/*-*- 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 2020 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 "libc/bits/bits.h"
#include "libc/bits/pushpop.h"
#include "libc/bits/weaken.h"
#include "libc/calls/internal.h"
#include "libc/dce.h"
#include "libc/fmt/fmt.h"
#include "libc/macros.internal.h"
#include "libc/nt/console.h"
#include "libc/nt/enum/consolemodeflags.h"
#include "libc/nt/enum/filemapflags.h"
#include "libc/nt/enum/filetype.h"
#include "libc/nt/enum/loadlibrarysearch.h"
#include "libc/nt/enum/pageflags.h"
#include "libc/nt/enum/version.h"
#include "libc/nt/files.h"
#include "libc/nt/memory.h"
#include "libc/nt/pedef.internal.h"
#include "libc/nt/process.h"
#include "libc/nt/runtime.h"
#include "libc/nt/struct/teb.h"
#include "libc/runtime/directmap.internal.h"
#include "libc/runtime/internal.h"
#include "libc/runtime/memtrack.h"
#include "libc/runtime/runtime.h"
#include "libc/sock/internal.h"

#define MAP_ANONYMOUS 32
#define MAP_PRIVATE   2
#define PROT_EXEC     4
#define PROT_READ     1
#define PROT_WRITE    2

/*
 * TODO: Why can't we allocate addresses above 4GB on Windows 7 x64?
 * TODO: How can we ensure we never overlap with KERNEL32.DLL?
 */

struct WinArgs {
  char *argv[4096];
  char *envp[4092];
  intptr_t auxv[2][2];
  char argblock[ARG_MAX];
  char envblock[ARG_MAX];
};

uint32_t __ntconsolemode;

static noasan textwindows void MakeLongDoubleLongAgain(void) {
  /* 8087 FPU Control Word
      IM: Invalid Operation ───────────────┐
      DM: Denormal Operand ───────────────┐│
      ZM: Zero Divide ───────────────────┐││
      OM: Overflow ─────────────────────┐│││
      UM: Underflow ───────────────────┐││││
      PM: Precision ──────────────────┐│││││
     PC: Precision Control ────────┐  ││││││
      {float,∅,double,long double} │  ││││││
     RC: Rounding Control ───────┐ │  ││││││
      {even, →-∞, →+∞, →0}       │┌┤  ││││││
                                ┌┤││  ││││││
                               d││││rr││││││*/
  int x87cw = 0b0000000000000000001101111111;
  asm volatile("fldcw\t%0" : /* no outputs */ : "m"(x87cw));
}

