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     no_close_handle,          /* close_handle */
  77     change_destroy            /* destroy */
  78 };
  79
  80 static struct list change_list = LIST_INIT(change_list);
  81
  82 static void adjust_changes( int fd, unsigned int filter )
  83 {
  84 #if defined(F_SETSIG) && defined(F_NOTIFY)
  85     unsigned int val;
  86     if ( 0 > fcntl( fd, F_SETSIG, SIGIO) )
  87         return;
  88
  89     val = DN_MULTISHOT;
  90     if (filter & FILE_NOTIFY_CHANGE_FILE_NAME)
  91         val |= DN_RENAME | DN_DELETE | DN_CREATE;
  92     if (filter & FILE_NOTIFY_CHANGE_DIR_NAME)
  93         val |= DN_RENAME | DN_DELETE | DN_CREATE;
  94     if (filter & FILE_NOTIFY_CHANGE_ATTRIBUTES)
  95         val |= DN_ATTRIB;
  96     if (filter & FILE_NOTIFY_CHANGE_SIZE)
  97         val |= DN_MODIFY;
  98     if (filter & FILE_NOTIFY_CHANGE_LAST_WRITE)
  99         val |= DN_MODIFY;
 100     if (filter & FILE_NOTIFY_CHANGE_LAST_ACCESS)
 101         val |= DN_ACCESS;
 102     if (filter & FILE_NOTIFY_CHANGE_CREATION)
 103         val |= DN_CREATE;
 104     if (filter & FILE_NOTIFY_CHANGE_SECURITY)
 105         val |= DN_ATTRIB;
 106     fcntl( fd, F_NOTIFY, val );
 107 #endif
 108 }
 109
 110 /* insert change in the global list */
 111 static inline void insert_change( struct change *change )
 112 {
 113     sigset_t sigset;
 114
 115     sigemptyset( &sigset );
 116     sigaddset( &sigset, SIGIO );
 117     sigprocmask( SIG_BLOCK, &sigset, NULL );
 118     list_add_head( &change_list, &change->entry );
 119     sigprocmask( SIG_UNBLOCK, &sigset, NULL );
 120 }
 121
 122 /* remove change from the global list */
 123 static inline void remove_change( struct change *change )
 124 {
 125     sigset_t sigset;
 126
 127     sigemptyset( &sigset );
 128     sigaddset( &sigset, SIGIO );
 129     sigprocmask( SIG_BLOCK, &sigset, NULL );
 130     list_remove( &change->entry );
 131     sigprocmask( SIG_UNBLOCK, &sigset, NULL );
 132 }
 133
 134 static struct change *create_change_notification( struct fd *fd, int subtree, unsigned int filter )
 135 {
 136     struct change *change;
 137     struct stat st;
 138     int unix_fd = get_unix_fd( fd );
 139
 140     if (fstat( unix_fd, &st ) == -1 || !S_ISDIR(st.st_mode))
 141     {
 142         set_error( STATUS_NOT_A_DIRECTORY );
 143         return NULL;
 144     }
 145
 146     if ((change = alloc_object( &change_ops )))
 147     {
 148         change->fd       = (struct fd *)grab_object( fd );
 149         change->subtree  = subtree;
 150         change->filter   = filter;
 151         change->notified = 0;
 152         change->signaled = 0;
 153         insert_change( change );
 154         adjust_changes( unix_fd, filter );
 155     }
 156     return change;
 157 }
 158
 159 static void change_dump( struct object *obj, int verbose )
 160 {
 161     struct change *change = (struct change *)obj;
 162     assert( obj->ops == &change_ops );
 163     fprintf( stderr, "Change notification fd=%p sub=%d filter=%08x\n",
 164              change->fd, change->subtree, change->filter );
 165 }
 166
 167 static int change_signaled( struct object *obj, struct thread *thread )
 168 {
 169     struct change *change = (struct change *)obj;
 170
 171     return change->signaled != 0;
 172 }
 173
 174 static void change_destroy( struct object *obj )
 175 {
 176     struct change *change = (struct change *)obj;
 177
 178     release_object( change->fd );
 179     remove_change( change );
 180 }
 181
 182 /* enter here directly from SIGIO signal handler */
 183 void do_change_notify( int unix_fd )
 184 {
 185     struct list *ptr;
 186
 187     /* FIXME: this is O(n) ... probably can be improved */
 188     LIST_FOR_EACH( ptr, &change_list )
 189     {
 190         struct change *change = LIST_ENTRY( ptr, struct change, entry );
 191         if (get_unix_fd( change->fd ) != unix_fd) continue;
 192         interlocked_xchg_add( &change->notified, 1 );
 193         break;
 194     }
 195 }
 196
 197 /* SIGIO callback, called synchronously with the poll loop */
 198 void sigio_callback(void)
 199 {
 200     struct list *ptr;
 201
 202     LIST_FOR_EACH( ptr, &change_list )
 203     {
 204         struct change *change = LIST_ENTRY( ptr, struct change, entry );
 205         long count = interlocked_xchg( &change->notified, 0 );
 206         if (count)
 207         {
 208             change->signaled += count;
 209             if (change->signaled == count)  /* was it 0? */
 210                 wake_up( &change->obj, 0 );
 211         }
 212     }
 213 }
 214
 215 /* create a change notification */
 216 DECL_HANDLER(create_change_notification)
 217 {
 218     struct change *change;
 219     struct file *file;
 220     struct fd *fd;
 221
 222     if (!(file = get_file_obj( current->process, req->handle, 0 ))) return;
 223     fd = get_obj_fd( (struct object *)file );
 224     release_object( file );
 225     if (!fd) return;
 226
 227     if ((change = create_change_notification( fd, req->subtree, req->filter )))
 228     {
 229         reply->handle = alloc_handle( current->process, change,
 230                                       STANDARD_RIGHTS_REQUIRED|SYNCHRONIZE, 0 );
 231         release_object( change );
 232     }
 233     release_object( fd );
 234 }
 235
 236 /* move to the next change notification */
 237 DECL_HANDLER(next_change_notification)
 238 {
 239     struct change *change;
 240
 241     if ((change = (struct change *)get_handle_obj( current->process, req->handle,
 242                                                    0, &change_ops )))
 243     {
 244         if (change->signaled > 0) change->signaled--;
 245         release_object( change );
 246     }
 247 }