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 #include "security.h"
  38
  39 struct semaphore
  40 {
  41     struct object  obj;    /* object header */
  42     unsigned int   count;  /* current count */
  43     unsigned int   max;    /* maximum possible count */
  44 };
  45
  46 static void semaphore_dump( struct object *obj, int verbose );
  47 static struct object_type *semaphore_get_type( struct object *obj );
  48 static int semaphore_signaled( struct object *obj, struct wait_queue_entry *entry );
  49 static void semaphore_satisfied( struct object *obj, struct wait_queue_entry *entry );
  50 static unsigned int semaphore_map_access( struct object *obj, unsigned int access );
  51 static int semaphore_signal( struct object *obj, unsigned int access );
  52
  53 static const struct object_ops semaphore_ops =
  54 {
  55     sizeof(struct semaphore),      /* size */
  56     semaphore_dump,                /* dump */
  57     semaphore_get_type,            /* get_type */
  58     add_queue,                     /* add_queue */
  59     remove_queue,                  /* remove_queue */
  60     semaphore_signaled,            /* signaled */
  61     semaphore_satisfied,           /* satisfied */
  62     semaphore_signal,              /* signal */
  63     no_get_fd,                     /* get_fd */
  64     semaphore_map_access,          /* map_access */
  65     default_get_sd,                /* get_sd */
  66     default_set_sd,                /* set_sd */
  67     no_lookup_name,                /* lookup_name */
  68     directory_link_name,           /* link_name */
  69     default_unlink_name,           /* unlink_name */
  70     no_open_file,                  /* open_file */
  71     no_close_handle,               /* close_handle */
  72     no_destroy                     /* destroy */
  73 };
  74
  75
  76 static struct semaphore *create_semaphore( struct object *root, const struct unicode_str *name,
  77                                            unsigned int attr, unsigned int initial, unsigned int max,
  78                                            const struct security_descriptor *sd )
  79 {
  80     struct semaphore *sem;
  81
  82     if (!max || (initial > max))
  83     {
  84         set_error( STATUS_INVALID_PARAMETER );
  85         return NULL;
  86     }
  87     if ((sem = create_named_object( root, &semaphore_ops, name, attr, sd )))
  88     {
  89         if (get_error() != STATUS_OBJECT_NAME_EXISTS)
  90         {
  91             /* initialize it if it didn't already exist */
  92             sem->count = initial;
  93             sem->max   = max;
  94         }
  95     }
  96     return sem;
  97 }
  98
  99 static int release_semaphore( struct semaphore *sem, unsigned int count,
 100                               unsigned int *prev )
 101 {
 102     if (prev) *prev = sem->count;
 103     if (sem->count + count < sem->count || sem->count + count > sem->max)
 104     {
 105         set_error( STATUS_SEMAPHORE_LIMIT_EXCEEDED );
 106         return 0;
 107     }
 108     else if (sem->count)
 109     {
 110         /* there cannot be any thread to wake up if the count is != 0 */
 111         sem->count += count;
 112     }
 113     else
 114     {
 115         sem->count = count;
 116         wake_up( &sem->obj, count );
 117     }
 118     return 1;
 119 }
 120
 121 static void semaphore_dump( struct object *obj, int verbose )
 122 {
 123     struct semaphore *sem = (struct semaphore *)obj;
 124     assert( obj->ops == &semaphore_ops );
 125     fprintf( stderr, "Semaphore count=%d max=%d\n", sem->count, sem->max );
 126 }
 127
 128 static struct object_type *semaphore_get_type( struct object *obj )
 129 {
 130     static const WCHAR name[] = {'S','e','m','a','p','h','o','r','e'};
