OpenSolaris Launch

1 files changed, 964 insertions, 0 deletions

diff --git a/usr/src/lib/librt/common/mqueue.c b/usr/src/lib/librt/common/mqueue.c
new file mode 100644
index 0000000000..2f830eb40f
--- /dev/null
+++ b/usr/src/lib/librt/common/mqueue.c
@@ -0,0 +1,964 @@
+/*
+ * CDDL HEADER START
+ *
+ * The contents of this file are subject to the terms of the
+ * Common Development and Distribution License, Version 1.0 only
+ * (the "License").  You may not use this file except in compliance
+ * with the License.
+ *
+ * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
+ * or http://www.opensolaris.org/os/licensing.
+ * See the License for the specific language governing permissions
+ * and limitations under the License.
+ *
+ * When distributing Covered Code, include this CDDL HEADER in each
+ * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
+ * If applicable, add the following below this CDDL HEADER, with the
+ * fields enclosed by brackets "[]" replaced with your own identifying
+ * information: Portions Copyright [yyyy] [name of copyright owner]
+ *
+ * CDDL HEADER END
+ */
+/*
+ * Copyright 2004 Sun Microsystems, Inc.  All rights reserved.
+ * Use is subject to license terms.
+ */
+
+#pragma ident	"%Z%%M%	%I%	%E% SMI"
+
+#pragma weak mq_open = _mq_open
+#pragma weak mq_close = _mq_close
+#pragma weak mq_unlink = _mq_unlink
+#pragma weak mq_send = _mq_send
+#pragma weak mq_timedsend = _mq_timedsend
+#pragma weak mq_reltimedsend_np = _mq_reltimedsend_np
+#pragma weak mq_receive = _mq_receive
+#pragma weak mq_timedreceive = _mq_timedreceive
+#pragma weak mq_reltimedreceive_np = _mq_reltimedreceive_np
+#pragma weak mq_notify = _mq_notify
+#pragma weak mq_setattr = _mq_setattr
+#pragma weak mq_getattr = _mq_getattr
+
+#include "synonyms.h"
+#define	_KMEMUSER
+#include <sys/param.h>		/* _MQ_OPEN_MAX, _MQ_PRIO_MAX, _SEM_VALUE_MAX */
+#undef	_KMEMUSER
+#include <mqueue.h>
+#include <sys/types.h>
+#include <sys/file.h>
+#include <sys/mman.h>
+#include <errno.h>
+#include <stdarg.h>
+#include <limits.h>
+#include <pthread.h>
+#include <assert.h>
+#include <string.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <sys/stat.h>
+#include <inttypes.h>
+
+#include "mqlib.h"
+#include "pos4obj.h"
+#include "pos4.h"
+
+#define	MQ_ALIGNSIZE	8	/* 64-bit alignment */
+
+#ifdef DEBUG
+#define	MQ_ASSERT(x) \
+	assert(x);
+
+#define	MQ_ASSERT_PTR(_m, _p) \
+	assert((_p) != NULL && !((uintptr_t)(_p) & (MQ_ALIGNSIZE -1)) && \
+	    !((uintptr_t)_m + (uintptr_t)(_p) >= (uintptr_t)_m + \
+	    _m->mq_totsize));
+
+#define	MQ_ASSERT_SEMVAL_LEQ(sem, val) { \
+	int _val; \
+	(void) sem_getvalue((sem), &_val); \
+	assert((_val) <= val); }
+#else
+#define	MQ_ASSERT(x)
+#define	MQ_ASSERT_PTR(_m, _p)
+#define	MQ_ASSERT_SEMVAL_LEQ(sem, val)
+#endif
+
+#define	MQ_PTR(m, n)	((msghdr_t *)((uintptr_t)m + (uintptr_t)n))
+#define	HEAD_PTR(m, n)	((uint64_t *)((uintptr_t)m + \
+			(uintptr_t)m->mq_headpp + n * sizeof (uint64_t)))
+#define	TAIL_PTR(m, n)	((uint64_t *)((uintptr_t)m + \
+			(uintptr_t)m->mq_tailpp + n * sizeof (uint64_t)))
+
+static	int open_count = 0; /* ref count to track the number of open M.Q.s */
+static	mqdes_t	*open_queue[_MQ_OPEN_MAX] = { NULL };	/* open msg queues */
+static	mutex_t	mqlock = DEFAULTMUTEX;
+#define	MQ_RESERVED	((mqdes_t *)-1)
+
+#define	ABS_TIME	0
+#define	REL_TIME	1
+
+static int
+mq_is_valid(mqdes_t *mqdp)
+{
+	int i;
+
+	/*
+	 * We don't need to acquire mqlock; this is a read-only operation.
