/* GLIB - Library of useful routines for C programming

 * Copyright (C) 1995-1997  Peter Mattis, Spencer Kimball and Josh MacDonald

 *

 * gpoll.c: poll(2) abstraction

 * Copyright 1998 Owen Taylor

 * Copyright 2008 Red Hat, Inc.

 *

 * This library is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Lesser General Public

 * License as published by the Free Software Foundation; either

 * version 2.1 of the License, or (at your option) any later version.

 *

 * This library 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

 * Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public

 * License along with this library; if not, see <http://www.gnu.org/licenses/>.

 */

/*

 * Modified by the GLib Team and others 1997-2000.  See the AUTHORS

 * file for a list of people on the GLib Team.  See the ChangeLog

 * files for a list of changes.  These files are distributed with

 * GLib at ftp://ftp.gtk.org/pub/gtk/.

 */

/*

 * MT safe

 */

#include "config.h"

#include "glibconfig.h"

#include "giochannel.h"

/* Uncomment the next line (and the corresponding line in gmain.c) to

 * enable debugging printouts if the environment variable

 * G_MAIN_POLL_DEBUG is set to some value.

 */

/* #define G_MAIN_POLL_DEBUG */

#ifdef _WIN32

/* Always enable debugging printout on Windows, as it is more often

 * needed there...

 */

#define G_MAIN_POLL_DEBUG

#endif

#include <sys/types.h>

#include <time.h>

#include <stdlib.h>

#ifdef HAVE_SYS_TIME_H

#include <sys/time.h>

#endif /* HAVE_SYS_TIME_H */

#ifdef HAVE_POLL

#  include <poll.h>

/* The poll() emulation on OS/X doesn't handle fds=NULL, nfds=0,

 * so we prefer our own poll emulation.

 */

#if defined(_POLL_EMUL_H_) || defined(BROKEN_POLL)

#undef HAVE_POLL

#endif

#endif /* GLIB_HAVE_SYS_POLL_H */

#ifdef G_OS_UNIX

#include <unistd.h>

#endif /* G_OS_UNIX */

#include <errno.h>

#ifdef G_OS_WIN32

#define STRICT

#include <windows.h>

#endif /* G_OS_WIN32 */

#include "gpoll.h"

#ifdef G_OS_WIN32

#include "gprintf.h"

#endif

#ifdef G_MAIN_POLL_DEBUG

extern gboolean _g_main_poll_debug;

#endif

#ifdef HAVE_POLL

/**

 * g_poll:

 * @fds: file descriptors to poll

 * @nfds: the number of file descriptors in @fds

 * @timeout: amount of time to wait, in milliseconds, or -1 to wait forever

 *

 * Polls @fds, as with the poll() system call, but portably. (On

 * systems that don't have poll(), it is emulated using select().)

 * This is used internally by #GMainContext, but it can be called

 * directly if you need to block until a file descriptor is ready, but

 * don't want to run the full main loop.

 *

 * Each element of @fds is a #GPollFD describing a single file

 * descriptor to poll. The @fd field indicates the file descriptor,

 * and the @events field indicates the events to poll for. On return,

 * the @revents fields will be filled with the events that actually

 * occurred.

 *

 * On POSIX systems, the file descriptors in @fds can be any sort of

 * file descriptor, but the situation is much more complicated on

 * Windows. If you need to use g_poll() in code that has to run on

 * Windows, the easiest solution is to construct all of your

 * #GPollFDs with g_io_channel_win32_make_pollfd().

 *

 * Returns: the number of entries in @fds whose @revents fields

 * were filled in, or 0 if the operation timed out, or -1 on error or

 * if the call was interrupted.

 *

 * Since: 2.20

 **/

gint

g_poll (GPollFD *fds,

	guint    nfds,

	gint     timeout)

{

  return poll ((struct pollfd *)fds, nfds, timeout);

}

#else	/* !HAVE_POLL */

#ifdef G_OS_WIN32

static int

poll_rest (GPollFD *msg_fd,

           HANDLE  *handles,

           GPollFD *handle_to_fd[],

           gint     nhandles,

           gint     timeout)

{

  DWORD ready;

  GPollFD *f;

  int recursed_result;

  if (msg_fd != NULL)