 131     static const struct unicode_str str = { name, sizeof(name) };
 132     return get_object_type( &str );
 133 }
 134
 135 static int semaphore_signaled( struct object *obj, struct wait_queue_entry *entry )
 136 {
 137     struct semaphore *sem = (struct semaphore *)obj;
 138     assert( obj->ops == &semaphore_ops );
 139     return (sem->count > 0);
 140 }
 141
 142 static void semaphore_satisfied( struct object *obj, struct wait_queue_entry *entry )
 143 {
 144     struct semaphore *sem = (struct semaphore *)obj;
 145     assert( obj->ops == &semaphore_ops );
 146     assert( sem->count );
 147     sem->count--;
 148 }
 149
 150 static unsigned int semaphore_map_access( struct object *obj, unsigned int access )
 151 {
 152     if (access & GENERIC_READ)    access |= STANDARD_RIGHTS_READ | SEMAPHORE_QUERY_STATE;
 153     if (access & GENERIC_WRITE)   access |= STANDARD_RIGHTS_WRITE | SEMAPHORE_MODIFY_STATE;
 154     if (access & GENERIC_EXECUTE) access |= STANDARD_RIGHTS_EXECUTE | SYNCHRONIZE;
 155     if (access & GENERIC_ALL)     access |= STANDARD_RIGHTS_ALL | SEMAPHORE_ALL_ACCESS;
 156     return access & ~(GENERIC_READ | GENERIC_WRITE | GENERIC_EXECUTE | GENERIC_ALL);
 157 }
 158
 159 static int semaphore_signal( struct object *obj, unsigned int access )
 160 {
 161     struct semaphore *sem = (struct semaphore *)obj;
 162     assert( obj->ops == &semaphore_ops );
 163
 164     if (!(access & SEMAPHORE_MODIFY_STATE))
 165     {
 166         set_error( STATUS_ACCESS_DENIED );
 167         return 0;
 168     }
 169     return release_semaphore( sem, 1, NULL );
 170 }
 171
 172 /* create a semaphore */
 173 DECL_HANDLER(create_semaphore)
 174 {
 175     struct semaphore *sem;
 176     struct unicode_str name;
 177     struct object *root;
 178     const struct security_descriptor *sd;
 179     const struct object_attributes *objattr = get_req_object_attributes( &sd, &name, &root );
 180
 181     if (!objattr) return;
 182
 183     if ((sem = create_semaphore( root, &name, objattr->attributes, req->initial, req->max, sd )))
 184     {
 185         if (get_error() == STATUS_OBJECT_NAME_EXISTS)
 186             reply->handle = alloc_handle( current->process, sem, req->access, objattr->attributes );
 187         else
 188             reply->handle = alloc_handle_no_access_check( current->process, sem,
 189                                                           req->access, objattr->attributes );
 190         release_object( sem );
 191     }
 192
 193     if (root) release_object( root );
 194 }
 195
 196 /* open a handle to a semaphore */
 197 DECL_HANDLER(open_semaphore)
 198 {
 199     struct unicode_str name = get_req_unicode_str();
 200
 201     reply->handle = open_object( current->process, req->rootdir, req->access,
 202                                  &semaphore_ops, &name, req->attributes );
 203 }
 204
 205 /* release a semaphore */
 206 DECL_HANDLER(release_semaphore)
 207 {
 208     struct semaphore *sem;
 209
 210     if ((sem = (struct semaphore *)get_handle_obj( current->process, req->handle,
 211                                                    SEMAPHORE_MODIFY_STATE, &semaphore_ops )))
 212     {
 213         release_semaphore( sem, req->count, &reply->prev_count );
 214         release_object( sem );
 215     }
 216 }
 217
 218 /* query details about the semaphore */
 219 DECL_HANDLER(query_semaphore)
 220 {
 221     struct semaphore *sem;
 222
 223     if ((sem = (struct semaphore *)get_handle_obj( current->process, req->handle,
 224                                                    SEMAPHORE_QUERY_STATE, &semaphore_ops )))
 225     {
 226         reply->current = sem->count;
 227         reply->max = sem->max;
 228         release_object( sem );
 229     }
 230 }