server/semaphore.c

   1 /*
   2  * Server-side semaphore 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., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, 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 #include <stdarg.h>
  28
  29 #include "ntstatus.h"
  30 #define WIN32_NO_STATUS
  31 #include "windef.h"
  32 #include "winternl.h"
  33
  34 #include "handle.h"
  35 #include "thread.h"
  36 #include "request.h"
  37
  38 struct semaphore
  39 {
  40     struct object  obj;    /* object header */
  41     unsigned int   count;  /* current count */
  42     unsigned int   max;    /* maximum possible count */
  43 };
  44
  45 static void semaphore_dump( struct object *obj, int verbose );
  46 static int semaphore_signaled( struct object *obj, struct thread *thread );
  47 static int semaphore_satisfied( struct object *obj, struct thread *thread );
  48 static unsigned int semaphore_map_access( struct object *obj, unsigned int access );
  49 static int semaphore_signal( struct object *obj, unsigned int access );
  50
  51 static const struct object_ops semaphore_ops =
  52 {
  53     sizeof(struct semaphore),      /* size */
  54     semaphore_dump,                /* dump */
  55     add_queue,                     /* add_queue */
  56     remove_queue,                  /* remove_queue */
  57     semaphore_signaled,            /* signaled */
  58     semaphore_satisfied,           /* satisfied */
  59     semaphore_signal,              /* signal */
  60     no_get_fd,                     /* get_fd */
  61     semaphore_map_access,          /* map_access */
  62     default_get_sd,                /* get_sd */
  63     default_set_sd,                /* set_sd */
  64     no_lookup_name,                /* lookup_name */
  65     no_open_file,                  /* open_file */
  66     no_close_handle,               /* close_handle */
  67     no_destroy                     /* destroy */
  68 };
  69
  70
  71 static struct semaphore *create_semaphore( struct directory *root, const struct unicode_str *name,
  72                                            unsigned int attr, unsigned int initial, unsigned int max )
  73 {
  74     struct semaphore *sem;
  75
  76     if (!max || (initial > max))
  77     {
  78         set_error( STATUS_INVALID_PARAMETER );
  79         return NULL;
  80     }
  81     if ((sem = create_named_object_dir( root, name, attr, &semaphore_ops )))
  82     {
  83         if (get_error() != STATUS_OBJECT_NAME_EXISTS)
  84         {
  85             /* initialize it if it didn't already exist */
  86             sem->count = initial;
  87             sem->max   = max;
  88         }
  89     }
  90     return sem;
  91 }
  92
  93 static int release_semaphore( struct semaphore *sem, unsigned int count,
  94                               unsigned int *prev )
  95 {
  96     if (prev) *prev = sem->count;
  97     if (sem->count + count < sem->count || sem->count + count > sem->max)
  98     {
  99         set_error( STATUS_SEMAPHORE_LIMIT_EXCEEDED );
 100         return 0;
 101     }
 102     else if (sem->count)
 103     {
 104         /* there cannot be any thread to wake up if the count is != 0 */
 105         sem->count += count;
 106     }
 107     else
 108     {
 109         sem->count = count;
 110         wake_up( &sem->obj, count );
 111     }
 112     return 1;
 113 }
 114
 115 static void semaphore_dump( struct object *obj, int verbose )
 116 {
 117     struct semaphore *sem = (struct semaphore *)obj;
 118     assert( obj->ops == &semaphore_ops );
 119     fprintf( stderr, "Semaphore count=%d max=%d ", sem->count, sem->max );
 120     dump_object_name( &sem->obj );
 121     fputc( '\n', stderr );
 122 }
 123
 124 static int semaphore_signaled( struct object *obj, struct thread *thread )
 125 {
 126     struct semaphore *sem = (struct semaphore *)obj;
 127     assert( obj->ops == &semaphore_ops );
 128     return (sem->count > 0);
 129 }
 130
 131 static int semaphore_satisfied( struct object *obj, struct thread *thread )
 132 {
 133     struct semaphore *sem = (struct semaphore *)obj;
 134     assert( obj->ops == &semaphore_ops );
 135     assert( sem->count );
 136     sem->count--;
 137     return 0;  /* not abandoned */
 138 }
 139
 140 static unsigned int semaphore_map_access( struct object *obj, unsigned int access )
 141 {
 142     if (access & GENERIC_READ)    access |= STANDARD_RIGHTS_READ | SYNCHRONIZE;
 143     if (access & GENERIC_WRITE)   access |= STANDARD_RIGHTS_WRITE | SEMAPHORE_MODIFY_STATE;
 144     if (access & GENERIC_EXECUTE) access |= STANDARD_RIGHTS_EXECUTE;
 145     if (access & GENERIC_ALL)     access |= STANDARD_RIGHTS_ALL | SEMAPHORE_ALL_ACCESS;
 146     return access & ~(GENERIC_READ | GENERIC_WRITE | GENERIC_EXECUTE | GENERIC_ALL);
 147 }
 148
 149 static int semaphore_signal( struct object *obj, unsigned int access )
 150 {
 151     struct semaphore *sem = (struct semaphore *)obj;
 152     assert( obj->ops == &semaphore_ops );
 153
 154     if (!(access & SEMAPHORE_MODIFY_STATE))
 155     {
 156         set_error( STATUS_ACCESS_DENIED );
 157         return 0;
 158     }
 159     return release_semaphore( sem, 1, NULL );
 160 }
 161
 162 /* create a semaphore */
 163 DECL_HANDLER(create_semaphore)
 164 {
 165     struct semaphore *sem;
 166     struct unicode_str name;
 167     struct directory *root = NULL;
 168
 169     reply->handle = 0;
 170     get_req_unicode_str( &name );
 171     if (req->rootdir && !(root = get_directory_obj( current->process, req->rootdir, 0 )))
 172         return;
 173
 174     if ((sem = create_semaphore( root, &name, req->attributes, req->initial, req->max )))
 175     {
 176         reply->handle = alloc_handle( current->process, sem, req->access, req->attributes );
 177         release_object( sem );
 178     }
 179
 180     if (root) release_object( root );
 181 }
 182
 183 /* open a handle to a semaphore */
 184 DECL_HANDLER(open_semaphore)
 185 {
 186     struct unicode_str name;
 187     struct directory *root = NULL;
 188     struct semaphore *sem;
 189
 190     get_req_unicode_str( &name );
 191     if (req->rootdir && !(root = get_directory_obj( current->process, req->rootdir, 0 )))
 192         return;
 193
 194     if ((sem = open_object_dir( root, &name, req->attributes, &semaphore_ops )))
 195     {
 196         reply->handle = alloc_handle( current->process, &sem->obj, req->access, req->attributes );
 197         release_object( sem );
 198     }
 199
 200     if (root) release_object( root );
 201 }
 202
 203 /* release a semaphore */
 204 DECL_HANDLER(release_semaphore)
 205 {
 206     struct semaphore *sem;
 207
 208     if ((sem = (struct semaphore *)get_handle_obj( current->process, req->handle,
 209                                                    SEMAPHORE_MODIFY_STATE, &semaphore_ops )))
 210     {
 211         release_semaphore( sem, req->count, &reply->prev_count );
 212         release_object( sem );
 213     }
 214 }