Commit | Line | Data |
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3a22ee35 | 1 | /* Copyright (C) 1985, 1986, 1987, 1993, 1994 Free Software Foundation, Inc. |
8489eb67 RS |
2 | |
3 | This file is part of GNU Emacs. | |
4 | ||
5 | GNU Emacs is free software; you can redistribute it and/or modify | |
6 | it under the terms of the GNU General Public License as published by | |
32676c08 | 7 | the Free Software Foundation; either version 2, or (at your option) |
8489eb67 RS |
8 | any later version. |
9 | ||
10 | GNU Emacs is distributed in the hope that it will be useful, | |
11 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
13 | GNU General Public License for more details. | |
14 | ||
15 | You should have received a copy of the GNU General Public License | |
16 | along with GNU Emacs; see the file COPYING. If not, write to | |
3b7ad313 EN |
17 | the Free Software Foundation, Inc., 59 Temple Place - Suite 330, |
18 | Boston, MA 02111-1307, USA. */ | |
8489eb67 RS |
19 | |
20 | ||
21 | #include <sys/types.h> | |
22 | #include <sys/stat.h> | |
18160b98 | 23 | #include <config.h> |
bfb61299 JB |
24 | |
25 | #ifdef VMS | |
b350a838 | 26 | #include "vms-pwd.h" |
bfb61299 | 27 | #else |
8489eb67 | 28 | #include <pwd.h> |
bfb61299 JB |
29 | #endif |
30 | ||
8489eb67 RS |
31 | #include <errno.h> |
32 | #include <sys/file.h> | |
33 | #ifdef USG | |
34 | #include <fcntl.h> | |
35 | #endif /* USG */ | |
36 | ||
8489eb67 | 37 | #include "lisp.h" |
2a6b3537 | 38 | #include <paths.h> |
8489eb67 RS |
39 | #include "buffer.h" |
40 | ||
25bef3dd KH |
41 | #ifdef SYSV_SYSTEM_DIR |
42 | #include <dirent.h> | |
43 | #else /* not SYSV_SYSTEM_DIR */ | |
44 | #ifdef NONSYSTEM_DIR_LIBRARY | |
45 | #include "ndir.h" | |
46 | #else /* not NONSYSTEM_DIR_LIBRARY */ | |
47 | #ifdef MSDOS | |
48 | #include <dirent.h> | |
49 | #else | |
50 | #include <sys/dir.h> | |
51 | #endif | |
52 | #endif /* not NONSYSTEM_DIR_LIBRARY */ | |
53 | #ifndef MSDOS | |
54 | extern DIR *opendir (); | |
55 | #endif /* not MSDOS */ | |
56 | #endif /* not SYSV_SYSTEM_DIR */ | |
57 | ||
8489eb67 RS |
58 | extern int errno; |
59 | ||
32676c08 | 60 | extern char *egetenv (); |
d8cafeb5 | 61 | extern char *strcpy (); |
32676c08 | 62 | |
a35e9c82 | 63 | #ifdef DECLARE_GETPWUID_WITH_UID_T |
46013500 RS |
64 | extern struct passwd *getpwuid (uid_t); |
65 | #else | |
79941276 RS |
66 | extern struct passwd *getpwuid (); |
67 | #endif | |
68 | ||
8489eb67 RS |
69 | #ifdef CLASH_DETECTION |
70 | ||
71 | /* If system does not have symbolic links, it does not have lstat. | |
72 | In that case, use ordinary stat instead. */ | |
73 | ||
74 | #ifndef S_IFLNK | |
75 | #define lstat stat | |
76 | #endif | |
77 | ||
32676c08 JB |
78 | |
79 | /* The name of the directory in which we keep lock files, with a '/' | |
80 | appended. */ | |
7b92975f | 81 | char *lock_dir; |
32676c08 JB |
82 | |
83 | /* The name of the file in the lock directory which is used to | |
84 | arbitrate access to the entire directory. */ | |
85 | #define SUPERLOCK_NAME "!!!SuperLock!!!" | |
86 | ||
7b92975f RS |
87 | /* The name of the superlock file. This is SUPERLOCK_NAME appended to |
88 | lock_dir. */ | |
89 | char *superlock_file; | |
32676c08 JB |
90 | |
91 | /* Set LOCK to the name of the lock file for the filename FILE. | |
92 | char *LOCK; Lisp_Object FILE; */ | |
e31fbc7a | 93 | |
6c10d0cd | 94 | #ifndef HAVE_LONG_FILE_NAMES |
