This file is suspend.def, from which is created suspend.c.
It implements the builtin "suspend" in Bash.

Copyright (C) 1987-2015 Free Software Foundation, Inc.

This file is part of GNU Bash, the Bourne Again SHell.

Bash 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.

Bash 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 Bash.  If not, see <http://www.gnu.org/licenses/>.

$PRODUCES suspend.c

$BUILTIN suspend
$DEPENDS_ON JOB_CONTROL
$FUNCTION suspend_builtin
$SHORT_DOC suspend [-f]
Suspend shell execution.

Suspend the execution of this shell until it receives a SIGCONT signal.
Unless forced, login shells cannot be suspended.

Options:
  -f	force the suspend, even if the shell is a login shell

Exit Status:
Returns success unless job control is not enabled or an error occurs.
$END

#include <config.h>

#if defined (JOB_CONTROL)
#if defined (HAVE_UNISTD_H)
#  ifdef _MINIX
#    include <sys/types.h>
#  endif
#  include <unistd.h>
#endif

#include "../bashtypes.h"
#include <signal.h>
#include "../bashintl.h"
#include "../shell.h"
#include "../jobs.h"
#include "common.h"
#include "bashgetopt.h"

static sighandler suspend_continue __P((int));

static SigHandler *old_cont;
#if 0
static SigHandler *old_stop;
#endif

/* Continue handler. */
static sighandler
suspend_continue (sig)
     int sig;
{
  set_signal_handler (SIGCONT, old_cont);
#if 0
  set_signal_handler (SIGSTOP, old_stop);
#endif
  SIGRETURN (0);
}

/* Suspending the shell.  If -f is the arg, then do the suspend
   no matter what.  Otherwise, complain if a login shell. */
int
suspend_builtin (list)
     WORD_LIST *list;
{
  int opt, force;

  reset_internal_getopt ();
  force = 0;
  while ((opt = internal_getopt (list, "f")) != -1)
    switch (opt)
      {
      case 'f':
	force++;
	break;
      CASE_HELPOPT;
      default:
	builtin_usage ();
	return (EX_USAGE);
      }
      
  list = loptend;

  if (job_control == 0)
    {
      sh_nojobs (_("cannot suspend"));
      return (EXECUTION_FAILURE);
    }

  if (force == 0)  
    {
      no_args (list);

      if (login_shell)
	{
	  builtin_error (_("cannot suspend a login shell"));
	  return (EXECUTION_FAILURE);
	}
    }

  /* XXX - should we put ourselves back into the original pgrp now?  If so,
     call end_job_control() here and do the right thing in suspend_continue
     (that is, call restart_job_control()). */
  old_cont = (SigHandler *)set_signal_handler (SIGCONT, suspend_continue);
#if 0
  old_stop = (SigHandler *)set_signal_handler (SIGSTOP, SIG_DFL);
#endif
  killpg (shell_pgrp, SIGSTOP);
  return (EXECUTION_SUCCESS);
}

#endif /* JOB_CONTROL */