src/gfilenotify.c

   1 /* Filesystem notifications support with glib API.
   2    Copyright (C) 2013-2016 Free Software Foundation, Inc.
   3
   4 This file is part of GNU Emacs.
   5
   6 GNU Emacs is free software: you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation, either version 3 of the License, or (at
   9 your option) any later version.
  10
  11 GNU Emacs 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
  14 GNU General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
  18
  19 #include <config.h>
  20
  21 #ifdef HAVE_GFILENOTIFY
  22 #include <stdio.h>
  23 #include <gio/gio.h>
  24 #include "lisp.h"
  25 #include "coding.h"
  26 #include "termhooks.h"
  27 #include "keyboard.h"
  28
  29 \f
  30 /* This is a list, elements are triples (DESCRIPTOR FILE FLAGS CALLBACK)  */
  31 static Lisp_Object watch_list;
  32
  33 /* This is the callback function for arriving signals from
  34    g_file_monitor.  It shall create a Lisp event, and put it into
  35    Emacs input queue.  */
  36 static gboolean
  37 dir_monitor_callback (GFileMonitor *monitor,
  38                       GFile *file,
  39                       GFile *other_file,
  40                       GFileMonitorEvent event_type,
  41                       gpointer user_data)
  42 {
  43   Lisp_Object symbol, monitor_object, watch_object, flags;
  44   char *name = g_file_get_parse_name (file);
  45   char *oname = other_file ? g_file_get_parse_name (other_file) : NULL;
  46
  47   /* Determine event symbol.  */
  48   switch (event_type)
  49     {
  50     case G_FILE_MONITOR_EVENT_CHANGED:
  51       symbol = Qchanged;
  52       break;
  53     case G_FILE_MONITOR_EVENT_CHANGES_DONE_HINT:
  54       symbol = Qchanges_done_hint;
  55       break;
  56     case G_FILE_MONITOR_EVENT_DELETED:
  57       symbol = Qdeleted;
  58       break;
  59     case G_FILE_MONITOR_EVENT_CREATED:
  60       symbol = Qcreated;
  61       break;
  62     case G_FILE_MONITOR_EVENT_ATTRIBUTE_CHANGED:
  63       symbol = Qattribute_changed;
  64       break;
  65     case G_FILE_MONITOR_EVENT_PRE_UNMOUNT:
  66       symbol = Qpre_unmount;
  67       break;
  68     case G_FILE_MONITOR_EVENT_UNMOUNTED:
  69       symbol = Qunmounted;
  70       break;
  71     case G_FILE_MONITOR_EVENT_MOVED:
  72       symbol = Qmoved;
  73       break;
  74     default:
  75       goto cleanup;
  76     }
  77
  78   /* Determine callback function.  */
  79   monitor_object = make_pointer_integer (monitor);
  80   eassert (INTEGERP (monitor_object));
  81   watch_object = assq_no_quit (monitor_object, watch_list);
  82
  83   if (CONSP (watch_object))
  84     {
  85       struct input_event event;
  86       Lisp_Object otail = oname ? list1 (build_string (oname)) : Qnil;
  87
  88       /* Check, whether event_type is expected.  */
  89       flags = XCAR (XCDR (XCDR (watch_object)));
  90       if ((!NILP (Fmember (Qchange, flags)) &&
  91            !NILP (Fmember (symbol, list5 (Qchanged, Qchanges_done_hint,
  92                                           Qdeleted, Qcreated, Qmoved)))) ||
  93           (!NILP (Fmember (Qattribute_change, flags)) &&
  94            ((EQ (symbol, Qattribute_changed)))))
  95         {
  96           /* Construct an event.  */
  97           EVENT_INIT (event);
  98           event.kind = FILE_NOTIFY_EVENT;
  99           event.frame_or_window = Qnil;
 100           event.arg = list2 (Fcons (monitor_object,
 101                                     Fcons (symbol,
 102                                            Fcons (build_string (name),
 103                                                   otail))),
 104                              XCAR (XCDR (XCDR (XCDR (watch_object)))));
 105
 106           /* Store it into the input event queue.  */
 107           kbd_buffer_store_event (&event);
 108           // XD_DEBUG_MESSAGE ("%s", XD_OBJECT_TO_STRING (event.arg));
 109         }
 110
 111       /* Cancel monitor if file or directory is deleted.  */
 112       if (!NILP (Fmember (symbol, list2 (Qdeleted, Qmoved))) &&
 113           (strcmp (name, SSDATA (XCAR (XCDR (watch_object)))) == 0) &&
 114           !g_file_monitor_is_cancelled (monitor))
 115         g_file_monitor_cancel (monitor);
 116     }
 117
 118   /* Cleanup.  */
 119  cleanup:
 120   g_free (name);
 121   g_free (oname);
 122
 123   return TRUE;
 124 }
 125
 126 DEFUN ("gfile-add-watch", Fgfile_add_watch, Sgfile_add_watch, 3, 3, 0,
 127        doc: /* Add a watch for filesystem events pertaining to FILE.
