryLeaks(void);
+  CheckForMemoryLeaks();
+#endif
+  pthread_exit(0);
 }
diff --git a/tool/net/definitions.lua b/tool/net/definitions.lua
index 39719c8f5..230ef1695 100644
--- a/tool/net/definitions.lua
+++ b/tool/net/definitions.lua
@@ -7267,7 +7267,7 @@ function unix.tiocgwinsz(fd) end
 --- This creates a secure temporary file inside `$TMPDIR`. If it isn't
 --- defined, then `/tmp` is used on UNIX and GetTempPath() is used on
 --- the New Technology. This resolution of `$TMPDIR` happens once in a
---- ctor, which is copied to the `kTmpDir` global.
+--- ctor, which is copied to the `kTmpPath` global.
 --- 
 --- Once close() is called, the returned file is guaranteed to be
 --- deleted automatically. On UNIX the file is unlink()'d before this
diff --git a/tool/net/help.txt b/tool/net/help.txt
index 50d47ef35..432a410db 100644
--- a/tool/net/help.txt
+++ b/tool/net/help.txt
@@ -4711,7 +4711,7 @@ UNIX MODULE
     This creates a secure temporary file inside `$TMPDIR`. If it isn't
     defined, then `/tmp` is used on UNIX and GetTempPath() is used on
     the New Technology. This resolution of `$TMPDIR` happens once in a
-    ctor, which is copied to the `kTmpDir` global.
+    ctor, which is copied to the `kTmpPath` global.
 
     Once close() is called, the returned file is guaranteed to be
     deleted automatically. On UNIX the file is unlink()'d before this
diff --git a/tool/tool.mk b/tool/tool.mk
index f23e92388..84360bb1b 100644
--- a/tool/tool.mk
+++ b/tool/tool.mk
@@ -7,7 +7,6 @@ o/$(MODE)/tool:			\
 	o/$(MODE)/tool/build	\
 	o/$(MODE)/tool/curl	\
 	o/$(MODE)/tool/decode	\
-	o/$(MODE)/tool/hello	\
 	o/$(MODE)/tool/lambda	\
 	o/$(MODE)/tool/net	\
 	o/$(MODE)/tool/plinko	\