e31fbc7a | 95 | |
7b92975f RS |
96 | #define MAKE_LOCK_NAME(lock, file) \ |
97 | (lock = (char *) alloca (14 + strlen (lock_dir) + 1), \ | |
e31fbc7a RS |
98 | fill_in_lock_short_file_name (lock, (file))) |
99 | ||
100 | ||
101 | fill_in_lock_short_file_name (lockfile, fn) | |
102 | register char *lockfile; | |
103 | register Lisp_Object fn; | |
104 | { | |
105 | register union | |
106 | { | |
107 | unsigned int word [2]; | |
108 | unsigned char byte [8]; | |
109 | } crc; | |
110 | register unsigned char *p, new; | |
111 | ||
112 | /* 7-bytes cyclic code for burst correction on byte-by-byte basis. | |
113 | the used polynomial is D^7 + D^6 + D^3 +1. pot@cnuce.cnr.it */ | |
114 | ||
115 | crc.word[0] = crc.word[1] = 0; | |
116 | ||
117 | for (p = XSTRING (fn)->data; new = *p++; ) | |
118 | { | |
953d263e | 119 | new += crc.byte[6]; |
e31fbc7a RS |
120 | crc.byte[6] = crc.byte[5] + new; |
121 | crc.byte[5] = crc.byte[4]; | |
122 | crc.byte[4] = crc.byte[3]; | |
123 | crc.byte[3] = crc.byte[2] + new; | |
124 | crc.byte[2] = crc.byte[1]; | |
125 | crc.byte[1] = crc.byte[0]; | |
126 | crc.byte[0] = new; | |
127 | } | |
7b92975f | 128 | sprintf (lockfile, "%s%.2x%.2x%.2x%.2x%.2x%.2x%.2x", lock_dir, |
e31fbc7a RS |
129 | crc.byte[0], crc.byte[1], crc.byte[2], crc.byte[3], |
130 | crc.byte[4], crc.byte[5], crc.byte[6]); | |
131 | } | |
132 | ||
6c10d0cd | 133 | #else /* defined HAVE_LONG_FILE_NAMES */ |
e31fbc7a | 134 | |
7b92975f RS |
135 | #define MAKE_LOCK_NAME(lock, file) \ |
136 | (lock = (char *) alloca (XSTRING (file)->size + strlen (lock_dir) + 1), \ | |
32676c08 JB |
137 | fill_in_lock_file_name (lock, (file))) |
138 | ||
e31fbc7a | 139 | |
32676c08 JB |
140 | fill_in_lock_file_name (lockfile, fn) |
141 | register char *lockfile; | |
142 | register Lisp_Object fn; | |
143 | { | |
144 | register char *p; | |
145 | ||
7b92975f | 146 | strcpy (lockfile, lock_dir); |
32676c08 JB |
147 | |
148 | p = lockfile + strlen (lockfile); | |
149 | ||
150 | strcpy (p, XSTRING (fn)->data); | |
151 | ||
152 | for (; *p; p++) | |
153 | { | |
154 | if (*p == '/') | |
155 | *p = '!'; | |
156 | } | |
157 | } | |
6c10d0cd | 158 | #endif /* !defined HAVE_LONG_FILE_NAMES */ |
32676c08 | 159 | |
8489eb67 RS |
160 | static Lisp_Object |
161 | lock_file_owner_name (lfname) | |
162 | char *lfname; | |
163 | { | |
164 | struct stat s; | |
165 | struct passwd *the_pw; | |
8489eb67 RS |
166 | |
167 | if (lstat (lfname, &s) == 0) | |
168 | the_pw = getpwuid (s.st_uid); | |
169 | return (the_pw == 0 ? Qnil : build_string (the_pw->pw_name)); | |
170 | } | |
171 | ||
172 | ||
173 | /* lock_file locks file fn, | |
174 | meaning it serves notice on the world that you intend to edit that file. | |
175 | This should be done only when about to modify a file-visiting | |
176 | buffer previously unmodified. | |
177 | Do not (normally) call lock_buffer for a buffer already modified, | |
178 | as either the file is already locked, or the user has already | |
179 | decided to go ahead without locking. | |
180 | ||
181 | When lock_buffer returns, either the lock is locked for us, | |
182 | or the user has said to go ahead without locking. | |
183 | ||
184 | If the file is locked by someone else, lock_buffer calls | |
185 | ask-user-about-lock (a Lisp function) with two arguments, | |
186 | the file name and the name of the user who did the locking. | |
187 | This function can signal an error, or return t meaning | |
