sem.c revision 7257d1b4d25bfac0c802847390e98a464fd787ac
/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (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 2008 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
#pragma ident "%Z%%M% %I% %E% SMI"
#include "lint.h"
#include "mtlib.h"
#include <sys/types.h>
#include <semaphore.h>
#include <synch.h>
#include <errno.h>
#include <stdarg.h>
#include <limits.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <unistd.h>
#include <thread.h>
#include "pos4obj.h"
typedef struct semaddr {
struct semaddr *sad_next; /* next in the link */
char sad_name[PATH_MAX + 1]; /* name of sem object */
sem_t *sad_addr; /* mmapped address of semaphore */
ino64_t sad_inode; /* inode # of the mmapped file */
} semaddr_t;
static long semvaluemax = 0;
static semaddr_t *semheadp = NULL;
static mutex_t semlock = DEFAULTMUTEX;
sem_t *
sem_open(const char *path, int oflag, /* mode_t mode, int value */ ...)
{
va_list ap;
mode_t crmode = 0;
sem_t *sem = NULL;
struct stat64 statbuf;
semaddr_t *next = NULL;
int fd = 0;
int error = 0;
int cr_flag = 0;
uint_t value = 0;
if (__pos4obj_check(path) == -1)
return (SEM_FAILED);
/* acquire semaphore lock to have atomic operation */
if (__pos4obj_lock(path, SEM_LOCK_TYPE) < 0)
return (SEM_FAILED);
/* modify oflag to have RDWR and filter CREATE mode only */
oflag = (oflag & (O_CREAT|O_EXCL)) | (O_RDWR);
if (oflag & O_CREAT) {
if (semvaluemax == 0 &&
(semvaluemax = _sysconf(_SC_SEM_VALUE_MAX)) <= 0)
semvaluemax = -1;
va_start(ap, oflag);
crmode = va_arg(ap, mode_t);
value = va_arg(ap, uint_t);
va_end(ap);
/* check value < the max for a named semaphore */
if (semvaluemax < 0 ||
(ulong_t)value > (ulong_t)semvaluemax) {
errno = EINVAL;
goto out;
}
}
errno = 0;
if ((fd = __pos4obj_open(path, SEM_DATA_TYPE,
oflag, crmode, &cr_flag)) < 0)
goto out;
if (cr_flag)
cr_flag = DFILE_CREATE | DFILE_OPEN;
else
cr_flag = DFILE_OPEN;
/* find out inode # for the opened file */
if (fstat64(fd, &statbuf) < 0)
goto out;
/* if created, acquire total_size in the file */
if ((cr_flag & DFILE_CREATE) != 0) {
if (ftruncate64(fd, (off64_t)sizeof (sem_t)) < 0)
goto out;
} else {
/*
* if this semaphore has already been opened, inode
* will indicate then return the same semaphore address
*/
lmutex_lock(&semlock);
for (next = semheadp; next != NULL; next = next->sad_next) {
if (statbuf.st_ino == next->sad_inode &&
strcmp(path, next->sad_name) == 0) {
(void) __close_nc(fd);
lmutex_unlock(&semlock);
(void) __pos4obj_unlock(path, SEM_LOCK_TYPE);
return (next->sad_addr);
}
}
lmutex_unlock(&semlock);
}
/* new sem descriptor to be allocated and new address to be mapped */
if ((next = malloc(sizeof (semaddr_t))) == NULL) {
errno = ENOMEM;
goto out;
}
cr_flag |= ALLOC_MEM;
/* LINTED */
sem = (sem_t *)mmap64(NULL, sizeof (sem_t), PROT_READ|PROT_WRITE,
MAP_SHARED, fd, (off64_t)0);
(void) __close_nc(fd);
cr_flag &= ~DFILE_OPEN;
if (sem == MAP_FAILED)
goto out;
cr_flag |= DFILE_MMAP;
/* if created, initialize */
if (cr_flag & DFILE_CREATE) {
error = sema_init((sema_t *)sem, value, USYNC_PROCESS, 0);
if (error) {
errno = error;
goto out;
}
}
if (__pos4obj_unlock(path, SEM_LOCK_TYPE) == 0) {
/* add to the list pointed by semheadp */
lmutex_lock(&semlock);
