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 #include <sys/stat.h>
  30
  31 #include "windef.h"
  32
  33 #include "file.h"
  34 #include "handle.h"
  35 #include "thread.h"
  36 #include "request.h"
  37
  38 #ifdef linux
  39 #ifndef F_NOTIFY
  40 #define F_NOTIFY 1026
  41 #define DN_ACCESS       0x00000001      /* File accessed */
  42 #define DN_MODIFY       0x00000002      /* File modified */
  43 #define DN_CREATE       0x00000004      /* File created */
  44 #define DN_DELETE       0x00000008      /* File removed */
  45 #define DN_RENAME       0x00000010      /* File renamed */
  46 #define DN_ATTRIB       0x00000020      /* File changed attibutes */
  47 #define DN_MULTISHOT    0x80000000      /* Don't remove notifier */
  48 #endif
  49 #endif
  50
  51 struct change
  52 {
  53     struct object  obj;      /* object header */
  54     struct fd     *fd;       /* file descriptor to the directory */
  55     struct list    entry;    /* entry in global change notifications list */
  56     int            subtree;  /* watch all the subtree */
  57     unsigned int   filter;   /* notification filter */
  58     long           notified; /* SIGIO counter */
  59     long           signaled; /* the file changed */
  60 };
  61
  62 static void change_dump( struct object *obj, int verbose );
  63 static int change_signaled( struct object *obj, struct thread *thread );
  64 static void change_destroy( struct object *obj );
  65
  66 static const struct object_ops change_ops =
  67 {
  68     sizeof(struct change),    /* size */
  69     change_dump,              /* dump */
  70     add_queue,                /* add_queue */
  71     remove_queue,             /* remove_queue */
  72     change_signaled,          /* signaled */
  73     no_satisfied,             /* satisfied */
  74     no_signal,                /* signal */
  75     no_get_fd,                /* get_fd */
  76     change_destroy            /* destroy */
  77 };
  78
  79 static struct list change_list = LIST_INIT(change_list);
  80
  81 static void adjust_changes( int fd, unsigned int filter )
  82 {
  83 #if defined(F_SETSIG) && defined(F_NOTIFY)
  84     unsigned int val;
  85     if ( 0 > fcntl( fd, F_SETSIG, SIGIO) )
  86         return;
  87
  88     val = DN_MULTISHOT;
  89     if( filter & FILE_NOTIFY_CHANGE_FILE_NAME )
  90         val |= DN_RENAME | DN_DELETE | DN_CREATE;
  91     if( filter & FILE_NOTIFY_CHANGE_DIR_NAME )
  92         val |= DN_RENAME | DN_DELETE | DN_CREATE;
  93     if( filter & FILE_NOTIFY_CHANGE_ATTRIBUTES )
  94         val |= DN_ATTRIB;
  95     if( filter & FILE_NOTIFY_CHANGE_SIZE )
  96         val |= DN_MODIFY;
  97     if( filter & FILE_NOTIFY_CHANGE_LAST_WRITE )
  98         val |= DN_MODIFY;
  99     if( filter & FILE_NOTIFY_CHANGE_LAST_ACCESS )
 100         val |= DN_ACCESS;
 101     if( filter & FILE_NOTIFY_CHANGE_CREATION )
 102         val |= DN_CREATE;
 103     if( filter & FILE_NOTIFY_CHANGE_SECURITY )
 104         val |= DN_ATTRIB;
 105     fcntl( fd, F_NOTIFY, val );
 106 #endif
 107 }
 108
 109 /* insert change in the global list */
 110 static inline void insert_change( struct change *change )
 111 {
 112     sigset_t sigset;
 113
 114     sigemptyset( &sigset );
 115     sigaddset( &sigset, SIGIO );
 116     sigprocmask( SIG_BLOCK, &sigset, NULL );
 117     list_add_head( &change_list, &change->entry );
 118     sigprocmask( SIG_UNBLOCK, &sigset, NULL );
 119 }
 120
 121 /* remove change from the global list */
 122 static inline void remove_change( struct change *change )
 123 {
 124     sigset_t sigset;
 125
 126     sigemptyset( &sigset );
 127     sigaddset( &sigset, SIGIO );
 128     sigprocmask( SIG_BLOCK, &sigset, NULL );
 129     list_remove( &change->entry );