+	 */
+	if (mqdp != NULL && mqdp != MQ_RESERVED) {
+		for (i = 0; i < _MQ_OPEN_MAX; i++) {
+			if (open_queue[i] == mqdp) {
+				/*
+				 * The MQ_MAGIC test is not really necessary.
+				 * We could just return 1.
+				 */
+				return (mqdp->mqd_magic == MQ_MAGIC);
+			}
+		}
+	}
+	return (0);
+}
+
+static void
+mq_init(mqhdr_t *mqhp, size_t msgsize, ssize_t maxmsg)
+{
+	int		i;
+	uint64_t	temp;
+	uint64_t	currentp;
+	uint64_t	nextp;
+
+	/*
+	 * We only need to initialize the non-zero fields.  The use of
+	 * ftruncate() on the message queue file assures that the
+	 * pages will be zfod.
+	 */
+	(void) sem_init(&mqhp->mq_exclusive, 1, 1);
+	(void) sem_init(&mqhp->mq_rblocked, 1, 0);
+	(void) sem_init(&mqhp->mq_notempty, 1, 0);
+	(void) sem_init(&mqhp->mq_notfull, 1, (uint_t)maxmsg);
+
+	mqhp->mq_maxsz = msgsize;
+	mqhp->mq_maxmsg = maxmsg;
+
+	/*
+	 * As of this writing (1997), there are 32 message queue priorities.
+	 * If this is to change, then the size of the mq_mask will also
+	 * have to change.  If NDEBUG isn't defined, assert that
+	 * _MQ_PRIO_MAX hasn't changed.
+	 */
+	mqhp->mq_maxprio = _MQ_PRIO_MAX;
+	MQ_ASSERT(sizeof (mqhp->mq_mask) * 8 >= _MQ_PRIO_MAX);
+
+	mqhp->mq_magic = MQ_MAGIC;
+
+	/*
+	 * Since the message queue can be mapped into different
+	 * virtual address ranges by different processes, we don't
+	 * keep track of pointers, only offsets into the shared region.
+	 */
+	mqhp->mq_headpp = sizeof (mqhdr_t);
+	mqhp->mq_tailpp = mqhp->mq_headpp +
+		mqhp->mq_maxprio * sizeof (uint64_t);
+	mqhp->mq_freep = mqhp->mq_tailpp +
+		mqhp->mq_maxprio * sizeof (uint64_t);
+
+	currentp = mqhp->mq_freep;
+	MQ_PTR(mqhp, currentp)->msg_next = 0;
+
+	temp = (mqhp->mq_maxsz + MQ_ALIGNSIZE - 1) & ~(MQ_ALIGNSIZE - 1);
+	for (i = 1; i < mqhp->mq_maxmsg; i++) {
+		nextp = currentp + sizeof (msghdr_t) + temp;
+		MQ_PTR(mqhp, currentp)->msg_next = nextp;
+		MQ_PTR(mqhp, nextp)->msg_next = 0;
+		currentp = nextp;
+	}
+}
+
+static size_t
+mq_getmsg(mqhdr_t *mqhp, char *msgp, uint_t *msg_prio)
+{
+	uint64_t currentp;
+	msghdr_t *curbuf;
+	uint64_t *headpp;
+	uint64_t *tailpp;
+
+	MQ_ASSERT_SEMVAL_LEQ(&mqhp->mq_exclusive, 0);
+
+	/*
+	 * Get the head and tail pointers for the queue of maximum
+	 * priority.  We shouldn't be here unless there is a message for
+	 * us, so it's fair to assert that both the head and tail
+	 * pointers are non-NULL.
+	 */
+	headpp = HEAD_PTR(mqhp, mqhp->mq_curmaxprio);
+	tailpp = TAIL_PTR(mqhp, mqhp->mq_curmaxprio);
+
+	if (msg_prio != NULL)
+		*msg_prio = mqhp->mq_curmaxprio;
+
+	currentp = *headpp;
+	MQ_ASSERT_PTR(mqhp, currentp);
+	curbuf = MQ_PTR(mqhp, currentp);
+
+	if ((*headpp = curbuf->msg_next) == NULL) {
+		/*
+		 * We just nuked the last message in this priority's queue.
+		 * Twiddle this priority's bit, and then find the next bit
+		 * tipped.
+		 */
+		uint_t prio = mqhp->mq_curmaxprio;
+
+		mqhp->mq_mask &= ~(1u << prio);
+
+		for (; prio != 0; prio--)
+			if (mqhp->mq_mask & (1u << prio))
+				break;
+		mqhp->mq_curmaxprio = prio;
+
+		*tailpp = NULL;
+	}
+
+	/*
+	 * Copy the message, and put the buffer back on the free list.
