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>
47 #include <semaphore.h>
49 #include "un-namespace.h"
50 #include "libc_private.h"
52 __weak_reference(_sem_close, sem_close);
53 __weak_reference(_sem_destroy, sem_destroy);
54 __weak_reference(_sem_getvalue, sem_getvalue);
55 __weak_reference(_sem_init, sem_init);
56 __weak_reference(_sem_open, sem_open);
57 __weak_reference(_sem_post, sem_post);
58 __weak_reference(_sem_timedwait, sem_timedwait);
59 __weak_reference(_sem_clockwait_np, sem_clockwait_np);
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)0x73656d32)
67 _Static_assert(SEM_VALUE_MAX <= USEM_MAX_COUNT, "SEM_VALUE_MAX too large");
75 LIST_ENTRY(sem_nameinfo) next;
78 static pthread_once_t once = PTHREAD_ONCE_INIT;
79 static pthread_mutex_t sem_llock;
80 static LIST_HEAD(,sem_nameinfo) sem_list = LIST_HEAD_INITIALIZER(sem_list);
86 _pthread_mutex_lock(&sem_llock);
92 _pthread_mutex_unlock(&sem_llock);
98 _pthread_mutex_unlock(&sem_llock);
102 sem_module_init(void)
104 pthread_mutexattr_t ma;
106 _pthread_mutexattr_init(&ma);
107 _pthread_mutexattr_settype(&ma, PTHREAD_MUTEX_RECURSIVE);
108 _pthread_mutex_init(&sem_llock, &ma);
109 _pthread_mutexattr_destroy(&ma);
110 _pthread_atfork(sem_prefork, sem_postfork, sem_child_postfork);
114 sem_check_validity(sem_t *sem)
117 if (sem->_magic == SEM_MAGIC)
126 _sem_init(sem_t *sem, int pshared, unsigned int value)
129 if (value > SEM_VALUE_MAX) {
134 bzero(sem, sizeof(sem_t));
135 sem->_magic = SEM_MAGIC;
136 sem->_kern._count = (u_int32_t)value;
137 sem->_kern._flags = pshared ? USYNC_PROCESS_SHARED : 0;
142 _sem_open(const char *name, int flags, ...)
148 struct sem_nameinfo *ni = NULL;
150 int fd = -1, mode, len, errsave;
153 if (name[0] != '/') {
158 strcpy(path, SEM_PREFIX);
159 if (strlcat(path, name, sizeof(path)) >= sizeof(path)) {
160 errno = ENAMETOOLONG;
163 if (flags & ~(O_CREAT|O_EXCL)) {
167 if ((flags & O_CREAT) != 0) {
169 mode = va_arg(ap, int);
170 value = va_arg(ap, int);
174 _pthread_once(&once, sem_module_init);
176 _pthread_mutex_lock(&sem_llock);
177 LIST_FOREACH(ni, &sem_list, next) {
178 if (ni->name != NULL && strcmp(name, ni->name) == 0) {
179 fd = _open(path, flags | O_RDWR | O_CLOEXEC |
181 if (fd == -1 || _fstat(fd, &sb) == -1) {
185 if ((flags & (O_CREAT | O_EXCL)) == (O_CREAT |
186 O_EXCL) || ni->dev != sb.st_dev ||
187 ni->ino != sb.st_ino) {
194 _pthread_mutex_unlock(&sem_llock);
200 len = sizeof(*ni) + strlen(name) + 1;
201 ni = (struct sem_nameinfo *)malloc(len);
207 ni->name = (char *)(ni+1);
208 strcpy(ni->name, name);
211 fd = _open(path, flags | O_RDWR | O_CLOEXEC | O_EXLOCK, mode);
212 if (fd == -1 || _fstat(fd, &sb) == -1)
215 if (sb.st_size < sizeof(sem_t)) {
218 tmp._magic = SEM_MAGIC;
219 tmp._kern._count = value;
220 tmp._kern._flags = USYNC_PROCESS_SHARED | SEM_NAMED;
221 if (_write(fd, &tmp, sizeof(tmp)) != sizeof(tmp))
225 sem = (sem_t *)mmap(NULL, sizeof(sem_t), PROT_READ|PROT_WRITE,
226 MAP_SHARED|MAP_NOSYNC, fd, 0);
227 if (sem == MAP_FAILED) {
233 if (sem->_magic != SEM_MAGIC) {
241 LIST_INSERT_HEAD(&sem_list, ni, next);
243 _pthread_mutex_unlock(&sem_llock);
