src/gfilenotify.c

   1 /* Filesystem notifications support with glib API.
   2    Copyright (C) 2013-2018 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 <https://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 quadruples (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   if (!FUNCTIONP (callback))
 182     wrong_type_argument (Qinvalid_function, callback);
 183
 184   /* Assemble flags.  */
 185   if (!NILP (Fmember (Qwatch_mounts, flags)))
 186     gflags |= G_FILE_MONITOR_WATCH_MOUNTS;
 187   if (!NILP (Fmember (Qsend_moved, flags)))
 188     gflags |= G_FILE_MONITOR_SEND_MOVED;
 189
 190   /* Create GFile name.  */
 191   gfile = g_file_new_for_path (SSDATA (ENCODE_FILE (file)));
 192
 193   /* Enable watch.  */
 194   monitor = g_file_monitor (gfile, gflags, NULL, &gerror);
 195   g_object_unref (gfile);
 196   if (gerror)
 197     {
 198       char msg[1024];
 199       strcpy (msg, gerror->message);
 200       g_error_free (gerror);
 201       xsignal1 (Qfile_notify_error, build_string (msg));
 202     }
 203   if (! monitor)
 204     xsignal2 (Qfile_notify_error, build_string ("Cannot watch file"), file);
 205
 206   Lisp_Object watch_descriptor = make_pointer_integer (monitor);
 207
 208   /* Check the dicey assumption that make_pointer_integer is safe.  */
 209   if (! INTEGERP (watch_descriptor))
 210     {
 211       g_object_unref (monitor);
 212       xsignal2 (Qfile_notify_error, build_string ("Unsupported file watcher"),
 213                 file);
 214     }
 215
 216   /* The default rate limit is 800 msec.  We adapt this.  */
 217   g_file_monitor_set_rate_limit (monitor, 100);
 218
 219   /* Subscribe to the "changed" signal.  */
 220   g_signal_connect (monitor, "changed",
 221                     (GCallback) dir_monitor_callback, NULL);
 222
 223   /* Store watch object in watch list.  */
 224   watch_object = list4 (watch_descriptor, file, flags, callback);
 225   watch_list = Fcons (watch_object, watch_list);
 226
 227   return watch_descriptor;
 228 }
 229
 230 DEFUN ("gfile-rm-watch", Fgfile_rm_watch, Sgfile_rm_watch, 1, 1, 0,
 231        doc: /* Remove an existing WATCH-DESCRIPTOR.
 232
 233 WATCH-DESCRIPTOR should be an object returned by `gfile-add-watch'.  */)
 234      (Lisp_Object watch_descriptor)
 235 {
 236   Lisp_Object watch_object = assq_no_quit (watch_descriptor, watch_list);
 237
 238   if (! CONSP (watch_object))
 239     xsignal2 (Qfile_notify_error, build_string ("Not a watch descriptor"),
 240               watch_descriptor);
 241
 242   eassert (INTEGERP (watch_descriptor));
 243   GFileMonitor *monitor = XINTPTR (watch_descriptor);
 244   if (!g_file_monitor_is_cancelled (monitor) &&
 245       !g_file_monitor_cancel (monitor))
 246       xsignal2 (Qfile_notify_error, build_string ("Could not rm watch"),
 247                 watch_descriptor);
 248
 249   /* Remove watch descriptor from watch list.  */
 250   watch_list = Fdelq (watch_object, watch_list);
 251
 252   /* Cleanup.  */
 253   g_object_unref (monitor);
 254
 255   return Qt;
 256 }
 257
 258 DEFUN ("gfile-valid-p", Fgfile_valid_p, Sgfile_valid_p, 1, 1, 0,
 259        doc: /* Check a watch specified by its WATCH-DESCRIPTOR.
