Commit | Line | Data |
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8dbbc384 | 1 | /* Copyright (C) 1985, 86, 87, 93, 94, 96 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> | |
dfcf069d | 23 | #include <signal.h> |
18160b98 | 24 | #include <config.h> |
bfb61299 JB |
25 | |
26 | #ifdef VMS | |
b350a838 | 27 | #include "vms-pwd.h" |
bfb61299 | 28 | #else |
8489eb67 | 29 | #include <pwd.h> |
8dbbc384 | 30 | #endif /* not VMS */ |
bfb61299 | 31 | |
8489eb67 RS |
32 | #include <sys/file.h> |
33 | #ifdef USG | |
34 | #include <fcntl.h> | |
8dbbc384 | 35 | #include <string.h> |
8489eb67 RS |
36 | #endif /* USG */ |
37 | ||
dfcf069d AS |
38 | #ifdef HAVE_UNISTD_H |
39 | #include <unistd.h> | |
40 | #endif | |
41 | ||
8489eb67 | 42 | #include "lisp.h" |
8489eb67 | 43 | #include "buffer.h" |
f4a4528d RS |
44 | #include "charset.h" |
45 | #include "coding.h" | |
8489eb67 | 46 | |
15e88d21 | 47 | #include <time.h> |
8dbbc384 RS |
48 | #include <errno.h> |
49 | #ifndef errno | |
8489eb67 | 50 | extern int errno; |
79941276 RS |
51 | #endif |
52 | ||
8489eb67 | 53 | #ifdef CLASH_DETECTION |
e788eecc KH |
54 | |
55 | #include <utmp.h> | |
8489eb67 | 56 | |
8dbbc384 RS |
57 | /* The strategy: to lock a file FN, create a symlink .#FN in FN's |
58 | directory, with link data `user@host.pid'. This avoids a single | |
59 | mount (== failure) point for lock files. | |
60 | ||
61 | When the host in the lock data is the current host, we can check if | |
62 | the pid is valid with kill. | |
63 | ||
64 | Otherwise, we could look at a separate file that maps hostnames to | |
65 | reboot times to see if the remote pid can possibly be valid, since we | |
66 | don't want Emacs to have to communicate via pipes or sockets or | |
67 | whatever to other processes, either locally or remotely; rms says | |
68 | that's too unreliable. Hence the separate file, which could | |
69 | theoretically be updated by daemons running separately -- but this | |
70 | whole idea is unimplemented; in practice, at least in our | |
1c4f857c | 71 | environment, it seems such stale locks arise fairly infrequently, and |
8dbbc384 RS |
72 | Emacs' standard methods of dealing with clashes suffice. |
73 | ||
74 | We use symlinks instead of normal files because (1) they can be | |
75 | stored more efficiently on the filesystem, since the kernel knows | |
76 | they will be small, and (2) all the info about the lock can be read | |
77 | in a single system call (readlink). Although we could use regular | |
1c4f857c | 78 | files to be useful on old systems lacking symlinks, nowadays |
8dbbc384 RS |
79 | virtually all such systems are probably single-user anyway, so it |
80 | didn't seem worth the complication. | |
81 | ||
82 | Similarly, we don't worry about a possible 14-character limit on | |
83 | file names, because those are all the same systems that don't have | |
84 | symlinks. | |
85 | ||
86 | This is compatible with the locking scheme used by Interleaf (which | |
87 | has contributed this implementation for Emacs), and was designed by | |
88 | Ethan Jacobson, Kimbo Mundy, and others. | |
89 | ||
90 | --karl@cs.umb.edu/karl@hq.ileaf.com. */ | |
8489eb67 | 91 | |
8dbbc384 | 92 | \f |
15e88d21 RS |
93 | /* Return the time of the last system boot. */ |
94 | ||
95 | static time_t boot_time; | |
96 | ||
97 | static time_t | |
98 | get_boot_time () | |
99 | { | |
bd26d5a3 | 100 | #ifdef BOOT_TIME |
15e88d21 RS |
101 | struct utmp ut, *utp; |
102 | ||
103 | if (boot_time) | |
104 | return boot_time; | |
105 | ||
106 | utmpname ("/var/log/wtmp"); | |
c321b190 RS |
107 | setutent (); |
108 | boot_time = 1; | |
109 | while (1) | |
110 | { | |
111 | /* Find the next reboot record. */ | |
