File: glib-unix.c

package info (click to toggle)
glib2.0 2.58.3-2+deb10u2
  • links: PTS, VCS
  • area: main
  • in suites: bullseye, buster, buster-backports, sid
  • size: 48,956 kB
  • sloc: ansic: 452,656; xml: 16,781; python: 6,149; makefile: 3,776; sh: 1,499; perl: 1,140; cpp: 9
file content (423 lines) | stat: -rw-r--r-- 12,057 bytes parent folder | download
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
/* GLIB - Library of useful routines for C programming
 * Copyright (C) 2011 Red Hat, Inc.
 *
 * glib-unix.c: UNIX specific API wrappers and convenience functions
 *
 * 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/>.
 *
 * Authors: Colin Walters <walters@verbum.org>
 */

#include "config.h"

/* To make bionic export pipe2() */
#ifndef _GNU_SOURCE
#define _GNU_SOURCE 1
#endif

#include "glib-unix.h"
#include "gmain-internal.h"

#include <string.h>

/**
 * SECTION:gunix
 * @title: UNIX-specific utilities and integration
 * @short_description: pipes, signal handling
 * @include: glib-unix.h
 *
 * Most of GLib is intended to be portable; in contrast, this set of
 * functions is designed for programs which explicitly target UNIX,
 * or are using it to build higher level abstractions which would be
 * conditionally compiled if the platform matches G_OS_UNIX.
 *
 * To use these functions, you must explicitly include the
 * "glib-unix.h" header.
 */

G_DEFINE_QUARK (g-unix-error-quark, g_unix_error)

static gboolean
g_unix_set_error_from_errno (GError **error,
                             gint     saved_errno)
{
  g_set_error_literal (error,
                       G_UNIX_ERROR,
                       0,
                       g_strerror (saved_errno));
  errno = saved_errno;
  return FALSE;
}

/**
 * g_unix_open_pipe:
 * @fds: Array of two integers
 * @flags: Bitfield of file descriptor flags, as for fcntl()
 * @error: a #GError
 *
 * Similar to the UNIX pipe() call, but on modern systems like Linux
 * uses the pipe2() system call, which atomically creates a pipe with
 * the configured flags. The only supported flag currently is
 * %FD_CLOEXEC. If for example you want to configure %O_NONBLOCK, that
 * must still be done separately with fcntl().
 *
 * This function does not take %O_CLOEXEC, it takes %FD_CLOEXEC as if
 * for fcntl(); these are different on Linux/glibc.
 *
 * Returns: %TRUE on success, %FALSE if not (and errno will be set).
 *
 * Since: 2.30
 */
gboolean
g_unix_open_pipe (int     *fds,
                  int      flags,
                  GError **error)
{
  int ecode;

  /* We only support FD_CLOEXEC */
  g_return_val_if_fail ((flags & (FD_CLOEXEC)) == flags, FALSE);

#ifdef HAVE_PIPE2
  {
    int pipe2_flags = 0;
    if (flags & FD_CLOEXEC)
      pipe2_flags |= O_CLOEXEC;
    /* Atomic */
    ecode = pipe2 (fds, pipe2_flags);
    if (ecode == -1 && errno != ENOSYS)
      return g_unix_set_error_from_errno (error, errno);
    else if (ecode == 0)
      return TRUE;
    /* Fall through on -ENOSYS, we must be running on an old kernel */
  }
#endif
  ecode = pipe (fds);
  if (ecode == -1)
    return g_unix_set_error_from_errno (error, errno);

  if (flags == 0)
    return TRUE;

  ecode = fcntl (fds[0], F_SETFD, flags);
  if (ecode == -1)
    {
      int saved_errno = errno;
      close (fds[0]);
      close (fds[1]);
      return g_unix_set_error_from_errno (error, saved_errno);
    }
  ecode = fcntl (fds[1], F_SETFD, flags);
  if (ecode == -1)
    {
      int saved_errno = errno;
      close (fds[0]);
      close (fds[1]);
      return g_unix_set_error_from_errno (error, saved_errno);
    }
  return TRUE;
}

