2 * Copyright (C) 2010 David Xu <davidxu@freebsd.org>.
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice(s), this list of conditions and the following disclaimer as
10 * the first lines of this file unmodified other than the possible
11 * addition of one or more copyright notices.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice(s), this list of conditions and the following disclaimer in
14 * the documentation and/or other materials provided with the
17 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
18 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
20 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE
21 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
22 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
23 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
24 * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
25 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
26 * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
27 * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
32 #include "namespace.h"
33 #include <sys/types.h>
34 #include <sys/queue.h>
38 #include <machine/atomic.h>
48 #include <semaphore.h>
50 #include "un-namespace.h"
51 #include "libc_private.h"
53 __weak_reference(_sem_close, sem_close);
54 __weak_reference(_sem_destroy, sem_destroy);
55 __weak_reference(_sem_getvalue, sem_getvalue);
56 __weak_reference(_sem_init, sem_init);
57 __weak_reference(_sem_open, sem_open);
58 __weak_reference(_sem_post, sem_post);
59 __weak_reference(_sem_timedwait, sem_timedwait);
60 __weak_reference(_sem_trywait, sem_trywait);
61 __weak_reference(_sem_unlink, sem_unlink);
62 __weak_reference(_sem_wait, sem_wait);
64 #define SEM_PREFIX "/tmp/SEMD"
65 #define SEM_MAGIC ((u_int32_t)0x73656d31)
73 LIST_ENTRY(sem_nameinfo) next;
76 static pthread_once_t once = PTHREAD_ONCE_INIT;
77 static pthread_mutex_t sem_llock;
78 static LIST_HEAD(, sem_nameinfo) sem_list = LIST_HEAD_INITIALIZER(sem_list);
84 _pthread_mutex_lock(&sem_llock);
91 _pthread_mutex_unlock(&sem_llock);
95 sem_child_postfork(void)
98 _pthread_mutex_unlock(&sem_llock);
102 sem_module_init(void)
105 _pthread_mutex_init(&sem_llock, NULL);
106 _pthread_atfork(sem_prefork, sem_postfork, sem_child_postfork);
110 sem_check_validity(sem_t *sem)
113 if (sem->_magic == SEM_MAGIC)
120 _sem_init(sem_t *sem, int pshared, unsigned int value)
123 if (value > SEM_VALUE_MAX) {
128 bzero(sem, sizeof(sem_t));
129 sem->_magic = SEM_MAGIC;
130 sem->_kern._count = (u_int32_t)value;
131 sem->_kern._has_waiters = 0;
132 sem->_kern._flags = pshared ? USYNC_PROCESS_SHARED : 0;
137 _sem_open(const char *name, int flags, ...)
142 struct sem_nameinfo *ni;
144 int errsave, fd, len, mode, value;
151 if (name[0] != '/') {
156 strcpy(path, SEM_PREFIX);
157 if (strlcat(path, name, sizeof(path)) >= sizeof(path)) {
158 errno = ENAMETOOLONG;
161 if (flags & ~(O_CREAT|O_EXCL)) {
165 if ((flags & O_CREAT) != 0) {
167 mode = va_arg(ap, int);
168 value = va_arg(ap, int);
172 _pthread_once(&once, sem_module_init);
174 _pthread_mutex_lock(&sem_llock);
175 LIST_FOREACH(ni, &sem_list, next) {
176 if (ni->name != NULL && strcmp(name, ni->name) == 0) {
177 fd = _open(path, flags | O_RDWR | O_CLOEXEC |
179 if (fd == -1 || _fstat(fd, &sb) == -1) {
183 if ((flags & (O_CREAT | O_EXCL)) == (O_CREAT |
184 O_EXCL) || ni->dev != sb.st_dev ||
185 ni->ino != sb.st_ino) {
192 _pthread_mutex_unlock(&sem_llock);