112 | ut.ut_type = BOOT_TIME; | |
113 | utp = getutid (&ut); | |
114 | if (! utp) | |
115 | break; | |
116 | /* Compare reboot times and use the newest one. */ | |
117 | if (utp->ut_time > boot_time) | |
118 | boot_time = utp->ut_time; | |
119 | /* Advance on element in the file | |
120 | so that getutid won't repeat the same one. */ | |
121 | utp = getutent (); | |
122 | if (! utp) | |
123 | break; | |
124 | } | |
15e88d21 RS |
125 | endutent (); |
126 | ||
c321b190 | 127 | return boot_time; |
bd26d5a3 RS |
128 | #else |
129 | return 0; | |
dd6f88fb | 130 | #endif |
15e88d21 RS |
131 | } |
132 | \f | |
8dbbc384 | 133 | /* Here is the structure that stores information about a lock. */ |
32676c08 | 134 | |
8dbbc384 RS |
135 | typedef struct |
136 | { | |
137 | char *user; | |
138 | char *host; | |
9005cb4f | 139 | unsigned long pid; |
15e88d21 | 140 | time_t boot_time; |
8dbbc384 | 141 | } lock_info_type; |
32676c08 | 142 | |
49b6d120 RS |
143 | /* When we read the info back, we might need this much more, |
144 | enough for decimal representation plus null. */ | |
145 | #define LOCK_PID_MAX (4 * sizeof (unsigned long)) | |
32676c08 | 146 | |
8dbbc384 RS |
147 | /* Free the two dynamically-allocated pieces in PTR. */ |
148 | #define FREE_LOCK_INFO(i) do { xfree ((i).user); xfree ((i).host); } while (0) | |
e31fbc7a | 149 | |
e31fbc7a | 150 | |
8dbbc384 RS |
151 | /* Write the name of the lock file for FN into LFNAME. Length will be |
152 | that of FN plus two more for the leading `.#' plus one for the null. */ | |
7b92975f | 153 | #define MAKE_LOCK_NAME(lock, file) \ |
fc932ac6 | 154 | (lock = (char *) alloca (STRING_BYTES (XSTRING (file)) + 2 + 1), \ |
8dbbc384 | 155 | fill_in_lock_file_name (lock, (file))) |
e31fbc7a | 156 | |
8dbbc384 RS |
157 | static void |
158 | fill_in_lock_file_name (lockfile, fn) | |
e31fbc7a RS |
159 | register char *lockfile; |
160 | register Lisp_Object fn; | |
161 | { | |
8dbbc384 RS |
162 | register char *p; |
163 | ||
164 | strcpy (lockfile, XSTRING (fn)->data); | |
165 | ||
166 | /* Shift the nondirectory part of the file name (including the null) | |
167 | right two characters. Here is one of the places where we'd have to | |
168 | do something to support 14-character-max file names. */ | |
169 | for (p = lockfile + strlen (lockfile); p != lockfile && *p != '/'; p--) | |
170 | p[2] = *p; | |
e31fbc7a | 171 | |
8dbbc384 RS |
172 | /* Insert the `.#'. */ |
173 | p[1] = '.'; | |
174 | p[2] = '#'; | |
175 | } | |
e31fbc7a | 176 | |
8dbbc384 RS |
177 | /* Lock the lock file named LFNAME. |
178 | If FORCE is nonzero, we do so even if it is already locked. | |
179 | Return 1 if successful, 0 if not. */ | |
e31fbc7a | 180 | |
8dbbc384 RS |
181 | static int |
182 | lock_file_1 (lfname, force) | |
183 | char *lfname; | |
184 | int force; | |
185 | { | |
186 | register int err; | |
bd26d5a3 | 187 | time_t boot_time; |
662c2ef2 RS |
188 | char *user_name; |
189 | char *host_name; | |
190 | char *lock_info_str; | |
191 | ||
192 | if (STRINGP (Fuser_login_name (Qnil))) | |
266d7a00 | 193 | user_name = (char *)XSTRING (Fuser_login_name (Qnil))->data; |
662c2ef2 RS |
194 | else |
195 | user_name = ""; | |
196 | if (STRINGP (Fsystem_name ())) | |
266d7a00 | 197 | host_name = (char *)XSTRING (Fsystem_name ())->data; |
662c2ef2 RS |
198 | else |
199 | host_name = ""; | |
266d7a00 | 200 | lock_info_str = (char *)alloca (strlen (user_name) + strlen (host_name) |
15e88d21 | 201 | + LOCK_PID_MAX + 5); |
8dbbc384 | 202 | |
bd26d5a3 RS |
203 | boot_time = get_boot_time (); |
204 | if (boot_time) | |
205 | sprintf (lock_info_str, "%s@%s.%lu:%lu", user_name, host_name, | |
206 | (unsigned long) getpid (), (unsigned long) boot_time); | |