188 | take away the lock, or return nil meaning ignore the lock. */ | |
189 | ||
190 | /* The lock file name is the file name with "/" replaced by "!" | |
191 | and put in the Emacs lock directory. */ | |
192 | /* (ie., /ka/king/junk.tex -> /!/!ka!king!junk.tex). */ | |
193 | ||
6c10d0cd | 194 | /* If HAVE_LONG_FILE_NAMES is not defined, the lock file name is the hex |
e31fbc7a RS |
195 | representation of a 14-bytes CRC generated from the file name |
196 | and put in the Emacs lock directory (not very nice, but it works). | |
953d263e | 197 | (ie., /ka/king/junk.tex -> /!/12a82c62f1c6da). */ |
e31fbc7a | 198 | |
8489eb67 RS |
199 | void |
200 | lock_file (fn) | |
201 | register Lisp_Object fn; | |
202 | { | |
5383bc6d | 203 | register Lisp_Object attack, orig_fn; |
8489eb67 RS |
204 | register char *lfname; |
205 | ||
5383bc6d | 206 | orig_fn = fn; |
1e89de84 KH |
207 | fn = Fexpand_file_name (fn, Qnil); |
208 | ||
7b92975f | 209 | MAKE_LOCK_NAME (lfname, fn); |
8489eb67 | 210 | |
32676c08 JB |
211 | /* See if this file is visited and has changed on disk since it was |
212 | visited. */ | |
8489eb67 | 213 | { |
a57bc488 | 214 | register Lisp_Object subject_buf; |
5383bc6d | 215 | subject_buf = get_truename_buffer (orig_fn); |
265a9e55 JB |
216 | if (!NILP (subject_buf) |
217 | && NILP (Fverify_visited_file_modtime (subject_buf)) | |
218 | && !NILP (Ffile_exists_p (fn))) | |
8489eb67 RS |
219 | call1 (intern ("ask-user-about-supersession-threat"), fn); |
220 | } | |
221 | ||
222 | /* Try to lock the lock. */ | |
223 | if (lock_if_free (lfname) <= 0) | |
224 | /* Return now if we have locked it, or if lock dir does not exist */ | |
225 | return; | |
226 | ||
227 | /* Else consider breaking the lock */ | |
228 | attack = call2 (intern ("ask-user-about-lock"), fn, | |
229 | lock_file_owner_name (lfname)); | |
265a9e55 | 230 | if (!NILP (attack)) |
8489eb67 RS |
231 | /* User says take the lock */ |
232 | { | |
233 | lock_superlock (lfname); | |
234 | lock_file_1 (lfname, O_WRONLY) ; | |
7b92975f | 235 | unlink (superlock_file); |
8489eb67 RS |
236 | return; |
237 | } | |
238 | /* User says ignore the lock */ | |
239 | } | |
240 | ||
8489eb67 RS |
241 | /* Lock the lock file named LFNAME. |
242 | If MODE is O_WRONLY, we do so even if it is already locked. | |
243 | If MODE is O_WRONLY | O_EXCL | O_CREAT, we do so only if it is free. | |
244 | Return 1 if successful, 0 if not. */ | |
245 | ||
246 | int | |
247 | lock_file_1 (lfname, mode) | |
248 | int mode; char *lfname; | |
249 | { | |
250 | register int fd; | |
251 | char buf[20]; | |
252 | ||
253 | if ((fd = open (lfname, mode, 0666)) >= 0) | |
254 | { | |
255 | #ifdef USG | |
256 | chmod (lfname, 0666); | |
257 | #else | |
258 | fchmod (fd, 0666); | |
259 | #endif | |
260 | sprintf (buf, "%d ", getpid ()); | |
261 | write (fd, buf, strlen (buf)); | |
262 | close (fd); | |
263 | return 1; | |
264 | } | |
265 | else | |
266 | return 0; | |
267 | } | |
268 | ||
269 | /* Lock the lock named LFNAME if possible. | |
270 | Return 0 in that case. | |
271 | Return positive if lock is really locked by someone else. | |
272 | Return -1 if cannot lock for any other reason. */ | |
273 | ||
274 | int | |
275 | lock_if_free (lfname) | |
276 | register char *lfname; | |
277 | { | |
278 | register int clasher; | |
279 | ||
280 | while (lock_file_1 (lfname, O_WRONLY | O_EXCL | O_CREAT) == 0) | |
281 | { | |