static noasan textwindows wontreturn void WinMainNew(void) {
  int64_t h;
  int version;
  size_t size;
  int i, count;
  uint64_t addr;
  int64_t inhand;
  struct WinArgs *wa;
  const char16_t *env16;
  extern char os asm("__hostos");
  os = WINDOWS; /* madness https://news.ycombinator.com/item?id=21019722 */
  version = NtGetPeb()->OSMajorVersion;
  if ((intptr_t)v_ntsubsystem == kNtImageSubsystemWindowsCui && version >= 10) {
    SetConsoleCP(kNtCpUtf8);
    SetConsoleOutputCP(kNtCpUtf8);
    inhand = GetStdHandle(pushpop(kNtStdInputHandle));
    SetEnvironmentVariable(u"TERM", u"xterm-truecolor");
    GetConsoleMode(inhand, &__ntconsolemode);
    SetConsoleMode(inhand, kNtEnableProcessedInput | kNtEnableLineInput |
                               kNtEnableEchoInput | kNtEnableMouseInput |
                               kNtEnableQuickEditMode | kNtEnableExtendedFlags |
                               kNtEnableAutoPosition |
                               kNtEnableVirtualTerminalInput);
    SetConsoleMode(GetStdHandle(pushpop(kNtStdOutputHandle)),
                   kNtEnableProcessedOutput | kNtEnableWrapAtEolOutput |
                       kNtEnableVirtualTerminalProcessing);
  }
  addr = version < 10 ? 0xff00000 : 0x777000000000;
  size = ROUNDUP(STACKSIZE + sizeof(struct WinArgs), FRAMESIZE);
  MapViewOfFileExNuma((_mmi.p[0].h = CreateFileMappingNuma(
                           -1, &kNtIsInheritable, kNtPageExecuteReadwrite,
                           size >> 32, size, NULL, kNtNumaNoPreferredNode)),
                      kNtFileMapWrite | kNtFileMapExecute, 0, 0, size,
                      (void *)addr, kNtNumaNoPreferredNode);
  _mmi.p[0].x = addr >> 16;
  _mmi.p[0].y = (addr >> 16) + ((size >> 16) - 1);
  _mmi.p[0].prot = PROT_READ | PROT_WRITE | PROT_EXEC;
  _mmi.p[0].flags = MAP_PRIVATE | MAP_ANONYMOUS;
  _mmi.i = 1;
  wa = (struct WinArgs *)(addr + size - sizeof(struct WinArgs));
  count = GetDosArgv(GetCommandLine(), wa->argblock, ARRAYLEN(wa->argblock),
                     wa->argv, ARRAYLEN(wa->argv));
  for (i = 0; wa->argv[0][i]; ++i) {
    if (wa->argv[0][i] == '\\') {
      wa->argv[0][i] = '/';
    }
  }
  env16 = GetEnvironmentStrings();
  GetDosEnviron(env16, wa->envblock, ARRAYLEN(wa->envblock), wa->envp,
                ARRAYLEN(wa->envp));
  FreeEnvironmentStrings(env16);
  wa->auxv[1][0] = pushpop(0L);
  wa->auxv[1][1] = pushpop(0L);
  wa->auxv[0][0] = (intptr_t)wa->argv[0];
  wa->auxv[0][1] = pushpop(31L);
  _jmpstack((char *)addr + STACKSIZE, cosmo, count, wa->argv, wa->envp,
            wa->auxv);
}

/**
 * Main function on Windows NT.
 *
 * The Cosmopolitan Runtime provides the following services, which aim
 * to bring Windows NT behavior closer in harmony with System Five:
 *
 * 1. We configure CMD.EXE for UTF-8 and enable ANSI colors on Win10.
 *
 * 2. Command line arguments are passed as a blob of UTF-16 text. We
 *    chop them up into an char *argv[] UTF-8 data structure, in
 *    accordance with the DOS conventions for argument quoting.
 *
 * 3. Environment variables are passed to us as a sorted UTF-16 double
 *    NUL terminated list. We translate this to char ** using UTF-8.
 *
 * 4. Allocates new stack at a high address. NT likes to choose a
 *    stack address that's beneath the program image. We want to be
 *    able to assume that stack addresses are located at higher
 *    addresses than heap and program memory.
 *
 * 5. Windows users are afraid of "drive-by downloads" where someone
 *    might accidentally an evil DLL to their Downloads folder which
 *    then overrides the behavior of a legitimate EXE being run from
 *    the downloads folder. Since we don't even use dynamic linking,
 *    we've cargo culted some API calls, that may harden against it.
 *
 * 6. Reconfigure x87 FPU so long double is actually long (80 bits).
 *
 * 7. Finally, we need fork. Microsoft designed Windows to prevent us
 *    from having fork() so we pass pipe handles in an environment
 *    variable literally copy all the memory.
 *
 * @param hInstance call GetModuleHandle(NULL) from main if you need it
 */
noasan textwindows int64_t WinMain(int64_t hInstance, int64_t hPrevInstance,
                                   const char *lpCmdLine, int nCmdShow) {
  MakeLongDoubleLongAgain();
  if (weaken(WinSockInit)) weaken(WinSockInit)();
  if (weaken(WinMainForked)) weaken(WinMainForked)();
  WinMainNew();
}
