src/gfilenotify.c

   1 /* Filesystem notifications support with glib API.
   2    Copyright (C) 2013 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
   9 (at 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 "frame.h"
  27 #include "termhooks.h"
  28 #include "keyboard.h"
  29 #include "process.h"
  30
  31 \f
  32 /* Subroutines.  */
  33 static Lisp_Object Qgfile_add_watch;
  34 static Lisp_Object Qgfile_rm_watch;
  35
  36 /* Filter objects.  */
  37 static Lisp_Object Qwatch_mounts;      /* G_FILE_MONITOR_WATCH_MOUNTS  */
  38 static Lisp_Object Qsend_moved;        /* G_FILE_MONITOR_SEND_MOVED  */
  39
  40 /* Event types.  */
  41 static Lisp_Object Qchanged;           /* G_FILE_MONITOR_EVENT_CHANGED  */
  42 static Lisp_Object Qchanges_done_hint; /* G_FILE_MONITOR_EVENT_CHANGES_DONE_HINT  */
  43 static Lisp_Object Qdeleted;           /* G_FILE_MONITOR_EVENT_DELETED  */
  44 static Lisp_Object Qcreated;           /* G_FILE_MONITOR_EVENT_CREATED  */
  45 static Lisp_Object Qattribute_changed; /* G_FILE_MONITOR_EVENT_ATTRIBUTE_CHANGED  */
  46 static Lisp_Object Qpre_unmount;       /* G_FILE_MONITOR_EVENT_PRE_UNMOUNT  */
  47 static Lisp_Object Qunmounted;         /* G_FILE_MONITOR_EVENT_UNMOUNTED  */
  48 static Lisp_Object Qmoved;             /* G_FILE_MONITOR_EVENT_MOVED  */
  49
  50 static Lisp_Object watch_list;
  51
  52 /* This is the callback function for arriving signals from
  53    g_file_monitor.  It shall create a Lisp event, and put it into
  54    Emacs input queue.  */
  55 static gboolean
  56 dir_monitor_callback (GFileMonitor *monitor,
  57                       GFile *file,
  58                       GFile *other_file,
  59                       GFileMonitorEvent event_type,
  60                       gpointer user_data)
  61 {
  62   Lisp_Object symbol, monitor_object, watch_object;
  63   char *name = g_file_get_parse_name (file);
  64   char *oname = other_file ? g_file_get_parse_name (other_file) : NULL;
  65
  66   /* Determine event symbol.  */
  67   switch (event_type)
  68     {
  69     case G_FILE_MONITOR_EVENT_CHANGED:
  70       symbol = Qchanged;
  71       break;
  72     case G_FILE_MONITOR_EVENT_CHANGES_DONE_HINT:
  73       symbol = Qchanges_done_hint;
  74       break;
  75     case G_FILE_MONITOR_EVENT_DELETED:
  76       symbol = Qdeleted;
  77       break;
  78     case G_FILE_MONITOR_EVENT_CREATED:
  79       symbol = Qcreated;
  80       break;
  81     case G_FILE_MONITOR_EVENT_ATTRIBUTE_CHANGED:
  82       symbol = Qattribute_changed;
  83       break;
  84     case G_FILE_MONITOR_EVENT_PRE_UNMOUNT:
  85       symbol = Qpre_unmount;
  86       break;
  87     case G_FILE_MONITOR_EVENT_UNMOUNTED:
  88       symbol = Qunmounted;
  89       break;
  90     case G_FILE_MONITOR_EVENT_MOVED:
  91       symbol = Qmoved;
  92       break;
  93     default:
  94       goto cleanup;
  95     }
  96
  97   /* Determine callback function.  */
  98   monitor_object = XIL ((intptr_t) monitor);
  99   eassert (INTEGERP (monitor_object));
 100   watch_object = assq_no_quit (monitor_object, watch_list);
 101
 102   if (CONSP (watch_object))
 103     {
 104       /* Construct an event.  */
 105       struct input_event event;
 106       Lisp_Object otail = oname ? list1 (build_string (oname)) : Qnil;
 107       EVENT_INIT (event);
 108       event.kind = FILE_NOTIFY_EVENT;
 109       event.frame_or_window = Qnil;
 110       event.arg = list2 (Fcons (monitor_object,
 111                                 Fcons (symbol,
 112                                        Fcons (build_string (name),
 113                                               otail))),
 114                          XCDR (watch_object));
 115
 116       /* Store it into the input event queue.  */
 117       kbd_buffer_store_event (&event);
 118     }
 119
 120   /* Cleanup.  */
 121  cleanup:
 122   g_free (name);
 123   g_free (oname);
 124
 125   return TRUE;
 126 }
 127
 128 DEFUN ("gfile-add-watch", Fgfile_add_watch, Sgfile_add_watch, 3, 3, 0,
 129        doc: /* Add a watch for filesystem events pertaining to FILE.
 130
 131 This arranges for filesystem events pertaining to FILE to be reported
 132 to Emacs.  Use `gfile-rm-watch' to cancel the watch.
 133
 134 Value is a descriptor for the added watch.  If the file cannot be
 135 watched for some reason, this function signals a `file-notify-error' error.
