1 /* GLIB - Library of useful routines for C programming
2 * Copyright (C) 1995-1997 Peter Mattis, Spencer Kimball and Josh MacDonald
4 * gpoll.c: poll(2) abstraction
5 * Copyright 1998 Owen Taylor
6 * Copyright 2008 Red Hat, Inc.
8 * This library is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU Lesser General Public
10 * License as published by the Free Software Foundation; either
11 * version 2 of the License, or (at your option) any later version.
13 * This library is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * Lesser General Public License for more details.
18 * You should have received a copy of the GNU Lesser General Public
19 * License along with this library; if not, write to the
20 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
21 * Boston, MA 02111-1307, USA.
25 * Modified by the GLib Team and others 1997-2000. See the AUTHORS
26 * file for a list of people on the GLib Team. See the ChangeLog
27 * files for a list of changes. These files are distributed with
28 * GLib at ftp://ftp.gtk.org/pub/gtk/.
36 #include "glibconfig.h"
38 /* Uncomment the next line (and the corresponding line in gmain.c) to
39 * enable debugging printouts if the environment variable
40 * G_MAIN_POLL_DEBUG is set to some value.
42 /* #define G_MAIN_POLL_DEBUG */
45 /* Always enable debugging printout on Windows, as it is more often
48 #define G_MAIN_POLL_DEBUG
51 #include <sys/types.h>
54 #ifdef HAVE_SYS_TIME_H
56 #endif /* HAVE_SYS_TIME_H */
57 #ifdef GLIB_HAVE_SYS_POLL_H
58 # include <sys/poll.h>
59 # undef events /* AIX 4.1.5 & 4.3.2 define this for SVR3,4 compatibility */
60 # undef revents /* AIX 4.1.5 & 4.3.2 define this for SVR3,4 compatibility */
62 /* The poll() emulation on OS/X doesn't handle fds=NULL, nfds=0,
63 * so we prefer our own poll emulation.
65 #if defined(_POLL_EMUL_H_) || defined(BROKEN_POLL)
69 #endif /* GLIB_HAVE_SYS_POLL_H */
72 #endif /* HAVE_UNISTD_H */
78 #endif /* G_OS_WIN32 */
86 #ifdef G_MAIN_POLL_DEBUG
87 extern gboolean _g_main_poll_debug;
91 /* SunOS has poll, but doesn't provide a prototype. */
92 # if defined (sun) && !defined (__SVR4)
93 extern gint poll (struct pollfd *fds, guint nfsd, gint timeout);
98 * @fds: file descriptors to poll
99 * @nfds: the number of file descriptors in @fds
100 * @timeout: amount of time to wait, in milliseconds, or -1 to wait forever
102 * Polls @fds, as with the poll() system call, but portably. (On
103 * systems that don't have poll(), it is emulated using select().)
104 * This is used internally by #GMainContext, but it can be called
105 * directly if you need to block until a file descriptor is ready, but
106 * don't want to run the full main loop.
108 * Each element of @fds is a #GPollFD describing a single file
109 * descriptor to poll. The %fd field indicates the file descriptor,
110 * and the %events field indicates the events to poll for. On return,
111 * the %revents fields will be filled with the events that actually
114 * On POSIX systems, the file descriptors in @fds can be any sort of
115 * file descriptor, but the situation is much more complicated on
116 * Windows. If you need to use g_poll() in code that has to run on
117 * Windows, the easiest solution is to construct all of your
118 * #GPollFD<!-- -->s with g_io_channel_win32_make_pollfd().
120 * Return value: the number of entries in @fds whose %revents fields
121 * were filled in, or 0 if the operation timed out, or -1 on error or
122 * if the call was interrupted.
127 g_poll (GPollFD *fds,
131 return poll ((struct pollfd *)fds, nfds, timeout);
134 #else /* !HAVE_POLL */
139 poll_rest (gboolean poll_msgs,
152 /* Wait for either messages or handles
153 * -> Use MsgWaitForMultipleObjectsEx
155 if (_g_main_poll_debug)
156 g_print (" MsgWaitForMultipleObjectsEx(%d, %d)\n", nhandles, timeout);
158 ready = MsgWaitForMultipleObjectsEx (nhandles, handles, timeout,
159 QS_ALLINPUT, MWMO_ALERTABLE);
161 if (ready == WAIT_FAILED)
163 gchar *emsg = g_win32_error_message (GetLastError ());
164 g_warning ("MsgWaitForMultipleObjectsEx failed: %s", emsg);
168 else if (nhandles == 0)
170 /* No handles to wait for, just the timeout */
171 if (timeout == INFINITE)
175 SleepEx (timeout, TRUE);
176 ready = WAIT_TIMEOUT;
181 /* Wait for just handles
182 * -> Use WaitForMultipleObjectsEx
184 if (_g_main_poll_debug)
185 g_print (" WaitForMultipleObjectsEx(%d, %d)\n", nhandles, timeout);
187 ready = WaitForMultipleObjectsEx (nhandles, handles, FALSE, timeout, TRUE);
188 if (ready == WAIT_FAILED)
190 gchar *emsg = g_win32_error_message (GetLastError ());
191 g_warning ("WaitForMultipleObjectsEx failed: %s", emsg);
196 if (_g_main_poll_debug)
197 g_print (" wait returns %ld%s\n",
199 (ready == WAIT_FAILED ? " (WAIT_FAILED)" :
200 (ready == WAIT_TIMEOUT ? " (WAIT_TIMEOUT)" :
201 (poll_msgs && ready == WAIT_OBJECT_0 + nhandles ? " (msg)" : ""))));
203 if (ready == WAIT_FAILED)
205 else if (ready == WAIT_TIMEOUT ||
206 ready == WAIT_IO_COMPLETION)
208 else if (poll_msgs && ready == WAIT_OBJECT_0 + nhandles)
210 for (f = fds; f < &fds[nfds]; ++f)
211 if (f->fd == G_WIN32_MSG_HANDLE && f->events & G_IO_IN)
212 f->revents |= G_IO_IN;
214 /* If we have a timeout, or no handles to poll, be satisfied
215 * with just noticing we have messages waiting.
