server/mutex.c

   1 /*
   2  * Server-side mutex management
   3  *
   4  * Copyright (C) 1998 Alexandre Julliard
   5  *
   6  * This library is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Lesser General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2.1 of the License, or (at your option) any later version.
  10  *
  11  * This library is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public
  17  * License along with this library; if not, write to the Free Software
  18  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  19  */
  20
  21 #include "config.h"
  22 #include "wine/port.h"
  23
  24 #include <assert.h>
  25 #include <stdio.h>
  26 #include <stdlib.h>
  27
  28 #include "windef.h"
  29
  30 #include "handle.h"
  31 #include "thread.h"
  32 #include "request.h"
  33
  34 struct mutex
  35 {
  36     struct object  obj;             /* object header */
  37     struct thread *owner;           /* mutex owner */
  38     unsigned int   count;           /* recursion count */
  39     int            abandoned;       /* has it been abandoned? */
  40     struct mutex  *next;
  41     struct mutex  *prev;
  42 };
  43
  44 static void mutex_dump( struct object *obj, int verbose );
  45 static int mutex_signaled( struct object *obj, struct thread *thread );
  46 static int mutex_satisfied( struct object *obj, struct thread *thread );
  47 static void mutex_destroy( struct object *obj );
  48
  49 static const struct object_ops mutex_ops =
  50 {
  51     sizeof(struct mutex),      /* size */
  52     mutex_dump,                /* dump */
  53     add_queue,                 /* add_queue */
  54     remove_queue,              /* remove_queue */
  55     mutex_signaled,            /* signaled */
  56     mutex_satisfied,           /* satisfied */
  57     no_get_fd,                 /* get_fd */
  58     mutex_destroy              /* destroy */
  59 };
  60
  61
  62 static struct mutex *create_mutex( const WCHAR *name, size_t len, int owned )
  63 {
  64     struct mutex *mutex;
  65
  66     if ((mutex = create_named_object( sync_namespace, &mutex_ops, name, len )))
  67     {
  68         if (get_error() != STATUS_OBJECT_NAME_COLLISION)
  69         {
  70             /* initialize it if it didn't already exist */
  71             mutex->count = 0;
  72             mutex->owner = NULL;
  73             mutex->abandoned = 0;
  74             mutex->next = mutex->prev = NULL;
  75             if (owned) mutex_satisfied( &mutex->obj, current );
  76         }
  77     }
  78     return mutex;
  79 }
  80
  81 /* release a mutex once the recursion count is 0 */
  82 static void do_release( struct mutex *mutex )
  83 {
  84     assert( !mutex->count );
  85     /* remove the mutex from the thread list of owned mutexes */
  86     if (mutex->next) mutex->next->prev = mutex->prev;
  87     if (mutex->prev) mutex->prev->next = mutex->next;
  88     else mutex->owner->mutex = mutex->next;
  89     mutex->owner = NULL;
  90     mutex->next = mutex->prev = NULL;
  91     wake_up( &mutex->obj, 0 );
  92 }
  93
  94 void abandon_mutexes( struct thread *thread )
  95 {
  96     while (thread->mutex)
  97     {
  98         struct mutex *mutex = thread->mutex;
  99         assert( mutex->owner == thread );
 100         mutex->count = 0;
 101         mutex->abandoned = 1;
 102         do_release( mutex );
 103     }
 104 }
 105
 106 static void mutex_dump( struct object *obj, int verbose )
 107 {
 108     struct mutex *mutex = (struct mutex *)obj;
 109     assert( obj->ops == &mutex_ops );
 110     fprintf( stderr, "Mutex count=%u owner=%p ", mutex->count, mutex->owner );
 111     dump_object_name( &mutex->obj );
 112     fputc( '\n', stderr );
 113 }
 114
 115 static int mutex_signaled( struct object *obj, struct thread *thread )
 116 {
 117     struct mutex *mutex = (struct mutex *)obj;
 118     assert( obj->ops == &mutex_ops );
 119     return (!mutex->count || (mutex->owner == thread));
 120 }
 121
 122 static int mutex_satisfied( struct object *obj, struct thread *thread )
 123 {
 124     struct mutex *mutex = (struct mutex *)obj;
 125     assert( obj->ops == &mutex_ops );
 126     assert( !mutex->count || (mutex->owner == thread) );
 127
 128     if (!mutex->count++)  /* FIXME: avoid wrap-around */
 129     {
 130         assert( !mutex->owner );
 131         mutex->owner = thread;
 132         mutex->prev  = NULL;
 133         if ((mutex->next = thread->mutex)) mutex->next->prev = mutex;
 134         thread->mutex = mutex;
 135     }
 136     if (!mutex->abandoned) return 0;
 137     mutex->abandoned = 0;
 138     return 1;
 139 }
 140
 141 static void mutex_destroy( struct object *obj )
 142 {
 143     struct mutex *mutex = (struct mutex *)obj;
 144     assert( obj->ops == &mutex_ops );
 145
 146     if (!mutex->count) return;
 147     mutex->count = 0;
 148     do_release( mutex );
 149 }
 150
 151 /* create a mutex */
 152 DECL_HANDLER(create_mutex)
 153 {
 154     struct mutex *mutex;
 155
 156     reply->handle = 0;
 157     if ((mutex = create_mutex( get_req_data(), get_req_data_size(), req->owned )))
 158     {
 159         reply->handle = alloc_handle( current->process, mutex, req->access, req->inherit );
 160         release_object( mutex );
 161     }
 162 }
 163
 164 /* open a handle to a mutex */
 165 DECL_HANDLER(open_mutex)
 166 {
 167     reply->handle = open_object( sync_namespace, get_req_data(), get_req_data_size(),
 168                                  &mutex_ops, req->access, req->inherit );
 169 }
 170
 171 /* release a mutex */
 172 DECL_HANDLER(release_mutex)
 173 {
 174     struct mutex *mutex;
 175
 176     if ((mutex = (struct mutex *)get_handle_obj( current->process, req->handle,
 177                                                  MUTEX_MODIFY_STATE, &mutex_ops )))
 178     {
 179         if (!mutex->count || (mutex->owner != current)) set_error( STATUS_MUTANT_NOT_OWNED );
 180         else
 181         {
 182             reply->prev_count = mutex->count;
 183             if (!--mutex->count) do_release( mutex );
 184         }
 185         release_object( mutex );
 186     }
 187 }