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-rw-r--r--src/pulsecore/fdsem.c320
1 files changed, 320 insertions, 0 deletions
diff --git a/src/pulsecore/fdsem.c b/src/pulsecore/fdsem.c
new file mode 100644
index 0000000..a7fbf95
--- /dev/null
+++ b/src/pulsecore/fdsem.c
@@ -0,0 +1,320 @@
+/***
+ This file is part of PulseAudio.
+
+ Copyright 2006 Lennart Poettering
+
+ PulseAudio 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.
+
+ PulseAudio 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 PulseAudio; if not, see <http://www.gnu.org/licenses/>.
+***/
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#ifdef HAVE_SYS_SYSCALL_H
+#include <sys/syscall.h>
+#endif
+
+#include <unistd.h>
+#include <errno.h>
+
+#include <pulsecore/atomic.h>
+#include <pulsecore/log.h>
+#include <pulsecore/macro.h>
+#include <pulsecore/core-util.h>
+#include <pulsecore/core-error.h>
+#include <pulse/xmalloc.h>
+
+#ifndef HAVE_PIPE
+#include <pulsecore/pipe.h>
+#endif
+
+#ifdef HAVE_SYS_EVENTFD_H
+#include <sys/eventfd.h>
+#endif
+
+#include "fdsem.h"
+
+struct pa_fdsem {
+ int fds[2];
+#ifdef HAVE_SYS_EVENTFD_H
+ int efd;
+#endif
+ int write_type;
+ pa_fdsem_data *data;
+};
+
+pa_fdsem *pa_fdsem_new(void) {
+ pa_fdsem *f;
+
+ f = pa_xmalloc0(PA_ALIGN(sizeof(pa_fdsem)) + PA_ALIGN(sizeof(pa_fdsem_data)));
+
+#ifdef HAVE_SYS_EVENTFD_H
+ if ((f->efd = eventfd(0, EFD_CLOEXEC)) >= 0)
+ f->fds[0] = f->fds[1] = -1;
+ else
+#endif
+ {
+ if (pa_pipe_cloexec(f->fds) < 0) {
+ pa_xfree(f);
+ return NULL;
+ }
+ }
+
+ f->data = (pa_fdsem_data*) ((uint8_t*) f + PA_ALIGN(sizeof(pa_fdsem)));
+
+ pa_atomic_store(&f->data->waiting, 0);
+ pa_atomic_store(&f->data->signalled, 0);
+ pa_atomic_store(&f->data->in_pipe, 0);
+
+ return f;
+}
+
+pa_fdsem *pa_fdsem_open_shm(pa_fdsem_data *data, int event_fd) {
+ pa_fdsem *f = NULL;
+
+ pa_assert(data);
+ pa_assert(event_fd >= 0);
+
+#ifdef HAVE_SYS_EVENTFD_H
+ f = pa_xnew0(pa_fdsem, 1);
+
+ f->efd = event_fd;
+ pa_make_fd_cloexec(f->efd);
+ f->fds[0] = f->fds[1] = -1;
+ f->data = data;
+#endif
+
+ return f;
+}
+
+pa_fdsem *pa_fdsem_new_shm(pa_fdsem_data *data) {
+ pa_fdsem *f = NULL;
+
+ pa_assert(data);
+
+#ifdef HAVE_SYS_EVENTFD_H
+
+ f = pa_xnew0(pa_fdsem, 1);
+
+ if ((f->efd = eventfd(0, EFD_CLOEXEC)) < 0) {
+ pa_xfree(f);
+ return NULL;
+ }
+
+ f->fds[0] = f->fds[1] = -1;
+ f->data = data;
+
+ pa_atomic_store(&f->data->waiting, 0);
+ pa_atomic_store(&f->data->signalled, 0);
+ pa_atomic_store(&f->data->in_pipe, 0);
+
+#endif
+
+ return f;
+}
+
+void pa_fdsem_free(pa_fdsem *f) {
+ pa_assert(f);
+
+#ifdef HAVE_SYS_EVENTFD_H
+ if (f->efd >= 0)
+ pa_close(f->efd);
+#endif
+ pa_close_pipe(f->fds);
+
+ pa_xfree(f);
+}
+
+static void flush(pa_fdsem *f) {
+ ssize_t r;
+ pa_assert(f);
+
+ if (pa_atomic_load(&f->data->in_pipe) <= 0)
+ return;
+
+ do {
+ char x[10];
+
+#ifdef HAVE_SYS_EVENTFD_H
+ if (f->efd >= 0) {
+ uint64_t u;
+
+ if ((r = pa_read(f->efd, &u, sizeof(u), NULL)) != sizeof(u)) {
+
+ if (r >= 0 || errno != EINTR) {
+ pa_log_error("Invalid read from eventfd: %s", r < 0 ? pa_cstrerror(errno) : "EOF");
