libc/winsup/cygwin/wait.cc

/* wait.cc: Posix wait routines.

This file is part of Cygwin.

This software is a copyrighted work licensed under the terms of the
Cygwin license.  Please consult the file "CYGWIN_LICENSE" for
details. */

#include "winsup.h"
#include <sys/wait.h>
#include "sigproc.h"
#include "thread.h"
#include "cygtls.h"
#include "cygwait.h"

/* This is called _wait and not wait because the real wait is defined
   in libc/syscalls/syswait.c.  It calls us.  */

extern "C" pid_t
wait (int *status)
{
  return wait4 (-1, status, 0, NULL);
}

extern "C" pid_t
waitpid (pid_t intpid, int *status, int options)
{
  return wait4 (intpid, status, options, NULL);
}

extern "C" pid_t
wait3 (int *status, int options, struct rusage *r)
{
  return wait4 (-1, status, options, r);
}

/* Wait for any child to complete.
 * Note: this is not thread safe.  Use of wait in multiple threads will
 * not work correctly.
 */

extern "C" pid_t
wait4 (int intpid, int *status, int options, struct rusage *r)
{
  int res;
  HANDLE waitfor;
  waitq *w = &_my_tls.wq;

  pthread_testcancel ();

  while (1)
    {
      sig_dispatch_pending ();
      if (options & ~(WNOHANG | WUNTRACED | WCONTINUED))
	{
	  set_errno (EINVAL);
	  res = -1;
	  break;
	}

      if (r)
	memset (r, 0, sizeof (*r));

      w->pid = intpid;
      w->options = options;
      w->rusage = r;
      sigproc_printf ("calling proc_subproc, pid %d, options %d",
		      w->pid, w->options);
      if (!proc_subproc (PROC_WAIT, (uintptr_t) w))
	{
	  set_errno (ENOSYS);
	  paranoid_printf ("proc_subproc returned 0");
	  res = -1;
	  break;
	}

      if ((waitfor = w->ev) == NULL)
	goto nochildren;

      res = cygwait (waitfor, cw_infinite, cw_cancel | cw_cancel_self);

      sigproc_printf ("%d = cygwait (...)", res);

      if (w->ev == NULL)
	{
	nochildren:
	  /* found no children */
	  set_errno (ECHILD);
	  res = -1;
	  break;
	}

      if (w->status == -1)
	{
	  if (_my_tls.call_signal_handler ())
	    continue;
	  set_sig_errno (EINTR);
	  res = -1;
	}
      else if (res != WAIT_OBJECT_0)
	{
	  set_errno (EINVAL);
	  res = -1;
	}
      else if ((res = w->pid) != 0 && status)
	*status = w->status;
      break;
    }

  syscall_printf ("%R = wait4(%d, %y, %d, %p)", res, intpid, w->status, options, r);
  w->status = -1;
  return res;
}