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

Copyright (C) 1987, 1989, 1991 Free Software Foundation, Inc.

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

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the terms of the GNU General Public License as published by the Free
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version.

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FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
for more details.

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with Bash; see the file COPYING.  If not, write to the Free Software
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$PRODUCES suspend.c

$BUILTIN suspend
$DEPENDS_ON JOB_CONTROL
$FUNCTION suspend_builtin
$SHORT_DOC suspend [-f]
Suspend the execution of this shell until it receives a SIGCONT
signal.  The `-f' if specified says not to complain about this
being a login shell if it is; just suspend anyway.
$END

#include <signal.h>
#include <sys/types.h>
#include "../shell.h"
#include "../jobs.h"

#if defined (JOB_CONTROL)
extern int job_control;

static SigHandler *old_cont, *old_tstp;

/* Continue handler. */
sighandler
suspend_continue (sig)
     int sig;
{
  signal (SIGCONT, old_cont);
  signal (SIGTSTP, old_tstp);
}

/* 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;
{
  if (!job_control)
    {
      builtin_error ("Cannot suspend a shell without job control");
      return (EXECUTION_FAILURE);
    }

  if (list)
    if (strcmp (list->word->word, "-f") == 0)
      goto do_suspend;

  no_args (list);

  if (login_shell)
    {
      builtin_error ("Can't suspend a login shell");
      return (EXECUTION_FAILURE);
    }

do_suspend:
  old_cont = (SigHandler *)signal (SIGCONT, suspend_continue);
  old_tstp = (SigHandler *)signal (SIGTSTP, SIG_DFL);
  killpg (shell_pgrp, SIGTSTP);
  return (EXECUTION_SUCCESS);
}

#endif /* JOB_CONTROL */