+	 */
+	(void) memcpy(msgp, (char *)&curbuf[1], curbuf->msg_len);
+	curbuf->msg_next = mqhp->mq_freep;
+	mqhp->mq_freep = currentp;
+
+	return (curbuf->msg_len);
+}
+
+
+static void
+mq_putmsg(mqhdr_t *mqhp, const char *msgp, ssize_t len, uint_t prio)
+{
+	uint64_t currentp;
+	msghdr_t *curbuf;
+	uint64_t *headpp;
+	uint64_t *tailpp;
+
+	MQ_ASSERT_SEMVAL_LEQ(&mqhp->mq_exclusive, 0);
+
+	/*
+	 * Grab a free message block, and link it in.  We shouldn't
+	 * be here unless there is room in the queue for us;  it's
+	 * fair to assert that the free pointer is non-NULL.
+	 */
+	currentp = mqhp->mq_freep;
+	MQ_ASSERT_PTR(mqhp, currentp);
+	curbuf = MQ_PTR(mqhp, currentp);
+
+	/*
+	 * Remove a message from the free list, and copy in the new contents.
+	 */
+	mqhp->mq_freep = curbuf->msg_next;
+	curbuf->msg_next = NULL;
+	(void) memcpy((char *)&curbuf[1], msgp, len);
+	curbuf->msg_len = len;
+
+	headpp = HEAD_PTR(mqhp, prio);
+	tailpp = TAIL_PTR(mqhp, prio);
+
+	if (*tailpp == 0) {
+		/*
+		 * This is the first message on this queue.  Set the
+		 * head and tail pointers, and tip the appropriate bit
+		 * in the priority mask.
+		 */
+		*headpp = currentp;
+		*tailpp = currentp;
+		mqhp->mq_mask |= (1u << prio);
+		if (prio > mqhp->mq_curmaxprio)
+			mqhp->mq_curmaxprio = prio;
+	} else {
+		MQ_ASSERT_PTR(mqhp, *tailpp);
+		MQ_PTR(mqhp, *tailpp)->msg_next = currentp;
+		*tailpp = currentp;
+	}
+}
+
+mqd_t
+_mq_open(const char *path, int oflag, /* mode_t mode, mq_attr *attr */ ...)
+{
+	va_list		ap;
+	mode_t		mode;
+	struct mq_attr	*attr;
+	int		fd;
+	int		err;
+	int		cr_flag = 0;
+	int		locked = 0;
+	int		i;
+	uint64_t	total_size;
+	size_t		msgsize;
+	ssize_t		maxmsg;
+	uint64_t	temp;
+	void		*ptr;
+	mqdes_t		*mqdp;
+	mqhdr_t		*mqhp;
+	struct mq_dn	*mqdnp;
+	mqdes_t		**open_slot = NULL;
+
+	if (__pos4obj_check(path) == -1)
+		return ((mqd_t)-1);
+
+	/* check that we do not exceed the max M.Q.s for this process */
+	(void) mutex_lock(&mqlock);
+	if (open_count >= _MQ_OPEN_MAX) {
+		errno = EMFILE;
+		(void) mutex_unlock(&mqlock);
+		return ((mqd_t)-1);
+	}
+	open_count++;
+	/* find an available slot in the array of open queues */
+	for (i = 0; i < _MQ_OPEN_MAX; i++) {
+		if (open_queue[i] == NULL) {
+			open_slot = &open_queue[i];
+			break;
+		}
+	}
+	*open_slot = MQ_RESERVED;
+	(void) mutex_unlock(&mqlock);
+
+	/* acquire MSGQ lock to have atomic operation */
+	if (__pos4obj_lock(path, MQ_LOCK_TYPE) < 0)
+		goto out;
+	locked = 1;
+
+	va_start(ap, oflag);
+	/* filter oflag to have READ/WRITE/CREATE modes only */
+	oflag = oflag & (O_RDONLY|O_WRONLY|O_RDWR|O_CREAT|O_EXCL|O_NONBLOCK);
+	if ((oflag & O_CREAT) != 0) {
+		mode = va_arg(ap, mode_t);
+		attr = va_arg(ap, struct mq_attr *);
+	}
+	va_end(ap);
+
+	if ((fd = __pos4obj_open(path, MQ_PERM_TYPE, oflag,
+	    mode, &cr_flag)) < 0)
+		goto out;
