1  /* gpoll.h - poll(2) support
       2   * Copyright (C) 2008 Red Hat, Inc.
       3   *
       4   * SPDX-License-Identifier: LGPL-2.1-or-later
       5   *
       6   * This library is free software; you can redistribute it and/or
       7   * modify it under the terms of the GNU Lesser General Public
       8   * License as published by the Free Software Foundation; either
       9   * version 2.1 of the License, or (at your option) any later version.
      10   *
      11   * This library is distributed in the hope that it will be useful,
      12   * but WITHOUT ANY WARRANTY; without even the implied warranty of
      13   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      14   * Lesser General Public License for more details.
      15   *
      16   * You should have received a copy of the GNU Lesser General Public License
      17   * along with this library; if not, see <http://www.gnu.org/licenses/>.
      18   */
      19  
      20  #ifndef __G_POLL_H__
      21  #define __G_POLL_H__
      22  
      23  #if !defined (__GLIB_H_INSIDE__) && !defined (__G_MAIN_H__) && !defined (GLIB_COMPILATION)
      24  #error "Only <glib.h> can be included directly."
      25  #endif
      26  
      27  #include <glibconfig.h>
      28  #include <glib/gtypes.h>
      29  
      30  G_BEGIN_DECLS
      31  
      32  /* Any definitions using GPollFD or GPollFunc are primarily
      33   * for Unix and not guaranteed to be the compatible on all
      34   * operating systems on which GLib runs. Right now, the
      35   * GLib does use these functions on Win32 as well, but interprets
      36   * them in a fairly different way than on Unix. If you use
      37   * these definitions, you are should be prepared to recode
      38   * for different operating systems.
      39   *
      40   * Note that on systems with a working poll(2), that function is used
      41   * in place of g_poll(). Thus g_poll() must have the same signature as
      42   * poll(), meaning GPollFD must have the same layout as struct pollfd.
      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 HANDLE 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  #ifndef __GTK_DOC_IGNORE__
      97    gint64	fd;
      98  #endif
      99  #else
     100    gint		fd;
     101  #endif
     102    gushort 	events;
     103    gushort 	revents;
     104  };
     105  
     106  /**
     107   * G_POLLFD_FORMAT:
     108   *
     109   * A format specifier that can be used in printf()-style format strings
     110   * when printing the @fd member of a #GPollFD.
     111   */
     112  /* defined in glibconfig.h */
     113  
     114  GLIB_AVAILABLE_IN_ALL
     115  gint
     116  g_poll (GPollFD *fds,
     117  	guint    nfds,
     118  	gint     timeout);
     119  
     120  G_END_DECLS
     121  
     122  #endif /* __G_POLL_H__ */