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_trywait, sem_trywait);
60 __weak_reference(_sem_unlink, sem_unlink);
61 __weak_reference(_sem_wait, sem_wait);
63 #define SEM_PREFIX "/tmp/SEMD"
64 #define SEM_MAGIC ((u_int32_t)0x73656d31)
72 LIST_ENTRY(sem_nameinfo) next;
75 static pthread_once_t once = PTHREAD_ONCE_INIT;
76 static pthread_mutex_t sem_llock;
77 static LIST_HEAD(,sem_nameinfo) sem_list = LIST_HEAD_INITIALIZER(sem_list);
83 _pthread_mutex_lock(&sem_llock);
89 _pthread_mutex_unlock(&sem_llock);
95 _pthread_mutex_unlock(&sem_llock);
101 pthread_mutexattr_t ma;
103 _pthread_mutexattr_init(&ma);
104 _pthread_mutexattr_settype(&ma, PTHREAD_MUTEX_RECURSIVE);
105 _pthread_mutex_init(&sem_llock, &ma);
106 _pthread_mutexattr_destroy(&ma);
107 _pthread_atfork(sem_prefork, sem_postfork, sem_child_postfork);
111 sem_check_validity(sem_t *sem)
114 if (sem->_magic == SEM_MAGIC)
123 _sem_init(sem_t *sem, int pshared, unsigned int value)
126 if (value > SEM_VALUE_MAX) {
131 bzero(sem, sizeof(sem_t));
132 sem->_magic = SEM_MAGIC;
133 sem->_kern._count = (u_int32_t)value;
134 sem->_kern._has_waiters = 0;
135 sem->_kern._flags = pshared ? USYNC_PROCESS_SHARED : 0;
140 _sem_open(const char *name, int flags, ...)
146 struct sem_nameinfo *ni = NULL;
148 int fd = -1, mode, len, errsave;
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)
181 if ((flags & (O_CREAT | O_EXCL)) == (O_CREAT |
182 O_EXCL) || ni->dev != sb.st_dev ||
183 ni->ino != sb.st_ino) {
190 _pthread_mutex_unlock(&sem_llock);
196 len = sizeof(*ni) + strlen(name) + 1;
197 ni = (struct sem_nameinfo *)malloc(len);
203 ni->name = (char *)(ni+1);
204 strcpy(ni->name, name);
207 fd = _open(path, flags | O_RDWR | O_CLOEXEC | O_EXLOCK, mode);
208 if (fd == -1 || _fstat(fd, &sb) == -1)
211 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 = (sem_t *)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;
260 if (sem_check_validity(sem) != 0)
263 if (!(sem->_kern._flags & SEM_NAMED)) {
268 _pthread_once(&once, sem_module_init);
270 _pthread_mutex_lock(&sem_llock);
271 LIST_FOREACH(ni, &sem_list, next) {
272 if (sem == ni->sem) {
273 if (--ni->open_count > 0) {
274 _pthread_mutex_unlock(&sem_llock);
283 LIST_REMOVE(ni, next);
284 _pthread_mutex_unlock(&sem_llock);
285 munmap(sem, sizeof(*sem));
289 _pthread_mutex_unlock(&sem_llock);
295 _sem_unlink(const char *name)
299 if (name[0] != '/') {
304 strcpy(path, SEM_PREFIX);
305 if (strlcat(path, name, sizeof(path)) >= sizeof(path)) {
306 errno = ENAMETOOLONG;
310 return (unlink(path));
314 _sem_destroy(sem_t *sem)
317 if (sem_check_validity(sem) != 0)
320 if (sem->_kern._flags & SEM_NAMED) {
329 _sem_getvalue(sem_t * __restrict sem, int * __restrict sval)
332 if (sem_check_validity(sem) != 0)
335 *sval = (int)sem->_kern._count;
340 usem_wake(struct _usem *sem)
342 if (!sem->_has_waiters)
344 return _umtx_op(sem, UMTX_OP_SEM_WAKE, 0, NULL, NULL);
348 usem_wait(struct _usem *sem, const struct timespec *timeout)
350 if (timeout && (timeout->tv_sec < 0 || (timeout->tv_sec == 0 &&
351 timeout->tv_nsec <= 0))) {
355 return _umtx_op(sem, UMTX_OP_SEM_WAIT, 0, NULL,
356 __DECONST(void*, timeout));
360 _sem_trywait(sem_t *sem)
364 if (sem_check_validity(sem) != 0)
367 while ((val = sem->_kern._count) > 0) {
368 if (atomic_cmpset_acq_int(&sem->_kern._count, val, val - 1))
375 #define TIMESPEC_SUB(dst, src, val) \
377 (dst)->tv_sec = (src)->tv_sec - (val)->tv_sec; \
378 (dst)->tv_nsec = (src)->tv_nsec - (val)->tv_nsec; \
379 if ((dst)->tv_nsec < 0) { \
381 (dst)->tv_nsec += 1000000000; \
387 _sem_timedwait(sem_t * __restrict sem,
388 const struct timespec * __restrict abstime)
390 struct timespec ts, ts2;
393 if (sem_check_validity(sem) != 0)
397 _pthread_testcancel();
399 while ((val = sem->_kern._count) > 0) {
400 if (atomic_cmpset_acq_int(&sem->_kern._count, val, val - 1))
405 _pthread_testcancel();
410 * The timeout argument is only supposed to
411 * be checked if the thread would have blocked.
413 if (abstime != NULL) {
414 if (abstime->tv_nsec >= 1000000000 || abstime->tv_nsec < 0) {
418 clock_gettime(CLOCK_REALTIME, &ts);
419 TIMESPEC_SUB(&ts2, abstime, &ts);
421 _pthread_cancel_enter(1);
422 retval = usem_wait(&sem->_kern, abstime ? &ts2 : NULL);
423 _pthread_cancel_leave(0);
429 _sem_wait(sem_t *sem)
431 return _sem_timedwait(sem, NULL);
436 * The sem_post() interface is reentrant with respect to signals and may be
437 * invoked from a signal-catching function.
438 * The implementation does not use lock, so it should be safe.
441 _sem_post(sem_t *sem)
444 if (sem_check_validity(sem) != 0)
447 atomic_add_rel_int(&sem->_kern._count, 1);
448 return usem_wake(&sem->_kern);