mirror of
https://github.com/jart/cosmopolitan.git
synced 2024-05-13 09:02:41 +00:00
a4b455185b
Renaming gc() to _gc() was a mistake since the better thing to do is put it behind the _COSMO_SOURCE macro. We need this change because I haven't wanted to use my amazing garbage collector ever since we renamed it. You now need to define _COSMO_SOURCE yourself when using amalgamation header and cosmocc users need to pass the -mcosmo flag to get the gc() function Some other issues relating to cancelation have been fixed along the way. We're also now putting cosmocc in a folder named `.cosmocc` so it can be more safely excluded by grep --exclude-dir=.cosmocc --exclude-dir=o etc.
126 lines
5 KiB
C
126 lines
5 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│ vi: set et ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi │
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2023 Justine Alexandra Roberts Tunney │
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│ │
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│ Permission to use, copy, modify, and/or distribute this software for │
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│ any purpose with or without fee is hereby granted, provided that the │
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│ above copyright notice and this permission notice appear in all copies. │
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│ │
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│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
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│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
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│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
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│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
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│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
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│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
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│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
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│ PERFORMANCE OF THIS SOFTWARE. │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/calls/struct/sigaction.h"
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#include "libc/calls/struct/sigaltstack.h"
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#include "libc/calls/struct/siginfo.h"
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#include "libc/calls/struct/ucontext.internal.h"
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#include "libc/calls/ucontext.h"
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#include "libc/intrin/kprintf.h"
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#include "libc/limits.h"
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#include "libc/mem/gc.h"
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#include "libc/mem/mem.h"
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#include "libc/runtime/runtime.h"
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#include "libc/runtime/sysconf.h"
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#include "libc/sysv/consts/sa.h"
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#include "libc/sysv/consts/sig.h"
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#include "libc/sysv/consts/ss.h"
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#include "libc/testlib/testlib.h"
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#include "libc/thread/thread.h"
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/**
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* stack overflow recovery technique #3
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* rewrite thread cpu state to call pthread_exit
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* this method returns gracefully from signal handlers
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* unfortunately it relies on cpu architecture knowledge
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*/
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volatile bool smashed_stack;
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void Exiter(void *rc) {
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struct sigaltstack ss;
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ASSERT_SYS(0, 0, sigaltstack(0, &ss));
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ASSERT_EQ(0, ss.ss_flags);
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pthread_exit(rc);
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}
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void CrashHandler(int sig, siginfo_t *si, void *arg) {
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ucontext_t *ctx = arg;
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struct sigaltstack ss;
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ASSERT_FALSE(smashed_stack);
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ASSERT_SYS(0, 0, sigaltstack(0, &ss));
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ASSERT_EQ(SS_ONSTACK, ss.ss_flags);
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kprintf("kprintf avoids overflowing %G %p\n", si->si_signo, si->si_addr);
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smashed_stack = true;
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// EXPECT_TRUE(__is_stack_overflow(si, ctx));
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//
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// the backtrace will look like this
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//
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// 0x000000000042561d: pthread_exit at pthread_exit.c:99
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// 0x0000000000418777: Exiter at stackoverflow2_test.c:40
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// 0x00000000004186d8: CrashHandler at stackoverflow2_test.c:49
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// 0x000000000041872a: StackOverflow at stackoverflow2_test.c:53
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// 0x000000000041872a: StackOverflow at stackoverflow2_test.c:53
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// 0x000000000041872a: StackOverflow at stackoverflow2_test.c:53
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// ...
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//
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ctx->uc_mcontext.ARG0 = 123;
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ctx->uc_mcontext.PC = (long)Exiter;
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ctx->uc_mcontext.SP += 32768;
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ctx->uc_mcontext.SP &= -16;
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#ifdef __x86_64__
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*(long *)(ctx->uc_mcontext.SP -= 8) = ctx->uc_mcontext.PC;
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#elif defined(__aarch64__)
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*(long *)(ctx->uc_mcontext.SP -= 8) = ctx->uc_mcontext.regs[30];
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*(long *)(ctx->uc_mcontext.SP -= 8) = ctx->uc_mcontext.regs[29];
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ctx->uc_mcontext.BP = ctx->uc_mcontext.SP;
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#else
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#error "unsupported architecture"
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#endif
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}
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int StackOverflow(int f(), int n) {
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if (n < INT_MAX) {
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return f(f, n + 1) - 1;
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} else {
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return INT_MAX;
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}
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}
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int (*pStackOverflow)(int (*)(), int) = StackOverflow;
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void *MyPosixThread(void *arg) {
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struct sigaction sa;
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struct sigaltstack ss;
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ss.ss_flags = 0;
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ss.ss_size = sysconf(_SC_MINSIGSTKSZ) + 4096;
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ss.ss_sp = gc(malloc(ss.ss_size));
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ASSERT_SYS(0, 0, sigaltstack(&ss, 0));
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sa.sa_flags = SA_SIGINFO | SA_ONSTACK; // <-- important
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sigemptyset(&sa.sa_mask);
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sa.sa_sigaction = CrashHandler;
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sigaction(SIGBUS, &sa, 0);
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sigaction(SIGSEGV, &sa, 0);
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exit(pStackOverflow(pStackOverflow, 0));
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return 0;
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}
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TEST(stackoverflow, standardStack_altStack_thread_teleport) {
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void *res;
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pthread_t th;
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struct sigaltstack ss;
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smashed_stack = false;
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pthread_create(&th, 0, MyPosixThread, 0);
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pthread_join(th, &res);
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ASSERT_EQ((void *)123L, res);
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ASSERT_TRUE(smashed_stack);
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// this should be SS_DISABLE but ShowCrashReports() creates an alt stack
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ASSERT_SYS(0, 0, sigaltstack(0, &ss));
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ASSERT_EQ(0, ss.ss_flags);
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}
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