251 munmap(sem, sizeof(sem_t));
253 _pthread_mutex_unlock(&sem_llock);
259 _sem_close(sem_t *sem)
261 struct sem_nameinfo *ni;
263 if (sem_check_validity(sem) != 0)
266 if (!(sem->_kern._flags & SEM_NAMED)) {
271 _pthread_once(&once, sem_module_init);
273 _pthread_mutex_lock(&sem_llock);
274 LIST_FOREACH(ni, &sem_list, next) {
275 if (sem == ni->sem) {
276 if (--ni->open_count > 0) {
277 _pthread_mutex_unlock(&sem_llock);
286 LIST_REMOVE(ni, next);
287 _pthread_mutex_unlock(&sem_llock);
288 munmap(sem, sizeof(*sem));
292 _pthread_mutex_unlock(&sem_llock);
298 _sem_unlink(const char *name)
302 if (name[0] != '/') {
307 strcpy(path, SEM_PREFIX);
308 if (strlcat(path, name, sizeof(path)) >= sizeof(path)) {
309 errno = ENAMETOOLONG;
313 return (unlink(path));
317 _sem_destroy(sem_t *sem)
320 if (sem_check_validity(sem) != 0)
323 if (sem->_kern._flags & SEM_NAMED) {
332 _sem_getvalue(sem_t * __restrict sem, int * __restrict sval)
335 if (sem_check_validity(sem) != 0)
338 *sval = (int)USEM_COUNT(sem->_kern._count);
343 usem_wake(struct _usem2 *sem)
345 return _umtx_op(sem, UMTX_OP_SEM2_WAKE, 0, NULL, NULL);
349 usem_wait(struct _usem2 *sem, clockid_t clock_id, int flags,
350 const struct timespec *rqtp, struct timespec *rmtp)
353 struct _umtx_time timeout;
354 struct timespec remain;
364 tms.timeout._clockid = clock_id;
365 tms.timeout._flags = (flags & TIMER_ABSTIME) ? UMTX_ABSTIME : 0;
366 tms.timeout._timeout = *rqtp;
368 tm_size = sizeof(tms);
370 retval = _umtx_op(sem, UMTX_OP_SEM2_WAIT, 0, (void *)tm_size, tm_p);
371 if (retval == -1 && errno == EINTR && (flags & TIMER_ABSTIME) == 0 &&
372 rqtp != NULL && rmtp != NULL) {
380 _sem_trywait(sem_t *sem)
384 if (sem_check_validity(sem) != 0)
387 while (USEM_COUNT(val = sem->_kern._count) > 0) {
388 if (atomic_cmpset_acq_int(&sem->_kern._count, val, val - 1))
396 _sem_clockwait_np(sem_t * __restrict sem, clockid_t clock_id, int flags,
397 const struct timespec *rqtp, struct timespec *rmtp)
401 if (sem_check_validity(sem) != 0)
405 _pthread_testcancel();
407 while (USEM_COUNT(val = sem->_kern._count) > 0) {
408 if (atomic_cmpset_acq_int(&sem->_kern._count, val,
414 _pthread_testcancel();
419 * The timeout argument is only supposed to
420 * be checked if the thread would have blocked.
423 if (rqtp->tv_nsec >= 1000000000 || rqtp->tv_nsec < 0) {
428 _pthread_cancel_enter(1);
429 retval = usem_wait(&sem->_kern, clock_id, flags, rqtp, rmtp);
430 _pthread_cancel_leave(0);
436 _sem_timedwait(sem_t * __restrict sem,
437 const struct timespec * __restrict abstime)
439 return (_sem_clockwait_np(sem, CLOCK_REALTIME, TIMER_ABSTIME, abstime,
444 _sem_wait(sem_t *sem)
446 return _sem_timedwait(sem, NULL);
451 * The sem_post() interface is reentrant with respect to signals and may be
452 * invoked from a signal-catching function.
453 * The implementation does not use lock, so it should be safe.
456 _sem_post(sem_t *sem)
460 if (sem_check_validity(sem) != 0)
464 count = sem->_kern._count;
465 if (USEM_COUNT(count) + 1 > SEM_VALUE_MAX) {
469 } while (!atomic_cmpset_rel_int(&sem->_kern._count, count, count + 1));
470 if (count & USEM_HAS_WAITERS)
471 usem_wake(&sem->_kern);