bash/builtins/wait.def

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

Copyright (C) 1987-2024 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 [-fn] [-p var] [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 job specification, waits for all processes
in that job's pipeline.

If the -n option is supplied, waits for a single job from the list of IDs,
or, if no IDs are supplied, for the next job to complete and returns its
exit status.

If the -p option is supplied, the process or job identifier of the job
for which the exit status is returned is assigned to the variable VAR
named by the option argument. The variable will be unset initially, before
any assignment. This is useful only when the -n option is supplied.

If the -f option is supplied, and job control is enabled, waits for the
specified ID to terminate, instead of waiting for it to change status.

Exit Status:
Returns the status of the last ID; fails if ID is invalid or an invalid
option is given, or if -n is supplied and the shell has no unwaited-for
children.
$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 "../execute_cmd.h"
#include "../jobs.h"
#include "../trap.h"
#include "../sig.h"
#include "common.h"
#include "bashgetopt.h"

extern int wait_signal_received;

procenv_t wait_intr_buf;
int wait_intr_flag;

static int set_waitlist (WORD_LIST *);
static void unset_waitlist (void);
static int check_nonjobs (WORD_LIST *, struct procstat *);

/* 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 \
    { \
      wait_signal_received = 0; \
      wait_intr_flag = 0; \
      return (s);\
    } \
  while (0)

int
wait_builtin (WORD_LIST *list)
{
  int status, code, opt, nflag, vflags, bindflags;
  volatile int wflags;
  char *vname;
  SHELL_VAR *pidvar;
  struct procstat pstat;

  USE_VAR(list);

  nflag = wflags = vflags = 0;
  vname = NULL;
  pidvar = (SHELL_VAR *)NULL;
  reset_internal_getopt ();
  while ((opt = internal_getopt (list, "fnp:")) != -1)
    {
      switch (opt)
	{
#if defined (JOB_CONTROL)
	case 'n':
	  nflag = 1;
	  break;
	case 'f':
	  wflags |= JWAIT_FORCE;
	  break;
	case 'p':
	  vname = list_optarg;
	  vflags = list_optflags;	  
	  break;	
#endif
	CASE_HELPOPT;
	default:
	  builtin_usage ();
	  return (EX_USAGE);
	}
    }
  list = loptend;

  /* Sanity-check variable name if -p supplied. */
  if (vname)
    {
#if defined (ARRAY_VARS)
      int arrayflags;

      SET_VFLAGS (vflags, arrayflags, bindflags);
      if (valid_identifier (vname) == 0 && valid_array_reference (vname, arrayflags) == 0)
#else
      bindflags = 0;
      if (valid_identifier (vname) == 0)
#endif
	{
	  sh_invalidid (vname);
	  WAIT_RETURN (EXECUTION_FAILURE);
	}
      if (builtin_unbind_variable (vname) == -2)
	WAIT_RETURN (EXECUTION_FAILURE);
    }

  /* 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 ();
#if defined (JOB_CONTROL)
      if (wflags & JWAIT_WAITING)
	unset_waitlist ();
#endif
      WAIT_RETURN (status);
    }

  opt = first_pending_trap ();
#if defined (SIGCHLD)
  /* We special case SIGCHLD when not in posix mode because we don't break
     out of the wait even when the signal is trapped; we run the trap after
     the wait completes. See how it's handled in jobs.c:waitchld(). */
  if (opt == SIGCHLD && posixly_correct == 0)
    opt = next_pending_trap (opt+1);
#endif
  if (opt != -1)
    {
      last_command_exit_signal = wait_signal_received = opt;
      status = opt + 128;
      WAIT_RETURN (status);
    }

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

#if defined (JOB_CONTROL)
  if (nflag)
    {
#if 1	/* TAG:bash-5.3 stevenpelley@gmail.com 01/22/2024 */
      /* First let's see if there are any requested pids that have already
	 been removed from the jobs list and saved on bgpids or are terminated
	 procsubs. */
      if (list)
	{
	  status = check_nonjobs (list, &pstat);
	  if (status != -1)
	    {
	      if (vname)
		builtin_bind_var_to_int (vname, pstat.pid, bindflags);
	      WAIT_RETURN (status);	      
	    }
	}
#endif

      if (list)
	{
	  opt = set_waitlist (list);
	  if (opt == 0)
	    WAIT_RETURN (127);
	  wflags |= JWAIT_WAITING;
	}

      status = wait_for_any_job (wflags, &pstat);
      if (vname && status >= 0)
	builtin_bind_var_to_int (vname, pstat.pid, bindflags);

      if (status < 0)
	status = 127;
      if (list)
	unset_waitlist ();
      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)
    {
      opt = wait_for_background_pids (&pstat);
#if 0
      /* Compatibility with NetBSD sh: don't set VNAME since it doesn't
	 correspond to the return status. */
      if (vname && opt)
	builtin_bind_var_to_int (vname, pstat.pid, bindflags);
#endif
      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 (valid_number (w, &pid_value) && pid_value == (pid_t)pid_value)
	    {
	      pid = (pid_t)pid_value;
	      status = wait_for_single_pid (pid, wflags|JWAIT_PERROR);
	      /* status > 256 means pid error */
	      pstat.pid = (status > 256) ? NO_PID : pid;
	      pstat.status = (status > 256) ? 127 : status;
	      if (status > 256)
		status = 127;
	    }
	  else
	    {
	      sh_badpid (w);
	      pstat.pid = NO_PID;
	      pstat.status = 127;
	      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 */
	      pstat.pid = NO_PID;
	      pstat.status = status;
	      list = list->next;
	      continue;
	    }

