lib/execve.c

   1 /* execve() function: Execute a program, replacing the current process.
   2    Copyright (C) 2020-2024 Free Software Foundation, Inc.
   3
   4    This file is free software: you can redistribute it and/or modify
   5    it under the terms of the GNU Lesser General Public License as
   6    published by the Free Software Foundation; either version 2.1 of the
   7    License, or (at your option) any later version.
   8
   9    This file is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public License
  15    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  16
  17 /* Written by Bruno Haible <bruno@clisp.org>, 2020.  */
  18
  19 /* Don't use __attribute__ __nonnull__ in this compilation unit.  Otherwise gcc
  20    may optimize away the program == NULL and argv == NULL tests below.  */
  21 #define _GL_ARG_NONNULL(params)
  22
  23 #include <config.h>
  24
  25 /* Specification.  */
  26 #include <unistd.h>
  27
  28 #if defined _WIN32 && !defined __CYGWIN__
  29
  30 # include <errno.h>
  31 # include <stdio.h>
  32 # include <spawn.h>
  33
  34 # include <sys/types.h>
  35 # include <sys/wait.h>
  36
  37 int
  38 execve (const char *program, char * const *argv, char * const *env)
  39 {
  40   if (program == NULL
  41       || argv == NULL
  42       /* The callee is not expecting a NULL argv[0].  */
  43       || argv[0] == NULL
  44       || env == NULL)
  45     {
  46       errno = EINVAL;
  47       return -1;
  48     }
  49
  50   pid_t child;
  51   int err = posix_spawn (&child, program, NULL, NULL, argv, env);
  52   if (err == 0)
  53     {
  54       /* Close all file descriptors, so that
  55          - for opened files, the child may close and unlink() the file,
  56          - for pipe handles, the pipe's reader or writer does not get stuck.
  57          Ideally we would also suspend all other threads and close all other
  58          HANDLEs (not associated with file descriptors) and SOCKETs, but we
  59          can't do so since we have no way to enumerate them.  */
  60       {
  61         unsigned int fdmax = _getmaxstdio ();
  62         unsigned int fd;
  63         for (fd = 0; fd < fdmax; fd++)
  64           close (fd);
  65       }
  66
  67       /* Wait until the child process is terminated.  */
  68       int status = 127;
  69       waitpid (child, &status, 0);
  70       int exitcode = status;
  71
  72       /* Pass its exit code to the parent process.  */
  73       _exit (exitcode);
  74     }
  75   errno = err;
  76   return -1;
  77 }
  78
  79 #endif