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     no_open_file,                  /* open_file */
  69     no_close_handle,               /* close_handle */
  70     no_destroy                     /* destroy */
  71 };
  72
  73
  74 static struct semaphore *create_semaphore( struct directory *root, const struct unicode_str *name,
  75                                            unsigned int attr, unsigned int initial, unsigned int max,
  76                                            const struct security_descriptor *sd )
  77 {
  78     struct semaphore *sem;
  79
  80     if (!max || (initial > max))
  81     {
  82         set_error( STATUS_INVALID_PARAMETER );
  83         return NULL;
  84     }
  85     if ((sem = create_named_object_dir( root, name, attr, &semaphore_ops )))
  86     {
  87         if (get_error() != STATUS_OBJECT_NAME_EXISTS)
  88         {
  89             /* initialize it if it didn't already exist */
  90             sem->count = initial;
  91             sem->max   = max;
  92             if (sd) default_set_sd( &sem->obj, sd, OWNER_SECURITY_INFORMATION|
  93                                                    GROUP_SECURITY_INFORMATION|
  94                                                    DACL_SECURITY_INFORMATION|
  95                                                    SACL_SECURITY_INFORMATION );
  96         }
  97     }
  98     return sem;
  99 }
 100
 101 static int release_semaphore( struct semaphore *sem, unsigned int count,
 102                               unsigned int *prev )
 103 {
 104     if (prev) *prev = sem->count;
 105     if (sem->count + count < sem->count || sem->count + count > sem->max)
 106     {
 107         set_error( STATUS_SEMAPHORE_LIMIT_EXCEEDED );
 108         return 0;
 109     }
 110     else if (sem->count)
 111     {
 112         /* there cannot be any thread to wake up if the count is != 0 */
 113         sem->count += count;
 114     }
 115     else
 116     {
 117         sem->count = count;
 118         wake_up( &sem->obj, count );
 119     }
 120     return 1;
 121 }
 122
 123 static void semaphore_dump( struct object *obj, int verbose )
 124 {
 125     struct semaphore *sem = (struct semaphore *)obj;
 126     assert( obj->ops == &semaphore_ops );
 127     fprintf( stderr, "Semaphore count=%d max=%d ", sem->count, sem->max );
 128     dump_object_name( &sem->obj );
 129     fputc( '\n', stderr );
 130 }
 131
 132 static struct object_type *semaphore_get_type( struct object *obj )
 133 {
 134     static const WCHAR name[] = {'S','e','m','a','p','h','o','r','e'};
 135     static const struct unicode_str str = { name, sizeof(name) };
 136     return get_object_type( &str );
 137 }
 138
 139 static int semaphore_signaled( struct object *obj, struct wait_queue_entry *entry )
 140 {
 141     struct semaphore *sem = (struct semaphore *)obj;
 142     assert( obj->ops == &semaphore_ops );
 143     return (sem->count > 0);
 144 }
 145
 146 static void semaphore_satisfied( struct object *obj, struct wait_queue_entry *entry )
 147 {
 148     struct semaphore *sem = (struct semaphore *)obj;
 149     assert( obj->ops == &semaphore_ops );
 150     assert( sem->count );
 151     sem->count--;
 152 }
 153
 154 static unsigned int semaphore_map_access( struct object *obj, unsigned int access )
 155 {
 156     if (access & GENERIC_READ)    access |= STANDARD_RIGHTS_READ | SYNCHRONIZE;
 157     if (access & GENERIC_WRITE)   access |= STANDARD_RIGHTS_WRITE | SEMAPHORE_MODIFY_STATE;
 158     if (access & GENERIC_EXECUTE) access |= STANDARD_RIGHTS_EXECUTE;
 159     if (access & GENERIC_ALL)     access |= STANDARD_RIGHTS_ALL | SEMAPHORE_ALL_ACCESS;
 160     return access & ~(GENERIC_READ | GENERIC_WRITE | GENERIC_EXECUTE | GENERIC_ALL);
 161 }
 162
 163 static int semaphore_signal( struct object *obj, unsigned int access )
 164 {
 165     struct semaphore *sem = (struct semaphore *)obj;
 166     assert( obj->ops == &semaphore_ops );
 167
 168     if (!(access & SEMAPHORE_MODIFY_STATE))
 169     {
 170         set_error( STATUS_ACCESS_DENIED );
 171         return 0;
 172     }
 173     return release_semaphore( sem, 1, NULL );
 174 }
 175
 176 /* create a semaphore */
 177 DECL_HANDLER(create_semaphore)
 178 {
 179     struct semaphore *sem;
 180     struct unicode_str name;
 181     struct directory *root = NULL;
 182     const struct object_attributes *objattr = get_req_data();
 183     const struct security_descriptor *sd;
 184
 185     reply->handle = 0;
 186
 187     if (!objattr_is_valid( objattr, get_req_data_size() ))
 188         return;
 189
 190     sd = objattr->sd_len ? (const struct security_descriptor *)(objattr + 1) : NULL;
 191     objattr_get_name( objattr, &name );
 192
 193     if (objattr->rootdir && !(root = get_directory_obj( current->process, objattr->rootdir, 0 )))
 194         return;
 195
 196     if ((sem = create_semaphore( root, &name, req->attributes, req->initial, req->max, sd )))
 197     {
 198         if (get_error() == STATUS_OBJECT_NAME_EXISTS)
 199             reply->handle = alloc_handle( current->process, sem, req->access, req->attributes );
 200         else
 201             reply->handle = alloc_handle_no_access_check( current->process, sem, req->access, req->attributes );
 202         release_object( sem );
 203     }
 204
 205     if (root) release_object( root );
 206 }
 207
 208 /* open a handle to a semaphore */
 209 DECL_HANDLER(open_semaphore)
 210 {
 211     struct unicode_str name;
 212     struct directory *root = NULL;
 213     struct semaphore *sem;
 214
 215     get_req_unicode_str( &name );
 216     if (req->rootdir && !(root = get_directory_obj( current->process, req->rootdir, 0 )))
 217         return;
 218
 219     if ((sem = open_object_dir( root, &name, req->attributes, &semaphore_ops )))
 220     {
 221         reply->handle = alloc_handle( current->process, &sem->obj, req->access, req->attributes );
 222         release_object( sem );
 223     }
 224
 225     if (root) release_object( root );
 226 }
 227
 228 /* release a semaphore */
 229 DECL_HANDLER(release_semaphore)
 230 {
 231     struct semaphore *sem;
 232
 233     if ((sem = (struct semaphore *)get_handle_obj( current->process, req->handle,
 234                                                    SEMAPHORE_MODIFY_STATE, &semaphore_ops )))
 235     {
 236         release_semaphore( sem, req->count, &reply->prev_count );
 237         release_object( sem );
 238     }
 239 }