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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  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_close_handle,               /* close_handle */
  64     no_destroy                     /* destroy */
  65 };
  66
  67
  68 static struct semaphore *create_semaphore( struct directory *root, const struct unicode_str *name,
  69                                            unsigned int attr, unsigned int initial, unsigned int max )
  70 {
  71     struct semaphore *sem;
  72
  73     if (!max || (initial > max))
  74     {
  75         set_error( STATUS_INVALID_PARAMETER );
  76         return NULL;
  77     }
  78     if ((sem = create_named_object_dir( root, name, attr, &semaphore_ops )))
  79     {
  80         if (get_error() != STATUS_OBJECT_NAME_EXISTS)
  81         {
  82             /* initialize it if it didn't already exist */
  83             sem->count = initial;
  84             sem->max   = max;
  85         }
  86     }
  87     return sem;
  88 }
  89
  90 static int release_semaphore( struct semaphore *sem, unsigned int count,
  91                               unsigned int *prev )
  92 {
  93     if (prev) *prev = sem->count;
  94     if (sem->count + count < sem->count || sem->count + count > sem->max)
  95     {
  96         set_error( STATUS_SEMAPHORE_LIMIT_EXCEEDED );
  97         return 0;
  98     }
  99     else if (sem->count)
 100     {
 101         /* there cannot be any thread to wake up if the count is != 0 */
 102         sem->count += count;
 103     }
 104     else
 105     {
 106         sem->count = count;
 107         wake_up( &sem->obj, count );
 108     }
 109     return 1;
 110 }
 111
 112 static void semaphore_dump( struct object *obj, int verbose )
 113 {
 114     struct semaphore *sem = (struct semaphore *)obj;
 115     assert( obj->ops == &semaphore_ops );
 116     fprintf( stderr, "Semaphore count=%d max=%d ", sem->count, sem->max );
 117     dump_object_name( &sem->obj );
 118     fputc( '\n', stderr );
 119 }
 120
 121 static int semaphore_signaled( struct object *obj, struct thread *thread )
 122 {
 123     struct semaphore *sem = (struct semaphore *)obj;
 124     assert( obj->ops == &semaphore_ops );
 125     return (sem->count > 0);
 126 }
 127
 128 static int semaphore_satisfied( struct object *obj, struct thread *thread )
 129 {
 130     struct semaphore *sem = (struct semaphore *)obj;
 131     assert( obj->ops == &semaphore_ops );
 132     assert( sem->count );
 133     sem->count--;
 134     return 0;  /* not abandoned */
 135 }
 136
 137 static unsigned int semaphore_map_access( struct object *obj, unsigned int access )
 138 {
 139     if (access & GENERIC_READ)    access |= STANDARD_RIGHTS_READ | SYNCHRONIZE;
 140     if (access & GENERIC_WRITE)   access |= STANDARD_RIGHTS_WRITE | SEMAPHORE_MODIFY_STATE;
 141     if (access & GENERIC_EXECUTE) access |= STANDARD_RIGHTS_EXECUTE;
 142     if (access & GENERIC_ALL)     access |= STANDARD_RIGHTS_ALL | SEMAPHORE_ALL_ACCESS;
 143     return access & ~(GENERIC_READ | GENERIC_WRITE | GENERIC_EXECUTE | GENERIC_ALL);
 144 }
 145
 146 static int semaphore_signal( struct object *obj, unsigned int access )
 147 {
 148     struct semaphore *sem = (struct semaphore *)obj;
 149     assert( obj->ops == &semaphore_ops );
 150
 151     if (!(access & SEMAPHORE_MODIFY_STATE))
 152     {
 153         set_error( STATUS_ACCESS_DENIED );
 154         return 0;
 155     }
 156     return release_semaphore( sem, 1, NULL );
 157 }
 158
 159 /* create a semaphore */
 160 DECL_HANDLER(create_semaphore)
 161 {
 162     struct semaphore *sem;
 163     struct unicode_str name;
 164     struct directory *root = NULL;
 165
 166     reply->handle = 0;
 167     get_req_unicode_str( &name );
 168     if (req->rootdir && !(root = get_directory_obj( current->process, req->rootdir, 0 )))
 169         return;
 170
 171     if ((sem = create_semaphore( root, &name, req->attributes, req->initial, req->max )))
 172     {
 173         reply->handle = alloc_handle( current->process, sem, req->access, req->attributes );
 174         release_object( sem );
 175     }
 176
 177     if (root) release_object( root );
 178 }
 179
 180 /* open a handle to a semaphore */
 181 DECL_HANDLER(open_semaphore)
 182 {
 183     struct unicode_str name;
 184     struct directory *root = NULL;
 185     struct semaphore *sem;
 186
 187     get_req_unicode_str( &name );
 188     if (req->rootdir && !(root = get_directory_obj( current->process, req->rootdir, 0 )))
 189         return;
 190
 191     if ((sem = open_object_dir( root, &name, req->attributes, &semaphore_ops )))
 192     {
 193         reply->handle = alloc_handle( current->process, &sem->obj, req->access, req->attributes );
 194         release_object( sem );
 195     }
 196
 197     if (root) release_object( root );
 198 }
 199
 200 /* release a semaphore */
 201 DECL_HANDLER(release_semaphore)
 202 {
 203     struct semaphore *sem;
 204
 205     if ((sem = (struct semaphore *)get_handle_obj( current->process, req->handle,
 206                                                    SEMAPHORE_MODIFY_STATE, &semaphore_ops )))
 207     {
 208         release_semaphore( sem, req->count, &reply->prev_count );
 209         release_object( sem );
 210     }
 211 }