/* Creation of autonomous subprocesses.
   Copyright (C) 2001 Free Software Foundation, Inc.
   Written by Bruno Haible <haible@clisp.cons.org>, 2001.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2, or (at your option)
   any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software Foundation,
   Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */


#ifdef HAVE_CONFIG_H
# include "config.h"
#endif

/* Specification.  */
#include "execute.h"

#include <errno.h>
#include <fcntl.h>
#include <stdbool.h>
#include <stdlib.h>

#ifdef HAVE_UNISTD_H
# include <unistd.h>
#endif

#ifdef HAVE_POSIX_SPAWN
# include <spawn.h>
#else
# ifdef HAVE_VFORK_H
#  include <vfork.h>
# endif
#endif

#include "error.h"
#include "exit.h"
#include "wait-process.h"
#include "gettext.h"

#ifndef STDIN_FILENO
# define STDIN_FILENO 0
#endif
#ifndef STDOUT_FILENO
# define STDOUT_FILENO 1
#endif
#ifndef STDERR_FILENO
# define STDERR_FILENO 2
#endif

#define _(str) gettext (str)


/* Prototypes for local functions.  Needed to ensure compiler checking of
   function argument counts despite of K&R C function definition syntax.  */
#ifdef EINTR
static inline int nonintr_close PARAMS ((int fd));
# ifdef __GNUC__
static inline int nonintr_open PARAMS ((const char *pathname, int oflag,
					mode_t mode));
# endif
#endif


#ifdef EINTR

/* EINTR handling for close(), open().
   These functions can return -1/EINTR even though we don't have any
   signal handlers set up, namely when we get interrupted via SIGSTOP.  */

static inline int
nonintr_close (fd)
     int fd;
{
  int retval;

  do
    retval = close (fd);
  while (retval < 0 && errno == EINTR);

  return retval;
}
#define close nonintr_close

static inline int
nonintr_open (pathname, oflag, mode)
     const char *pathname;
     int oflag;
     mode_t mode;
{
  int retval;

  do
    retval = open (pathname, oflag, mode);
  while (retval < 0 && errno == EINTR);

  return retval;
}
#define open nonintr_open

#endif


/* Execute a command, optionally redirecting any of the three standard file
   descriptors to /dev/null.  Return its exit code.
   If it didn't terminate correctly, exit if exit_on_error is true, otherwise
   return 127.  */
int
execute (progname, prog_path, prog_argv, null_stdin, null_stdout, null_stderr, exit_on_error)
     const char *progname;
     const char *prog_path;
     char **prog_argv;
     bool null_stdin;
     bool null_stdout;
     bool null_stderr;
     bool exit_on_error;
{
  /* Note about 127: Some errors during posix_spawnp() cause the function
     posix_spawnp() to return an error code; some other errors cause the
     subprocess to exit with return code 127.  It is implementation
     dependent which error is reported which way.  We treat both cases as
     equivalent.  */
#if HAVE_POSIX_SPAWN
  posix_spawn_file_actions_t actions;
  bool actions_allocated;
  int err;
  pid_t child;
#else
  int child;
#endif

#if HAVE_POSIX_SPAWN
  actions_allocated = false;
  if ((err = posix_spawn_file_actions_init (&actions)) != 0
      || (actions_allocated = true,
	  (null_stdin
	    && (err = posix_spawn_file_actions_addopen (&actions,
							STDIN_FILENO,
							"/dev/null", O_RDONLY,
							0))
	       != 0)
	  || (null_stdout
	      && (err = posix_spawn_file_actions_addopen (&actions,
							  STDOUT_FILENO,
							  "/dev/null", O_RDWR,
							  0))
		 != 0)
	  || (null_stderr
	      && (err = posix_spawn_file_actions_addopen (&actions,
							  STDERR_FILENO,
							  "/dev/null", O_RDWR,
							  0))
		 != 0)
	  || (err = posix_spawnp (&child, prog_path, &actions, NULL, prog_argv,
				  environ))
	     != 0))
    {
      if (actions_allocated)
	posix_spawn_file_actions_destroy (&actions);
      if (exit_on_error)
	error (EXIT_FAILURE, err, _("%s subprocess failed"), progname);
      else
	return 127;
    }
  posix_spawn_file_actions_destroy (&actions);
#else
  /* Use vfork() instead of fork() for efficiency.  */
  if ((child = vfork ()) == 0)
    {
      /* Child process code.  */
      int nullinfd;
      int nulloutfd;

      if ((!null_stdin
	   || ((nullinfd = open ("/dev/null", O_RDONLY, 0)) >= 0
	       && (nullinfd == STDIN_FILENO
		   || (dup2 (nullinfd, STDIN_FILENO) >= 0
		       && close (nullinfd) >= 0))))
	  && (!(null_stdout || null_stderr)
	      || ((nulloutfd = open ("/dev/null", O_RDWR, 0)) >= 0
		  && (!null_stdout
		      || nulloutfd == STDOUT_FILENO
		      || dup2 (nulloutfd, STDOUT_FILENO) >= 0)
		  && (!null_stderr
		      || nulloutfd == STDERR_FILENO
		      || dup2 (nulloutfd, STDERR_FILENO) >= 0)
		  && ((null_stdout && nulloutfd == STDOUT_FILENO)
		      || (null_stderr && nulloutfd == STDERR_FILENO)
		      || close (nulloutfd) >= 0))))
	execvp (prog_path, prog_argv);
      _exit (127);
    }
  if (child == -1)
    {
      if (exit_on_error)
	error (EXIT_FAILURE, errno, _("%s subprocess failed"), progname);
      else
	return 127;
    }
#endif

  return wait_subprocess (child, progname, exit_on_error);
}