282 | if (errno != EEXIST) | |
283 | return -1; | |
284 | clasher = current_lock_owner (lfname); | |
285 | if (clasher != 0) | |
286 | if (clasher != getpid ()) | |
287 | return (clasher); | |
288 | else return (0); | |
289 | /* Try again to lock it */ | |
290 | } | |
291 | return 0; | |
292 | } | |
293 | ||
294 | /* Return the pid of the process that claims to own the lock file LFNAME, | |
295 | or 0 if nobody does or the lock is obsolete, | |
296 | or -1 if something is wrong with the locking mechanism. */ | |
297 | ||
298 | int | |
299 | current_lock_owner (lfname) | |
300 | char *lfname; | |
301 | { | |
302 | int owner = current_lock_owner_1 (lfname); | |
303 | if (owner == 0 && errno == ENOENT) | |
304 | return (0); | |
305 | /* Is it locked by a process that exists? */ | |
306 | if (owner != 0 && (kill (owner, 0) >= 0 || errno == EPERM)) | |
307 | return (owner); | |
308 | if (unlink (lfname) < 0) | |
309 | return (-1); | |
310 | return (0); | |
311 | } | |
312 | ||
313 | int | |
314 | current_lock_owner_1 (lfname) | |
315 | char *lfname; | |
316 | { | |
317 | register int fd; | |
318 | char buf[20]; | |
319 | int tem; | |
320 | ||
321 | fd = open (lfname, O_RDONLY, 0666); | |
322 | if (fd < 0) | |
323 | return 0; | |
324 | tem = read (fd, buf, sizeof buf); | |
325 | close (fd); | |
326 | return (tem <= 0 ? 0 : atoi (buf)); | |
327 | } | |
328 | ||
329 | \f | |
330 | void | |
331 | unlock_file (fn) | |
332 | register Lisp_Object fn; | |
333 | { | |
334 | register char *lfname; | |
335 | ||
1e89de84 KH |
336 | fn = Fexpand_file_name (fn, Qnil); |
337 | ||
7b92975f | 338 | MAKE_LOCK_NAME (lfname, fn); |
8489eb67 RS |
339 | |
340 | lock_superlock (lfname); | |
341 | ||
342 | if (current_lock_owner_1 (lfname) == getpid ()) | |
343 | unlink (lfname); | |
344 | ||
7b92975f | 345 | unlink (superlock_file); |
8489eb67 RS |
346 | } |
347 | ||
348 | lock_superlock (lfname) | |
349 | char *lfname; | |
350 | { | |
351 | register int i, fd; | |
25bef3dd | 352 | DIR *lockdir; |
8489eb67 | 353 | |
7b92975f | 354 | for (i = -20; i < 0 && (fd = open (superlock_file, |
8489eb67 RS |
355 | O_WRONLY | O_EXCL | O_CREAT, 0666)) < 0; |
356 | i++) | |
357 | { | |
358 | if (errno != EEXIST) | |
359 | return; | |
25bef3dd KH |
360 | |
361 | /* This seems to be necessary to prevent Emacs from hanging when the | |
362 | competing process has already deleted the superlock, but it's still | |
363 | in the NFS cache. So we force NFS to synchronize the cache. */ | |
7b92975f | 364 | if (lockdir = opendir (lock_dir)) |
25bef3dd KH |
365 | closedir (lockdir); |
366 | ||
8489eb67 RS |
367 | sleep (1); |
368 | } | |
369 | if (fd >= 0) | |
370 | { | |
371 | #ifdef USG | |
7b92975f | 372 | chmod (superlock_file, 0666); |
8489eb67 RS |
373 | #else |
374 | fchmod (fd, 0666); | |
375 | #endif | |
376 | write (fd, lfname, strlen (lfname)); | |
377 | close (fd); | |
378 | } | |
379 | } | |
380 | ||
381 | void | |
382 | unlock_all_files () | |
383 | { | |
384 | register Lisp_Object tail; | |
385 | register struct buffer *b; | |
386 | ||
4e6c9d9e | 387 | for (tail = Vbuffer_alist; GC_CONSP (tail); tail = XCONS (tail)->cdr) |
8489eb67 RS |
388 | { |
389 | b = XBUFFER (XCONS (XCONS (tail)->car)->cdr); | |
5757b805 RS |
390 | if (STRINGP (b->file_truename) && BUF_SAVE_MODIFF (b) < BUF_MODIFF (b)) |
391 | unlock_file (b->file_truename); | |
8489eb67 RS |
392 | } |
393 | } | |
394 | ||
395 | \f | |