+
+	/* closing permission file */
+	(void) __close_nc(fd);
+
+	/* Try to open/create data file */
+	if (cr_flag) {
+		cr_flag = PFILE_CREATE;
+		if (attr == NULL) {
+			maxmsg = MQ_MAXMSG;
+			msgsize = MQ_MAXSIZE;
+		} else if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0) {
+			errno = EINVAL;
+			goto out;
+		} else if (attr->mq_maxmsg > _SEM_VALUE_MAX) {
+			errno = ENOSPC;
+			goto out;
+		} else {
+			maxmsg = attr->mq_maxmsg;
+			msgsize = attr->mq_msgsize;
+		}
+
+		/* adjust for message size at word boundary */
+		temp = (msgsize + MQ_ALIGNSIZE - 1) & ~(MQ_ALIGNSIZE - 1);
+
+		total_size = sizeof (mqhdr_t) +
+			maxmsg * (temp + sizeof (msghdr_t)) +
+			2 * _MQ_PRIO_MAX * sizeof (uint64_t);
+
+		if (total_size > SSIZE_MAX) {
+			errno = ENOSPC;
+			goto out;
+		}
+
+		/*
+		 * data file is opened with read/write to those
+		 * who have read or write permission
+		 */
+		mode = mode | (mode & 0444) >> 1 | (mode & 0222) << 1;
+		if ((fd = __pos4obj_open(path, MQ_DATA_TYPE,
+		    (O_RDWR|O_CREAT|O_EXCL), mode, &err)) < 0)
+			goto out;
+
+		cr_flag |= DFILE_CREATE | DFILE_OPEN;
+
+		/* force permissions to avoid umask effect */
+		if (fchmod(fd, mode) < 0)
+			goto out;
+
+		if (ftruncate64(fd, (off64_t)total_size) < 0)
+			goto out;
+	} else {
+		if ((fd = __pos4obj_open(path, MQ_DATA_TYPE,
+		    O_RDWR, 0666, &err)) < 0)
+			goto out;
+		cr_flag = DFILE_OPEN;
+
+		/* Message queue has not been initialized yet */
+		if (read(fd, &total_size, sizeof (total_size)) !=
+		    sizeof (total_size) || total_size == 0) {
+			errno = ENOENT;
+			goto out;
+		}
+
+		/* Message queue too big for this process to handle */
+		if (total_size > SSIZE_MAX) {
+			errno = EFBIG;
+			goto out;
+		}
+	}
+
+	if ((mqdp = (mqdes_t *)malloc(sizeof (mqdes_t))) == NULL) {
+		errno = ENOMEM;
+		goto out;
+	}
+	cr_flag |= ALLOC_MEM;
+
+	if ((ptr = mmap64(NULL, total_size, PROT_READ|PROT_WRITE,
+	    MAP_SHARED, fd, (off64_t)0)) == MAP_FAILED)
+		goto out;
+	mqhp = ptr;
+	cr_flag |= DFILE_MMAP;
+
+	/* closing data file */
+	(void) __close_nc(fd);
+	cr_flag &= ~DFILE_OPEN;
+
+	/*
+	 * create, unlink, size, mmap, and close description file
+	 * all for a flag word in anonymous shared memory
+	 */
+	if ((fd = __pos4obj_open(path, MQ_DSCN_TYPE, O_RDWR | O_CREAT,
+	    0666, &err)) < 0)
+		goto out;
+	cr_flag |= DFILE_OPEN;
+	(void) __pos4obj_unlink(path, MQ_DSCN_TYPE);
+	if (ftruncate64(fd, (off64_t)sizeof (struct mq_dn)) < 0)
+		goto out;
+
+	if ((ptr = mmap64(NULL, sizeof (struct mq_dn),
+	    PROT_READ | PROT_WRITE, MAP_SHARED, fd, (off64_t)0)) == MAP_FAILED)
+		goto out;
+	mqdnp = ptr;
+	cr_flag |= MQDNP_MMAP;
+
+	(void) __close_nc(fd);
+	cr_flag &= ~DFILE_OPEN;
+
+	/*
+	 * we follow the same strategy as filesystem open() routine,
+	 * where fcntl.h flags are changed to flags defined in file.h.