	  /* Job spec used.  Wait for the last pid in the pipeline. */
	  UNBLOCK_CHILD (oset);
	  status = wait_for_job (job, wflags, &pstat);
	}
#endif /* JOB_CONTROL */
      else
	{
	  sh_badpid (w);
	  pstat.pid = NO_PID;
	  pstat.status = 127;
	  status = EXECUTION_FAILURE;
	}

      /* Don't waste time with a longjmp. */
      if (wait_signal_received)
	{
	  last_command_exit_signal = wait_signal_received;
	  status = 128 + wait_signal_received;
	  wait_sigint_cleanup ();
	  WAIT_RETURN (status);
	}

      list = list->next;
    }

  if (vname && pstat.pid != NO_PID)
    builtin_bind_var_to_int (vname, pstat.pid, bindflags);

  WAIT_RETURN (status);
}

#if defined (JOB_CONTROL)
/* Take each valid pid or jobspec in LIST and mark the corresponding job as
   J_WAITING, so wait -n knows which jobs to wait for.
   If we have process substitutions, allow wait -n to wait for procsubs by
   pid by marking them with PROC_WAITING.
   Return the number of jobs or procsubs we found. */
static int
set_waitlist (WORD_LIST *list)
{
  sigset_t set, oset;
  int job, njob;
  intmax_t ipid;
  pid_t pid;
  PROCESS *child;
  WORD_LIST *l;

  BLOCK_CHILD (set, oset);
  njob = 0;
  for (l = list; l; l = l->next)
    {
      child = NULL;

      pid = (l && l->word && valid_number (l->word->word, &ipid) && ipid == (pid_t)ipid) ? (pid_t)ipid : NO_PID;
      job = (pid != NO_PID) ? get_job_by_pid (pid, 0, 0) : get_job_spec (l);

      if (job == NO_JOB || jobs == 0 || INVALID_JOB (job))
	{
#if defined (PROCESS_SUBSTITUTION)
	  child = (pid >= 0) ? procsub_search (pid, 0) : NULL;
#endif
	  if (child)
	    {
	      /* If we don't have a valid job, maybe we have a procsub */
	      njob++;
	      child->flags |= PROC_WAITING;
	    }
	  else if (l->word->word[0] == '%')
	    sh_badjob (l->word->word);
	  else if (job == BAD_JOBSPEC)
	    sh_invalidjob (l->word->word);
	  else
	    sh_badpid (l->word->word);
	  continue;
	}

      /* We don't check yet to see if one of the desired jobs has already
	 terminated, but we could. We wait until wait_for_any_job(). This
	 has the advantage of validating all the arguments. */
      if ((jobs[job]->flags & J_WAITING) == 0)
	{
	  njob++;
	  jobs[job]->flags |= J_WAITING;
	}
    }
  UNBLOCK_CHILD (oset);
  return (njob);
}

/* Clean up after a call to wait -n jobs */
static void
unset_waitlist (void)
{
  int i;
  sigset_t set, oset;

  BLOCK_CHILD (set, oset);
  for (i = 0; i < js.j_jobslots; i++)
    if (jobs[i] && (jobs[i]->flags & J_WAITING))
      jobs[i]->flags &= ~J_WAITING;
#if defined (PROCESS_SUBSTITUTION)
  procsub_unsetflag (ANY_PID, PROC_WAITING, 0);
#endif
  UNBLOCK_CHILD (oset);
}

/* For each pid in LIST, check the bgpids list and the procsub list, if we
   have process substitutions. */
static int
check_nonjobs (WORD_LIST *list, struct procstat *pstat)
{
  sigset_t set, oset;
  pid_t pid;
  intmax_t ipid;
  WORD_LIST *l;
  PROCESS *child;
  int r, s;

  r = -1;

  BLOCK_CHILD (set, oset);
  for (l = list; l; l = l->next)
    {
      if (l && valid_number (l->word->word, &ipid) && ipid == (pid_t) ipid && ipid >= 0)
        pid = ipid;
      else if (l && l->word->word[0] == '%')
	continue;	/* skip job ids for now */
      else
	{
	  r = -1;
	  continue;
	}

      /* check bgpids */
      if ((s = retrieve_proc_status (pid, 0)) != -1)
	{
	  pstat->pid = pid;
	  pstat->status = r = s;
	  /* If running in posix mode, `wait -n pid' deletes pid from bgpids,
	     just like `wait pid'. */
	  if (posixly_correct)
	    delete_proc_status (pid, 0);
	  break;
	}

#if defined (PROCESS_SUBSTITUTION)
      /* If this corresponds to a terminated procsub, return it. */
      if ((child = procsub_search (pid, 0)) && child->running == PS_DONE)
	{
	  pstat->pid = pid;
	  pstat->status = r = process_exit_status (child->status);
	  procsub_delete (pid, 0);	/* moves to bgpids list */
	  if (posixly_correct)
	    delete_proc_status (pid, 0);
	  break;
	}
#endif
    }
  UNBLOCK_CHILD (oset);

  return r;
}
#endif