 260
 261 WATCH-DESCRIPTOR should be an object returned by `gfile-add-watch'.
 262
 263 A watch can become invalid if the file or directory it watches is
 264 deleted, or if the watcher thread exits abnormally for any other
 265 reason.  Removing the watch by calling `gfile-rm-watch' also makes it
 266 invalid.  */)
 267      (Lisp_Object watch_descriptor)
 268 {
 269   Lisp_Object watch_object = Fassoc (watch_descriptor, watch_list, Qnil);
 270   if (NILP (watch_object))
 271     return Qnil;
 272   else
 273     {
 274       GFileMonitor *monitor = XINTPTR (watch_descriptor);
 275       return g_file_monitor_is_cancelled (monitor) ? Qnil : Qt;
 276     }
 277 }
 278
 279 DEFUN ("gfile-monitor-name", Fgfile_monitor_name, Sgfile_monitor_name, 1, 1, 0,
 280        doc: /* Return the internal monitor name for WATCH-DESCRIPTOR.
 281
 282 The result is a symbol, either `GInotifyFileMonitor',
 283 `GKqueueFileMonitor', `GFamFileMonitor', or `GPollFileMonitor'.
 284
 285 WATCH-DESCRIPTOR should be an object returned by `gfile-add-watch'.
 286 If WATCH-DESCRIPTOR is not valid, nil is returned.  */)
 287      (Lisp_Object watch_descriptor)
 288 {
 289   if (NILP (Fgfile_valid_p (watch_descriptor)))
 290     return Qnil;
 291   else
 292     {
 293       GFileMonitor *monitor = XINTPTR (watch_descriptor);
 294       return intern (G_OBJECT_TYPE_NAME (monitor));
 295     }
 296 }
 297
 298 \f
 299 void
 300 globals_of_gfilenotify (void)
 301 {
 302 #if ! GLIB_CHECK_VERSION (2, 36, 0)
 303   g_type_init ();
 304 #endif
 305   watch_list = Qnil;
 306 }
 307
 308 void
 309 syms_of_gfilenotify (void)
 310 {
 311   defsubr (&Sgfile_add_watch);
 312   defsubr (&Sgfile_rm_watch);
 313   defsubr (&Sgfile_valid_p);
 314   defsubr (&Sgfile_monitor_name);
 315
 316   /* Filter objects.  */
 317   DEFSYM (Qchange, "change");
 318   DEFSYM (Qattribute_change, "attribute-change");
 319   DEFSYM (Qwatch_mounts, "watch-mounts"); /* G_FILE_MONITOR_WATCH_MOUNTS  */
 320   DEFSYM (Qsend_moved, "send-moved");   /* G_FILE_MONITOR_SEND_MOVED  */
 321
 322   /* Event types.  */
 323   DEFSYM (Qchanged, "changed"); /* G_FILE_MONITOR_EVENT_CHANGED  */
 324   DEFSYM (Qchanges_done_hint, "changes-done-hint");
 325                                 /* G_FILE_MONITOR_EVENT_CHANGES_DONE_HINT  */
 326   DEFSYM (Qdeleted, "deleted"); /* G_FILE_MONITOR_EVENT_DELETED  */
 327   DEFSYM (Qcreated, "created"); /* G_FILE_MONITOR_EVENT_CREATED  */
 328   DEFSYM (Qattribute_changed, "attribute-changed");
 329                                 /* G_FILE_MONITOR_EVENT_ATTRIBUTE_CHANGED  */
 330   DEFSYM (Qpre_unmount, "pre-unmount"); /* G_FILE_MONITOR_EVENT_PRE_UNMOUNT  */
 331   DEFSYM (Qunmounted, "unmounted");     /* G_FILE_MONITOR_EVENT_UNMOUNTED  */
 332   DEFSYM (Qmoved, "moved");     /* G_FILE_MONITOR_EVENT_MOVED  */
 333
 334   staticpro (&watch_list);
 335
 336   Fprovide (intern_c_string ("gfilenotify"), Qnil);
 337
 338 }
 339
 340 #endif /* HAVE_GFILENOTIFY  */