+	 */
+	mqdp->mqd_flags = (oflag - FOPEN) & (FREAD|FWRITE);
+	mqdnp->mqdn_flags = (oflag - FOPEN) & (FNONBLOCK);
+
+	/* new message queue requires initialization */
+	if ((cr_flag & DFILE_CREATE) != 0) {
+		/* message queue header has to be initialized */
+		mq_init(mqhp, msgsize, maxmsg);
+		mqhp->mq_totsize = total_size;
+	}
+	mqdp->mqd_mq = mqhp;
+	mqdp->mqd_mqdn = mqdnp;
+	mqdp->mqd_magic = MQ_MAGIC;
+	if (__pos4obj_unlock(path, MQ_LOCK_TYPE) == 0) {
+		*open_slot = mqdp;
+		return ((mqd_t)mqdp);
+	}
+	locked = 0;	/* fall into the error case */
+out:
+	err = errno;
+	if ((cr_flag & DFILE_OPEN) != 0)
+		(void) __close_nc(fd);
+	if ((cr_flag & DFILE_CREATE) != 0)
+		(void) __pos4obj_unlink(path, MQ_DATA_TYPE);
+	if ((cr_flag & PFILE_CREATE) != 0)
+		(void) __pos4obj_unlink(path, MQ_PERM_TYPE);
+	if ((cr_flag & ALLOC_MEM) != 0)
+		free((void *)mqdp);
+	if ((cr_flag & DFILE_MMAP) != 0)
+		(void) munmap((caddr_t)mqhp, (size_t)total_size);
+	if ((cr_flag & MQDNP_MMAP) != 0)
+		(void) munmap((caddr_t)mqdnp, sizeof (struct mq_dn));
+	if (open_slot) {
+		(void) mutex_lock(&mqlock);
+		*open_slot = NULL;
+		open_count--;
+		(void) mutex_unlock(&mqlock);
+	}
+	if (locked)
+		(void) __pos4obj_unlock(path, MQ_LOCK_TYPE);
+	errno = err;
+	return ((mqd_t)-1);
+}
+
+int
+_mq_close(mqd_t mqdes)
+{
+	mqdes_t *mqdp = (mqdes_t *)mqdes;
+	mqhdr_t *mqhp;
+	struct mq_dn *mqdnp;
+	int canstate;
+	int i;
+
+	if (!mq_is_valid(mqdp)) {
+		errno = EBADF;
+		return (-1);
+	}
+
+	mqhp = mqdp->mqd_mq;
+	mqdnp = mqdp->mqd_mqdn;
+
+	(void) pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &canstate);
+	while (sem_wait(&mqhp->mq_exclusive) == -1 && errno == EINTR)
+		continue;
+	(void) pthread_setcancelstate(canstate, NULL);
+
+	if (mqhp->mq_des == (uintptr_t)mqdp &&
+	    mqhp->mq_sigid.sn_pid == getpid()) {
+		/* Notification is set for this descriptor, remove it */
+		(void) __signotify(SN_CANCEL, NULL, &mqhp->mq_sigid);
+		mqhp->mq_sigid.sn_pid = 0;
+		mqhp->mq_des = 0;
+	}
+	(void) sem_post(&mqhp->mq_exclusive);
+
+	(void) mutex_lock(&mqlock);
+	open_count--;
+	/* vacate the queue's open_queue[] slot */
+	for (i = 0; i < _MQ_OPEN_MAX; i++) {
+		if (open_queue[i] == mqdp) {
+			open_queue[i] = NULL;
+			break;
+		}
+	}
+	(void) mutex_unlock(&mqlock);
+	/* Invalidate the descriptor before freeing it */
+	mqdp->mqd_magic = 0;
+	free(mqdp);
+
+	(void) munmap((caddr_t)mqdnp, sizeof (struct mq_dn));
+	return (munmap((caddr_t)mqhp, (size_t)mqhp->mq_totsize));
+}
+
+int
+_mq_unlink(const char *path)
+{
+	int err;
+
+	if (__pos4obj_check(path) < 0)
+		return (-1);
+
+	if (__pos4obj_lock(path, MQ_LOCK_TYPE) < 0) {
+		return (-1);
+	}
+
+	err = __pos4obj_unlink(path, MQ_PERM_TYPE);
+
+	if (err == 0 || (err == -1 && errno == EEXIST)) {
+		errno = 0;
+		err = __pos4obj_unlink(path, MQ_DATA_TYPE);
+	}
+
+	if (__pos4obj_unlock(path, MQ_LOCK_TYPE) < 0)
+		return (-1);
+
+	return (err);
+
+}
+
+static int
+__mq_timedsend(mqd_t mqdes, const char *msg_ptr, size_t msg_len,
+	uint_t msg_prio, const timespec_t *timeout, int abs_rel)
+{
+	mqdes_t *mqdp = (mqdes_t *)mqdes;
+	mqhdr_t *mqhp;
+	int err;
+	int canstate;
+	int notify = 0;
+
+	/*
+	 * sem_*wait() does cancellation, if called.
+	 * pthread_testcancel() ensures that cancellation takes place if
+	 * there is a cancellation pending when mq_*send() is called.
