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_kernel_obj_list,            /* get_kernel_obj_list */
  72     no_close_handle,               /* close_handle */
  73     no_destroy                     /* destroy */
  74 };
  75
  76
  77 static struct semaphore *create_semaphore( struct object *root, const struct unicode_str *name,
  78                                            unsigned int attr, unsigned int initial, unsigned int max,
  79                                            const struct security_descriptor *sd )
  80 {
  81     struct semaphore *sem;
  82
  83     if (!max || (initial > max))
  84     {
  85         set_error( STATUS_INVALID_PARAMETER );
  86         return NULL;
  87     }
  88     if ((sem = create_named_object( root, &semaphore_ops, name, attr, sd )))
  89     {
  90         if (get_error() != STATUS_OBJECT_NAME_EXISTS)
  91         {
  92             /* initialize it if it didn't already exist */
  93             sem->count = initial;
  94             sem->max   = max;
  95         }
  96     }
  97     return sem;
  98 }
  99
 100 static int release_semaphore( struct semaphore *sem, unsigned int count,
 101                               unsigned int *prev )
 102 {
 103     if (prev) *prev = sem->count;
 104     if (sem->count + count < sem->count || sem->count + count > sem->max)
 105     {
 106         set_error( STATUS_SEMAPHORE_LIMIT_EXCEEDED );
 107         return 0;
 108     }
 109     else if (sem->count)
 110     {
 111         /* there cannot be any thread to wake up if the count is != 0 */
 112         sem->count += count;
 113     }
 114     else
 115     {
 116         sem->count = count;
 117         wake_up( &sem->obj, count );
 118     }
 119     return 1;
 120 }
 121
 122 static void semaphore_dump( struct object *obj, int verbose )
 123 {
 124     struct semaphore *sem = (struct semaphore *)obj;
 125     assert( obj->ops == &semaphore_ops );
 126     fprintf( stderr, "Semaphore count=%d max=%d\n", sem->count, sem->max );
 127 }
 128
 129 static struct object_type *semaphore_get_type( struct object *obj )
 130 {
 131     static const WCHAR name[] = {'S','e','m','a','p','h','o','r','e'};
 132     static const struct unicode_str str = { name, sizeof(name) };
 133     return get_object_type( &str );
 134 }
 135
 136 static int semaphore_signaled( struct object *obj, struct wait_queue_entry *entry )
 137 {
 138     struct semaphore *sem = (struct semaphore *)obj;
 139     assert( obj->ops == &semaphore_ops );
 140     return (sem->count > 0);
 141 }
 142
 143 static void semaphore_satisfied( struct object *obj, struct wait_queue_entry *entry )
 144 {
 145     struct semaphore *sem = (struct semaphore *)obj;
 146     assert( obj->ops == &semaphore_ops );
 147     assert( sem->count );
 148     sem->count--;
 149 }
 150
 151 static unsigned int semaphore_map_access( struct object *obj, unsigned int access )
 152 {
 153     if (access & GENERIC_READ)    access |= STANDARD_RIGHTS_READ | SEMAPHORE_QUERY_STATE;
 154     if (access & GENERIC_WRITE)   access |= STANDARD_RIGHTS_WRITE | SEMAPHORE_MODIFY_STATE;
 155     if (access & GENERIC_EXECUTE) access |= STANDARD_RIGHTS_EXECUTE | SYNCHRONIZE;
 156     if (access & GENERIC_ALL)     access |= STANDARD_RIGHTS_ALL | SEMAPHORE_ALL_ACCESS;
 157     return access & ~(GENERIC_READ | GENERIC_WRITE | GENERIC_EXECUTE | GENERIC_ALL);
 158 }
 159
 160 static int semaphore_signal( struct object *obj, unsigned int access )
 161 {
 162     struct semaphore *sem = (struct semaphore *)obj;
 163     assert( obj->ops == &semaphore_ops );
 164
 165     if (!(access & SEMAPHORE_MODIFY_STATE))
 166     {
 167         set_error( STATUS_ACCESS_DENIED );
 168         return 0;
 169     }
 170     return release_semaphore( sem, 1, NULL );
 171 }
 172
 173 /* create a semaphore */
 174 DECL_HANDLER(create_semaphore)
 175 {
 176     struct semaphore *sem;
 177     struct unicode_str name;
 178     struct object *root;
 179     const struct security_descriptor *sd;
 180     const struct object_attributes *objattr = get_req_object_attributes( &sd, &name, &root );
 181
 182     if (!objattr) return;
 183
 184     if ((sem = create_semaphore( root, &name, objattr->attributes, req->initial, req->max, sd )))
 185     {
 186         if (get_error() == STATUS_OBJECT_NAME_EXISTS)
 187             reply->handle = alloc_handle( current->process, sem, req->access, objattr->attributes );
 188         else
 189             reply->handle = alloc_handle_no_access_check( current->process, sem,
 190                                                           req->access, objattr->attributes );
 191         release_object( sem );
 192     }
 193
 194     if (root) release_object( root );
 195 }
 196
 197 /* open a handle to a semaphore */
 198 DECL_HANDLER(open_semaphore)
 199 {
 200     struct unicode_str name = get_req_unicode_str();
 201
 202     reply->handle = open_object( current->process, req->rootdir, req->access,
 203                                  &semaphore_ops, &name, req->attributes );
 204 }
 205
 206 /* release a semaphore */
 207 DECL_HANDLER(release_semaphore)
 208 {
 209     struct semaphore *sem;
 210
 211     if ((sem = (struct semaphore *)get_handle_obj( current->process, req->handle,
 212                                                    SEMAPHORE_MODIFY_STATE, &semaphore_ops )))
 213     {
 214         release_semaphore( sem, req->count, &reply->prev_count );
 215         release_object( sem );
 216     }
 217 }
 218
 219 /* query details about the semaphore */
 220 DECL_HANDLER(query_semaphore)
 221 {
 222     struct semaphore *sem;
 223
 224     if ((sem = (struct semaphore *)get_handle_obj( current->process, req->handle,
 225                                                    SEMAPHORE_QUERY_STATE, &semaphore_ops )))
 226     {
 227         reply->current = sem->count;
 228         reply->max = sem->max;
 229         release_object( sem );
 230     }
 231 }