2 This file is part of PulseAudio.
4 Copyright 2008 Lennart Poettering
6 PulseAudio is free software; you can redistribute it and/or modify
7 it under the terms of the GNU Lesser General Public License as published
8 by the Free Software Foundation; either version 2.1 of the License,
9 or (at your option) any later version.
11 PulseAudio is distributed in the hope that it will be useful, but
12 WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 General Public License for more details.
16 You should have received a copy of the GNU Lesser General Public License
17 along with PulseAudio; if not, write to the Free Software
18 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
33 #include <pulse/i18n.h>
34 #include <pulse/xmalloc.h>
36 #include <pulsecore/mutex.h>
37 #include <pulsecore/thread.h>
38 #include <pulsecore/core-util.h>
40 #include "lock-autospawn.h"
42 /* So, why do we have this complex code here with threads and pipes
43 * and stuff? For two reasons: POSIX file locks are per-process, not
44 * per-file descriptor. That means that two contexts within the same
45 * process that try to create the autospawn lock might end up assuming
46 * they both managed to lock the file. And then, POSIX locking
47 * operations are synchronous. If two contexts run from the same event
48 * loop it must be made sure that they do not block each other, but
49 * that the locking operation can happen asynchronously. */
51 #define AUTOSPAWN_LOCK "autospawn.lock"
53 static pa_mutex *mutex;
55 static unsigned n_ref = 0;
56 static int lock_fd = -1;
57 static pa_mutex *lock_fd_mutex = NULL;
58 static pa_bool_t taken = FALSE;
59 static pa_thread *thread;
60 static int pipe_fd[2] = { -1, -1 };
62 static void destroy_mutex(void) PA_GCC_DESTRUCTOR;
64 static int ref(void) {
68 pa_assert(pipe_fd[0] >= 0);
69 pa_assert(pipe_fd[1] >= 0);
76 pa_assert(lock_fd < 0);
77 pa_assert(!lock_fd_mutex);
80 pa_assert(pipe_fd[0] < 0);
81 pa_assert(pipe_fd[1] < 0);
83 if (pipe(pipe_fd) < 0)
86 lock_fd_mutex = pa_mutex_new(FALSE, FALSE);
88 pa_make_fd_cloexec(pipe_fd[0]);
89 pa_make_fd_cloexec(pipe_fd[1]);
91 pa_make_fd_nonblock(pipe_fd[1]);
92 pa_make_fd_nonblock(pipe_fd[0]);
98 static void unref(pa_bool_t after_fork) {
100 pa_assert(n_ref > 0);
101 pa_assert(pipe_fd[0] >= 0);
102 pa_assert(pipe_fd[1] >= 0);
103 pa_assert(lock_fd_mutex);
113 pa_thread_free(thread);
117 pa_mutex_lock(lock_fd_mutex);
125 if (!(lf = pa_runtime_path(AUTOSPAWN_LOCK)))
126 pa_log_warn(_("Cannot access autospawn lock."));
128 pa_unlock_lockfile(lf, lock_fd);
134 pa_mutex_unlock(lock_fd_mutex);
136 pa_mutex_free(lock_fd_mutex);
137 lock_fd_mutex = NULL;
139 pa_close(pipe_fd[0]);
140 pa_close(pipe_fd[1]);
141 pipe_fd[0] = pipe_fd[1] = -1;
144 static void ping(void) {
147 pa_assert(pipe_fd[1] >= 0);
152 if ((s = write(pipe_fd[1], &x, 1)) == 1)
160 pa_assert(errno == EINTR);
164 static void wait_for_ping(void) {
170 pa_assert(pipe_fd[0] >= 0);
172 memset(&pfd, 0, sizeof(pfd));
176 if ((k = poll(&pfd, 1, -1)) != 1) {
178 pa_assert(errno == EINTR);
179 } else if ((s = read(pipe_fd[0], &x, 1)) != 1) {
181 pa_assert(errno == EAGAIN);
185 static void empty_pipe(void) {
189 pa_assert(pipe_fd[0] >= 0);
191 if ((s = read(pipe_fd[0], &x, sizeof(x))) < 1) {
193 pa_assert(errno == EAGAIN);
197 static void thread_func(void *u) {
202 /* No signals in this thread please */
203 sigfillset(&fullset);
204 pthread_sigmask(SIG_BLOCK, &fullset, NULL);
206 if (!(lf = pa_runtime_path(AUTOSPAWN_LOCK))) {
207 pa_log_warn(_("Cannot access autospawn lock."));
211 if ((fd = pa_lock_lockfile(lf)) < 0)
214 pa_mutex_lock(lock_fd_mutex);
215 pa_assert(lock_fd < 0);
217 pa_mutex_unlock(lock_fd_mutex);
225 static int start_thread(void) {
228 if (!(thread = pa_thread_new(thread_func, NULL)))
234 static void create_mutex(void) {
236 mutex = pa_mutex_new(FALSE, FALSE);
240 static void destroy_mutex(void) {
243 pa_mutex_free(mutex);
247 int pa_autospawn_lock_init(void) {
251 pa_mutex_lock(mutex);
258 pa_mutex_unlock(mutex);
263 int pa_autospawn_lock_acquire(pa_bool_t block) {
267 pa_mutex_lock(mutex);
268 pa_assert(n_ref >= 1);
270 pa_mutex_lock(lock_fd_mutex);
276 if (lock_fd >= 0 && !taken) {
283 if (start_thread() < 0)
291 pa_mutex_unlock(lock_fd_mutex);
292 pa_mutex_unlock(mutex);
296 pa_mutex_lock(mutex);
297 pa_mutex_lock(lock_fd_mutex);
300 pa_mutex_unlock(lock_fd_mutex);
302 pa_mutex_unlock(mutex);
307 void pa_autospawn_lock_release(void) {
310 pa_mutex_lock(mutex);
311 pa_assert(n_ref >= 1);
318 pa_mutex_unlock(mutex);
321 void pa_autospawn_lock_done(pa_bool_t after_fork) {
324 pa_mutex_lock(mutex);
325 pa_assert(n_ref >= 1);
329 pa_mutex_unlock(mutex);