system.c

/**
 * @file
 * Execute external programs
 *
 * @authors
 * Copyright (C) 1996-2000,2013 Michael R. Elkins <me@mutt.org>
 *
 * @copyright
 * 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 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/>.
 */

/**
 * @page system Execute external programs
 *
 * Execute external programs
 */

#include "config.h"
#include <signal.h>
#include <stdbool.h>
#include <stdlib.h>
#include <sys/wait.h> // IWYU pragma: keep
#include <unistd.h>
#include "mutt/mutt.h"
#include "mutt.h"
#include "protos.h" // IWYU pragma: keep
#ifdef USE_IMAP
#include "imap/imap.h"
#endif

/**
 * mutt_system - Run an external command
 * @param cmd Command and arguments
 * @retval -1  Error
 * @retval >=0 Success (command's return code)
 *
 * Fork and run an external command with arguments.
 *
 * @note This function won't return until the command finishes.
 */
int mutt_system(const char *cmd)
{
  int rc = -1;
  struct sigaction act;
  struct sigaction oldtstp;
  struct sigaction oldcont;
  pid_t pid;

  if (!cmd || !*cmd)
    return 0;

  /* must ignore SIGINT and SIGQUIT */

  mutt_sig_block_system();

  act.sa_handler = SIG_DFL;
/* we want to restart the waitpid() below */
#ifdef SA_RESTART
  act.sa_flags = SA_RESTART;
#endif
  sigemptyset(&act.sa_mask);
  sigaction(SIGTSTP, &act, &oldtstp);
  sigaction(SIGCONT, &act, &oldcont);

  pid = fork();
  if (pid == 0)
  {
    act.sa_flags = 0;

    /* reset signals for the child; not really needed, but... */
    mutt_sig_unblock_system(false);
    act.sa_handler = SIG_DFL;
    act.sa_flags = 0;
    sigemptyset(&act.sa_mask);
    sigaction(SIGTERM, &act, NULL);
    sigaction(SIGTSTP, &act, NULL);
    sigaction(SIGCONT, &act, NULL);

    execle(EXEC_SHELL, "sh", "-c", cmd, NULL, mutt_envlist_getlist());
    _exit(127); /* execl error */
  }
  else if (pid != -1)
  {
#ifdef USE_IMAP
    rc = imap_wait_keepalive(pid);
#endif
  }

  sigaction(SIGCONT, &oldcont, NULL);
  sigaction(SIGTSTP, &oldtstp, NULL);

  /* reset SIGINT, SIGQUIT and SIGCHLD */
  mutt_sig_unblock_system(true);

  rc = (pid != -1) ? (WIFEXITED(rc) ? WEXITSTATUS(rc) : -1) : -1;

  return rc;
}