 128
 129 This arranges for filesystem events pertaining to FILE to be reported
 130 to Emacs.  Use `gfile-rm-watch' to cancel the watch.
 131
 132 Value is a descriptor for the added watch.  If the file cannot be
 133 watched for some reason, this function signals a `file-notify-error' error.
 134
 135 FLAGS is a list of conditions to set what will be watched for.  It can
 136 include the following symbols:
 137
 138   `change'           -- watch for file changes
 139   `attribute-change' -- watch for file attributes changes, like
 140                         permissions or modification time
 141   `watch-mounts'     -- watch for mount events
 142   `send-moved'       -- pair `deleted' and `created' events caused by
 143                         file renames and send a single `renamed' event
 144                         instead
 145
 146 When any event happens, Emacs will call the CALLBACK function passing
 147 it a single argument EVENT, which is of the form
 148
 149   (DESCRIPTOR ACTION FILE [FILE1])
 150
 151 DESCRIPTOR is the same object as the one returned by this function.
 152 ACTION is the description of the event.  It could be any one of the
 153 following:
 154
 155   `changed'           -- FILE has changed
 156   `changes-done-hint' -- a hint that this was probably the last change
 157                          in a set of changes
 158   `deleted'           -- FILE was deleted
 159   `created'           -- FILE was created
 160   `attribute-changed' -- a FILE attribute was changed
 161   `pre-unmount'       -- the FILE location will soon be unmounted
 162   `unmounted'         -- the FILE location was unmounted
 163   `moved'             -- FILE was moved to FILE1
 164
 165 FILE is the name of the file whose event is being reported.  FILE1
 166 will be reported only in case of the `moved' event.  */)
 167   (Lisp_Object file, Lisp_Object flags, Lisp_Object callback)
 168 {
 169   Lisp_Object watch_object;
 170   GFile *gfile;
 171   GFileMonitor *monitor;
 172   GFileMonitorFlags gflags = G_FILE_MONITOR_NONE;
 173   GError *gerror = NULL;
 174
 175   /* Check parameters.  */
 176   CHECK_STRING (file);
 177   file = Fdirectory_file_name (Fexpand_file_name (file, Qnil));
 178   if (NILP (Ffile_exists_p (file)))
 179     report_file_error ("File does not exist", file);
 180
 181   CHECK_LIST (flags);
 182
 183   if (!FUNCTIONP (callback))
 184     wrong_type_argument (Qinvalid_function, callback);
 185
 186   /* Create GFile name.  */
 187   gfile = g_file_new_for_path (SSDATA (ENCODE_FILE (file)));
 188
 189   /* Assemble flags.  */
 190   if (!NILP (Fmember (Qwatch_mounts, flags)))
 191     gflags |= G_FILE_MONITOR_WATCH_MOUNTS;
 192   if (!NILP (Fmember (Qsend_moved, flags)))
 193     gflags |= G_FILE_MONITOR_SEND_MOVED;
 194
 195   /* Enable watch.  */
 196   monitor = g_file_monitor (gfile, gflags, NULL, &gerror);
 197   g_object_unref (gfile);
 198   if (gerror)
 199     {
 200       char msg[1024];
 201       strcpy (msg, gerror->message);
 202       g_error_free (gerror);
 203       xsignal1 (Qfile_notify_error, build_string (msg));
 204     }
 205   if (! monitor)
 206     xsignal2 (Qfile_notify_error, build_string ("Cannot watch file"), file);
 207
 208   Lisp_Object watch_descriptor = make_pointer_integer (monitor);
 209
 210   /* Check the dicey assumption that make_pointer_integer is safe.  */
 211   if (! INTEGERP (watch_descriptor))
 212     {
 213       g_object_unref (monitor);
 214       xsignal2 (Qfile_notify_error, build_string ("Unsupported file watcher"),
 215                 file);
 216     }
 217
 218   /* The default rate limit is 800 msec.  We adapt this.  */
 219   g_file_monitor_set_rate_limit (monitor, 100);
 220
 221   /* Subscribe to the "changed" signal.  */
 222   g_signal_connect (monitor, "changed",
 223                     (GCallback) dir_monitor_callback, NULL);
 224
 225   /* Store watch object in watch list.  */
 226   watch_object = list4 (watch_descriptor, file, flags, callback);
 227   watch_list = Fcons (watch_object, watch_list);
 228
 229   return watch_descriptor;
 230 }
 231
 232 DEFUN ("gfile-rm-watch", Fgfile_rm_watch, Sgfile_rm_watch, 1, 1, 0,
 233        doc: /* Remove an existing WATCH-DESCRIPTOR.
