port/rt/sem.c

/*
 * 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 (c) 1994, 2011, Oracle and/or its affiliates. All rights reserved.
 */

#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;

    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);
}