mutex.c 5.88 KB
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/*
 * Server-side mutex management
 *
 * Copyright (C) 1998 Alexandre Julliard
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 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
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 */

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#include "config.h"
#include "wine/port.h"

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#include <assert.h>
#include <stdio.h>
#include <stdlib.h>

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#include "windef.h"
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#include "handle.h"
#include "thread.h"
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#include "request.h"
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struct mutex
{
    struct object  obj;             /* object header */
    struct thread *owner;           /* mutex owner */
    unsigned int   count;           /* recursion count */
    int            abandoned;       /* has it been abandoned? */
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    struct list    entry;           /* entry in owner thread mutex list */
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};

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static void mutex_dump( struct object *obj, int verbose );
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static int mutex_signaled( struct object *obj, struct thread *thread );
static int mutex_satisfied( struct object *obj, struct thread *thread );
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static void mutex_destroy( struct object *obj );
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static int mutex_signal( struct object *obj, unsigned int access );
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static const struct object_ops mutex_ops =
{
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    sizeof(struct mutex),      /* size */
    mutex_dump,                /* dump */
    add_queue,                 /* add_queue */
    remove_queue,              /* remove_queue */
    mutex_signaled,            /* signaled */
    mutex_satisfied,           /* satisfied */
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    mutex_signal,              /* signal */
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    no_get_fd,                 /* get_fd */
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    mutex_destroy              /* destroy */
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};


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static struct mutex *create_mutex( const WCHAR *name, size_t len, int owned )
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{
    struct mutex *mutex;

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    if ((mutex = create_named_object( sync_namespace, &mutex_ops, name, len )))
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    {
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        if (get_error() != STATUS_OBJECT_NAME_COLLISION)
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        {
            /* initialize it if it didn't already exist */
            mutex->count = 0;
            mutex->owner = NULL;
            mutex->abandoned = 0;
            if (owned) mutex_satisfied( &mutex->obj, current );
        }
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    }
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    return mutex;
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}

/* release a mutex once the recursion count is 0 */
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static void do_release( struct mutex *mutex )
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{
    assert( !mutex->count );
    /* remove the mutex from the thread list of owned mutexes */
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    list_remove( &mutex->entry );
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    mutex->owner = NULL;
    wake_up( &mutex->obj, 0 );
}

void abandon_mutexes( struct thread *thread )
{
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    struct list *ptr;

    while ((ptr = list_head( &thread->mutex_list )) != NULL)
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    {
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        struct mutex *mutex = LIST_ENTRY( ptr, struct mutex, entry );
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        assert( mutex->owner == thread );
        mutex->count = 0;
        mutex->abandoned = 1;
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        do_release( mutex );
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    }
}

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static void mutex_dump( struct object *obj, int verbose )
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{
    struct mutex *mutex = (struct mutex *)obj;
    assert( obj->ops == &mutex_ops );
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    fprintf( stderr, "Mutex count=%u owner=%p ", mutex->count, mutex->owner );
    dump_object_name( &mutex->obj );
    fputc( '\n', stderr );
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}

static int mutex_signaled( struct object *obj, struct thread *thread )
{
    struct mutex *mutex = (struct mutex *)obj;
    assert( obj->ops == &mutex_ops );
    return (!mutex->count || (mutex->owner == thread));
}

static int mutex_satisfied( struct object *obj, struct thread *thread )
{
    struct mutex *mutex = (struct mutex *)obj;
    assert( obj->ops == &mutex_ops );
    assert( !mutex->count || (mutex->owner == thread) );

    if (!mutex->count++)  /* FIXME: avoid wrap-around */
    {
        assert( !mutex->owner );
        mutex->owner = thread;
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        list_add_head( &thread->mutex_list, &mutex->entry );
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    }
    if (!mutex->abandoned) return 0;
    mutex->abandoned = 0;
    return 1;
}

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static int mutex_signal( struct object *obj, unsigned int access )
{
    struct mutex *mutex = (struct mutex *)obj;
    assert( obj->ops == &mutex_ops );

    if (!(access & SYNCHRONIZE))  /* FIXME: MUTEX_MODIFY_STATE? */
    {
        set_error( STATUS_ACCESS_DENIED );
        return 0;
    }
    if (!mutex->count || (mutex->owner != current))
    {
        set_error( STATUS_MUTANT_NOT_OWNED );
        return 0;
    }
    if (!--mutex->count) do_release( mutex );
    return 1;
}

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static void mutex_destroy( struct object *obj )
{
    struct mutex *mutex = (struct mutex *)obj;
    assert( obj->ops == &mutex_ops );

    if (!mutex->count) return;
    mutex->count = 0;
    do_release( mutex );
}

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/* create a mutex */
DECL_HANDLER(create_mutex)
{
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    struct mutex *mutex;

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    reply->handle = 0;
    if ((mutex = create_mutex( get_req_data(), get_req_data_size(), req->owned )))
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    {
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        reply->handle = alloc_handle( current->process, mutex, req->access, req->inherit );
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        release_object( mutex );
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    }
}

/* open a handle to a mutex */
DECL_HANDLER(open_mutex)
{
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    reply->handle = open_object( sync_namespace, get_req_data(), get_req_data_size(),
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                                 &mutex_ops, req->access, req->inherit );
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}

/* release a mutex */
DECL_HANDLER(release_mutex)
{
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    struct mutex *mutex;

    if ((mutex = (struct mutex *)get_handle_obj( current->process, req->handle,
                                                 MUTEX_MODIFY_STATE, &mutex_ops )))
    {
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        if (!mutex->count || (mutex->owner != current)) set_error( STATUS_MUTANT_NOT_OWNED );
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        else
        {
            reply->prev_count = mutex->count;
            if (!--mutex->count) do_release( mutex );
        }
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        release_object( mutex );
    }
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}