 234
 235 WATCH-DESCRIPTOR should be an object returned by `gfile-add-watch'.  */)
 236      (Lisp_Object watch_descriptor)
 237 {
 238   Lisp_Object watch_object = assq_no_quit (watch_descriptor, watch_list);
 239
 240   if (! CONSP (watch_object))
 241     xsignal2 (Qfile_notify_error, build_string ("Not a watch descriptor"),
 242               watch_descriptor);
 243
 244   eassert (INTEGERP (watch_descriptor));
 245   GFileMonitor *monitor = XINTPTR (watch_descriptor);
 246   if (!g_file_monitor_is_cancelled (monitor) &&
 247       !g_file_monitor_cancel (monitor))
 248       xsignal2 (Qfile_notify_error, build_string ("Could not rm watch"),
 249                 watch_descriptor);
 250
 251   /* Remove watch descriptor from watch list.  */
 252   watch_list = Fdelq (watch_object, watch_list);
 253
 254   /* Cleanup.  */
 255   g_object_unref (monitor);
 256
 257   return Qt;
 258 }
 259
 260 DEFUN ("gfile-valid-p", Fgfile_valid_p, Sgfile_valid_p, 1, 1, 0,
 261        doc: /* "Check a watch specified by its WATCH-DESCRIPTOR.
 262
 263 WATCH-DESCRIPTOR should be an object returned by `gfile-add-watch'.
 264
 265 A watch can become invalid if the file or directory it watches is
 266 deleted, or if the watcher thread exits abnormally for any other
 267 reason.  Removing the watch by calling `gfile-rm-watch' also makes it
 268 invalid.  */)
 269      (Lisp_Object watch_descriptor)
 270 {
 271   Lisp_Object watch_object = Fassoc (watch_descriptor, watch_list);
 272   if (NILP (watch_object))
 273     return Qnil;
 274   else
 275     {
 276       GFileMonitor *monitor = XINTPTR (watch_descriptor);
 277       return g_file_monitor_is_cancelled (monitor) ? Qnil : Qt;
 278     }
 279 }
 280
 281 \f
 282 void
 283 globals_of_gfilenotify (void)
 284 {
 285 #if ! GLIB_CHECK_VERSION (2, 36, 0)
 286   g_type_init ();
 287 #endif
 288   watch_list = Qnil;
 289 }
 290
 291 void
 292 syms_of_gfilenotify (void)
 293 {
 294   defsubr (&Sgfile_add_watch);
 295   defsubr (&Sgfile_rm_watch);
 296   defsubr (&Sgfile_valid_p);
 297
 298   /* Filter objects.  */
 299   DEFSYM (Qchange, "change");
 300   DEFSYM (Qattribute_change, "attribute-change");
 301   DEFSYM (Qwatch_mounts, "watch-mounts"); /* G_FILE_MONITOR_WATCH_MOUNTS  */
 302   DEFSYM (Qsend_moved, "send-moved");   /* G_FILE_MONITOR_SEND_MOVED  */
 303
 304   /* Event types.  */
 305   DEFSYM (Qchanged, "changed"); /* G_FILE_MONITOR_EVENT_CHANGED  */
 306   DEFSYM (Qchanges_done_hint, "changes-done-hint");
 307                                 /* G_FILE_MONITOR_EVENT_CHANGES_DONE_HINT  */
 308   DEFSYM (Qdeleted, "deleted"); /* G_FILE_MONITOR_EVENT_DELETED  */
 309   DEFSYM (Qcreated, "created"); /* G_FILE_MONITOR_EVENT_CREATED  */
 310   DEFSYM (Qattribute_changed, "attribute-changed");
 311                                 /* G_FILE_MONITOR_EVENT_ATTRIBUTE_CHANGED  */
 312   DEFSYM (Qpre_unmount, "pre-unmount"); /* G_FILE_MONITOR_EVENT_PRE_UNMOUNT  */
 313   DEFSYM (Qunmounted, "unmounted");     /* G_FILE_MONITOR_EVENT_UNMOUNTED  */
 314   DEFSYM (Qmoved, "moved");     /* G_FILE_MONITOR_EVENT_MOVED  */
 315
 316   staticpro (&watch_list);
 317
 318   Fprovide (intern_c_string ("gfilenotify"), Qnil);
 319
 320 }
 321
 322 #endif /* HAVE_GFILENOTIFY  */