diff options
Diffstat (limited to 'lib/libc/gen/sem_new.c')
| -rw-r--r-- | lib/libc/gen/sem_new.c | 470 |
1 files changed, 470 insertions, 0 deletions
diff --git a/lib/libc/gen/sem_new.c b/lib/libc/gen/sem_new.c new file mode 100644 index 000000000000..ba81fb0ded78 --- /dev/null +++ b/lib/libc/gen/sem_new.c @@ -0,0 +1,470 @@ +/*- + * SPDX-License-Identifier: BSD-2-Clause + * + * Copyright (C) 2010 David Xu <davidxu@freebsd.org>. + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice(s), this list of conditions and the following disclaimer as + * the first lines of this file unmodified other than the possible + * addition of one or more copyright notices. + * 2. Redistributions in binary form must reproduce the above copyright + * notice(s), this list of conditions and the following disclaimer in + * the documentation and/or other materials provided with the + * distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY + * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR + * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE + * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR + * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF + * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR + * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, + * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE + * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, + * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + */ + +#include "namespace.h" +#include <sys/types.h> +#include <sys/queue.h> +#include <sys/mman.h> +#include <sys/stat.h> +#include <errno.h> +#include <machine/atomic.h> +#include <sys/umtx.h> +#include <limits.h> +#include <fcntl.h> +#include <pthread.h> +#include <stdarg.h> +#include <stdbool.h> +#include <stdlib.h> +#include <string.h> +#include <time.h> +#include <semaphore.h> +#include <unistd.h> +#include "un-namespace.h" +#include "libc_private.h" + +__weak_reference(_sem_close, sem_close); +__weak_reference(_sem_destroy, sem_destroy); +__weak_reference(_sem_getvalue, sem_getvalue); +__weak_reference(_sem_init, sem_init); +__weak_reference(_sem_open, sem_open); +__weak_reference(_sem_post, sem_post); +__weak_reference(_sem_timedwait, sem_timedwait); +__weak_reference(_sem_clockwait_np, sem_clockwait_np); +__weak_reference(_sem_trywait, sem_trywait); +__weak_reference(_sem_unlink, sem_unlink); +__weak_reference(_sem_wait, sem_wait); + +#define SEM_PREFIX "/tmp/SEMD" +#define SEM_MAGIC ((u_int32_t)0x73656d32) + +_Static_assert(SEM_VALUE_MAX <= USEM_MAX_COUNT, "SEM_VALUE_MAX too large"); + +struct sem_nameinfo { + int open_count; + char *name; + dev_t dev; + ino_t ino; + sem_t *sem; + LIST_ENTRY(sem_nameinfo) next; +}; + +static pthread_once_t once = PTHREAD_ONCE_INIT; +static pthread_mutex_t sem_llock; +static LIST_HEAD(, sem_nameinfo) sem_list = LIST_HEAD_INITIALIZER(sem_list); + +static void +sem_prefork(void) +{ + + _pthread_mutex_lock(&sem_llock); +} + +static void +sem_postfork(void) +{ + + _pthread_mutex_unlock(&sem_llock); +} + +static void +sem_child_postfork(void) +{ + + _pthread_mutex_unlock(&sem_llock); +} + +static void +sem_module_init(void) +{ + + _pthread_mutex_init(&sem_llock, NULL); + _pthread_atfork(sem_prefork, sem_postfork, sem_child_postfork); +} + +static inline int +sem_check_validity(sem_t *sem) +{ + + if (sem->_magic == SEM_MAGIC) + return (0); + errno = EINVAL; + return (-1); +} + +int +_sem_init(sem_t *sem, int