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glib2.0/glib/gpoll.c

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/* 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.
*
* SPDX-License-Identifier: LGPL-2.1-or-later
*
* 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>
#include <process.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,
GPollFD *stop_fd,
HANDLE *handles,
GPollFD *handle_to_fd[],
gint nhandles,
DWORD timeout_ms)
{
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, %lu)\n", nhandles, timeout_ms);
ready = MsgWaitForMultipleObjectsEx (nhandles, handles, timeout_ms,
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_ms == INFINITE)
ready = WAIT_FAILED;
else
{
/* Wait for the current process to die, more efficient than SleepEx(). */
WaitForSingleObjectEx (GetCurrentProcess (), timeout_ms, TRUE);
ready = WAIT_TIMEOUT;
}
}
else
{
/* Wait for just handles
* -> Use WaitForMultipleObjectsEx
*/
if (_g_main_poll_debug)
g_print (" WaitForMultipleObjectsEx(%d, %lu)\n", nhandles, timeout_ms);
ready = WaitForMultipleObjectsEx (nhandles, handles, FALSE, timeout_ms, 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_ms != 0 || nhandles == 0)
return 1;
/* If no timeout and handles to poll, recurse to poll them,
* too.
*/
recursed_result = poll_rest (NULL, stop_fd, handles, handle_to_fd, nhandles, 0);
return (recursed_result == -1) ? -1 : 1 + recursed_result;
}
else if (ready < WAIT_OBJECT_0 + nhandles)
{
int retval;
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);
/* Do not count the stop_fd */
retval = (f != stop_fd) ? 1 : 0;
/* If no timeout and polling several handles, recurse to poll
* the rest of them.
*/
if (timeout_ms == 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, stop_fd, shorter_handles, shorter_handle_to_fd, shorter_nhandles, 0);
return (recursed_result == -1) ? -1 : retval + recursed_result;
}
return retval;
}
return 0;
}
typedef struct
{
HANDLE handles[MAXIMUM_WAIT_OBJECTS];
GPollFD *handle_to_fd[MAXIMUM_WAIT_OBJECTS];
GPollFD *msg_fd;
GPollFD *stop_fd;
gint nhandles;
DWORD timeout_ms;
} GWin32PollThreadData;
static gint
poll_single_thread (GWin32PollThreadData *data)
{
int retval;
/* Polling for several things? */
if (data->nhandles > 1 || (data->nhandles > 0 && data->msg_fd != NULL))
{
/* First check if one or several of them are immediately
* available
*/
retval = poll_rest (data->msg_fd, data->stop_fd, data->handles, data->handle_to_fd, data->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 && (data->timeout_ms == INFINITE || data->timeout_ms > 0))
retval = poll_rest (data->msg_fd, data->stop_fd, data->handles, data->handle_to_fd, data->nhandles, data->timeout_ms);
}
else
{
/* Just polling for one thing, so no need to check first if
* available immediately
*/
retval = poll_rest (data->msg_fd, data->stop_fd, data->handles, data->handle_to_fd, data->nhandles, data->timeout_ms);
}
return retval;
}
static void
fill_poll_thread_data (GPollFD *fds,
guint nfds,
DWORD timeout_ms,
GPollFD *stop_fd,
GWin32PollThreadData *data)
{
GPollFD *f;
data->timeout_ms = timeout_ms;
if (stop_fd != NULL)
{
if (_g_main_poll_debug)
g_print (" Stop FD: %p", (HANDLE) stop_fd->fd);
g_assert (data->nhandles < MAXIMUM_WAIT_OBJECTS);
data->stop_fd = stop_fd;
data->handle_to_fd[data->nhandles] = stop_fd;
data->handles[data->nhandles++] = (HANDLE) stop_fd->fd;
}
for (f = fds; f < &fds[nfds]; ++f)
{
if ((data->nhandles == MAXIMUM_WAIT_OBJECTS) ||
(data->msg_fd != NULL && (data->nhandles == MAXIMUM_WAIT_OBJECTS - 1)))
{
g_warning ("Too many handles to wait for!");
break;
}
if (f->fd == G_WIN32_MSG_HANDLE && (f->events & G_IO_IN))
{
if (_g_main_poll_debug && data->msg_fd == NULL)
g_print (" MSG");
data->msg_fd = f;
}
else if (f->fd > 0)
{
if (_g_main_poll_debug)
g_print (" %p", (HANDLE) f->fd);
data->handle_to_fd[data->nhandles] = f;