396 | DEFUN ("lock-buffer", Flock_buffer, Slock_buffer, | |
397 | 0, 1, 0, | |
398 | "Lock FILE, if current buffer is modified.\n\ | |
399 | FILE defaults to current buffer's visited file,\n\ | |
400 | or else nothing is done if current buffer isn't visiting a file.") | |
e9319ef2 EN |
401 | (file) |
402 | Lisp_Object file; | |
8489eb67 | 403 | { |
e9319ef2 EN |
404 | if (NILP (file)) |
405 | file = current_buffer->file_truename; | |
8489eb67 | 406 | else |
e9319ef2 | 407 | CHECK_STRING (file, 0); |
6a140159 | 408 | if (SAVE_MODIFF < MODIFF |
e9319ef2 EN |
409 | && !NILP (file)) |
410 | lock_file (file); | |
8489eb67 RS |
411 | return Qnil; |
412 | } | |
413 | ||
414 | DEFUN ("unlock-buffer", Funlock_buffer, Sunlock_buffer, | |
415 | 0, 0, 0, | |
416 | "Unlock the file visited in the current buffer,\n\ | |
417 | if it should normally be locked.") | |
418 | () | |
419 | { | |
6a140159 | 420 | if (SAVE_MODIFF < MODIFF |
5757b805 RS |
421 | && STRINGP (current_buffer->file_truename)) |
422 | unlock_file (current_buffer->file_truename); | |
8489eb67 RS |
423 | return Qnil; |
424 | } | |
425 | ||
426 | \f | |
427 | /* Unlock the file visited in buffer BUFFER. */ | |
428 | ||
429 | unlock_buffer (buffer) | |
430 | struct buffer *buffer; | |
431 | { | |
6a140159 | 432 | if (BUF_SAVE_MODIFF (buffer) < BUF_MODIFF (buffer) |
5757b805 RS |
433 | && STRINGP (buffer->file_truename)) |
434 | unlock_file (buffer->file_truename); | |
8489eb67 RS |
435 | } |
436 | ||
437 | DEFUN ("file-locked-p", Ffile_locked_p, Sfile_locked_p, 0, 1, 0, | |
438 | "Return nil if the FILENAME is not locked,\n\ | |
439 | t if it is locked by you, else a string of the name of the locker.") | |
e9319ef2 EN |
440 | (filename) |
441 | Lisp_Object filename; | |
8489eb67 RS |
442 | { |
443 | register char *lfname; | |
444 | int owner; | |
445 | ||
e9319ef2 | 446 | filename = Fexpand_file_name (filename, Qnil); |
8489eb67 | 447 | |
e9319ef2 | 448 | MAKE_LOCK_NAME (lfname, filename); |
8489eb67 RS |
449 | |
450 | owner = current_lock_owner (lfname); | |
451 | if (owner <= 0) | |
452 | return (Qnil); | |
453 | else if (owner == getpid ()) | |
454 | return (Qt); | |
455 | ||
456 | return (lock_file_owner_name (lfname)); | |
457 | } | |
458 | ||
32676c08 JB |
459 | \f |
460 | /* Initialization functions. */ | |
461 | ||
462 | init_filelock () | |
463 | { | |
66e7fd46 | 464 | char *new_name; |
8600e6ed | 465 | |
7b92975f RS |
466 | lock_dir = egetenv ("EMACSLOCKDIR"); |
467 | if (! lock_dir) | |
468 | lock_dir = PATH_LOCK; | |
32676c08 | 469 | |
7b92975f RS |
470 | /* Copy the name in case egetenv got it from a Lisp string. */ |
471 | new_name = (char *) xmalloc (strlen (lock_dir) + 2); | |
472 | strcpy (new_name, lock_dir); | |
473 | lock_dir = new_name; | |
8600e6ed | 474 | |
32676c08 | 475 | /* Make sure it ends with a slash. */ |
7b92975f RS |
476 | if (lock_dir[strlen (lock_dir) - 1] != '/') |
477 | strcat (lock_dir, "/"); | |
32676c08 | 478 | |
7b92975f | 479 | superlock_file = (char *) xmalloc ((strlen (lock_dir) |
32676c08 | 480 | + sizeof (SUPERLOCK_NAME))); |
7b92975f RS |
481 | strcpy (superlock_file, lock_dir); |
482 | strcat (superlock_file, SUPERLOCK_NAME); | |
32676c08 JB |
483 | } |
484 | ||
8489eb67 RS |
485 | syms_of_filelock () |
486 | { | |
487 | defsubr (&Sunlock_buffer); | |
488 | defsubr (&Slock_buffer); | |
489 | defsubr (&Sfile_locked_p); | |
490 | } | |
491 | ||
492 | #endif /* CLASH_DETECTION */ |