pshared, unsigned int value) +{ + + if (value > SEM_VALUE_MAX) { + errno = EINVAL; + return (-1); + } + + bzero(sem, sizeof(sem_t)); + sem->_magic = SEM_MAGIC; + sem->_kern._count = (u_int32_t)value; + sem->_kern._flags = pshared ? USYNC_PROCESS_SHARED : 0; + return (0); +} + +sem_t * +_sem_open(const char *name, int flags, ...) +{ + char path[PATH_MAX]; + struct stat sb; + va_list ap; + struct sem_nameinfo *ni; + sem_t *sem, tmp; + int errsave, fd, len, mode, value; + + ni = NULL; + sem = NULL; + fd = -1; + value = 0; + + if (name[0] != '/') { + errno = EINVAL; + return (SEM_FAILED); + } + name++; + strcpy(path, SEM_PREFIX); + if (strlcat(path, name, sizeof(path)) >= sizeof(path)) { + errno = ENAMETOOLONG; + return (SEM_FAILED); + } + if (flags & ~(O_CREAT|O_EXCL)) { + errno = EINVAL; + return (SEM_FAILED); + } + if ((flags & O_CREAT) != 0) { + va_start(ap, flags); + mode = va_arg(ap, int); + value = va_arg(ap, int); + va_end(ap); + } + fd = -1; + _pthread_once(&once, sem_module_init); + + _pthread_mutex_lock(&sem_llock); + LIST_FOREACH(ni, &sem_list, next) { + if (ni->name != NULL && strcmp(name, ni->name) == 0) { + fd = _open(path, flags | O_RDWR | O_CLOEXEC | + O_EXLOCK, mode); + if (fd == -1 || _fstat(fd, &sb) == -1) { + ni = NULL; + goto error; + } + if ((flags & (O_CREAT | O_EXCL)) == (O_CREAT | + O_EXCL) || ni->dev != sb.st_dev || + ni->ino != sb.st_ino) { + ni->name = NULL; + ni = NULL; + break; + } + ni->open_count++; + sem = ni->sem; + _pthread_mutex_unlock(&sem_llock); + _close(fd); + return (sem); + } + } + + len = sizeof(*ni) + strlen(name) + 1; + ni = (struct sem_nameinfo *)malloc(len); + if (ni == NULL) { + errno = ENOSPC; + goto error; + } + + ni->name = (char *)(ni+1); + strcpy(ni->name, name); + + if (fd == -1) { + fd = _open(path, flags | O_RDWR | O_CLOEXEC | O_EXLOCK, mode); + if (fd == -1 || _fstat(fd, &sb) == -1) + goto error; + } + if (sb.st_size < sizeof(sem_t)) { + tmp._magic = SEM_MAGIC; + tmp._kern._count = value; + tmp._kern._flags = USYNC_PROCESS_SHARED | SEM_NAMED; + if (_write(fd, &tmp, sizeof(tmp)) != sizeof(tmp)) + goto error; + } + flock(fd, LOCK_UN); + sem = mmap(NULL, sizeof(sem_t), PROT_READ | PROT_WRITE, + MAP_SHARED | MAP_NOSYNC, fd, 0); + if (sem == MAP_FAILED) { + sem = NULL; + if (errno == ENOMEM) + errno = ENOSPC; + goto error; + } + if (sem->_magic != SEM_MAGIC) { + errno = EINVAL; + goto error; + } + ni->open_count = 1; + ni->sem = sem; + ni->dev = sb.st_dev; + ni->ino = sb.st_ino; + LIST_INSERT_HEAD(&sem_list, ni, next); + _close(fd); + _pthread_mutex_unlock(&sem_llock); + return (sem); + +error: + errsave = errno; + if (fd != -1) + _close(fd); + if (sem != NULL) + munmap(sem, sizeof(sem_t)); + free(ni); + _pthread_mutex_unlock(&sem_llock); + errno = errsave; + return (SEM_FAILED); +} + +int +_sem_close(sem_t *sem) +{ + struct sem_nameinfo *ni; + bool last; + + if (sem_check_validity(sem) != 0) + return (-1); + + if (!(sem->_kern._flags & SEM_NAMED)) { + errno = EINVAL; + return (-1); + } + + _pthread_once(&once, sem_module_init); + + _pthread_mutex_lock(&sem_llock); + LIST_FOREACH(ni, &sem_list, next) { + if (sem == ni->sem) { + last = --ni->open_count == 0; + if (last) + LIST_REMOVE(ni, next); + _pthread_mutex_unlock(&sem_llock); + if (last) { + munmap(sem, sizeof(*sem)); + free(ni); + } + return (0); + } + } + _pthread_mutex_unlock(&sem_llock); + errno = EINVAL; + return (-1); +} + +int +_sem_unlink(const char *name) +{ + char