+	 */
+	pthread_testcancel();
+
+	if (!mq_is_valid(mqdp) || (mqdp->mqd_flags & FWRITE) == 0) {
+		errno = EBADF;
+		return (-1);
+	}
+
+	mqhp = mqdp->mqd_mq;
+
+	if (msg_prio >= mqhp->mq_maxprio) {
+		errno = EINVAL;
+		return (-1);
+	}
+	if (msg_len > mqhp->mq_maxsz) {
+		errno = EMSGSIZE;
+		return (-1);
+	}
+
+	if ((mqdp->mqd_mqdn->mqdn_flags & O_NONBLOCK) != 0)
+		err = sem_trywait(&mqhp->mq_notfull);
+	else {
+		/*
+		 * We might get cancelled here...
+		 */
+		if (timeout == NULL)
+			err = sem_wait(&mqhp->mq_notfull);
+		else if (abs_rel == ABS_TIME)
+			err = sem_timedwait(&mqhp->mq_notfull, timeout);
+		else
+			err = sem_reltimedwait_np(&mqhp->mq_notfull, timeout);
+	}
+	if (err == -1) {
+		/*
+		 * errno has been set to EAGAIN / EINTR / ETIMEDOUT
+		 * by sem_*wait(), so we can just return.
+		 */
+		return (-1);
+	}
+
+	/*
+	 * By the time we're here, we know that we've got the capacity
+	 * to add to the queue...now acquire the exclusive lock.
+	 */
+	(void) pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &canstate);
+	err = sem_wait(&mqhp->mq_exclusive);
+	(void) pthread_setcancelstate(canstate, NULL);
+	if (err == -1) {
+		/*
+		 * We must have been interrupted by a signal.
+		 * Post on mq_notfull so someone else can take our slot.
+		 */
+		(void) sem_post(&mqhp->mq_notfull);
+		return (-1);
+	}
+
+	/*
+	 * Now determine if we want to kick the notification.  POSIX
+	 * requires that if a process has registered for notification,
+	 * we must kick it when the queue makes an empty to non-empty
+	 * transition, and there are no blocked receivers.  Note that
+	 * this mechanism does _not_ guarantee that the kicked process
+	 * will be able to receive a message without blocking;  another
+	 * receiver could intervene in the meantime.  Thus,
+	 * the notification mechanism is inherently racy;  all we can
+	 * do is hope to minimize the window as much as possible.  In
+	 * general, we want to avoid kicking the notification when
+	 * there are clearly receivers blocked.  We'll determine if we
+	 * want to kick the notification before the mq_putmsg(), but the
+	 * actual signotify() won't be done until the message is on
+	 * the queue.
+	 */
+	if (mqhp->mq_sigid.sn_pid != 0) {
+		int nmessages, nblocked;
+		(void) sem_getvalue(&mqhp->mq_notempty, &nmessages);
+		(void) sem_getvalue(&mqhp->mq_rblocked, &nblocked);
+
+		if (nmessages == 0 && nblocked == 0)
+			notify = 1;
+	}
+
+	mq_putmsg(mqhp, msg_ptr, (ssize_t)msg_len, msg_prio);
+
+	/*
+	 * The ordering here is important.  We want to make sure that
+	 * one has to have mq_exclusive before being able to kick
+	 * mq_notempty.
+	 */
+	(void) sem_post(&mqhp->mq_notempty);
+
+	if (notify) {
+		(void) __signotify(SN_SEND, NULL, &mqhp->mq_sigid);
+		mqhp->mq_sigid.sn_pid = 0;
+		mqhp->mq_des = 0;
+	}
+
+	(void) sem_post(&mqhp->mq_exclusive);
+	MQ_ASSERT_SEMVAL_LEQ(&mqhp->mq_notempty, ((int)mqhp->mq_maxmsg));
+
+	return (0);
+}
+
+int
+_mq_send(mqd_t mqdes, const char *msg_ptr, size_t msg_len, uint_t msg_prio)
+{
+	return (__mq_timedsend(mqdes, msg_ptr, msg_len, msg_prio,
+		NULL, ABS_TIME));
+}
+
+int
+_mq_timedsend(mqd_t mqdes, const char *msg_ptr, size_t msg_len,
+	uint_t msg_prio, const timespec_t *abs_timeout)
+{
+	return (__mq_timedsend(mqdes, msg_ptr, msg_len, msg_prio,
+		abs_timeout, ABS_TIME));
+}
+
+int
+_mq_reltimedsend_np(mqd_t mqdes, const char *msg_ptr, size_t msg_len,
+	uint_t msg_prio, const timespec_t *rel_timeout)
+{
+	return (__mq_timedsend(mqdes, msg_ptr, msg_len, msg_prio,
+		rel_timeout, REL_TIME));
+}
+
+static void
+decrement_rblocked(mqhdr_t *mqhp)
+{
+	int canstate;
+
+	(void) pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &canstate);
+	while (sem_wait(&mqhp->mq_rblocked) == -1)
+		continue;
+	(void) pthread_setcancelstate(canstate, NULL);
+}
+
+static ssize_t
+__mq_timedreceive(mqd_t mqdes, char *msg_ptr, size_t msg_len,
+	uint_t *msg_prio, const timespec_t *timeout, int abs_rel)
+{
+	mqdes_t *mqdp = (mqdes_t *)mqdes;
+	mqhdr_t *mqhp;
+	ssize_t	msg_size;
+	int canstate;
+	int err;
+
+	/*
+	 * sem_*wait() does cancellation, if called.
