src/inotify.c

   1 /* Inotify support for Emacs
   2
   3 Copyright (C) 2012-2015 Free Software Foundation, Inc.
   4
   5 This file is part of GNU Emacs.
   6
   7 GNU Emacs is free software: you can redistribute it and/or modify
   8 it under the terms of the GNU General Public License as published by
   9 the Free Software Foundation, either version 3 of the License, or
  10 (at your option) any later version.
  11
  12 GNU Emacs is distributed in the hope that it will be useful,
  13 but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 GNU General Public License for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
  19
  20 #include <config.h>
  21
  22 #ifdef HAVE_INOTIFY
  23
  24 #include "lisp.h"
  25 #include "coding.h"
  26 #include "process.h"
  27 #include "keyboard.h"
  28 #include "character.h"
  29 #include "frame.h" /* Required for termhooks.h.  */
  30 #include "termhooks.h"
  31
  32 #include <sys/inotify.h>
  33 #include <sys/ioctl.h>
  34
  35 /* Ignore bits that might be undefined on old GNU/Linux systems.  */
  36 #ifndef IN_EXCL_UNLINK
  37 # define IN_EXCL_UNLINK 0
  38 #endif
  39 #ifndef IN_DONT_FOLLOW
  40 # define IN_DONT_FOLLOW 0
  41 #endif
  42 #ifndef IN_ONLYDIR
  43 # define IN_ONLYDIR 0
  44 #endif
  45
  46 /* File handle for inotify.  */
  47 static int inotifyfd = -1;
  48
  49 /* Assoc list of files being watched.
  50    Format:
  51    (watch-descriptor . callback)
  52  */
  53 static Lisp_Object watch_list;
  54
  55 static Lisp_Object
  56 make_watch_descriptor (int wd)
  57 {
  58   /* TODO replace this with a Misc Object! */
  59   return make_number (wd);
  60 }
  61
  62 static Lisp_Object
  63 mask_to_aspects (uint32_t mask) {
  64   Lisp_Object aspects = Qnil;
  65   if (mask & IN_ACCESS)
  66     aspects = Fcons (Qaccess, aspects);
  67   if (mask & IN_ATTRIB)
  68     aspects = Fcons (Qattrib, aspects);
  69   if (mask & IN_CLOSE_WRITE)
  70     aspects = Fcons (Qclose_write, aspects);
  71   if (mask & IN_CLOSE_NOWRITE)
  72     aspects = Fcons (Qclose_nowrite, aspects);
  73   if (mask & IN_CREATE)
  74     aspects = Fcons (Qcreate, aspects);
  75   if (mask & IN_DELETE)
  76     aspects = Fcons (Qdelete, aspects);
  77   if (mask & IN_DELETE_SELF)
  78     aspects = Fcons (Qdelete_self, aspects);
  79   if (mask & IN_MODIFY)
  80     aspects = Fcons (Qmodify, aspects);
  81   if (mask & IN_MOVE_SELF)
  82     aspects = Fcons (Qmove_self, aspects);
  83   if (mask & IN_MOVED_FROM)
  84     aspects = Fcons (Qmoved_from, aspects);
  85   if (mask & IN_MOVED_TO)
  86     aspects = Fcons (Qmoved_to, aspects);
  87   if (mask & IN_OPEN)
  88     aspects = Fcons (Qopen,  aspects);
  89   if (mask & IN_IGNORED)
  90     aspects = Fcons (Qignored, aspects);
  91   if (mask & IN_ISDIR)
  92     aspects = Fcons (Qisdir, aspects);
  93   if (mask & IN_Q_OVERFLOW)
  94     aspects = Fcons (Qq_overflow, aspects);
  95   if (mask & IN_UNMOUNT)
  96     aspects = Fcons (Qunmount, aspects);
  97   return aspects;
  98 }
  99
 100 static Lisp_Object
 101 inotifyevent_to_event (Lisp_Object watch_object, struct inotify_event const *ev)
 102 {
 103   Lisp_Object name = Qnil;
 104   if (ev->len > 0)
 105     {
 106       size_t const len = strlen (ev->name);
 107       name = make_unibyte_string (ev->name, min (len, ev->len));
 108       name = DECODE_FILE (name);
 109     }
 110
 111   return list2 (list4 (make_watch_descriptor (ev->wd),
 112                        mask_to_aspects (ev->mask),
 113                        name,
 114                        make_number (ev->cookie)),
 115                 XCDR (watch_object));
 116 }
 117
 118 /* This callback is called when the FD is available for read.  The inotify
