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     no_lookup_name,                /* lookup_name */
  63     no_open_file,                  /* open_file */
  64     no_close_handle,               /* close_handle */
  65     no_destroy                     /* destroy */
  66 };
  67
  68
  69 static struct semaphore *create_semaphore( struct directory *root, const struct unicode_str *name,
  70                                            unsigned int attr, unsigned int initial, unsigned int max )
  71 {
  72     struct semaphore *sem;
  73
  74     if (!max || (initial > max))
  75     {
  76         set_error( STATUS_INVALID_PARAMETER );
  77         return NULL;
  78     }
  79     if ((sem = create_named_object_dir( root, name, attr, &semaphore_ops )))
  80     {
  81         if (get_error() != STATUS_OBJECT_NAME_EXISTS)
  82         {
  83             /* initialize it if it didn't already exist */
  84             sem->count = initial;
  85             sem->max   = max;
  86         }
  87     }
  88     return sem;
  89 }
  90
  91 static int release_semaphore( struct semaphore *sem, unsigned int count,
  92                               unsigned int *prev )
  93 {
  94     if (prev) *prev = sem->count;
  95     if (sem->count + count < sem->count || sem->count + count > sem->max)
  96     {
  97         set_error( STATUS_SEMAPHORE_LIMIT_EXCEEDED );
  98         return 0;
  99     }
 100     else if (sem->count)
 101     {
 102         /* there cannot be any thread to wake up if the count is != 0 */
 103         sem->count += count;
 104     }
 105     else
 106     {
 107         sem->count = count;
 108         wake_up( &sem->obj, count );
 109     }
 110     return 1;
 111 }
 112
 113 static void semaphore_dump( struct object *obj, int verbose )
 114 {
 115     struct semaphore *sem = (struct semaphore *)obj;
 116     assert( obj->ops == &semaphore_ops );
 117     fprintf( stderr, "Semaphore count=%d max=%d ", sem->count, sem->max );
 118     dump_object_name( &sem->obj );
 119     fputc( '\n', stderr );
 120 }
 121
 122 static int semaphore_signaled( struct object *obj, struct thread *thread )
 123 {
 124     struct semaphore *sem = (struct semaphore *)obj;
 125     assert( obj->ops == &semaphore_ops );
 126     return (sem->count > 0);
 127 }
 128
 129 static int semaphore_satisfied( struct object *obj, struct thread *thread )
 130 {
 131     struct semaphore *sem = (struct semaphore *)obj;
 132     assert( obj->ops == &semaphore_ops );
 133     assert( sem->count );
 134     sem->count--;
 135     return 0;  /* not abandoned */
 136 }
 137
 138 static unsigned int semaphore_map_access( struct object *obj, unsigned int access )
 139 {
 140     if (access & GENERIC_READ)    access |= STANDARD_RIGHTS_READ | SYNCHRONIZE;
 141     if (access & GENERIC_WRITE)   access |= STANDARD_RIGHTS_WRITE | SEMAPHORE_MODIFY_STATE;
 142     if (access & GENERIC_EXECUTE) access |= STANDARD_RIGHTS_EXECUTE;
 143     if (access & GENERIC_ALL)     access |= STANDARD_RIGHTS_ALL | SEMAPHORE_ALL_ACCESS;
 144     return access & ~(GENERIC_READ | GENERIC_WRITE | GENERIC_EXECUTE | GENERIC_ALL);
 145 }
 146
 147 static int semaphore_signal( struct object *obj, unsigned int access )
 148 {
 149     struct semaphore *sem = (struct semaphore *)obj;
 150     assert( obj->ops == &semaphore_ops );
 151
 152     if (!(access & SEMAPHORE_MODIFY_STATE))
 153     {
 154         set_error( STATUS_ACCESS_DENIED );
 155         return 0;
 156     }
 157     return release_semaphore( sem, 1, NULL );
 158 }
 159
 160 /* create a semaphore */
 161 DECL_HANDLER(create_semaphore)
 162 {
 163     struct semaphore *sem;
 164     struct unicode_str name;
 165     struct directory *root = NULL;
 166
 167     reply->handle = 0;
 168     get_req_unicode_str( &name );
 169     if (req->rootdir && !(root = get_directory_obj( current->process, req->rootdir, 0 )))
 170         return;
 171
 172     if ((sem = create_semaphore( root, &name, req->attributes, req->initial, req->max )))
 173     {
 174         reply->handle = alloc_handle( current->process, sem, req->access, req->attributes );
 175         release_object( sem );
 176     }
 177
 178     if (root) release_object( root );
 179 }
 180
 181 /* open a handle to a semaphore */
 182 DECL_HANDLER(open_semaphore)
 183 {
 184     struct unicode_str name;
 185     struct directory *root = NULL;
 186     struct semaphore *sem;
 187
 188     get_req_unicode_str( &name );
 189     if (req->rootdir && !(root = get_directory_obj( current->process, req->rootdir, 0 )))
 190         return;
 191
 192     if ((sem = open_object_dir( root, &name, req->attributes, &semaphore_ops )))
 193     {
 194         reply->handle = alloc_handle( current->process, &sem->obj, req->access, req->attributes );
 195         release_object( sem );
 196     }
 197
 198     if (root) release_object( root );
 199 }
 200
 201 /* release a semaphore */
 202 DECL_HANDLER(release_semaphore)
 203 {
 204     struct semaphore *sem;
 205
 206     if ((sem = (struct semaphore *)get_handle_obj( current->process, req->handle,
 207                                                    SEMAPHORE_MODIFY_STATE, &semaphore_ops )))
 208     {
 209         release_semaphore( sem, req->count, &reply->prev_count );
 210         release_object( sem );
 211     }
 212 }