/**
 * g_unix_set_fd_nonblocking:
 * @fd: A file descriptor
 * @nonblock: If %TRUE, set the descriptor to be non-blocking
 * @error: a #GError
 *
 * Control the non-blocking state of the given file descriptor,
 * according to @nonblock. On most systems this uses %O_NONBLOCK, but
 * on some older ones may use %O_NDELAY.
 *
 * Returns: %TRUE if successful
 *
 * Since: 2.30
 */
gboolean
g_unix_set_fd_nonblocking (gint       fd,
                           gboolean   nonblock,
                           GError   **error)
{
#ifdef F_GETFL
  glong fcntl_flags;
  fcntl_flags = fcntl (fd, F_GETFL);

  if (fcntl_flags == -1)
    return g_unix_set_error_from_errno (error, errno);

  if (nonblock)
    {
#ifdef O_NONBLOCK
      fcntl_flags |= O_NONBLOCK;
#else
      fcntl_flags |= O_NDELAY;
#endif
    }
  else
    {
#ifdef O_NONBLOCK
      fcntl_flags &= ~O_NONBLOCK;
#else
      fcntl_flags &= ~O_NDELAY;
#endif
    }

  if (fcntl (fd, F_SETFL, fcntl_flags) == -1)
    return g_unix_set_error_from_errno (error, errno);
  return TRUE;
#else
  return g_unix_set_error_from_errno (error, EINVAL);
#endif
}

/**
 * g_unix_signal_source_new:
 * @signum: A signal number
 *
 * Create a #GSource that will be dispatched upon delivery of the UNIX
 * signal @signum.  In GLib versions before 2.36, only `SIGHUP`, `SIGINT`,
 * `SIGTERM` can be monitored.  In GLib 2.36, `SIGUSR1` and `SIGUSR2`
 * were added. In GLib 2.54, `SIGWINCH` was added.
 *
 * Note that unlike the UNIX default, all sources which have created a
 * watch will be dispatched, regardless of which underlying thread
 * invoked g_unix_signal_source_new().
 *
 * For example, an effective use of this function is to handle `SIGTERM`
 * cleanly; flushing any outstanding files, and then calling
 * g_main_loop_quit ().  It is not safe to do any of this a regular
 * UNIX signal handler; your handler may be invoked while malloc() or
 * another library function is running, causing reentrancy if you
 * attempt to use it from the handler.  None of the GLib/GObject API
 * is safe against this kind of reentrancy.
 *
 * The interaction of this source when combined with native UNIX
 * functions like sigprocmask() is not defined.
 *
 * The source will not initially be associated with any #GMainContext
 * and must be added to one with g_source_attach() before it will be
 * executed.
 *
 * Returns: A newly created #GSource
 *
 * Since: 2.30
 */
GSource *
g_unix_signal_source_new (int signum)
{
  g_return_val_if_fail (signum == SIGHUP || signum == SIGINT || signum == SIGTERM ||
                        signum == SIGUSR1 || signum == SIGUSR2 || signum == SIGWINCH,
                        NULL);

  return _g_main_create_unix_signal_watch (signum);
}

/**
 * g_unix_signal_add_full: (rename-to g_unix_signal_add)
 * @priority: the priority of the signal source. Typically this will be in
 *            the range between #G_PRIORITY_DEFAULT and #G_PRIORITY_HIGH.
 * @signum: Signal number
 * @handler: Callback
 * @user_data: Data for @handler
 * @notify: #GDestroyNotify for @handler
 *
 * A convenience function for g_unix_signal_source_new(), which
 * attaches to the default #GMainContext.  You can remove the watch
 * using g_source_remove().
 *
 * Returns: An ID (greater than 0) for the event source
 *
 * Since: 2.30
 */
guint
g_unix_signal_add_full (int            priority,
                        int            signum,
                        GSourceFunc    handler,
                        gpointer       user_data,
                        GDestroyNotify notify)
{
  guint id;
  GSource *source;

  source = g_unix_signal_source_new (signum);

  if (priority != G_PRIORITY_DEFAULT)
    g_source_set_priority (source, priority);

  g_source_set_callback (source, handler, user_data, notify);
  id = g_source_attach (source, NULL);
  g_source_unref (source);

  return id;
}

/**
 * g_unix_signal_add:
 * @signum: Signal number
 * @handler: Callback
 * @user_data: Data for @handler
 *
 * A convenience function for g_unix_signal_source_new(), which
 * attaches to the default #GMainContext.  You can remove the watch
 * using g_source_remove().
 *
 * Returns: An ID (greater than 0) for the event source
 *
 * Since: 2.30
 */
guint
g_unix_signal_add (int         signum,
                   GSourceFunc handler,
                   gpointer    user_data)
{
  return g_unix_signal_add_full (G_PRIORITY_DEFAULT, signum, handler, user_data, NULL);
}

