server/change.c

   1 /*
   2  * Server-side change notification 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 <fcntl.h>
  26 #include <stdio.h>
  27 #include <stdlib.h>
  28 #include <signal.h>
  29
  30 #include "windef.h"
  31
  32 #include "file.h"
  33 #include "handle.h"
  34 #include "thread.h"
  35 #include "request.h"
  36 #include "list.h"
  37
  38 struct change
  39 {
  40     struct object  obj;      /* object header */
  41     struct fd     *fd;       /* file descriptor to the directory */
  42     struct list    entry;    /* entry in global change notifications list */
  43     int            subtree;  /* watch all the subtree */
  44     unsigned int   filter;   /* notification filter */
  45     long           notified; /* SIGIO counter */
  46     long           signaled; /* the file changed */
  47 };
  48
  49 static void change_dump( struct object *obj, int verbose );
  50 static int change_signaled( struct object *obj, struct thread *thread );
  51 static void change_destroy( struct object *obj );
  52
  53 static const struct object_ops change_ops =
  54 {
  55     sizeof(struct change),    /* size */
  56     change_dump,              /* dump */
  57     add_queue,                /* add_queue */
  58     remove_queue,             /* remove_queue */
  59     change_signaled,          /* signaled */
  60     no_satisfied,             /* satisfied */
  61     no_get_fd,                /* get_fd */
  62     change_destroy            /* destroy */
  63 };
  64
  65 static struct list change_list = LIST_INIT(change_list);
  66
  67 static void adjust_changes( int fd, unsigned int filter )
  68 {
  69 #ifdef F_NOTIFY
  70     unsigned int val;
  71     if ( 0 > fcntl( fd, F_SETSIG, SIGIO) )
  72         return;
  73
  74     val = DN_MULTISHOT;
  75     if( filter & FILE_NOTIFY_CHANGE_FILE_NAME )
  76         val |= DN_RENAME | DN_DELETE | DN_CREATE;
  77     if( filter & FILE_NOTIFY_CHANGE_DIR_NAME )
  78         val |= DN_RENAME | DN_DELETE | DN_CREATE;
  79     if( filter & FILE_NOTIFY_CHANGE_ATTRIBUTES )
  80         val |= DN_ATTRIB;
  81     if( filter & FILE_NOTIFY_CHANGE_SIZE )
  82         val |= DN_MODIFY;
  83     if( filter & FILE_NOTIFY_CHANGE_LAST_WRITE )
  84         val |= DN_MODIFY;
  85     if( filter & FILE_NOTIFY_CHANGE_SECURITY )
  86         val |= DN_ATTRIB;
  87     fcntl( fd, F_NOTIFY, val );
  88 #endif
  89 }
  90
  91 /* insert change in the global list */
  92 static inline void insert_change( struct change *change )
  93 {
  94     sigset_t sigset;
  95
  96     sigemptyset( &sigset );
  97     sigaddset( &sigset, SIGIO );
  98     sigprocmask( SIG_BLOCK, &sigset, NULL );
  99     list_add_head( &change_list, &change->entry );
 100     sigprocmask( SIG_UNBLOCK, &sigset, NULL );
 101 }
 102
 103 /* remove change from the global list */
 104 static inline void remove_change( struct change *change )
 105 {
 106     sigset_t sigset;
 107
 108     sigemptyset( &sigset );
 109     sigaddset( &sigset, SIGIO );
 110     sigprocmask( SIG_BLOCK, &sigset, NULL );
 111     list_remove( &change->entry );
 112     sigprocmask( SIG_UNBLOCK, &sigset, NULL );
 113 }
 114
 115 static struct change *create_change_notification( struct fd *fd, int subtree, unsigned int filter )
 116 {
 117     struct change *change;
 118
 119     if ((change = alloc_object( &change_ops )))
 120     {
 121         change->fd       = (struct fd *)grab_object( fd );
 122         change->subtree  = subtree;
 123         change->filter   = filter;
 124         change->notified = 0;
 125         change->signaled = 0;
 126         insert_change( change );
 127         adjust_changes( get_unix_fd(fd), filter );
 128     }
 129     return change;
 130 }
 131
 132 static void change_dump( struct object *obj, int verbose )
 133 {
 134     struct change *change = (struct change *)obj;
 135     assert( obj->ops == &change_ops );
 136     fprintf( stderr, "Change notification fd=%p sub=%d filter=%08x\n",
 137              change->fd, change->subtree, change->filter );
 138 }
 139
 140 static int change_signaled( struct object *obj, struct thread *thread )
 141 {
 142     struct change *change = (struct change *)obj;
 143
 144     return change->signaled != 0;
 145 }
 146
 147 static void change_destroy( struct object *obj )
 148 {
 149     struct change *change = (struct change *)obj;
 150
 151     release_object( change->fd );
 152     remove_change( change );
 153 }
 154
 155 /* enter here directly from SIGIO signal handler */
 156 void do_change_notify( int unix_fd )
 157 {
 158     struct list *ptr;
 159
 160     /* FIXME: this is O(n) ... probably can be improved */
 161     LIST_FOR_EACH( ptr, &change_list )
 162     {
 163         struct change *change = LIST_ENTRY( ptr, struct change, entry );
 164         if (get_unix_fd( change->fd ) != unix_fd) continue;
 165         interlocked_xchg_add( &change->notified, 1 );
 166         break;
 167     }
 168 }
 169
 170 /* SIGIO callback, called synchronously with the poll loop */
 171 void sigio_callback(void)
 172 {
 173     struct list *ptr;
 174
 175     LIST_FOR_EACH( ptr, &change_list )
 176     {
 177         struct change *change = LIST_ENTRY( ptr, struct change, entry );
 178         long count = interlocked_xchg( &change->notified, 0 );
 179         if (count)
 180         {
 181             change->signaled += count;
 182             if (change->signaled == count)  /* was it 0? */
 183                 wake_up( &change->obj, 0 );
 184         }
 185     }
 186 }
 187
 188 /* create a change notification */
 189 DECL_HANDLER(create_change_notification)
 190 {
 191     struct change *change;
 192     struct file *file;
 193     struct fd *fd;
 194
 195     if (!(file = get_file_obj( current->process, req->handle, 0 ))) return;
 196     fd = get_obj_fd( (struct object *)file );
 197     release_object( file );
 198     if (!fd) return;
 199
 200     if ((change = create_change_notification( fd, req->subtree, req->filter )))
 201     {
 202         reply->handle = alloc_handle( current->process, change,
 203                                       STANDARD_RIGHTS_REQUIRED|SYNCHRONIZE, 0 );
 204         release_object( change );
 205     }
 206     release_object( fd );
 207 }
 208
 209 /* move to the next change notification */
 210 DECL_HANDLER(next_change_notification)
 211 {
 212     struct change *change;
 213
 214     if ((change = (struct change *)get_handle_obj( current->process, req->handle,
 215                                                    0, &change_ops )))
 216     {
 217         if (change->signaled > 0) change->signaled--;
 218         release_object( change );
 219     }
 220 }