/* Creation of autonomous subprocesses.
   Copyright (C) 2001-2004, 2006-2008 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 3 of the License, 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, see <http://www.gnu.org/licenses/>.  */


#include <config.h>

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

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

#include "error.h"
#include "fatal-signal.h"
#include "wait-process.h"
#include "gettext.h"

#define _(str) gettext (str)

#if defined _MSC_VER || defined __MINGW32__

/* Native Woe32 API.  */
# include <process.h>
# include "w32spawn.h"

#else

/* Unix API.  */
# if HAVE_POSIX_SPAWN
#  include <spawn.h>
# else
#  if HAVE_VFORK_H
#   include <vfork.h>
#  endif
# endif

#endif

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

/* The results of open() in this file are not used with fchdir,
   therefore save some unnecessary work in fchdir.c.  */
#undef open
#undef close


#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 (int fd)
{
  int retval;

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

  return retval;
}
#define close nonintr_close

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

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

  return retval;
}
#undef open /* avoid warning on VMS */
#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.
   If slave_process is true, the child process will be terminated when its
   creator receives a catchable fatal signal.  */
int
execute (const char *progname,
	 const char *prog_path, char **prog_argv,
	 bool ignore_sigpipe,
	 bool null_stdin, bool null_stdout, bool null_stderr,
	 bool slave_process, bool exit_on_error,
	 int *termsigp)
{
#if defined _MSC_VER || defined __MINGW32__

  /* Native Woe32 API.  */
  int orig_stdin;
  int orig_stdout;
  int orig_stderr;
  int exitcode;
  int nullinfd;
  int nulloutfd;

  prog_argv = prepare_spawn (prog_argv);

  /* Save standard file handles of parent process.  */
  if (null_stdin)
    orig_stdin = dup_noinherit (STDIN_FILENO);
  if (null_stdout)
    orig_stdout = dup_noinherit (STDOUT_FILENO);
  if (null_stderr)
    orig_stderr = dup_noinherit (STDERR_FILENO);
  exitcode = -1;

  /* Create standard file handles of child process.  */
  nullinfd = -1;
  nulloutfd = -1;
  if ((!null_stdin
       || ((nullinfd = open ("NUL", O_RDONLY, 0)) >= 0
	   && (nullinfd == STDIN_FILENO
	       || (dup2 (nullinfd, STDIN_FILENO) >= 0
		   && close (nullinfd) >= 0))))
      && (!(null_stdout || null_stderr)
	  || ((nulloutfd = open ("NUL", 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))))
    exitcode = spawnvp (P_WAIT, prog_path, prog_argv);
  if (nulloutfd >= 0)
    close (nulloutfd);
  if (nullinfd >= 0)
    close (nullinfd);

  /* Restore standard file handles of parent process.  */
  if (null_stderr)
    dup2 (orig_stderr, STDERR_FILENO), close (orig_stderr);
  if (null_stdout)
    dup2 (orig_stdout, STDOUT_FILENO), close (orig_stdout);
  if (null_stdin)
    dup2 (orig_stdin, STDIN_FILENO), close (orig_stdin);

  if (termsigp != NULL)
    *termsigp = 0;

  if (exitcode == -1)
    {
      if (exit_on_error || !null_stderr)
	error (exit_on_error ? EXIT_FAILURE : 0, errno,
	       _("%s subprocess failed"), progname);
      return 127;
    }

  return exitcode;

#else

  /* Unix API.  */
  /* 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
  sigset_t blocked_signals;
  posix_spawn_file_actions_t actions;
  bool actions_allocated;
  posix_spawnattr_t attrs;
  bool attrs_allocated;
  int err;
  pid_t child;
#else
  int child;
#endif

#if HAVE_POSIX_SPAWN
  if (slave_process)
    {
      sigprocmask (SIG_SETMASK, NULL, &blocked_signals);
      block_fatal_signals ();
    }
  actions_allocated = false;
  attrs_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)
	  || (slave_process
	      && ((err = posix_spawnattr_init (&attrs)) != 0
		  || (attrs_allocated = true,
		      (err = posix_spawnattr_setsigmask (&attrs,
							 &blocked_signals))
		      != 0
		      || (err = posix_spawnattr_setflags (&attrs,
							POSIX_SPAWN_SETSIGMASK))
			 != 0)))
	  || (err = posix_spawnp (&child, prog_path, &actions,
				  attrs_allocated ? &attrs : NULL, prog_argv,
				  environ))
	     != 0))
    {
      if (actions_allocated)
	posix_spawn_file_actions_destroy (&actions);
      if (attrs_allocated)
	posix_spawnattr_destroy (&attrs);
      if (slave_process)
	unblock_fatal_signals ();
      if (termsigp != NULL)
	*termsigp = 0;
      if (exit_on_error || !null_stderr)
	error (exit_on_error ? EXIT_FAILURE : 0, err,
	       _("%s subprocess failed"), progname);
      return 127;
    }
  posix_spawn_file_actions_destroy (&actions);
  if (attrs_allocated)
    posix_spawnattr_destroy (&attrs);
#else
  if (slave_process)
    block_fatal_signals ();
  /* 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)))
	  && (!slave_process || (unblock_fatal_signals (), true)))
	execvp (prog_path, prog_argv);
      _exit (127);
    }
  if (child == -1)
    {
      if (slave_process)
	unblock_fatal_signals ();
      if (termsigp != NULL)
	*termsigp = 0;
      if (exit_on_error || !null_stderr)
	error (exit_on_error ? EXIT_FAILURE : 0, errno,
	       _("%s subprocess failed"), progname);
      return 127;
    }
#endif
  if (slave_process)
    {
      register_slave_subprocess (child);
      unblock_fatal_signals ();
    }

  return wait_subprocess (child, progname, ignore_sigpipe, null_stderr,
			  slave_process, exit_on_error, termsigp);

#endif
}