+ pa_assert_not_reached();
+ }
+
+ continue;
+ }
+ r = (ssize_t) u;
+ } else
+#endif
+
+ if ((r = pa_read(f->fds[0], &x, sizeof(x), NULL)) <= 0) {
+
+ if (r >= 0 || errno != EINTR) {
+ pa_log_error("Invalid read from pipe: %s", r < 0 ? pa_cstrerror(errno) : "EOF");
+ pa_assert_not_reached();
+ }
+
+ continue;
+ }
+
+ } while (pa_atomic_sub(&f->data->in_pipe, (int) r) > (int) r);
+}
+
+void pa_fdsem_post(pa_fdsem *f) {
+ pa_assert(f);
+
+ if (pa_atomic_cmpxchg(&f->data->signalled, 0, 1)) {
+
+ if (pa_atomic_load(&f->data->waiting)) {
+ ssize_t r;
+ char x = 'x';
+
+ pa_atomic_inc(&f->data->in_pipe);
+
+ for (;;) {
+
+#ifdef HAVE_SYS_EVENTFD_H
+ if (f->efd >= 0) {
+ uint64_t u = 1;
+
+ if ((r = pa_write(f->efd, &u, sizeof(u), &f->write_type)) != sizeof(u)) {
+ if (r >= 0 || errno != EINTR) {
+ pa_log_error("Invalid write to eventfd: %s", r < 0 ? pa_cstrerror(errno) : "EOF");
+ pa_assert_not_reached();
+ }
+
+ continue;
+ }
+ } else
+#endif
+
+ if ((r = pa_write(f->fds[1], &x, 1, &f->write_type)) != 1) {
+ if (r >= 0 || errno != EINTR) {
+ pa_log_error("Invalid write to pipe: %s", r < 0 ? pa_cstrerror(errno) : "EOF");
+ pa_assert_not_reached();
+ }
+
+ continue;
+ }
+
+ break;
+ }
+ }
+ }
+}
+
+void pa_fdsem_wait(pa_fdsem *f) {
+ pa_assert(f);
+
+ flush(f);
+
+ if (pa_atomic_cmpxchg(&f->data->signalled, 1, 0))
+ return;
+
+ pa_atomic_inc(&f->data->waiting);
+
+ while (!pa_atomic_cmpxchg(&f->data->signalled, 1, 0)) {
+ char x[10];
+ ssize_t r;
+
+#ifdef HAVE_SYS_EVENTFD_H
+ if (f->efd >= 0) {
+ uint64_t u;
+
+ if ((r = pa_read(f->efd, &u, sizeof(u), NULL)) != sizeof(u)) {
+
+ if (r >= 0 || errno != EINTR) {
+ pa_log_error("Invalid read from eventfd: %s", r < 0 ? pa_cstrerror(errno) : "EOF");
+ pa_assert_not_reached();
+ }
+
+ continue;
+ }
+
+ r = (ssize_t) u;
+ } else
+#endif
+
+ if ((r = pa_read(f->fds[0], &x, sizeof(x), NULL)) <= 0) {
+
+ if (r >= 0 || errno != EINTR) {
+ pa_log_error("Invalid read from pipe: %s", r < 0 ? pa_cstrerror(errno) : "EOF");
+ pa_assert_not_reached();
+ }
+
+ continue;
+ }
+
+ pa_atomic_sub(&f->data->in_pipe, (int) r);
+ }
+
+ pa_assert_se(pa_atomic_dec(&f->data->waiting) >= 1);
+}
+
+int pa_fdsem_try(pa_fdsem *f) {
+ pa_assert(f);
+
+ flush(f);
+
+ if (pa_atomic_cmpxchg(&f->data->signalled, 1, 0))
+ return 1;
+
+ return 0;
+}
+
+int pa_fdsem_get(pa_fdsem *f) {
+ pa_assert(f);
+
+#ifdef HAVE_SYS_EVENTFD_H
+ if (f->efd >= 0)
+ return f->efd;
+#endif
+
+ return f->fds[0];
+}
+
+int pa_fdsem_before_poll(pa_fdsem *f) {
+ pa_assert(f);
+
+ flush(f);
+
+ if (pa_atomic_cmpxchg(&f->data->signalled, 1, 0))
+ return -1;
+
+ pa_atomic_inc(&f->data->waiting);
+
+ if (pa_atomic_cmpxchg(&f->data->signalled, 1, 0)) {
+ pa_assert_se(pa_atomic_dec(&f->data->waiting) >= 1);
+ return -1;
+ }
+ return 0;
+}
+
+int pa_fdsem_after_poll(pa_fdsem *f) {
+ pa_assert(f);
+
+ pa_assert_se(pa_atomic_dec(&f->data->waiting) >= 1);
+
+ flush(f);
+
+ if (pa_atomic_cmpxchg(&f->data->signalled, 1, 0))
+ return 1;
+
+ return 0;
+}
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