/* Copyright (C) 1991-2018 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or

   modify it under the terms of the GNU Lesser General Public

   License as published by the Free Software Foundation; either

   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library 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

   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public

   License along with the GNU C Library; if not, see

   <http://www.gnu.org/licenses/>.  */

#include <errno.h>

#include <signal.h>

#include <stddef.h>

#include <stdlib.h>

#include <unistd.h>

#include <sys/types.h>

#include <sys/wait.h>

#include <libc-lock.h>

#include <sysdep-cancel.h>

#include <sigsetops.h>

#define	SHELL_PATH	"/bin/sh"	/* Path of the shell.  */

#define	SHELL_NAME	"sh"		/* Name to give it.  */

#ifdef _LIBC_REENTRANT

static struct sigaction intr, quit;

static int sa_refcntr;

__libc_lock_define_initialized (static, lock);

# define DO_LOCK() __libc_lock_lock (lock)

# define DO_UNLOCK() __libc_lock_unlock (lock)

# define INIT_LOCK() ({ __libc_lock_init (lock); sa_refcntr = 0; })

# define ADD_REF() sa_refcntr++

# define SUB_REF() --sa_refcntr

#else

# define DO_LOCK()

# define DO_UNLOCK()

# define INIT_LOCK()

# define ADD_REF() 0

# define SUB_REF() 0

#endif

/* Execute LINE as a shell command, returning its status.  */

static int

do_system (const char *line)

{

  int status, save;

  pid_t pid;

  struct sigaction sa;

#ifndef _LIBC_REENTRANT

  struct sigaction intr, quit;

#endif

  sigset_t omask;

  sa.sa_handler = SIG_IGN;

  sa.sa_flags = 0;

  __sigemptyset (&sa.sa_mask);

  DO_LOCK ();

  if (ADD_REF () == 0)

    {

      if (__sigaction (SIGINT, &sa, &intr) < 0)

	{

	  (void) SUB_REF ();

	  goto out;

	}

      if (__sigaction (SIGQUIT, &sa, &quit) < 0)

	{

	  save = errno;

	  (void) SUB_REF ();

	  goto out_restore_sigint;

	}

    }

  DO_UNLOCK ();

  /* We reuse the bitmap in the 'sa' structure.  */

  __sigaddset (&sa.sa_mask, SIGCHLD);

  save = errno;

  if (__sigprocmask (SIG_BLOCK, &sa.sa_mask, &omask) < 0)

    {

#ifndef _LIBC

      if (errno == ENOSYS)

	__set_errno (save);

      else

#endif

	{

	  DO_LOCK ();

	  if (SUB_REF () == 0)

	    {

	      save = errno;

	      (void) __sigaction (SIGQUIT, &quit, (struct sigaction *) NULL);

	    out_restore_sigint:

	      (void) __sigaction (SIGINT, &intr, (struct sigaction *) NULL);

	      __set_errno (save);

	    }

	out:

	  DO_UNLOCK ();

	  return -1;

	}

    }

#ifdef CLEANUP_HANDLER

  CLEANUP_HANDLER;

#endif

#ifdef FORK

  pid = FORK ();

#else

  pid = __fork ();

#endif

  if (pid == (pid_t) 0)

    {

      /* Child side.  */

      const char *new_argv[4];

      new_argv[0] = SHELL_NAME;

      new_argv[1] = "-c";

      new_argv[2] = line;

      new_argv[3] = NULL;

      /* Restore the signals.  */

      (void) __sigaction (SIGINT, &intr, (struct sigaction *) NULL);

      (void) __sigaction (SIGQUIT, &quit, (struct sigaction *) NULL);

      (void) __sigprocmask (SIG_SETMASK, &omask, (sigset_t *) NULL);

      INIT_LOCK ();

      /* Exec the shell.  */

      (void) __execve (SHELL_PATH, (char *const *) new_argv, __environ);

      _exit (127);

    }

  else if (pid < (pid_t) 0)

    /* The fork failed.  */

    status = -1;

  else

    /* Parent side.  */

    {

      /* Note the system() is a cancellation point.  But since we call

	 waitpid() which itself is a cancellation point we do not

	 have to do anything here.  */

      if (TEMP_FAILURE_RETRY (__waitpid (pid, &status, 0)) != pid)

	status = -1;

    }

#ifdef CLEANUP_HANDLER

  CLEANUP_RESET;

#endif

  save = errno;

  DO_LOCK ();

  if ((SUB_REF () == 0

       && (__sigaction (SIGINT, &intr, (struct sigaction *) NULL)

	   | __sigaction (SIGQUIT, &quit, (struct sigaction *) NULL)) != 0)

      || __sigprocmask (SIG_SETMASK, &omask, (sigset_t *) NULL) != 0)

    {

#ifndef _LIBC

      /* glibc cannot be used on systems without waitpid.  */

      if (errno == ENOSYS)

	__set_errno (save);

      else

#endif

	status = -1;

    }

  DO_UNLOCK ();

  return status;

}

int

__libc_system (const char *line)

{

  if (line == NULL)

    /* Check that we have a command processor available.  It might

       not be available after a chroot(), for example.  */

    return do_system ("exit 0") == 0;

  return do_system (line);

}

weak_alias (__libc_system, system)