+	 * pthread_testcancel() ensures that cancellation takes place if
+	 * there is a cancellation pending when mq_*receive() is called.
+	 */
+	pthread_testcancel();
+
+	if (!mq_is_valid(mqdp) || (mqdp->mqd_flags & FREAD) == 0) {
+		errno = EBADF;
+		return (ssize_t)(-1);
+	}
+
+	mqhp = mqdp->mqd_mq;
+
+	if (msg_len < mqhp->mq_maxsz) {
+		errno = EMSGSIZE;
+		return (ssize_t)(-1);
+	}
+
+	/*
+	 * The semaphoring scheme for mq_[timed]receive is a little hairy
+	 * thanks to POSIX.1b's arcane notification mechanism.  First,
+	 * we try to take the common case and do a sem_trywait().
+	 * If that doesn't work, and O_NONBLOCK hasn't been set,
+	 * then note that we're going to sleep by incrementing the rblocked
+	 * semaphore.  We decrement that semaphore after waking up.
+	 */
+	if (sem_trywait(&mqhp->mq_notempty) == -1) {
+		if ((mqdp->mqd_mqdn->mqdn_flags & O_NONBLOCK) != 0) {
+			/*
+			 * errno has been set to EAGAIN or EINTR by
+			 * sem_trywait(), so we can just return.
+			 */
+			return (-1);
+		}
+		/*
+		 * If we're here, then we're probably going to block...
+		 * increment the rblocked semaphore.  If we get
+		 * cancelled, decrement_rblocked() will decrement it.
+		 */
+		(void) sem_post(&mqhp->mq_rblocked);
+
+		pthread_cleanup_push(decrement_rblocked, mqhp);
+		if (timeout == NULL)
+			err = sem_wait(&mqhp->mq_notempty);
+		else if (abs_rel == ABS_TIME)
+			err = sem_timedwait(&mqhp->mq_notempty, timeout);
+		else
+			err = sem_reltimedwait_np(&mqhp->mq_notempty, timeout);
+		pthread_cleanup_pop(1);
+
+		if (err == -1) {
+			/*
+			 * We took a signal or timeout while waiting
+			 * on mq_notempty...
+			 */
+			return (-1);
+		}
+	}
+
+	(void) pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &canstate);
+	err = sem_wait(&mqhp->mq_exclusive);
+	(void) pthread_setcancelstate(canstate, NULL);
+	if (err == -1) {
+		/*
+		 * We must have been interrupted by a signal.
+		 * Post on mq_notfull so someone else can take our message.