217 if (timeout != 0 || nhandles == 0)
220 /* If no timeout and handles to poll, recurse to poll them,
223 recursed_result = poll_rest (FALSE, handles, nhandles, fds, nfds, 0);
224 return (recursed_result == -1) ? -1 : 1 + recursed_result;
226 else if (ready >= WAIT_OBJECT_0 && ready < WAIT_OBJECT_0 + nhandles)
228 for (f = fds; f < &fds[nfds]; ++f)
230 if ((HANDLE) f->fd == handles[ready - WAIT_OBJECT_0])
232 f->revents = f->events;
233 if (_g_main_poll_debug)
234 g_print (" got event %p\n", (HANDLE) f->fd);
238 /* If no timeout and polling several handles, recurse to poll
241 if (timeout == 0 && nhandles > 1)
243 /* Remove the handle that fired */
245 if (ready < nhandles - 1)
246 for (i = ready - WAIT_OBJECT_0 + 1; i < nhandles; i++)
247 handles[i-1] = handles[i];
249 recursed_result = poll_rest (FALSE, handles, nhandles, fds, nfds, 0);
250 return (recursed_result == -1) ? -1 : 1 + recursed_result;
259 g_poll (GPollFD *fds,
263 HANDLE handles[MAXIMUM_WAIT_OBJECTS];
264 gboolean poll_msgs = FALSE;
269 if (_g_main_poll_debug)
270 g_print ("g_poll: waiting for");
272 for (f = fds; f < &fds[nfds]; ++f)
273 if (f->fd == G_WIN32_MSG_HANDLE && (f->events & G_IO_IN))
275 if (_g_main_poll_debug && !poll_msgs)
281 /* Don't add the same handle several times into the array, as
282 * docs say that is not allowed, even if it actually does seem
287 for (i = 0; i < nhandles; i++)
288 if (handles[i] == (HANDLE) f->fd)
293 if (nhandles == MAXIMUM_WAIT_OBJECTS)
295 g_warning ("Too many handles to wait for!\n");
300 if (_g_main_poll_debug)
301 g_print (" %p", (HANDLE) f->fd);
302 handles[nhandles++] = (HANDLE) f->fd;
307 if (_g_main_poll_debug)
310 for (f = fds; f < &fds[nfds]; ++f)
316 /* Polling for several things? */
317 if (nhandles > 1 || (nhandles > 0 && poll_msgs))
319 /* First check if one or several of them are immediately
322 retval = poll_rest (poll_msgs, handles, nhandles, fds, nfds, 0);
324 /* If not, and we have a significant timeout, poll again with
325 * timeout then. Note that this will return indication for only
326 * one event, or only for messages. We ignore timeouts less than
327 * ten milliseconds as they are mostly pointless on Windows, the
328 * MsgWaitForMultipleObjectsEx() call will timeout right away
331 if (retval == 0 && (timeout == INFINITE || timeout >= 10))
332 retval = poll_rest (poll_msgs, handles, nhandles, fds, nfds, timeout);
336 /* Just polling for one thing, so no need to check first if
337 * available immediately
339 retval = poll_rest (poll_msgs, handles, nhandles, fds, nfds, timeout);
343 for (f = fds; f < &fds[nfds]; ++f)
349 #else /* !G_OS_WIN32 */
351 /* The following implementation of poll() comes from the GNU C Library.
352 * Copyright (C) 1994, 1996, 1997 Free Software Foundation, Inc.
355 #include <string.h> /* for bzero on BSD systems */
357 #ifdef HAVE_SYS_SELECT_H
358 #include <sys/select.h>
359 #endif /* HAVE_SYS_SELECT_H */
363 #endif /* G_OS_BEOS */
366 # define SELECT_MASK fd_set
367 #else /* !NO_FD_SET */
369 typedef long fd_mask;
372 # define SELECT_MASK void
374 # define SELECT_MASK int
375 # endif /* !_IBMR2 */
376 #endif /* !NO_FD_SET */
379 g_poll (GPollFD *fds,
384 SELECT_MASK rset, wset, xset;
393 for (f = fds; f < &fds[nfds]; ++f)
396 if (f->events & G_IO_IN)
397 FD_SET (f->fd, &rset);
398 if (f->events & G_IO_OUT)
399 FD_SET (f->fd, &wset);
400 if (f->events & G_IO_PRI)
401 FD_SET (f->fd, &xset);
402 if (f->fd > maxfd && (f->events & (G_IO_IN|G_IO_OUT|G_IO_PRI)))
406 tv.tv_sec = timeout / 1000;
407 tv.tv_usec = (timeout % 1000) * 1000;
409 ready = select (maxfd + 1, &rset, &wset, &xset,
410 timeout == -1 ? NULL : &tv);
412 for (f = fds; f < &fds[nfds]; ++f)
417 if (FD_ISSET (f->fd, &rset))
418 f->revents |= G_IO_IN;
419 if (FD_ISSET (f->fd, &wset))
420 f->revents |= G_IO_OUT;
421 if (FD_ISSET (f->fd, &xset))
422 f->revents |= G_IO_PRI;
429 #endif /* !G_OS_WIN32 */
431 #endif /* !HAVE_POLL */