389-ds-base/lib/base/fsmutex.cpp

/** BEGIN COPYRIGHT BLOCK
 * Copyright (C) 2001 Sun Microsystems, Inc. Used by permission.
 * Copyright (C) 2005 Red Hat, Inc.
 * All rights reserved.
 *
 * License: GPL (version 3 or any later version).
 * See LICENSE for details. 
 * END COPYRIGHT BLOCK **/

#ifdef HAVE_CONFIG_H
#  include <config.h>
#endif

/*
 * fsmutex: Mutexes that are filesystem-based so they're available from more
 * than one process and address space
 * 
 * Rob McCool
 */

#include "base/fsmutex.h"
#ifdef THREAD_ANY
#include "base/crit.h"
#include "base/systhr.h"
#endif

#include "base/util.h"

#include "base/file.h"
typedef SYS_FILE sys_fsmutex_t;


typedef struct {
    sys_fsmutex_t mutex;
    char *id;
#ifdef THREAD_ANY
    CRITICAL crit;
#endif
    int flags;
} fsmutex_s;



/* ----------------------------- fsmutex_init ----------------------------- */


static int 
_fsmutex_create(fsmutex_s *fsm, char *name, int number)
{
    char tn[256];
    SYS_FILE lfd;
    int visible = (fsm->flags & FSMUTEX_VISIBLE ? 1 : 0);

    util_snprintf(tn, 256, "/tmp/%s.%d", name, number);
    if(!visible)
        unlink(tn);
    if( (lfd = PR_Open(tn, PR_RDWR|PR_CREATE_FILE, 0644)) == NULL)
        return -1;

    if(!visible)
        unlink(tn);
    else
        fsm->id = PERM_STRDUP(tn);
    fsm->mutex = lfd;
    return 0;
}

NSAPI_PUBLIC FSMUTEX
fsmutex_init(char *name, int number, int flags)
{
    fsmutex_s *ret = (fsmutex_s *) PERM_MALLOC(sizeof(fsmutex_s));

    ret->flags = flags;
    if(_fsmutex_create(ret, name, number) == -1) {
        PERM_FREE(ret);
        return NULL;
    }
#ifdef THREAD_ANY
    if(flags & FSMUTEX_NEEDCRIT)
        ret->crit = crit_init();
#endif
    return (FSMUTEX) ret;
}

NSAPI_PUBLIC void 
fsmutex_setowner(FSMUTEX fsm, uid_t uid, gid_t gid)
{
    if(!geteuid()) {
        int rc = chown( ((fsmutex_s *)fsm)->id, uid, gid);
        PR_ASSERT(rc == 0);
        if (rc != 0 ) {
            return; /* just to suppress compiler warning... */
        }
    }
}

/* -------------------------- fsmutex_terminate --------------------------- */

static void 
_fsmutex_delete(fsmutex_s *fsm)
{
    if(fsm->flags & FSMUTEX_VISIBLE)
        unlink(fsm->id);
    PERM_FREE(fsm->id);
    PR_Close(fsm->mutex);
}

NSAPI_PUBLIC void
fsmutex_terminate(FSMUTEX id)
{
    fsmutex_s *fsm = (fsmutex_s *) id;

    _fsmutex_delete(fsm);
#ifdef THREAD_ANY
    if(fsm->flags & FSMUTEX_NEEDCRIT)
        crit_terminate(fsm->crit);
#endif
    PERM_FREE(fsm);
}


/* ----------------------------- fsmutex_lock ----------------------------- */


NSAPI_PUBLIC void
fsmutex_lock(FSMUTEX id)
{
    fsmutex_s *fsm = (fsmutex_s *) id;
#ifdef THREAD_ANY
    if(fsm->flags & FSMUTEX_NEEDCRIT)
        crit_enter(fsm->crit);
#endif
#ifdef THREAD_NSPR_USER
    /* Poll to avoid blocking. XXXrobm If errno is wrong this may go awry. */
    while(system_tlock(fsm->mutex) == -1)
        systhread_sleep(1000);
#else
    system_flock(fsm->mutex );
#endif
}


/* ---------------------------- fsmutex_unlock ---------------------------- */


NSAPI_PUBLIC void
fsmutex_unlock(FSMUTEX id)
{
    fsmutex_s *fsm = (fsmutex_s *) id;
    system_ulock(fsm->mutex);
#ifdef THREAD_ANY
    if(fsm->flags & FSMUTEX_NEEDCRIT)
        crit_exit(fsm->crit);
#endif
}