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 int semaphore_signaled( struct object *obj, struct thread *thread );
  48 static int semaphore_satisfied( struct object *obj, struct thread *thread );
  49 static unsigned int semaphore_map_access( struct object *obj, unsigned int access );
  50 static int semaphore_signal( struct object *obj, unsigned int access );
  51
  52 static const struct object_ops semaphore_ops =
  53 {
  54     sizeof(struct semaphore),      /* size */
  55     semaphore_dump,                /* dump */
  56     add_queue,                     /* add_queue */
  57     remove_queue,                  /* remove_queue */
  58     semaphore_signaled,            /* signaled */
  59     semaphore_satisfied,           /* satisfied */
  60     semaphore_signal,              /* signal */
  61     no_get_fd,                     /* get_fd */
  62     semaphore_map_access,          /* map_access */
  63     default_get_sd,                /* get_sd */
  64     default_set_sd,                /* set_sd */
  65     no_lookup_name,                /* lookup_name */
  66     no_open_file,                  /* open_file */
  67     no_close_handle,               /* close_handle */
  68     no_destroy                     /* destroy */
  69 };
  70
  71
  72 static struct semaphore *create_semaphore( struct directory *root, const struct unicode_str *name,
  73                                            unsigned int attr, unsigned int initial, unsigned int max,
  74                                            const struct security_descriptor *sd )
  75 {
  76     struct semaphore *sem;
  77
  78     if (!max || (initial > max))
  79     {
  80         set_error( STATUS_INVALID_PARAMETER );
  81         return NULL;
  82     }
  83     if ((sem = create_named_object_dir( root, name, attr, &semaphore_ops )))
  84     {
  85         if (get_error() != STATUS_OBJECT_NAME_EXISTS)
  86         {
  87             /* initialize it if it didn't already exist */
  88             sem->count = initial;
  89             sem->max   = max;
  90             if (sd) default_set_sd( &sem->obj, sd, OWNER_SECURITY_INFORMATION|
  91                                                    GROUP_SECURITY_INFORMATION|
  92                                                    DACL_SECURITY_INFORMATION|
  93                                                    SACL_SECURITY_INFORMATION );
  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 ", sem->count, sem->max );
 126     dump_object_name( &sem->obj );
 127     fputc( '\n', stderr );
 128 }
 129
 130 static int semaphore_signaled( struct object *obj, struct thread *thread )
 131 {
 132     struct semaphore *sem = (struct semaphore *)obj;
 133     assert( obj->ops == &semaphore_ops );
 134     return (sem->count > 0);
 135 }
 136
 137 static int semaphore_satisfied( struct object *obj, struct thread *thread )
 138 {
 139     struct semaphore *sem = (struct semaphore *)obj;
 140     assert( obj->ops == &semaphore_ops );
 141     assert( sem->count );
 142     sem->count--;
 143     return 0;  /* not abandoned */
 144 }
 145
 146 static unsigned int semaphore_map_access( struct object *obj, unsigned int access )
 147 {
 148     if (access & GENERIC_READ)    access |= STANDARD_RIGHTS_READ | SYNCHRONIZE;
 149     if (access & GENERIC_WRITE)   access |= STANDARD_RIGHTS_WRITE | SEMAPHORE_MODIFY_STATE;
 150     if (access & GENERIC_EXECUTE) access |= STANDARD_RIGHTS_EXECUTE;
 151     if (access & GENERIC_ALL)     access |= STANDARD_RIGHTS_ALL | SEMAPHORE_ALL_ACCESS;
 152     return access & ~(GENERIC_READ | GENERIC_WRITE | GENERIC_EXECUTE | GENERIC_ALL);
 153 }
 154
 155 static int semaphore_signal( struct object *obj, unsigned int access )
 156 {
 157     struct semaphore *sem = (struct semaphore *)obj;
 158     assert( obj->ops == &semaphore_ops );
 159
 160     if (!(access & SEMAPHORE_MODIFY_STATE))
 161     {
 162         set_error( STATUS_ACCESS_DENIED );
 163         return 0;
 164     }
 165     return release_semaphore( sem, 1, NULL );
 166 }
 167
 168 /* create a semaphore */
 169 DECL_HANDLER(create_semaphore)
 170 {
 171     struct semaphore *sem;
 172     struct unicode_str name;
 173     struct directory *root = NULL;
 174     const struct object_attributes *objattr = get_req_data();
 175     const struct security_descriptor *sd;
 176
 177     reply->handle = 0;
 178
 179     if (!objattr_is_valid( objattr, get_req_data_size() ))
 180         return;
 181
 182     sd = objattr->sd_len ? (const struct security_descriptor *)(objattr + 1) : NULL;
 183     objattr_get_name( objattr, &name );
 184
 185     if (objattr->rootdir && !(root = get_directory_obj( current->process, objattr->rootdir, 0 )))
 186         return;
 187
 188     if ((sem = create_semaphore( root, &name, req->attributes, req->initial, req->max, sd )))
 189     {
 190         if (get_error() == STATUS_OBJECT_NAME_EXISTS)
 191             reply->handle = alloc_handle( current->process, sem, req->access, req->attributes );
 192         else
 193             reply->handle = alloc_handle_no_access_check( current->process, sem, req->access, req->attributes );
 194         release_object( sem );
 195     }
 196
 197     if (root) release_object( root );
 198 }
 199
 200 /* open a handle to a semaphore */
 201 DECL_HANDLER(open_semaphore)
 202 {
 203     struct unicode_str name;
 204     struct directory *root = NULL;
 205     struct semaphore *sem;
 206
 207     get_req_unicode_str( &name );
 208     if (req->rootdir && !(root = get_directory_obj( current->process, req->rootdir, 0 )))
 209         return;
 210
 211     if ((sem = open_object_dir( root, &name, req->attributes, &semaphore_ops )))
 212     {
 213         reply->handle = alloc_handle( current->process, &sem->obj, req->access, req->attributes );
 214         release_object( sem );
 215     }
 216
 217     if (root) release_object( root );
 218 }
 219
 220 /* release a semaphore */
 221 DECL_HANDLER(release_semaphore)
 222 {
 223     struct semaphore *sem;
 224
 225     if ((sem = (struct semaphore *)get_handle_obj( current->process, req->handle,
 226                                                    SEMAPHORE_MODIFY_STATE, &semaphore_ops )))
 227     {
 228         release_semaphore( sem, req->count, &reply->prev_count );
 229         release_object( sem );
 230     }
 231 }