This file is wait.def, from which is created wait.c.
It implements the builtin "wait" 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/>.

$BUILTIN wait
$FUNCTION wait_builtin
$DEPENDS_ON JOB_CONTROL
$PRODUCES wait.c
$SHORT_DOC wait [-n] [id ...]
Wait for job completion and return exit status.

Waits for each process identified by an ID, which may be a process ID or a
job specification, and reports its termination status.  If ID is not
given, waits for all currently active child processes, and the return
status is zero.  If ID is a a job specification, waits for all processes
in that job's pipeline.

If the -n option is supplied, waits for the next job to terminate and
returns its exit status.

Exit Status:
Returns the status of the last ID; fails if ID is invalid or an invalid
option is given.
$END

$BUILTIN wait
$FUNCTION wait_builtin
$DEPENDS_ON !JOB_CONTROL
$SHORT_DOC wait [pid ...]
Wait for process completion and return exit status.

Waits for each process specified by a PID and reports its termination status.
If PID is not given, waits for all currently active child processes,
and the return status is zero.  PID must be a process ID.

Exit Status:
Returns the status of the last PID; fails if PID is invalid or an invalid
option is given.
$END

#include <config.h>

#include "../bashtypes.h"
#include <signal.h>

#if defined (HAVE_UNISTD_H)
#  include <unistd.h>
#endif

#include <chartypes.h>

#include "../bashansi.h"

#include "../shell.h"
#include "../jobs.h"
#include "common.h"
#include "bashgetopt.h"

extern int wait_signal_received;
extern int last_command_exit_signal;

procenv_t wait_intr_buf;
int wait_intr_flag;

/* Wait for the pid in LIST to stop or die.  If no arguments are given, then
   wait for all of the active background processes of the shell and return
   0.  If a list of pids or job specs are given, return the exit status of
   the last one waited for. */

#define WAIT_RETURN(s) \
  do \
    { \
      interrupt_immediately = old_interrupt_immediately;\
      wait_signal_received = 0; \
      wait_intr_flag = 0; \
      return (s);\
    } \
  while (0)

int
wait_builtin (list)
     WORD_LIST *list;
{
  int status, code, opt, nflag;
  volatile int old_interrupt_immediately;

  USE_VAR(list);

  nflag = 0;
  reset_internal_getopt ();
  while ((opt = internal_getopt (list, "n")) != -1)
    {
      switch (opt)
	{
#if defined (JOB_CONTROL)
	case 'n':
	  nflag = 1;
	  break;
#endif
	CASE_HELPOPT;
	default:
	  builtin_usage ();
	  return (EX_USAGE);
	}
    }
  list = loptend;

  old_interrupt_immediately = interrupt_immediately;
#if 0
  interrupt_immediately++;
#endif

  /* POSIX.2 says:  When the shell is waiting (by means of the wait utility)
     for asynchronous commands to complete, the reception of a signal for
     which a trap has been set shall cause the wait utility to return
     immediately with an exit status greater than 128, after which the trap
     associated with the signal shall be taken.

     We handle SIGINT here; it's the only one that needs to be treated
     specially (I think), since it's handled specially in {no,}jobs.c. */
  wait_intr_flag = 1;
  code = setjmp_sigs (wait_intr_buf);

  if (code)
    {
      last_command_exit_signal = wait_signal_received;
      status = 128 + wait_signal_received;
      wait_sigint_cleanup ();
      WAIT_RETURN (status);
    }

  /* We support jobs or pids.
     wait <pid-or-job> [pid-or-job ...] */

#if defined (JOB_CONTROL)
  if (nflag)
    {
      status = wait_for_any_job ();
      if (status < 0)
	status = 127;
      WAIT_RETURN (status);
    }
#endif
      
  /* But wait without any arguments means to wait for all of the shell's
     currently active background processes. */
  if (list == 0)
    {
      wait_for_background_pids ();
      WAIT_RETURN (EXECUTION_SUCCESS);
    }

  status = EXECUTION_SUCCESS;
  while (list)
    {
      pid_t pid;
      char *w;
      intmax_t pid_value;

      w = list->word->word;
      if (DIGIT (*w))
	{
	  if (legal_number (w, &pid_value) && pid_value == (pid_t)pid_value)
	    {
	      pid = (pid_t)pid_value;
	      status = wait_for_single_pid (pid, 1);
	    }
	  else
	    {
	      sh_badpid (w);
	      WAIT_RETURN (EXECUTION_FAILURE);
	    }
	}
#if defined (JOB_CONTROL)
      else if (*w && *w == '%')
	/* Must be a job spec.  Check it out. */
	{
	  int job;
	  sigset_t set, oset;

	  BLOCK_CHILD (set, oset);
	  job = get_job_spec (list);

	  if (INVALID_JOB (job))
	    {
	      if (job != DUP_JOB)
		sh_badjob (list->word->word);
	      UNBLOCK_CHILD (oset);
	      status = 127;	/* As per Posix.2, section 4.70.2 */
	      list = list->next;
	      continue;
	    }

	  /* Job spec used.  Wait for the last pid in the pipeline. */
	  UNBLOCK_CHILD (oset);
	  status = wait_for_job (job);
	}
#endif /* JOB_CONTROL */
      else
	{
	  sh_badpid (w);
	  status = EXECUTION_FAILURE;
	}
      list = list->next;
    }

  WAIT_RETURN (status);
}