    {

      /* Wait for either messages or handles

       * -> Use MsgWaitForMultipleObjectsEx

       */

      if (_g_main_poll_debug)

	g_print ("  MsgWaitForMultipleObjectsEx(%d, %d)\n", nhandles, timeout);

      ready = MsgWaitForMultipleObjectsEx (nhandles, handles, timeout,

					   QS_ALLINPUT, MWMO_ALERTABLE);

      if (ready == WAIT_FAILED)

	{

	  gchar *emsg = g_win32_error_message (GetLastError ());

	  g_warning ("MsgWaitForMultipleObjectsEx failed: %s", emsg);

	  g_free (emsg);

	}

    }

  else if (nhandles == 0)

    {

      /* No handles to wait for, just the timeout */

      if (timeout == INFINITE)

	ready = WAIT_FAILED;

      else

        {

          /* Wait for the current process to die, more efficient than SleepEx(). */

          WaitForSingleObjectEx (GetCurrentProcess (), timeout, TRUE);

          ready = WAIT_TIMEOUT;

        }

    }

  else

    {

      /* Wait for just handles

       * -> Use WaitForMultipleObjectsEx

       */

      if (_g_main_poll_debug)

	g_print ("  WaitForMultipleObjectsEx(%d, %d)\n", nhandles, timeout);

      ready = WaitForMultipleObjectsEx (nhandles, handles, FALSE, timeout, TRUE);

      if (ready == WAIT_FAILED)

	{

	  gchar *emsg = g_win32_error_message (GetLastError ());

	  g_warning ("WaitForMultipleObjectsEx failed: %s", emsg);

	  g_free (emsg);

	}

    }

  if (_g_main_poll_debug)

    g_print ("  wait returns %ld%s\n",

	     ready,

	     (ready == WAIT_FAILED ? " (WAIT_FAILED)" :

	      (ready == WAIT_TIMEOUT ? " (WAIT_TIMEOUT)" :

	       (msg_fd != NULL && ready == WAIT_OBJECT_0 + nhandles ? " (msg)" : ""))));

  if (ready == WAIT_FAILED)

    return -1;

  else if (ready == WAIT_TIMEOUT ||

	   ready == WAIT_IO_COMPLETION)

    return 0;

  else if (msg_fd != NULL && ready == WAIT_OBJECT_0 + nhandles)

    {

      msg_fd->revents |= G_IO_IN;

      /* If we have a timeout, or no handles to poll, be satisfied

       * with just noticing we have messages waiting.

       */

      if (timeout != 0 || nhandles == 0)

	return 1;

      /* If no timeout and handles to poll, recurse to poll them,

       * too.

       */

      recursed_result = poll_rest (NULL, handles, handle_to_fd, nhandles, 0);

      return (recursed_result == -1) ? -1 : 1 + recursed_result;

    }

  else if (ready >= WAIT_OBJECT_0 && ready < WAIT_OBJECT_0 + nhandles)

    {

      f = handle_to_fd[ready - WAIT_OBJECT_0];

      f->revents = f->events;

      if (_g_main_poll_debug)

        g_print ("  got event %p\n", (HANDLE) f->fd);

      /* If no timeout and polling several handles, recurse to poll

       * the rest of them.

       */

      if (timeout == 0 && nhandles > 1)

	{

	  /* Poll the handles with index > ready */

          HANDLE  *shorter_handles;

          GPollFD **shorter_handle_to_fd;

          gint     shorter_nhandles;

          shorter_handles = &handles[ready - WAIT_OBJECT_0 + 1];

          shorter_handle_to_fd = &handle_to_fd[ready - WAIT_OBJECT_0 + 1];

          shorter_nhandles = nhandles - (ready - WAIT_OBJECT_0 + 1);

	  recursed_result = poll_rest (NULL, shorter_handles, shorter_handle_to_fd, shorter_nhandles, 0);

	  return (recursed_result == -1) ? -1 : 1 + recursed_result;

	}

      return 1;

    }

  return 0;

}

gint

g_poll (GPollFD *fds,

	guint    nfds,

	gint     timeout)

{

  HANDLE handles[MAXIMUM_WAIT_OBJECTS];

  GPollFD *handle_to_fd[MAXIMUM_WAIT_OBJECTS];

  GPollFD *msg_fd = NULL;