198 len = sizeof(*ni) + strlen(name) + 1;
199 ni = (struct sem_nameinfo *)malloc(len);
205 ni->name = (char *)(ni+1);
206 strcpy(ni->name, name);
209 fd = _open(path, flags | O_RDWR | O_CLOEXEC | O_EXLOCK, mode);
210 if (fd == -1 || _fstat(fd, &sb) == -1)
213 if (sb.st_size < sizeof(sem_t)) {
214 tmp._magic = SEM_MAGIC;
215 tmp._kern._has_waiters = 0;
216 tmp._kern._count = value;
217 tmp._kern._flags = USYNC_PROCESS_SHARED | SEM_NAMED;
218 if (_write(fd, &tmp, sizeof(tmp)) != sizeof(tmp))
222 sem = mmap(NULL, sizeof(sem_t), PROT_READ | PROT_WRITE,
223 MAP_SHARED | MAP_NOSYNC, fd, 0);
224 if (sem == MAP_FAILED) {
230 if (sem->_magic != SEM_MAGIC) {
238 LIST_INSERT_HEAD(&sem_list, ni, next);
240 _pthread_mutex_unlock(&sem_llock);
248 munmap(sem, sizeof(sem_t));
250 _pthread_mutex_unlock(&sem_llock);
256 _sem_close(sem_t *sem)
258 struct sem_nameinfo *ni;
261 if (sem_check_validity(sem) != 0)
264 if (!(sem->_kern._flags & SEM_NAMED)) {
269 _pthread_once(&once, sem_module_init);
271 _pthread_mutex_lock(&sem_llock);
272 LIST_FOREACH(ni, &sem_list, next) {
273 if (sem == ni->sem) {
274 last = --ni->open_count == 0;
276 LIST_REMOVE(ni, next);
277 _pthread_mutex_unlock(&sem_llock);
279 munmap(sem, sizeof(*sem));
285 _pthread_mutex_unlock(&sem_llock);
291 _sem_unlink(const char *name)
295 if (name[0] != '/') {
300 strcpy(path, SEM_PREFIX);
301 if (strlcat(path, name, sizeof(path)) >= sizeof(path)) {
302 errno = ENAMETOOLONG;
306 return (unlink(path));
310 _sem_destroy(sem_t *sem)
313 if (sem_check_validity(sem) != 0)
316 if (sem->_kern._flags & SEM_NAMED) {
325 _sem_getvalue(sem_t * __restrict sem, int * __restrict sval)
328 if (sem_check_validity(sem) != 0)
331 *sval = (int)sem->_kern._count;
336 usem_wake(struct _usem *sem)
339 return (_umtx_op(sem, UMTX_OP_SEM_WAKE, 0, NULL, NULL));
343 usem_wait(struct _usem *sem, const struct timespec *abstime)
345 struct _umtx_time *tm_p, timeout;
348 if (abstime == NULL) {
352 timeout._clockid = CLOCK_REALTIME;
353 timeout._flags = UMTX_ABSTIME;
354 timeout._timeout = *abstime;
356 tm_size = sizeof(timeout);
358 return _umtx_op(sem, UMTX_OP_SEM_WAIT, 0,
359 (void *)tm_size, __DECONST(void*, tm_p));
363 _sem_trywait(sem_t *sem)
367 if (sem_check_validity(sem) != 0)
370 while ((val = sem->_kern._count) > 0) {
371 if (atomic_cmpset_acq_int(&sem->_kern._count, val, val - 1))
379 _sem_timedwait(sem_t * __restrict sem,
380 const struct timespec * __restrict abstime)
384 if (sem_check_validity(sem) != 0)
388 _pthread_testcancel();
390 while ((val = sem->_kern._count) > 0) {
391 if (atomic_cmpset_acq_int(&sem->_kern._count, val, val - 1))
396 _pthread_testcancel();
401 * The timeout argument is only supposed to
402 * be checked if the thread would have blocked.
404 if (abstime != NULL) {
405 if (abstime->tv_nsec >= 1000000000 || abstime->tv_nsec < 0) {
410 _pthread_cancel_enter(1);
411 retval = usem_wait(&sem->_kern, abstime);
412 _pthread_cancel_leave(0);
418 _sem_wait(sem_t *sem)
421 return (_sem_timedwait(sem, NULL));
426 * The sem_post() interface is reentrant with respect to signals and may be
427 * invoked from a signal-catching function.
428 * The implementation does not use lock, so it should be safe.
431 _sem_post(sem_t *sem)
435 if (sem_check_validity(sem) != 0)
439 count = sem->_kern._count;
440 if (count + 1 > SEM_VALUE_MAX) {
444 } while(!atomic_cmpset_rel_int(&sem->_kern._count, count, count+1));
445 (void)usem_wake(&sem->_kern);