1 /* Function for handling the GLib event loop.
3 Copyright (C) 2009-2016 Free Software Foundation, Inc.
5 This file is part of GNU Emacs.
7 GNU Emacs is free software: you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation, either version 3 of the License, or (at
10 your option) any later version.
12 GNU Emacs is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>. */
28 #include "blockinput.h"
31 /* `xg_select' is a `pselect' replacement. Why do we need a separate function?
32 1. Timeouts. Glib and Gtk rely on timer events. If we did pselect
33 with a greater timeout then the one scheduled by Glib, we would
34 not allow Glib to process its timer events. We want Glib to
35 work smoothly, so we need to reduce our timeout to match Glib.
36 2. Descriptors. Glib may listen to more file descriptors than we do.
37 So we add Glib descriptors to our pselect pool, but we don't change
38 the value returned by the function. The return value matches only
39 the descriptors passed as arguments, making it compatible with
43 xg_select (int fds_lim
, fd_set
*rfds
, fd_set
*wfds
, fd_set
*efds
,
44 struct timespec
const *timeout
, sigset_t
const *sigmask
)
46 fd_set all_rfds
, all_wfds
;
48 struct timespec
const *tmop
= timeout
;
50 GMainContext
*context
;
51 bool have_wfds
= wfds
!= NULL
;
52 GPollFD gfds_buf
[128];
53 GPollFD
*gfds
= gfds_buf
;
54 int gfds_size
= ARRAYELTS (gfds_buf
);
55 int n_gfds
, retval
= 0, our_fds
= 0, max_fds
= fds_lim
- 1;
56 bool context_acquired
= false;
57 int i
, nfds
, tmo_in_millisec
;
58 bool need_to_dispatch
;
61 context
= g_main_context_default ();
62 context_acquired
= g_main_context_acquire (context
);
63 /* FIXME: If we couldn't acquire the context, we just silently proceed
64 because this function handles more than just glib file descriptors.
65 Note that, as implemented, this failure is completely silent: there is
66 no feedback to the caller. */
68 if (rfds
) all_rfds
= *rfds
;
69 else FD_ZERO (&all_rfds
);
70 if (wfds
) all_wfds
= *wfds
;
71 else FD_ZERO (&all_wfds
);
73 n_gfds
= (context_acquired
74 ? g_main_context_query (context
, G_PRIORITY_LOW
, &tmo_in_millisec
,
78 if (gfds_size
< n_gfds
)
80 SAFE_NALLOCA (gfds
, sizeof *gfds
, n_gfds
);
82 n_gfds
= g_main_context_query (context
, G_PRIORITY_LOW
, &tmo_in_millisec
,
86 for (i
= 0; i
< n_gfds
; ++i
)
88 if (gfds
[i
].events
& G_IO_IN
)
90 FD_SET (gfds
[i
].fd
, &all_rfds
);
91 if (gfds
[i
].fd
> max_fds
) max_fds
= gfds
[i
].fd
;
93 if (gfds
[i
].events
& G_IO_OUT
)
95 FD_SET (gfds
[i
].fd
, &all_wfds
);
96 if (gfds
[i
].fd
> max_fds
) max_fds
= gfds
[i
].fd
;
103 if (n_gfds
>= 0 && tmo_in_millisec
>= 0)
105 tmo
= make_timespec (tmo_in_millisec
/ 1000,
106 1000 * 1000 * (tmo_in_millisec
% 1000));
107 if (!timeout
|| timespec_cmp (tmo
, *timeout
) < 0)
111 fds_lim
= max_fds
+ 1;
112 nfds
= pselect (fds_lim
, &all_rfds
, have_wfds
? &all_wfds
: NULL
,
113 efds
, tmop
, sigmask
);
119 for (i
= 0; i
< fds_lim
; ++i
)
121 if (FD_ISSET (i
, &all_rfds
))
123 if (rfds
&& FD_ISSET (i
, rfds
)) ++retval
;
129 if (have_wfds
&& FD_ISSET (i
, &all_wfds
))
131 if (wfds
&& FD_ISSET (i
, wfds
)) ++retval
;
137 if (efds
&& FD_ISSET (i
, efds
))
142 /* If Gtk+ is in use eventually gtk_main_iteration will be called,
143 unless retval is zero. */
145 need_to_dispatch
= retval
== 0;
147 need_to_dispatch
= true;
149 if (need_to_dispatch
)
151 int pselect_errno
= errno
;
152 /* Prevent g_main_dispatch recursion, that would occur without
153 block_input wrapper, because event handlers call
154 unblock_input. Event loop recursion was causing Bug#15801. */
156 while (g_main_context_pending (context
))
157 g_main_context_dispatch (context
);
159 errno
= pselect_errno
;
162 if (context_acquired
)
163 g_main_context_release (context
);
165 /* To not have to recalculate timeout, return like this. */
166 if ((our_fds
> 0 || (nfds
== 0 && tmop
== &tmo
)) && (retval
== 0))
174 #endif /* HAVE_GLIB */