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diff --git a/lib/libc/gen/sem.c b/lib/libc/gen/sem.c
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+/*
+ * Copyright (C) 2010 David Xu <davidxu@freebsd.org>.
+ * Copyright (C) 2000 Jason Evans <jasone@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.
+ *
+ * $FreeBSD$
+ */
+
+/*
+ * Some notes about this implementation.
+ *
+ * This is mostly a simple implementation of POSIX semaphores that
+ * does not need threading. Any semaphore created is a kernel-based
+ * semaphore regardless of the pshared attribute. This is necessary
+ * because libc's stub for pthread_cond_wait() doesn't really wait,
+ * and it is not worth the effort impose this behavior on libc.
+ *
+ * All functions here are designed to be thread-safe so that a
+ * threads library need not provide wrappers except to make
+ * sem_wait() and sem_timedwait() cancellation points or to
+ * provide a faster userland implementation for non-pshared
+ * semaphores.
+ *
+ * Also, this implementation of semaphores cannot really support
+ * real pshared semaphores. The sem_t is an allocated object
+ * and can't be seen by other processes when placed in shared
+ * memory. It should work across forks as long as the semaphore
+ * is created before any forks.
+ *
+ * The function sem_init() should be overridden by a threads
+ * library if it wants to provide a different userland version
+ * of semaphores. The functions sem_wait() and sem_timedwait()
+ * need to be wrapped to provide cancellation points. The function
+ * sem_post() may need to be wrapped to be signal-safe.
+ */
+#include "namespace.h"
+#include <sys/types.h>
+#include <sys/queue.h>
+#include <machine/atomic.h>
+#include <errno.h>
+#include <sys/umtx.h>
+#include <sys/_semaphore.h>
+#include <limits.h>
+#include <fcntl.h>
+#include <pthread.h>
+#include <stdarg.h>
+#include <stdlib.h>
+#include <time.h>
+#include "un-namespace.h"
+#include "libc_private.h"
+
+/*
+ * Old semaphore definitions.
+ */
+struct sem {
+#define SEM_MAGIC ((u_int32_t) 0x09fa4012)
+ u_int32_t magic;
+ pthread_mutex_t lock;
+ pthread_cond_t gtzero;
+ u_int32_t count;
+ u_int32_t nwaiters;
+#define SEM_USER (NULL)
+ semid_t semid; /* semaphore id if kernel (shared) semaphore */
+ int syssem; /* 1 if kernel (shared) semaphore */
+ LIST_ENTRY(sem) entry;
+ struct sem **backpointer;
+};
+
+typedef struct sem* sem_t;
+
+#define SEM_FAILED ((sem_t *)0)
+#define SEM_VALUE_MAX __INT_MAX
+
+#define SYM_FB10(sym) __CONCAT(sym, _fb10)
+#define WEAK_REF(sym, alias) __weak_reference(sym, alias)
+#define SYM_COMPAT(sym, impl, ver) __sym_compat(sym, impl, ver)
+
+#define FB10_COMPAT(func, sym) \
+ WEAK_REF(func, SYM_FB10(sym)); \
+ SYM_COMPAT(sym, SYM_FB10(sym), FBSD_1.0)
+
+static sem_t sem_alloc(unsigned int value, semid_t semid, int system_sem);
+static void sem_free(sem_t sem);
+
+static LIST_HEAD(, sem) named_sems = LIST_HEAD_INITIALIZER(named_sems);
+static pthread_mutex_t named_sems_mtx = PTHREAD_MUTEX_INITIALIZER;
+
+FB10_COMPAT(_libc_sem_init_compat, sem_init);
+FB10_COMPAT(_libc_sem_destroy_compat, sem_destroy);
+FB10_COMPAT(_libc_sem_open_compat, sem_open);
+FB10_COMPAT(_libc_sem_close_compat, sem_close);
+FB10_COMPAT(_libc_sem_unlink_compat, sem_unlink);
+FB10_COMPAT(_libc_sem_wait_compat, sem_wait);
+FB10_COMPAT(_libc_sem_trywait_compat, sem_trywait);
+FB10_COMPAT(_libc_sem_timedwait_compat, sem_timedwait);
+FB10_COMPAT(_libc_sem_post_compat, sem_post);
+FB10_COMPAT(_libc_sem_getvalue_compat, sem_getvalue);
+
+static inline int
+sem_check_validity(sem_t *sem)
+{
+
+ if ((sem != NULL) && ((*sem)->magic == SEM_MAGIC))
+ return (0);
+ else {
+ errno = EINVAL;
+ return (-1);
+ }
+}
+
+static void
+sem_free(sem_t sem)
+{
+
+ sem->magic = 0;
+ free(sem);
+}
+
+static sem_t
+sem_alloc(unsigned int value, semid_t semid, int system_sem)
+{
+ sem_t sem;
+
+ if (value > SEM_VALUE_MAX) {
+ errno = EINVAL;
+ return (NULL);
+ }
+
+ sem = (sem_t)malloc(sizeof(struct sem));
+ if (sem == NULL) {
+ errno = ENOSPC;
+ return (NULL);
+ }
+
+ sem->count = (u_int32_t)value;
+ sem->nwaiters = 0;
+ sem->magic = SEM_MAGIC;
+ sem->semid = semid;
+ sem->syssem = system_sem;
+ return (sem);
+}
+
+int
+_libc_sem_init_compat(sem_t *sem, int pshared, unsigned int value)
+{
+ semid_t semid;
+
+ /*
+ * We always have to create the kernel semaphore if the
+ * threads library isn't present since libc's version of
+ * pthread_cond_wait() is just a stub that doesn't really
+ * wait.
