cosmopolitan/libc/calls/execve-sysv.c

/*-*- 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 "libc/bits/safemacros.h"
#include "libc/calls/calls.h"
#include "libc/calls/internal.h"
#include "libc/errno.h"
#include "libc/mem/alloca.h"
#include "libc/paths.h"
#include "libc/str/str.h"

int execve$sysv(const char *prog, char *const argv[], char *const envp[]) {
  size_t i, n;
  char **shargs, bash[PATH_MAX];
  if (__execve$sysv(prog, argv, envp) != -1) return 0;
  if (errno != ENOEXEC) return -1;
  for (i = 0; argv[i];) ++i;
  shargs = alloca((i + 2) * sizeof(char *));
  memcpy(shargs + 2, argv + 1, i * sizeof(char *));
  shargs[0] = !IsFreebsd() ? _PATH_BSHELL
                           : firstnonnull(commandv("bash", bash), _PATH_BSHELL);
  shargs[1] = prog;
  return __execve$sysv(shargs[0], shargs, envp);
}