/*-*- 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.                                                │
╚─────────────────────────────────────────────────────────────────────────────*/
#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/intrin/strace.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/memory.h"
#include "libc/nt/runtime.h"
#include "libc/nt/struct/processinformation.h"
#include "libc/nt/struct/startupinfo.h"
#include "libc/nt/synchronization.h"
#include "libc/nt/thunk/msabi.h"
#include "libc/runtime/memtrack.internal.h"
#include "libc/runtime/runtime.h"
#include "libc/str/str.h"
#include "libc/sysv/consts/at.h"
#include "libc/sysv/consts/map.h"
#include "libc/sysv/consts/o.h"
#include "libc/sysv/consts/ok.h"
#include "libc/sysv/errfuns.h"

__msabi extern typeof(CloseHandle) *const __imp_CloseHandle;
__msabi extern typeof(WaitForSingleObject) *const __imp_WaitForSingleObject;
__msabi extern typeof(GetExitCodeProcess) *const __imp_GetExitCodeProcess;
__msabi extern typeof(UnmapViewOfFile) *const __imp_UnmapViewOfFile;

static dontinstrument __msabi bool32
BlockExecveConsoleEvent(uint32_t dwCtrlType) {
  // block SIGINT and SIGQUIT in execve() parent process
  return true;
}

textwindows int sys_execve_nt(const char *program, char *const argv[],
                              char *const envp[]) {
  int rc;
  size_t i;
  uint32_t dwExitCode;
  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");
      if (sys_faccessat_nt(AT_FDCWD, progbuf, X_OK, 0) != -1) {
        program = progbuf;
      } else {
        return eacces();
      }
    }
  }

  //////////////////////////////////////////////////////////////////////////////
  // execve operation is unrecoverable from this point

  // close cloexec handles
  for (i = 3; i < g_fds.n; ++i) {
    if (g_fds.p[i].kind != kFdEmpty && (g_fds.p[i].flags & O_CLOEXEC)) {
      __imp_CloseHandle(g_fds.p[i].handle);
    }
  }

  bzero(&startinfo, sizeof(startinfo));
  startinfo.cb = sizeof(struct NtStartupInfo);
  startinfo.dwFlags = kNtStartfUsestdhandles;
  startinfo.hStdInput = __getfdhandleactual(0);
  startinfo.hStdOutput = __getfdhandleactual(1);
  startinfo.hStdError = __getfdhandleactual(2);

  // spawn the process
  rc = ntspawn(program, argv, envp, 0, 0, 0, true, 0, 0, &startinfo, &procinfo);
  if (rc == -1) {
    STRACE("panic: unrecoverable ntspawn(%#s) error: %m", program);
    __imp_ExitProcess(6543);
  }

  //////////////////////////////////////////////////////////////////////////////
  // zombie shell process remains, to wait for child and propagate its exit
  // code

  __imp_CloseHandle(g_fds.p[0].handle);
  __imp_CloseHandle(g_fds.p[1].handle);
  __imp_CloseHandle(procinfo.hThread);
  __imp_SetConsoleCtrlHandler((void *)BlockExecveConsoleEvent, 1);
  do {
    __imp_WaitForSingleObject(procinfo.hProcess, -1);
    dwExitCode = kNtStillActive;
    __imp_GetExitCodeProcess(procinfo.hProcess, &dwExitCode);
  } while (dwExitCode == kNtStillActive);
  __imp_CloseHandle(procinfo.hProcess);
  __imp_ExitProcess(dwExitCode);
  notpossible;
}