+ */
+ semid = (semid_t)SEM_USER;
+ if ((pshared != 0) && ksem_init(&semid, value) != 0)
+ return (-1);
+
+ *sem = sem_alloc(value, semid, pshared);
+ if ((*sem) == NULL) {
+ if (pshared != 0)
+ ksem_destroy(semid);
+ return (-1);
+ }
+ return (0);
+}
+
+int
+_libc_sem_destroy_compat(sem_t *sem)
+{
+ int retval;
+
+ if (sem_check_validity(sem) != 0)
+ return (-1);
+
+ /*
+ * If this is a system semaphore let the kernel track it otherwise
+ * make sure there are no waiters.
+ */
+ if ((*sem)->syssem != 0)
+ retval = ksem_destroy((*sem)->semid);
+ else if ((*sem)->nwaiters > 0) {
+ errno = EBUSY;
+ retval = -1;
+ }
+ else {
+ retval = 0;
+ (*sem)->magic = 0;
+ }
+
+ if (retval == 0)
+ sem_free(*sem);
+ return (retval);
+}
+
+sem_t *
+_libc_sem_open_compat(const char *name, int oflag, ...)
+{
+ sem_t *sem;
+ sem_t s;
+ semid_t semid;
+ mode_t mode;
+ unsigned int value;
+
+ mode = 0;
+ value = 0;
+
+ if ((oflag & O_CREAT) != 0) {
+ va_list ap;
+
+ va_start(ap, oflag);
+ mode = va_arg(ap, int);
+ value = va_arg(ap, unsigned int);
+ va_end(ap);
+ }
+ /*
+ * we can be lazy and let the kernel handle the "oflag",
+ * we'll just merge duplicate IDs into our list.
+ */
+ if (ksem_open(&semid, name, oflag, mode, value) == -1)
+ return (SEM_FAILED);
+ /*
+ * search for a duplicate ID, we must return the same sem_t *
+ * if we locate one.
+ */
+ _pthread_mutex_lock(&named_sems_mtx);
+ LIST_FOREACH(s, &named_sems, entry) {
+ if (s->semid == semid) {
+ sem = s->backpointer;
+ _pthread_mutex_unlock(&named_sems_mtx);
+ return (sem);
+ }
+ }
+ sem = (sem_t *)malloc(sizeof(*sem));
+ if (sem == NULL)
+ goto err;
+ *sem = sem_alloc(value, semid, 1);
+ if ((*sem) == NULL)
+ goto err;
+ LIST_INSERT_HEAD(&named_sems, *sem, entry);
+ (*sem)->backpointer = sem;
+ _pthread_mutex_unlock(&named_sems_mtx);
+ return (sem);
+err:
+ _pthread_mutex_unlock(&named_sems_mtx);
+ ksem_close(semid);
+ if (sem != NULL) {
+ if (*sem != NULL)
+ sem_free(*sem);
+ else
+ errno = ENOSPC;
+ free(sem);
+ } else {
+ errno = ENOSPC;
+ }
+ return (SEM_FAILED);
+}
+
+int
+_libc_sem_close_compat(sem_t *sem)
+{
+
+ if (sem_check_validity(sem) != 0)
+ return (-1);
+
+ if ((*sem)->syssem == 0) {
+ errno = EINVAL;
+ return (-1);
+ }
+
+ _pthread_mutex_lock(&named_sems_mtx);
+ if (ksem_close((*sem)->semid) != 0) {
+ _pthread_mutex_unlock(&named_sems_mtx);
+ return (-1);
+ }
+ LIST_REMOVE((*sem), entry);
+ _pthread_mutex_unlock(&named_sems_mtx);
+ sem_free(*sem);
+ *sem = NULL;
+ free(sem);
+ return (0);
+}
+
+int
+_libc_sem_unlink_compat(const char *name)
+{
+
+ return (ksem_unlink(name));
+}
+
+static int
+_umtx_wait_uint(volatile unsigned *mtx, unsigned id, const struct timespec *abstime)
+{
+ struct _umtx_time *tm_p, timeout;
+ size_t tm_size;
+
+ if (abstime == NULL) {
+ tm_p = NULL;
+ tm_size = 0;
+ } else {
+ timeout._clockid = CLOCK_REALTIME;
+ timeout._flags = UMTX_ABSTIME;