  GPollFD *f;

  gint nhandles = 0;

  int retval;

  if (_g_main_poll_debug)

    g_print ("g_poll: waiting for");

  for (f = fds; f < &fds[nfds]; ++f)

    {

      if (f->fd == G_WIN32_MSG_HANDLE && (f->events & G_IO_IN))

        {

          if (_g_main_poll_debug && msg_fd == NULL)

            g_print (" MSG");

          msg_fd = f;

        }

      else if (f->fd > 0)

        {

          if (nhandles == MAXIMUM_WAIT_OBJECTS)

            {

              g_warning ("Too many handles to wait for!\n");

              break;

            }

          else

            {

              if (_g_main_poll_debug)

                g_print (" %p", (HANDLE) f->fd);

              handle_to_fd[nhandles] = f;

              handles[nhandles++] = (HANDLE) f->fd;

            }

        }

      f->revents = 0;

    }

  if (_g_main_poll_debug)

    g_print ("\n");

  if (timeout == -1)

    timeout = INFINITE;

  /* Polling for several things? */

  if (nhandles > 1 || (nhandles > 0 && msg_fd != NULL))

    {

      /* First check if one or several of them are immediately

       * available

       */

      retval = poll_rest (msg_fd, handles, handle_to_fd, nhandles, 0);

      /* If not, and we have a significant timeout, poll again with

       * timeout then. Note that this will return indication for only

       * one event, or only for messages.

       */

      if (retval == 0 && (timeout == INFINITE || timeout > 0))

	retval = poll_rest (msg_fd, handles, handle_to_fd, nhandles, timeout);

    }

  else

    {

      /* Just polling for one thing, so no need to check first if

       * available immediately

       */

      retval = poll_rest (msg_fd, handles, handle_to_fd, nhandles, timeout);

    }

  if (retval == -1)

    for (f = fds; f < &fds[nfds]; ++f)

      f->revents = 0;

  return retval;

}

#else  /* !G_OS_WIN32 */

/* The following implementation of poll() comes from the GNU C Library.

 * Copyright (C) 1994, 1996, 1997 Free Software Foundation, Inc.

 */

#include <string.h> /* for bzero on BSD systems */

#ifdef HAVE_SYS_SELECT_H

#include <sys/select.h>

#endif /* HAVE_SYS_SELECT_H */

#ifndef NO_FD_SET

#  define SELECT_MASK fd_set

#else /* !NO_FD_SET */

#  ifndef _AIX

typedef long fd_mask;

#  endif /* _AIX */

#  ifdef _IBMR2

#    define SELECT_MASK void

#  else /* !_IBMR2 */

#    define SELECT_MASK int

#  endif /* !_IBMR2 */

#endif /* !NO_FD_SET */

gint

g_poll (GPollFD *fds,

	guint    nfds,

	gint     timeout)

{

  struct timeval tv;

  SELECT_MASK rset, wset, xset;

  GPollFD *f;

  int ready;

  int maxfd = 0;

  FD_ZERO (&rset);

  FD_ZERO (&wset);

  FD_ZERO (&xset);

  for (f = fds; f < &fds[nfds]; ++f)

    if (f->fd >= 0)

      {

	if (f->events & G_IO_IN)

	  FD_SET (f->fd, &rset);

	if (f->events & G_IO_OUT)

	  FD_SET (f->fd, &wset);

	if (f->events & G_IO_PRI)

	  FD_SET (f->fd, &xset);

	if (f->fd > maxfd && (f->events & (G_IO_IN|G_IO_OUT|G_IO_PRI)))

	  maxfd = f->fd;

      }

  tv.tv_sec = timeout / 1000;

  tv.tv_usec = (timeout % 1000) * 1000;

  ready = select (maxfd + 1, &rset, &wset, &xset,

		  timeout == -1 ? NULL : &tv;;

  if (ready > 0)

    for (f = fds; f < &fds[nfds]; ++f)

      {

	f->revents = 0;

	if (f->fd >= 0)

	  {

	    if (FD_ISSET (f->fd, &rset))

	      f->revents |= G_IO_IN;

	    if (FD_ISSET (f->fd, &wset))

	      f->revents |= G_IO_OUT;

	    if (FD_ISSET (f->fd, &xset))

	      f->revents |= G_IO_PRI;

	  }

      }

  return ready;

}

#endif /* !G_OS_WIN32 */

#endif	/* !HAVE_POLL */