data->handles[data->nhandles++] = (HANDLE) f->fd;
}
f->revents = 0;
}
}
static guint __stdcall
poll_thread_run (gpointer user_data)
{
GWin32PollThreadData *data = user_data;
/* Docs say that it is safer to call _endthreadex by our own:
* https://docs.microsoft.com/en-us/cpp/c-runtime-library/reference/endthread-endthreadex
*/
_endthreadex (poll_single_thread (data));
g_assert_not_reached ();
return 0;
}
/* One slot for a possible msg object or the stop event */
#define MAXIMUM_WAIT_OBJECTS_PER_THREAD (MAXIMUM_WAIT_OBJECTS - 1)
gint
g_poll (GPollFD *fds,
guint nfds,
gint timeout)
{
guint nthreads, threads_remain;
HANDLE thread_handles[MAXIMUM_WAIT_OBJECTS];
GWin32PollThreadData *threads_data;
GPollFD stop_event = { 0, };
GPollFD *f;
guint i, fds_idx = 0;
DWORD ready;
DWORD thread_retval;
int retval;
GPollFD *msg_fd = NULL;
if (timeout == -1)
timeout = INFINITE;
/* Simple case without extra threads */
if (nfds <= MAXIMUM_WAIT_OBJECTS)
{
GWin32PollThreadData data = { 0, };
if (_g_main_poll_debug)
g_print ("g_poll: waiting for");
fill_poll_thread_data (fds, nfds, timeout, NULL, &data);
if (_g_main_poll_debug)
g_print ("\n");
retval = poll_single_thread (&data);
if (retval == -1)
for (f = fds; f < &fds[nfds]; ++f)
f->revents = 0;
return retval;
}
if (_g_main_poll_debug)
g_print ("g_poll: polling with threads\n");
nthreads = nfds / MAXIMUM_WAIT_OBJECTS_PER_THREAD;
threads_remain = nfds % MAXIMUM_WAIT_OBJECTS_PER_THREAD;
if (threads_remain > 0)
nthreads++;
if (nthreads > MAXIMUM_WAIT_OBJECTS_PER_THREAD)
{
g_warning ("Too many handles to wait for in threads!");
nthreads = MAXIMUM_WAIT_OBJECTS_PER_THREAD;
}
#if GLIB_SIZEOF_VOID_P == 8
stop_event.fd = (gint64)CreateEventW (NULL, TRUE, FALSE, NULL);
#else
stop_event.fd = (gint)CreateEventW (NULL, TRUE, FALSE, NULL);
#endif
stop_event.events = G_IO_IN;
threads_data = g_new0 (GWin32PollThreadData, nthreads);
for (i = 0; i < nthreads; i++)
{
guint thread_fds;
guint ignore;
if (i == (nthreads - 1) && threads_remain > 0)
thread_fds = threads_remain;
else
thread_fds = MAXIMUM_WAIT_OBJECTS_PER_THREAD;
fill_poll_thread_data (fds + fds_idx, thread_fds, timeout, &stop_event, &threads_data[i]);
fds_idx += thread_fds;
/* We must poll for messages from the same thread, so poll it along with the threads */
if (threads_data[i].msg_fd != NULL)
{
msg_fd = threads_data[i].msg_fd;
threads_data[i].msg_fd = NULL;
}
thread_handles[i] = (HANDLE) _beginthreadex (NULL, 0, poll_thread_run, &threads_data[i], 0, &ignore);
}
/* Wait for at least one thread to return */
if (msg_fd != NULL)
ready = MsgWaitForMultipleObjectsEx (nthreads, thread_handles, timeout,
QS_ALLINPUT, MWMO_ALERTABLE);
else
ready = WaitForMultipleObjects (nthreads, thread_handles, FALSE, timeout);
/* Signal the stop in case any of the threads did not stop yet */
if (!SetEvent ((HANDLE)stop_event.fd))
{
gchar *emsg = g_win32_error_message (GetLastError ());
g_warning ("gpoll: failed to signal the stop event: %s", emsg);
g_free (emsg);
}
/* Wait for the rest of the threads to finish */
WaitForMultipleObjects (nthreads, thread_handles, TRUE, INFINITE);
/* The return value of all the threads give us all the fds that changed state */
retval = 0;
if (msg_fd != NULL && ready == WAIT_OBJECT_0 + nthreads)
{
msg_fd->revents |= G_IO_IN;
retval = 1;
}
for (i = 0; i < nthreads; i++)
{
if (GetExitCodeThread (thread_handles[i], &thread_retval))
retval = (retval == -1) ? -1 : ((thread_retval == (DWORD) -1) ? -1 : (int) (retval + thread_retval));
CloseHandle (thread_handles[i]);
}
if (retval == -1)
for (f = fds; f < &fds[nfds]; ++f)
f->revents = 0;
g_free (threads_data);
CloseHandle ((HANDLE)stop_event.fd);
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 */
gint
g_poll (GPollFD *fds,
guint nfds,
gint timeout)
{
struct timeval tv;
fd_set 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 */
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