+ timeout._timeout = *abstime;
+ tm_p = &timeout;
+ tm_size = sizeof(timeout);
+ }
+ return _umtx_op(__DEVOLATILE(void *, mtx),
+ UMTX_OP_WAIT_UINT_PRIVATE, id,
+ (void *)tm_size, __DECONST(void*, tm_p));
+}
+
+static int
+_umtx_wake(volatile void *mtx)
+{
+ return _umtx_op(__DEVOLATILE(void *, mtx), UMTX_OP_WAKE_PRIVATE,
+ 1, NULL, NULL);
+}
+
+#define TIMESPEC_SUB(dst, src, val) \
+ do { \
+ (dst)->tv_sec = (src)->tv_sec - (val)->tv_sec; \
+ (dst)->tv_nsec = (src)->tv_nsec - (val)->tv_nsec; \
+ if ((dst)->tv_nsec < 0) { \
+ (dst)->tv_sec--; \
+ (dst)->tv_nsec += 1000000000; \
+ } \
+ } while (0)
+
+
+static void
+sem_cancel_handler(void *arg)
+{
+ sem_t *sem = arg;
+
+ atomic_add_int(&(*sem)->nwaiters, -1);
+ if ((*sem)->nwaiters && (*sem)->count)
+ _umtx_wake(&(*sem)->count);
+}
+
+int
+_libc_sem_timedwait_compat(sem_t * __restrict sem,
+ const struct timespec * __restrict abstime)
+{
+ int val, retval;
+
+ if (sem_check_validity(sem) != 0)
+ return (-1);
+
+ if ((*sem)->syssem != 0) {
+ _pthread_cancel_enter(1);
+ retval = ksem_wait((*sem)->semid); /* XXX no timeout */
+ _pthread_cancel_leave(retval == -1);
+ return (retval);
+ }
+
+ retval = 0;
+ _pthread_testcancel();
+ for (;;) {
+ while ((val = (*sem)->count) > 0) {
+ if (atomic_cmpset_acq_int(&(*sem)->count, val, val - 1))
+ return (0);
+ }
+ if (retval) {
+ _pthread_testcancel();
+ break;
+ }
+ if (abstime) {
+ if (abstime->tv_nsec >= 1000000000 || abstime->tv_nsec < 0) {
+ errno = EINVAL;
+ return (-1);
+ }
+ }
+ atomic_add_int(&(*sem)->nwaiters, 1);
+ pthread_cleanup_push(sem_cancel_handler, sem);
+ _pthread_cancel_enter(1);
+ retval = _umtx_wait_uint(&(*sem)->count, 0, abstime);
+ _pthread_cancel_leave(0);
+ pthread_cleanup_pop(0);
+ atomic_add_int(&(*sem)->nwaiters, -1);
+ }
+ return (retval);
+}
+
+int
+_libc_sem_wait_compat(sem_t *sem)
+{
+ return _libc_sem_timedwait_compat(sem, NULL);
+}
+
+int
+_libc_sem_trywait_compat(sem_t *sem)
+{
+ int val;
+
+ if (sem_check_validity(sem) != 0)
+ return (-1);
+
+ if ((*sem)->syssem != 0)
+ return ksem_trywait((*sem)->semid);
+
+ while ((val = (*sem)->count) > 0) {
+ if (atomic_cmpset_acq_int(&(*sem)->count, val, val - 1))
+ return (0);
+ }
+ errno = EAGAIN;
+ return (-1);
+}
+
+int
+_libc_sem_post_compat(sem_t *sem)
+{
+
+ if (sem_check_validity(sem) != 0)
+ return (-1);
+
+ if ((*sem)->syssem != 0)
+ return ksem_post((*sem)->semid);
+
+ atomic_add_rel_int(&(*sem)->count, 1);
+ rmb();
+ if ((*sem)->nwaiters)
+ return _umtx_wake(&(*sem)->count);
+ return (0);
+}
+
+int
+_libc_sem_getvalue_compat(sem_t * __restrict sem, int * __restrict sval)
+{
+ int retval;
+
+ if (sem_check_validity(sem) != 0)
+ return (-1);
+
+ if ((*sem)->syssem != 0)
+ retval = ksem_getvalue((*sem)->semid, sval);
+ else {
+ *sval = (int)(*sem)->count;
+ retval = 0;
+ }
+ return (retval);
+}
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