 119    events are read from FD and converted into input_events.  */
 120 static void
 121 inotify_callback (int fd, void *_)
 122 {
 123   struct input_event event;
 124   Lisp_Object watch_object;
 125   int to_read;
 126   char *buffer;
 127   ssize_t n;
 128   size_t i;
 129
 130   to_read = 0;
 131   if (ioctl (fd, FIONREAD, &to_read) == -1)
 132     xsignal1
 133       (Qfile_notify_error,
 134        build_string ("Error while trying to retrieve file system events"));
 135   buffer = xmalloc (to_read);
 136   n = read (fd, buffer, to_read);
 137   if (n < 0)
 138     {
 139       xfree (buffer);
 140       xsignal1
 141       (Qfile_notify_error,
 142        build_string ("Error while trying to read file system events"));
 143     }
 144
 145   EVENT_INIT (event);
 146   event.kind = FILE_NOTIFY_EVENT;
 147
 148   i = 0;
 149   while (i < (size_t)n)
 150     {
 151       struct inotify_event *ev = (struct inotify_event*)&buffer[i];
 152
 153       watch_object = Fassoc (make_watch_descriptor (ev->wd), watch_list);
 154       if (!NILP (watch_object))
 155         {
 156           event.arg = inotifyevent_to_event (watch_object, ev);
 157
 158           /* If event was removed automatically: Drop it from watch list.  */
 159           if (ev->mask & IN_IGNORED)
 160             watch_list = Fdelete (watch_object, watch_list);
 161
 162           if (!NILP (event.arg))
 163             kbd_buffer_store_event (&event);
 164         }
 165
 166       i += sizeof (*ev) + ev->len;
 167     }
 168
 169   xfree (buffer);
 170 }
 171
 172 static uint32_t
 173 symbol_to_inotifymask (Lisp_Object symb)
 174 {
 175   if (EQ (symb, Qaccess))
 176     return IN_ACCESS;
 177   else if (EQ (symb, Qattrib))
 178     return IN_ATTRIB;
 179   else if (EQ (symb, Qclose_write))
 180     return IN_CLOSE_WRITE;
 181   else if (EQ (symb, Qclose_nowrite))
 182     return IN_CLOSE_NOWRITE;
 183   else if (EQ (symb, Qcreate))
 184     return IN_CREATE;
 185   else if (EQ (symb, Qdelete))
 186     return IN_DELETE;
 187   else if (EQ (symb, Qdelete_self))
 188     return IN_DELETE_SELF;
 189   else if (EQ (symb, Qmodify))
 190     return IN_MODIFY;
 191   else if (EQ (symb, Qmove_self))
 192     return IN_MOVE_SELF;
 193   else if (EQ (symb, Qmoved_from))
 194     return IN_MOVED_FROM;
 195   else if (EQ (symb, Qmoved_to))
 196     return IN_MOVED_TO;
 197   else if (EQ (symb, Qopen))
 198     return IN_OPEN;
 199   else if (EQ (symb, Qmove))
 200     return IN_MOVE;
 201   else if (EQ (symb, Qclose))
 202     return IN_CLOSE;
 203
 204   else if (EQ (symb, Qdont_follow))
 205     return IN_DONT_FOLLOW;
 206   else if (EQ (symb, Qexcl_unlink))
 207     return IN_EXCL_UNLINK;
 208   else if (EQ (symb, Qmask_add))
 209     return IN_MASK_ADD;
 210   else if (EQ (symb, Qoneshot))
 211     return IN_ONESHOT;
 212   else if (EQ (symb, Qonlydir))
 213     return IN_ONLYDIR;
 214
 215   else if (EQ (symb, Qt) || EQ (symb, Qall_events))
 216     return IN_ALL_EVENTS;
 217   else
 218       xsignal2 (Qfile_notify_error, build_string ("Unknown aspect"), symb);
 219 }
 220
 221 static uint32_t
 222 aspect_to_inotifymask (Lisp_Object aspect)
 223 {
 224   if (CONSP (aspect))
 225     {
 226       Lisp_Object x = aspect;
 227       uint32_t mask = 0;
 228       while (CONSP (x))
 229         {
 230           mask |= symbol_to_inotifymask (XCAR (x));
 231           x = XCDR (x);
 232         }
 233       return mask;
 234     }
 235   else
 236     return symbol_to_inotifymask (aspect);
 237 }
 238
 239 DEFUN ("inotify-add-watch", Finotify_add_watch, Sinotify_add_watch, 3, 3, 0,
 240        doc: /* Add a watch for FILE-NAME to inotify.