next->sad_next = semheadp;
semheadp = next;
next->sad_addr = sem;
next->sad_inode = statbuf.st_ino;
(void) strcpy(next->sad_name, path);
lmutex_unlock(&semlock);
return (sem);
}
/* fall into the error case */
out:
error = errno;
if ((cr_flag & DFILE_OPEN) != 0)
(void) __close_nc(fd);
if ((cr_flag & DFILE_CREATE) != 0)
(void) __pos4obj_unlink(path, SEM_DATA_TYPE);
if ((cr_flag & ALLOC_MEM) != 0)
free(next);
if ((cr_flag & DFILE_MMAP) != 0)
(void) munmap((caddr_t)sem, sizeof (sem_t));
(void) __pos4obj_unlock(path, SEM_LOCK_TYPE);
errno = error;
return (SEM_FAILED);
}
int
sem_close(sem_t *sem)
{
semaddr_t **next;
semaddr_t *freeit;
lmutex_lock(&semlock);
for (next = &semheadp; (freeit = *next) != NULL;
next = &(freeit->sad_next)) {
if (freeit->sad_addr == sem) {
*next = freeit->sad_next;
lmutex_unlock(&semlock);
free(freeit);
return (munmap((caddr_t)sem, sizeof (sem_t)));
}
}
lmutex_unlock(&semlock);
errno = EINVAL;
return (-1);
}
int
sem_unlink(const char *path)
{
int error;
int oerrno;
if (__pos4obj_check(path) < 0)
return (-1);
if (__pos4obj_lock(path, SEM_LOCK_TYPE) < 0)
return (-1);
error = __pos4obj_unlink(path, SEM_DATA_TYPE);
oerrno = errno;
(void) __pos4obj_unlock(path, SEM_LOCK_TYPE);
errno = oerrno;
return (error);
}
/*
* SUSV3 requires ("shall fail") an EINVAL failure for operations
* on invalid semaphores, including uninitialized unnamed semaphores.
* The best we can do is check that the magic number is correct.
* This is not perfect, but it allows the test suite to pass.
* (Standards bodies are filled with fools and idiots.)
*/
static int
sem_invalid(sem_t *sem)
{
if (sem->sem_magic != SEMA_MAGIC) {
errno = EINVAL;
return (-1);
}
return (0);
}
int
sem_init(sem_t *sem, int pshared, uint_t value)
{
int error;
if ((error = sema_init((sema_t *)sem, value,
pshared ? USYNC_PROCESS : USYNC_THREAD, NULL)) != 0) {
errno = error;
return (-1);
}
return (0);
}
int
sem_destroy(sem_t *sem)
{
int error;
if (sem_invalid(sem))
return (-1);
if ((error = sema_destroy((sema_t *)sem)) != 0) {
errno = error;
return (-1);
}
return (0);
}
int
sem_post(sem_t *sem)
{
int error;
if (sem_invalid(sem))
return (-1);
if ((error = sema_post((sema_t *)sem)) != 0) {
errno = error;
return (-1);
}
return (0);
}
int
sem_wait(sem_t *sem)
{
int error;
if (sem_invalid(sem))
return (-1);
if ((error = sema_wait((sema_t *)sem)) != 0) {
errno = error;
return (-1);
}
return (0);
}
int
sem_timedwait(sem_t *sem, const timespec_t *abstime)
{
int error;
if (sem_invalid(sem))
return (-1);
if ((error = sema_timedwait((sema_t *)sem, abstime)) != 0) {
if (error == ETIME)
error = ETIMEDOUT;
errno = error;
return (-1);
}
return (0);
}
int
sem_reltimedwait_np(sem_t *sem, const timespec_t *reltime)
{
int error;
if (sem_invalid(sem))
return (-1);
if ((error = sema_reltimedwait((sema_t *)sem, reltime)) != 0) {
if (error == ETIME)
error = ETIMEDOUT;
errno = error;
return (-1);
}
return (0);
}
int
sem_trywait(sem_t *sem)
{
int error;
if (sem_invalid(sem))
return (-1);
if ((error = sema_trywait((sema_t *)sem)) != 0) {
if (error == EBUSY)
error = EAGAIN;
errno = error;
return (-1);
}
return (0);
}
int
sem_getvalue(sem_t *sem, int *sval)
{
if (sem_invalid(sem))
return (-1);
*sval = (int)sem->sem_count;
return (0);
}