 130     sigprocmask( SIG_UNBLOCK, &sigset, NULL );
 131 }
 132
 133 static struct change *create_change_notification( struct fd *fd, int subtree, unsigned int filter )
 134 {
 135     struct change *change;
 136     struct stat st;
 137     int unix_fd = get_unix_fd( fd );
 138
 139     if (fstat( unix_fd, &st ) == -1 || !S_ISDIR(st.st_mode))
 140     {
 141         set_error( STATUS_NOT_A_DIRECTORY );
 142         return NULL;
 143     }
 144
 145     if ((change = alloc_object( &change_ops )))
 146     {
 147         change->fd       = (struct fd *)grab_object( fd );
 148         change->subtree  = subtree;
 149         change->filter   = filter;
 150         change->notified = 0;
 151         change->signaled = 0;
 152         insert_change( change );
 153         adjust_changes( unix_fd, filter );
 154     }
 155     return change;
 156 }
 157
 158 static void change_dump( struct object *obj, int verbose )
 159 {
 160     struct change *change = (struct change *)obj;
 161     assert( obj->ops == &change_ops );
 162     fprintf( stderr, "Change notification fd=%p sub=%d filter=%08x\n",
 163              change->fd, change->subtree, change->filter );
 164 }
 165
 166 static int change_signaled( struct object *obj, struct thread *thread )
 167 {
 168     struct change *change = (struct change *)obj;
 169
 170     return change->signaled != 0;
 171 }
 172
 173 static void change_destroy( struct object *obj )
 174 {
 175     struct change *change = (struct change *)obj;
 176
 177     release_object( change->fd );
 178     remove_change( change );
 179 }
 180
 181 /* enter here directly from SIGIO signal handler */
 182 void do_change_notify( int unix_fd )
 183 {
 184     struct list *ptr;
 185
 186     /* FIXME: this is O(n) ... probably can be improved */
 187     LIST_FOR_EACH( ptr, &change_list )
 188     {
 189         struct change *change = LIST_ENTRY( ptr, struct change, entry );
 190         if (get_unix_fd( change->fd ) != unix_fd) continue;
 191         interlocked_xchg_add( &change->notified, 1 );
 192         break;
 193     }
 194 }
 195
 196 /* SIGIO callback, called synchronously with the poll loop */
 197 void sigio_callback(void)
 198 {
 199     struct list *ptr;
 200
 201     LIST_FOR_EACH( ptr, &change_list )
 202     {
 203         struct change *change = LIST_ENTRY( ptr, struct change, entry );
 204         long count = interlocked_xchg( &change->notified, 0 );
 205         if (count)
 206         {
 207             change->signaled += count;
 208             if (change->signaled == count)  /* was it 0? */
 209                 wake_up( &change->obj, 0 );
 210         }
 211     }
 212 }
 213
 214 /* create a change notification */
 215 DECL_HANDLER(create_change_notification)
 216 {
 217     struct change *change;
 218     struct file *file;
 219     struct fd *fd;
 220
 221     if (!(file = get_file_obj( current->process, req->handle, 0 ))) return;
 222     fd = get_obj_fd( (struct object *)file );
 223     release_object( file );
 224     if (!fd) return;
 225
 226     if ((change = create_change_notification( fd, req->subtree, req->filter )))
 227     {
 228         reply->handle = alloc_handle( current->process, change,
 229                                       STANDARD_RIGHTS_REQUIRED|SYNCHRONIZE, 0 );
 230         release_object( change );
 231     }
 232     release_object( fd );
 233 }
 234
 235 /* move to the next change notification */
 236 DECL_HANDLER(next_change_notification)
 237 {
 238     struct change *change;
 239
 240     if ((change = (struct change *)get_handle_obj( current->process, req->handle,
 241                                                    0, &change_ops )))
 242     {
 243         if (change->signaled > 0) change->signaled--;
 244         release_object( change );
 245     }
 246 }