 136
 137 FLAGS is a list of conditions to set what will be watched for.  It can
 138 include the following symbols:
 139
 140   'watch-mounts' -- watch for mount events
 141   'send-moved'   -- pair 'deleted' and 'created' events caused by file
 142                     renames and send a single 'renamed' event instead
 143
 144 When any event happens, Emacs will call the CALLBACK function passing
 145 it a single argument EVENT, which is of the form
 146
 147   (DESCRIPTOR ACTION FILE [FILE1])
 148
 149 DESCRIPTOR is the same object as the one returned by this function.
 150 ACTION is the description of the event.  It could be any one of the
 151 following:
 152
 153   'changed'           -- FILE has changed
 154   'changes-done-hint' -- a hint that this was probably the last change
 155                          in a set of changes
 156   'deleted'           -- FILE was deleted
 157   'created'           -- FILE was created
 158   'attribute-changed' -- a FILE attribute was changed
 159   'pre-unmount'       -- the FILE location will soon be unmounted
 160   'unmounted'         -- the FILE location was unmounted
 161   'moved'             -- FILE was moved to FILE1
 162
 163 FILE is the name of the file whose event is being reported.  FILE1
 164 will be reported only in case of the 'moved' event.  */)
 165   (Lisp_Object file, Lisp_Object flags, Lisp_Object callback)
 166 {
 167   Lisp_Object watch_descriptor, watch_object;
 168   GFile *gfile;
 169   GFileMonitor *monitor;
 170   GFileMonitorFlags gflags = G_FILE_MONITOR_NONE;
 171
 172   /* Check parameters.  */
 173   CHECK_STRING (file);
 174   file = Fdirectory_file_name (Fexpand_file_name (file, Qnil));
 175   if (NILP (Ffile_exists_p (file)))
 176     report_file_error ("File does not exist", file);
 177
 178   CHECK_LIST (flags);
 179
 180   if (!FUNCTIONP (callback))
 181     wrong_type_argument (Qinvalid_function, callback);
 182
 183   /* Create GFile name.  */
 184   gfile = g_file_new_for_path (SSDATA (ENCODE_FILE (file)));
 185
 186   /* Assemble flags.  */
 187   if (!NILP (Fmember (Qwatch_mounts, flags)))
 188     gflags |= G_FILE_MONITOR_WATCH_MOUNTS;
 189   if (!NILP (Fmember (Qsend_moved, flags)))
 190     gflags |= G_FILE_MONITOR_SEND_MOVED;
 191
 192   /* Enable watch.  */
 193   monitor = g_file_monitor (gfile, gflags, NULL, NULL);
 194   if (! monitor)
 195     xsignal2 (Qfile_notify_error, build_string ("Cannot watch file"), file);
 196
 197   /* On all known glib platforms, converting MONITOR directly to a
 198      Lisp_Object value results is a Lisp integer, which is safe.  This
 199      assumption is dicey, though, so check it now.  */
 200   watch_descriptor = XIL ((intptr_t) monitor);
 201   if (! INTEGERP (watch_descriptor))
 202     {
 203       g_object_unref (monitor);
 204       xsignal2 (Qfile_notify_error, build_string ("Unsupported file watcher"),
 205                 file);
 206     }
 207
 208   g_signal_connect (monitor, "changed",
 209                     (GCallback) dir_monitor_callback, NULL);
 210
 211   /* Store watch object in watch list.  */
 212   watch_object = Fcons (watch_descriptor, callback);
 213   watch_list = Fcons (watch_object, watch_list);
 214
 215   return watch_descriptor;
 216 }
 217
 218 DEFUN ("gfile-rm-watch", Fgfile_rm_watch, Sgfile_rm_watch, 1, 1, 0,
 219        doc: /* Remove an existing WATCH-DESCRIPTOR.
 220
 221 WATCH-DESCRIPTOR should be an object returned by `gfile-add-watch'.  */)
 222      (Lisp_Object watch_descriptor)
 223 {
 224   intptr_t int_monitor;
 225   GFileMonitor *monitor;
 226   Lisp_Object watch_object = assq_no_quit (watch_descriptor, watch_list);
 227
 228   if (! CONSP (watch_object))
 229     xsignal2 (Qfile_notify_error, build_string ("Not a watch descriptor"),
 230               watch_descriptor);
 231
 232   eassert (INTEGERP (watch_descriptor));
 233   int_monitor = XLI (watch_descriptor);
 234   monitor = (GFileMonitor *) int_monitor;
 235   if (!g_file_monitor_cancel (monitor))
 236     xsignal2 (Qfile_notify_error, build_string ("Could not rm watch"),
 237               watch_descriptor);
 238
 239   /* Remove watch descriptor from watch list. */
 240   watch_list = Fdelq (watch_object, watch_list);
 241
 242   /* Cleanup.  */
 243   g_object_unref (monitor);
 244
 245   return Qt;
 246 }
 247
 248 \f
 249 void
 250 globals_of_gfilenotify (void)
 251 {
 252 #if ! GLIB_CHECK_VERSION (2, 36, 0)
 253   g_type_init ();
 254 #endif
 255   watch_list = Qnil;
 256 }
 257
 258 void
 259 syms_of_gfilenotify (void)
 260 {
 261
 262   DEFSYM (Qgfile_add_watch, "gfile-add-watch");
 263   defsubr (&Sgfile_add_watch);
 264
 265   DEFSYM (Qgfile_rm_watch, "gfile-rm-watch");
 266   defsubr (&Sgfile_rm_watch);
 267
 268   DEFSYM (Qwatch_mounts, "watch-mounts");
 269   DEFSYM (Qsend_moved, "send-moved");
 270   DEFSYM (Qchanged, "changed");
 271   DEFSYM (Qchanges_done_hint, "changes-done-hint");
 272   DEFSYM (Qdeleted, "deleted");
 273   DEFSYM (Qcreated, "created");
 274   DEFSYM (Qattribute_changed, "attribute-changed");
 275   DEFSYM (Qpre_unmount, "pre-unmount");
 276   DEFSYM (Qunmounted, "unmounted");
 277   DEFSYM (Qmoved, "moved");
 278
 279   staticpro (&watch_list);
 280
 281   Fprovide (intern_c_string ("gfilenotify"), Qnil);
 282
 283 }
 284
 285 #endif /* HAVE_GFILENOTIFY  */