glib/gpoll.h

   1 /* gpoll.h - poll(2) support
   2  * Copyright (C) 2008 Red Hat, Inc.
   3  *
   4  * This library is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU Library General Public
   6  * License as published by the Free Software Foundation; either
   7  * version 2 of the License, or (at your option) any later version.
   8  *
   9  * This library is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * Library General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU Library General Public
  15  * License along with this library; if not, write to the
  16  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  17  * Boston, MA 02111-1307, USA.
  18  */
  19
  20 #if !defined (__GLIB_H_INSIDE__) && !defined (__G_MAIN_H__) && !defined (GLIB_COMPILATION)
  21 #error "Only <glib.h> can be included directly."
  22 #endif
  23
  24 #ifndef __G_POLL_H__
  25 #define __G_POLL_H__
  26
  27 #include <glib/gtypes.h>
  28
  29 G_BEGIN_DECLS
  30
  31 /* Any definitions using GPollFD or GPollFunc are primarily
  32  * for Unix and not guaranteed to be the compatible on all
  33  * operating systems on which GLib runs. Right now, the
  34  * GLib does use these functions on Win32 as well, but interprets
  35  * them in a fairly different way than on Unix. If you use
  36  * these definitions, you are should be prepared to recode
  37  * for different operating systems.
  38  *
  39  * Note that on systems with a working poll(2), that function is used
  40  * in place of g_poll(). Thus g_poll() must have the same signature as
  41  * poll(), meaning GPollFD must have the same layout as struct pollfd.
  42  *
  43  *
  44  * On Win32, the fd in a GPollFD should be Win32 HANDLE (*not* a file
  45  * descriptor as provided by the C runtime) that can be used by
  46  * MsgWaitForMultipleObjects. This does *not* include file handles
  47  * from CreateFile, SOCKETs, nor pipe handles. (But you can use
  48  * WSAEventSelect to signal events when a SOCKET is readable).
  49  *
  50  * On Win32, fd can also be the special value G_WIN32_MSG_HANDLE to
  51  * indicate polling for messages.
  52  *
  53  * But note that G_WIN32_MSG_HANDLE GPollFDs should not be used by GDK
  54  * (GTK) programs, as GDK itself wants to read messages and convert them
  55  * to GDK events.
  56  *
  57  * So, unless you really know what you are doing, it's best not to try
  58  * to use the main loop polling stuff for your own needs on
  59  * Windows.
  60  */
  61 typedef struct _GPollFD GPollFD;
  62
  63 /**
  64  * GPollFunc:
  65  * @ufds: an array of #GPollFD elements
  66  * @nfsd: the number of elements in @ufds
  67  * @timeout_: the maximum time to wait for an event of the file descriptors.
  68  *     A negative value indicates an infinite timeout.
  69  *
  70  * Specifies the type of function passed to g_main_context_set_poll_func().
  71  * The semantics of the function should match those of the poll() system call.
  72  *
  73  * Returns: the number of #GPollFD elements which have events or errors
  74  *     reported, or -1 if an error occurred.
  75  */
  76 typedef gint    (*GPollFunc)    (GPollFD *ufds,
  77                                  guint    nfsd,
  78                                  gint     timeout_);
  79
  80 /**
  81  * GPollFD:
  82  * @fd: the file descriptor to poll (or a <type>HANDLE</type> on Win32)
  83  * @events: a bitwise combination from #GIOCondition, specifying which
  84  *     events should be polled for. Typically for reading from a file
  85  *     descriptor you would use %G_IO_IN | %G_IO_HUP | %G_IO_ERR, and
  86  *     for writing you would use %G_IO_OUT | %G_IO_ERR.
  87  * @revents: a bitwise combination of flags from #GIOCondition, returned
  88  *     from the poll() function to indicate which events occurred.
  89  *
  90  * Represents a file descriptor, which events to poll for, and which events
  91  * occurred.
  92  */
  93 struct _GPollFD
  94 {
  95 #if defined (G_OS_WIN32) && GLIB_SIZEOF_VOID_P == 8
  96   gint64        fd;
  97 #else
  98   gint          fd;
  99 #endif
 100   gushort       events;
 101   gushort       revents;
 102 };
 103
 104 #ifdef G_OS_WIN32
 105 #if GLIB_SIZEOF_VOID_P == 8
 106 #define G_POLLFD_FORMAT "%#I64x"
 107 #else
 108 #define G_POLLFD_FORMAT "%#x"
 109 #endif
 110 #else
 111 #define G_POLLFD_FORMAT "%d"
 112 #endif
 113
 114 gint g_poll (GPollFD *fds,
 115              guint    nfds,
 116              gint     timeout);
 117
 118 G_END_DECLS
 119
 120 #endif /* __G_POLL_H__ */