+		 */
+		(void) sem_post(&mqhp->mq_notempty);
+		return (-1);
+	}
+
+	msg_size = mq_getmsg(mqhp, msg_ptr, msg_prio);
+
+	(void) sem_post(&mqhp->mq_notfull);
+	(void) sem_post(&mqhp->mq_exclusive);
+	MQ_ASSERT_SEMVAL_LEQ(&mqhp->mq_notfull, ((int)mqhp->mq_maxmsg));
+
+	return (msg_size);
+}
+
+ssize_t
+_mq_receive(mqd_t mqdes, char *msg_ptr, size_t msg_len, uint_t *msg_prio)
+{
+	return (__mq_timedreceive(mqdes, msg_ptr, msg_len, msg_prio,
+		NULL, ABS_TIME));
+}
+
+ssize_t
+_mq_timedreceive(mqd_t mqdes, char *msg_ptr, size_t msg_len,
+	uint_t *msg_prio, const timespec_t *abs_timeout)
+{
+	return (__mq_timedreceive(mqdes, msg_ptr, msg_len, msg_prio,
+		abs_timeout, ABS_TIME));
+}
+
+ssize_t
+_mq_reltimedreceive_np(mqd_t mqdes, char *msg_ptr, size_t msg_len,
+	uint_t *msg_prio, const timespec_t *rel_timeout)
+{
+	return (__mq_timedreceive(mqdes, msg_ptr, msg_len, msg_prio,
+		rel_timeout, REL_TIME));
+}
+
+int
+_mq_notify(mqd_t mqdes, const struct sigevent *notification)
+{
+	mqdes_t *mqdp = (mqdes_t *)mqdes;
+	mqhdr_t *mqhp;
+	int canstate;
+	siginfo_t mq_siginfo;
+
+	if (!mq_is_valid(mqdp)) {
+		errno = EBADF;
+		return (-1);
+	}
+
+	mqhp = mqdp->mqd_mq;
+
+	(void) pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &canstate);
+	while (sem_wait(&mqhp->mq_exclusive) == -1 && errno == EINTR)
+		continue;
+	(void) pthread_setcancelstate(canstate, NULL);
+
+	if (notification == NULL) {
+		if (mqhp->mq_des == (uintptr_t)mqdp &&
+		    mqhp->mq_sigid.sn_pid == getpid()) {
+			/*
+			 * Remove signotify_id if queue is registered with
+			 * this process
+			 */
+			(void) __signotify(SN_CANCEL, NULL, &mqhp->mq_sigid);
+			mqhp->mq_sigid.sn_pid = 0;
+			mqhp->mq_des = 0;
+		} else {
+			/*
+			 * if registered with another process or mqdes
+			 */
+			errno = EBUSY;
+			goto bad;
+		}
+	} else {
+		/*
+		 * Register notification with this process.
+		 */
+
+		switch (notification->sigev_notify) {
+		case SIGEV_NONE:
+			mq_siginfo.si_signo = 0;
+			mq_siginfo.si_code = SI_MESGQ;
+			break;
+		case SIGEV_SIGNAL:
+			mq_siginfo.si_signo = notification->sigev_signo;
+			mq_siginfo.si_value = notification->sigev_value;
+			mq_siginfo.si_code = SI_MESGQ;
+			break;
+		case SIGEV_THREAD:
+			errno = ENOSYS;
+			goto bad;
+		default:
+			errno = EINVAL;
+			goto bad;
+		}
+
+		/*
+		 * Either notification is not present, or if
+		 * notification is already present, but the process
+		 * which registered notification does not exist then
+		 * kernel can register notification for current process.
+		 */
+
+		if (__signotify(SN_PROC, &mq_siginfo, &mqhp->mq_sigid) < 0)
+			goto bad;
+		mqhp->mq_des = (uintptr_t)mqdp;
+	}
+
+	(void) sem_post(&mqhp->mq_exclusive);
+	return (0);
+
+bad:
+	(void) sem_post(&mqhp->mq_exclusive);
+	return (-1);
+}
+
+int
+_mq_setattr(mqd_t mqdes, const struct mq_attr *mqstat, struct mq_attr *omqstat)
+{
+	mqdes_t *mqdp = (mqdes_t *)mqdes;
+	mqhdr_t *mqhp;
+	uint_t	flag = 0;
+
+	if (!mq_is_valid(mqdp)) {
+		errno = EBADF;
+		return (-1);
+	}
+
+	/* store current attributes */
+	if (omqstat != NULL) {
+		int	count;
+
+		mqhp = mqdp->mqd_mq;
+		omqstat->mq_flags = mqdp->mqd_mqdn->mqdn_flags;
+		omqstat->mq_maxmsg = (long)mqhp->mq_maxmsg;
+		omqstat->mq_msgsize = (long)mqhp->mq_maxsz;
+		(void) sem_getvalue(&mqhp->mq_notempty, &count);
+		omqstat->mq_curmsgs = count;
+	}
+
+	/* set description attributes */
+	if ((mqstat->mq_flags & O_NONBLOCK) != 0)
+		flag = FNONBLOCK;
+	mqdp->mqd_mqdn->mqdn_flags = flag;
+
+	return (0);
+}
+
+int
+_mq_getattr(mqd_t mqdes, struct mq_attr *mqstat)
+{
+	mqdes_t *mqdp = (mqdes_t *)mqdes;
+	mqhdr_t *mqhp;
+	int count;
+
+	if (!mq_is_valid(mqdp)) {
+		errno = EBADF;
+		return (-1);
+	}
+
+	mqhp = mqdp->mqd_mq;
+
+	mqstat->mq_flags = mqdp->mqd_mqdn->mqdn_flags;
+	mqstat->mq_maxmsg = (long)mqhp->mq_maxmsg;
+	mqstat->mq_msgsize = (long)mqhp->mq_maxsz;
+	(void) sem_getvalue(&mqhp->mq_notempty, &count);
+	mqstat->mq_curmsgs = count;
+	return (0);
+}