 241
 242 Return a watch descriptor.  The watch will look for ASPECT events and
 243 invoke CALLBACK when an event occurs.
 244
 245 ASPECT might be one of the following symbols or a list of those symbols:
 246
 247 access
 248 attrib
 249 close-write
 250 close-nowrite
 251 create
 252 delete
 253 delete-self
 254 modify
 255 move-self
 256 moved-from
 257 moved-to
 258 open
 259
 260 all-events or t
 261 move
 262 close
 263
 264 The following symbols can also be added to a list of aspects:
 265
 266 dont-follow
 267 excl-unlink
 268 mask-add
 269 oneshot
 270 onlydir
 271
 272 Watching a directory is not recursive.  CALLBACK is passed a single argument
 273 EVENT which contains an event structure of the format
 274
 275 (WATCH-DESCRIPTOR ASPECTS NAME COOKIE)
 276
 277 WATCH-DESCRIPTOR is the same object that was returned by this function.  It can
 278 be tested for equality using `equal'.  ASPECTS describes the event.  It is a
 279 list of ASPECT symbols described above and can also contain one of the following
 280 symbols
 281
 282 ignored
 283 isdir
 284 q-overflow
 285 unmount
 286
 287 If a directory is watched then NAME is the name of file that caused the event.
 288
 289 COOKIE is an object that can be compared using `equal' to identify two matching
 290 renames (moved-from and moved-to).
 291
 292 See inotify(7) and inotify_add_watch(2) for further information.  The inotify fd
 293 is managed internally and there is no corresponding inotify_init.  Use
 294 `inotify-rm-watch' to remove a watch.
 295              */)
 296      (Lisp_Object file_name, Lisp_Object aspect, Lisp_Object callback)
 297 {
 298   uint32_t mask;
 299   Lisp_Object watch_object;
 300   Lisp_Object encoded_file_name;
 301   Lisp_Object watch_descriptor;
 302   int watchdesc = -1;
 303
 304   CHECK_STRING (file_name);
 305
 306   if (inotifyfd < 0)
 307     {
 308       inotifyfd = inotify_init1 (IN_NONBLOCK|IN_CLOEXEC);
 309       if (inotifyfd < 0)
 310         xsignal1
 311           (Qfile_notify_error,
 312            build_string ("File watching feature (inotify) is not available"));
 313       watch_list = Qnil;
 314       add_read_fd (inotifyfd, &inotify_callback, NULL);
 315     }
 316
 317   mask = aspect_to_inotifymask (aspect);
 318   encoded_file_name = ENCODE_FILE (file_name);
 319   watchdesc = inotify_add_watch (inotifyfd, SSDATA (encoded_file_name), mask);
 320   if (watchdesc == -1)
 321     xsignal2 (Qfile_notify_error,
 322               build_string ("Could not add watch for file"), file_name);
 323
 324   watch_descriptor = make_watch_descriptor (watchdesc);
 325
 326   /* Delete existing watch object.  */
 327   watch_object = Fassoc (watch_descriptor, watch_list);
 328   if (!NILP (watch_object))
 329       watch_list = Fdelete (watch_object, watch_list);
 330
 331   /* Store watch object in watch list.  */
 332   watch_object = Fcons (watch_descriptor, callback);
 333   watch_list = Fcons (watch_object, watch_list);
 334
 335   return watch_descriptor;
 336 }
 337
 338 DEFUN ("inotify-rm-watch", Finotify_rm_watch, Sinotify_rm_watch, 1, 1, 0,
 339        doc: /* Remove an existing WATCH-DESCRIPTOR.