typedef struct
{
  GSource source;

  gint     fd;
  gpointer tag;
} GUnixFDSource;

static gboolean
g_unix_fd_source_dispatch (GSource     *source,
                           GSourceFunc  callback,
                           gpointer     user_data)
{
  GUnixFDSource *fd_source = (GUnixFDSource *) source;
  GUnixFDSourceFunc func = (GUnixFDSourceFunc) callback;

  if (!callback)
    {
      g_warning ("GUnixFDSource dispatched without callback. "
                 "You must call g_source_set_callback().");
      return FALSE;
    }

  return (* func) (fd_source->fd, g_source_query_unix_fd (source, fd_source->tag), user_data);
}

GSourceFuncs g_unix_fd_source_funcs = {
  NULL, NULL, g_unix_fd_source_dispatch, NULL
};

/**
 * g_unix_fd_source_new:
 * @fd: a file descriptor
 * @condition: IO conditions to watch for on @fd
 *
 * Creates a #GSource to watch for a particular IO condition on a file
 * descriptor.
 *
 * The source will never close the fd -- you must do it yourself.
 *
 * Returns: the newly created #GSource
 *
 * Since: 2.36
 **/
GSource *
g_unix_fd_source_new (gint         fd,
                      GIOCondition condition)
{
  GUnixFDSource *fd_source;
  GSource *source;

  source = g_source_new (&g_unix_fd_source_funcs, sizeof (GUnixFDSource));
  fd_source = (GUnixFDSource *) source;

  fd_source->fd = fd;
  fd_source->tag = g_source_add_unix_fd (source, fd, condition);

  return source;
}

/**
 * g_unix_fd_add_full:
 * @priority: the priority of the source
 * @fd: a file descriptor
 * @condition: IO conditions to watch for on @fd
 * @function: a #GUnixFDSourceFunc
 * @user_data: data to pass to @function
 * @notify: function to call when the idle is removed, or %NULL
 *
 * Sets a function to be called when the IO condition, as specified by
 * @condition becomes true for @fd.
 *
 * This is the same as g_unix_fd_add(), except that it allows you to
 * specify a non-default priority and a provide a #GDestroyNotify for
 * @user_data.
 *
 * Returns: the ID (greater than 0) of the event source
 *
 * Since: 2.36
 **/
guint
g_unix_fd_add_full (gint              priority,
                    gint              fd,
                    GIOCondition      condition,
                    GUnixFDSourceFunc function,
                    gpointer          user_data,
                    GDestroyNotify    notify)
{
  GSource *source;
  guint id;

  g_return_val_if_fail (function != NULL, 0);

  source = g_unix_fd_source_new (fd, condition);

  if (priority != G_PRIORITY_DEFAULT)
    g_source_set_priority (source, priority);

  g_source_set_callback (source, (GSourceFunc) function, user_data, notify);
  id = g_source_attach (source, NULL);
  g_source_unref (source);

  return id;
}

/**
 * g_unix_fd_add:
 * @fd: a file descriptor
 * @condition: IO conditions to watch for on @fd
 * @function: a #GUnixFDSourceFunc
 * @user_data: data to pass to @function
 *
 * Sets a function to be called when the IO condition, as specified by
 * @condition becomes true for @fd.
 *
 * @function will be called when the specified IO condition becomes
 * %TRUE.  The function is expected to clear whatever event caused the
 * IO condition to become true and return %TRUE in order to be notified
 * when it happens again.  If @function returns %FALSE then the watch
 * will be cancelled.
 *
 * The return value of this function can be passed to g_source_remove()
 * to cancel the watch at any time that it exists.
 *
 * The source will never close the fd -- you must do it yourself.
 *
 * Returns: the ID (greater than 0) of the event source
 *
 * Since: 2.36
 **/
guint
g_unix_fd_add (gint              fd,
               GIOCondition      condition,
               GUnixFDSourceFunc function,
               gpointer          user_data)
{
  return g_unix_fd_add_full (G_PRIORITY_DEFAULT, fd, condition, function, user_data, NULL);
}