path[PATH_MAX]; + + if (name[0] != '/') { + errno = ENOENT; + return -1; + } + name++; + strcpy(path, SEM_PREFIX); + if (strlcat(path, name, sizeof(path)) >= sizeof(path)) { + errno = ENAMETOOLONG; + return (-1); + } + + return (unlink(path)); +} + +int +_sem_destroy(sem_t *sem) +{ + + if (sem_check_validity(sem) != 0) + return (-1); + + if (sem->_kern._flags & SEM_NAMED) { + errno = EINVAL; + return (-1); + } + sem->_magic = 0; + return (0); +} + +int +_sem_getvalue(sem_t * __restrict sem, int * __restrict sval) +{ + + if (sem_check_validity(sem) != 0) + return (-1); + + *sval = (int)USEM_COUNT(sem->_kern._count); + return (0); +} + +static __inline int +usem_wake(struct _usem2 *sem) +{ + + return (_umtx_op(sem, UMTX_OP_SEM2_WAKE, 0, NULL, NULL)); +} + +static __inline int +usem_wait(struct _usem2 *sem, clockid_t clock_id, int flags, + const struct timespec *rqtp, struct timespec *rmtp) +{ + struct { + struct _umtx_time timeout; + struct timespec remain; + } tms; + void *tm_p; + size_t tm_size; + int retval; + + if (rqtp == NULL) { + tm_p = NULL; + tm_size = 0; + } else { + tms.timeout._clockid = clock_id; + tms.timeout._flags = (flags & TIMER_ABSTIME) ? UMTX_ABSTIME : 0; + tms.timeout._timeout = *rqtp; + tm_p = &tms; + tm_size = sizeof(tms); + } + retval = _umtx_op(sem, UMTX_OP_SEM2_WAIT, 0, (void *)tm_size, tm_p); + if (retval == -1 && errno == EINTR && (flags & TIMER_ABSTIME) == 0 && + rqtp != NULL && rmtp != NULL) { + *rmtp = tms.remain; + } + + return (retval); +} + +int +_sem_trywait(sem_t *sem) +{ + int val; + + if (sem_check_validity(sem) != 0) + return (-1); + + while (USEM_COUNT(val = sem->_kern._count) > 0) { + if (atomic_cmpset_acq_int(&sem->_kern._count, val, val - 1)) + return (0); + } + errno = EAGAIN; + return (-1); +} + +int +_sem_clockwait_np(sem_t * __restrict sem, clockid_t clock_id, int flags, + const struct timespec *rqtp, struct timespec *rmtp) +{ + int val, retval; + + if (sem_check_validity(sem) != 0) + return (-1); + + retval = 0; + _pthread_testcancel(); + for (;;) { + while (USEM_COUNT(val = sem->_kern._count) > 0) { + if (atomic_cmpset_acq_int(&sem->_kern._count, val, + val - 1)) + return (0); + } + + if (retval) { + _pthread_testcancel(); + break; + } + + /* + * The timeout argument is only supposed to + * be checked if the thread would have blocked. + */ + if (rqtp != NULL) { + if (rqtp->tv_nsec >= 1000000000 || rqtp->tv_nsec < 0) { + errno = EINVAL; + return (-1); + } + } + _pthread_cancel_enter(1); + retval = usem_wait(&sem->_kern, clock_id, flags, rqtp, rmtp); + _pthread_cancel_leave(0); + } + return (retval); +} + +int +_sem_timedwait(sem_t * __restrict sem, + const struct timespec * __restrict abstime) +{ + + return (_sem_clockwait_np(sem, CLOCK_REALTIME, TIMER_ABSTIME, abstime, + NULL)); +}; + +int +_sem_wait(sem_t *sem) +{ + + return (_sem_timedwait(sem, NULL)); +} + +/* + * POSIX: + * The sem_post() interface is reentrant with respect to signals and may be + * invoked from a signal-catching function. + * The implementation does not use lock, so it should be safe. + */ +int +_sem_post(sem_t *sem) +{ + unsigned int count; + + if (sem_check_validity(sem) != 0) + return (-1); + + do { + count = sem->_kern._count; + if (USEM_COUNT(count) + 1 > SEM_VALUE_MAX) { + errno = EOVERFLOW; + return (-1); + } + } while (!atomic_cmpset_rel_int(&sem->_kern._count, count, count + 1)); + if (count & USEM_HAS_WAITERS) + usem_wake(&sem->_kern); + return (0); +} |