 340
 341 WATCH-DESCRIPTOR should be an object returned by `inotify-add-watch'.
 342
 343 See inotify_rm_watch(2) for more information.
 344              */)
 345      (Lisp_Object watch_descriptor)
 346 {
 347   Lisp_Object watch_object;
 348   int wd = XINT (watch_descriptor);
 349
 350   if (inotify_rm_watch (inotifyfd, wd) == -1)
 351     xsignal2 (Qfile_notify_error,
 352               build_string ("Could not rm watch"), watch_descriptor);
 353
 354   /* Remove watch descriptor from watch list.  */
 355   watch_object = Fassoc (watch_descriptor, watch_list);
 356   if (!NILP (watch_object))
 357     watch_list = Fdelete (watch_object, watch_list);
 358
 359   /* Cleanup if no more files are watched.  */
 360   if (NILP (watch_list))
 361     {
 362       emacs_close (inotifyfd);
 363       delete_read_fd (inotifyfd);
 364       inotifyfd = -1;
 365     }
 366
 367   return Qt;
 368 }
 369
 370 DEFUN ("inotify-valid-p", Finotify_valid_p, Sinotify_valid_p, 1, 1, 0,
 371        doc: /* "Check a watch specified by its WATCH-DESCRIPTOR.
 372
 373 WATCH-DESCRIPTOR should be an object returned by `inotify-add-watch'.
 374
 375 A watch can become invalid if the file or directory it watches is
 376 deleted, or if the watcher thread exits abnormally for any other
 377 reason.  Removing the watch by calling `inotify-rm-watch' also makes
 378 it invalid.  */)
 379      (Lisp_Object watch_descriptor)
 380 {
 381   Lisp_Object watch_object = Fassoc (watch_descriptor, watch_list);
 382   return NILP (watch_object) ? Qnil : Qt;
 383 }
 384
 385 void
 386 syms_of_inotify (void)
 387 {
 388   DEFSYM (Qaccess, "access");           /* IN_ACCESS */
 389   DEFSYM (Qattrib, "attrib");           /* IN_ATTRIB */
 390   DEFSYM (Qclose_write, "close-write"); /* IN_CLOSE_WRITE */
 391   DEFSYM (Qclose_nowrite, "close-nowrite");
 392                                         /* IN_CLOSE_NOWRITE */
 393   DEFSYM (Qcreate, "create");           /* IN_CREATE */
 394   DEFSYM (Qdelete, "delete");           /* IN_DELETE */
 395   DEFSYM (Qdelete_self, "delete-self"); /* IN_DELETE_SELF */
 396   DEFSYM (Qmodify, "modify");           /* IN_MODIFY */
 397   DEFSYM (Qmove_self, "move-self");     /* IN_MOVE_SELF */
 398   DEFSYM (Qmoved_from, "moved-from");   /* IN_MOVED_FROM */
 399   DEFSYM (Qmoved_to, "moved-to");       /* IN_MOVED_TO */
 400   DEFSYM (Qopen, "open");               /* IN_OPEN */
 401
 402   DEFSYM (Qall_events, "all-events");   /* IN_ALL_EVENTS */
 403   DEFSYM (Qmove, "move");               /* IN_MOVE */
 404   DEFSYM (Qclose, "close");             /* IN_CLOSE */
 405
 406   DEFSYM (Qdont_follow, "dont-follow"); /* IN_DONT_FOLLOW */
 407   DEFSYM (Qexcl_unlink, "excl-unlink"); /* IN_EXCL_UNLINK */
 408   DEFSYM (Qmask_add, "mask-add");       /* IN_MASK_ADD */
 409   DEFSYM (Qoneshot, "oneshot");         /* IN_ONESHOT */
 410   DEFSYM (Qonlydir, "onlydir");         /* IN_ONLYDIR */
 411
 412   DEFSYM (Qignored, "ignored");         /* IN_IGNORED */
 413   DEFSYM (Qisdir, "isdir");             /* IN_ISDIR */
 414   DEFSYM (Qq_overflow, "q-overflow");   /* IN_Q_OVERFLOW */
 415   DEFSYM (Qunmount, "unmount");         /* IN_UNMOUNT */
 416
 417   defsubr (&Sinotify_add_watch);
 418   defsubr (&Sinotify_rm_watch);
 419   defsubr (&Sinotify_valid_p);
 420
 421   staticpro (&watch_list);
 422
 423   Fprovide (intern_c_string ("inotify"), Qnil);
 424 }
 425
 426 #endif /* HAVE_INOTIFY */