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     int            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_lookup_name,           /* lookup_name */
  77     no_close_handle,          /* close_handle */
  78     change_destroy            /* destroy */
  79 };
  80
  81 static struct list change_list = LIST_INIT(change_list);
  82
  83 static void adjust_changes( int fd, unsigned int filter )
  84 {
  85 #if defined(F_SETSIG) && defined(F_NOTIFY)
  86     unsigned int val;
  87     if ( 0 > fcntl( fd, F_SETSIG, SIGIO) )
  88         return;
  89
  90     val = DN_MULTISHOT;
  91     if (filter & FILE_NOTIFY_CHANGE_FILE_NAME)
  92         val |= DN_RENAME | DN_DELETE | DN_CREATE;
  93     if (filter & FILE_NOTIFY_CHANGE_DIR_NAME)
  94         val |= DN_RENAME | DN_DELETE | DN_CREATE;
  95     if (filter & FILE_NOTIFY_CHANGE_ATTRIBUTES)
  96         val |= DN_ATTRIB;
  97     if (filter & FILE_NOTIFY_CHANGE_SIZE)
  98         val |= DN_MODIFY;
  99     if (filter & FILE_NOTIFY_CHANGE_LAST_WRITE)
 100         val |= DN_MODIFY;
 101     if (filter & FILE_NOTIFY_CHANGE_LAST_ACCESS)
 102         val |= DN_ACCESS;
 103     if (filter & FILE_NOTIFY_CHANGE_CREATION)
 104         val |= DN_CREATE;
 105     if (filter & FILE_NOTIFY_CHANGE_SECURITY)
 106         val |= DN_ATTRIB;
 107     fcntl( fd, F_NOTIFY, val );
 108 #endif
 109 }
 110
 111 /* insert change in the global list */
 112 static inline void insert_change( struct change *change )
 113 {
 114     sigset_t sigset;
 115
 116     sigemptyset( &sigset );
 117     sigaddset( &sigset, SIGIO );
 118     sigprocmask( SIG_BLOCK, &sigset, NULL );
 119     list_add_head( &change_list, &change->entry );
 120     sigprocmask( SIG_UNBLOCK, &sigset, NULL );
 121 }
 122
 123 /* remove change from the global list */
 124 static inline void remove_change( struct change *change )
 125 {
 126     sigset_t sigset;
 127
 128     sigemptyset( &sigset );
 129     sigaddset( &sigset, SIGIO );
 130     sigprocmask( SIG_BLOCK, &sigset, NULL );
 131     list_remove( &change->entry );
 132     sigprocmask( SIG_UNBLOCK, &sigset, NULL );
 133 }
 134
 135 static struct change *create_change_notification( struct fd *fd, int subtree, unsigned int filter )
 136 {
 137     struct change *change;
 138     struct stat st;
 139     int unix_fd = get_unix_fd( fd );
 140
 141     if (unix_fd == -1) return NULL;
 142
 143     if (fstat( unix_fd, &st ) == -1 || !S_ISDIR(st.st_mode))
 144     {
 145         set_error( STATUS_NOT_A_DIRECTORY );
 146         return NULL;
 147     }
 148
 149     if ((change = alloc_object( &change_ops )))
 150     {
 151         change->fd       = (struct fd *)grab_object( fd );
 152         change->subtree  = subtree;
 153         change->filter   = filter;
 154         change->notified = 0;
 155         change->signaled = 0;
 156         insert_change( change );
 157         adjust_changes( unix_fd, filter );
 158     }
 159     return change;
 160 }
 161
 162 static void change_dump( struct object *obj, int verbose )
 163 {
 164     struct change *change = (struct change *)obj;
 165     assert( obj->ops == &change_ops );
 166     fprintf( stderr, "Change notification fd=%p sub=%d filter=%08x\n",
 167              change->fd, change->subtree, change->filter );
 168 }
 169
 170 static int change_signaled( struct object *obj, struct thread *thread )
 171 {
 172     struct change *change = (struct change *)obj;
 173
 174     return change->signaled != 0;
 175 }
 176
 177 static void change_destroy( struct object *obj )
 178 {
 179     struct change *change = (struct change *)obj;
 180
 181     release_object( change->fd );
 182     remove_change( change );
 183 }
 184
 185 /* enter here directly from SIGIO signal handler */
 186 void do_change_notify( int unix_fd )
 187 {
 188     struct list *ptr;
 189
 190     /* FIXME: this is O(n) ... probably can be improved */
 191     LIST_FOR_EACH( ptr, &change_list )
 192     {
 193         struct change *change = LIST_ENTRY( ptr, struct change, entry );
 194         if (get_unix_fd( change->fd ) != unix_fd) continue;
 195         interlocked_xchg_add( &change->notified, 1 );
 196         break;
 197     }
 198 }
 199
 200 /* SIGIO callback, called synchronously with the poll loop */
 201 void sigio_callback(void)
 202 {
 203     struct list *ptr;
 204
 205     LIST_FOR_EACH( ptr, &change_list )
 206     {
 207         struct change *change = LIST_ENTRY( ptr, struct change, entry );
 208         long count = interlocked_xchg( &change->notified, 0 );
 209         if (count)
 210         {
 211             change->signaled += count;
 212             if (change->signaled == count)  /* was it 0? */
 213                 wake_up( &change->obj, 0 );
 214         }
 215     }
 216 }
 217
 218 /* create a change notification */
 219 DECL_HANDLER(create_change_notification)
 220 {
 221     struct change *change;
 222     struct file *file;
 223     struct fd *fd;
 224
 225     if (!(file = get_file_obj( current->process, req->handle, 0 ))) return;
 226     fd = get_obj_fd( (struct object *)file );
 227     release_object( file );
 228     if (!fd) return;
 229
 230     if ((change = create_change_notification( fd, req->subtree, req->filter )))
 231     {
 232         reply->handle = alloc_handle( current->process, change,
 233                                       STANDARD_RIGHTS_REQUIRED|SYNCHRONIZE, 0 );
 234         release_object( change );
 235     }
 236     release_object( fd );
 237 }
 238
 239 /* move to the next change notification */
 240 DECL_HANDLER(next_change_notification)
 241 {
 242     struct change *change;
 243
 244     if ((change = (struct change *)get_handle_obj( current->process, req->handle,
 245                                                    0, &change_ops )))
 246     {
 247         if (change->signaled > 0) change->signaled--;
 248         release_object( change );
 249     }
 250 }