207 | else | |
208 | sprintf (lock_info_str, "%s@%s.%lu", user_name, host_name, | |
209 | (unsigned long) getpid ()); | |
8dbbc384 RS |
210 | |
211 | err = symlink (lock_info_str, lfname); | |
212 | if (errno == EEXIST && force) | |
e31fbc7a | 213 | { |
8dbbc384 RS |
214 | unlink (lfname); |
215 | err = symlink (lock_info_str, lfname); | |
e31fbc7a | 216 | } |
e31fbc7a | 217 | |
8dbbc384 RS |
218 | return err == 0; |
219 | } | |
e31fbc7a | 220 | |
32676c08 | 221 | |
8dbbc384 RS |
222 | \f |
223 | /* Return 0 if nobody owns the lock file LFNAME or the lock is obsolete, | |
224 | 1 if another process owns it (and set OWNER (if non-null) to info), | |
225 | 2 if the current process owns it, | |
226 | or -1 if something is wrong with the locking mechanism. */ | |
e31fbc7a | 227 | |
8dbbc384 RS |
228 | static int |
229 | current_lock_owner (owner, lfname) | |
230 | lock_info_type *owner; | |
231 | char *lfname; | |
32676c08 | 232 | { |
8dbbc384 RS |
233 | #ifndef index |
234 | extern char *rindex (), *index (); | |
235 | #endif | |
236 | int o, p, len, ret; | |
237 | int local_owner = 0; | |
15e88d21 | 238 | char *at, *dot, *colon; |
8dbbc384 RS |
239 | char *lfinfo = 0; |
240 | int bufsize = 50; | |
241 | /* Read arbitrarily-long contents of symlink. Similar code in | |
242 | file-symlink-p in fileio.c. */ | |
243 | do | |
244 | { | |
245 | bufsize *= 2; | |
246 | lfinfo = (char *) xrealloc (lfinfo, bufsize); | |
247 | len = readlink (lfname, lfinfo, bufsize); | |
248 | } | |
249 | while (len >= bufsize); | |
250 | ||
251 | /* If nonexistent lock file, all is well; otherwise, got strange error. */ | |
252 | if (len == -1) | |
253 | { | |
254 | xfree (lfinfo); | |
255 | return errno == ENOENT ? 0 : -1; | |
256 | } | |
32676c08 | 257 | |
8dbbc384 RS |
258 | /* Link info exists, so `len' is its length. Null terminate. */ |
259 | lfinfo[len] = 0; | |
260 | ||
261 | /* Even if the caller doesn't want the owner info, we still have to | |
262 | read it to determine return value, so allocate it. */ | |
263 | if (!owner) | |
264 | { | |
3609a53b | 265 | owner = (lock_info_type *) alloca (sizeof (lock_info_type)); |
8dbbc384 RS |
266 | local_owner = 1; |
267 | } | |
268 | ||
15e88d21 | 269 | /* Parse USER@HOST.PID:BOOT_TIME. If can't parse, return -1. */ |
8dbbc384 RS |
270 | /* The USER is everything before the first @. */ |
271 | at = index (lfinfo, '@'); | |
272 | dot = rindex (lfinfo, '.'); | |
15e88d21 RS |
273 | if (!at || !dot) |
274 | { | |
275 | xfree (lfinfo); | |
276 | return -1; | |
277 | } | |
8dbbc384 RS |
278 | len = at - lfinfo; |
279 | owner->user = (char *) xmalloc (len + 1); | |
280 | strncpy (owner->user, lfinfo, len); | |
281 | owner->user[len] = 0; | |
282 | ||
15e88d21 | 283 | /* The PID is everything from the last `.' to the `:'. */ |
8dbbc384 | 284 | owner->pid = atoi (dot + 1); |
15e88d21 RS |
285 | colon = dot; |
286 | while (*colon && *colon != ':') | |
287 | colon++; | |
288 | /* After the `:', if there is one, comes the boot time. */ | |
289 | if (*colon == ':') | |
290 | owner->boot_time = atoi (colon + 1); | |
291 | else | |
292 | owner->boot_time = 0; | |
32676c08 | 293 | |
8dbbc384 RS |
294 | /* The host is everything in between. */ |
295 | len = dot - at - 1; | |
296 | owner->host = (char *) xmalloc (len + 1); | |
297 | strncpy (owner->host, at + 1, len); | |
298 | owner->host[len] = 0; | |
32676c08 | 299 | |
8dbbc384 RS |
300 | /* We're done looking at the link info. */ |
301 | xfree (lfinfo); | |
302 | ||
303 | /* On current host? */ | |
662c2ef2 RS |
304 | if (STRINGP (Fsystem_name ()) |
305 | && strcmp (owner->host, XSTRING (Fsystem_name ())->data) == 0) | |
32676c08 | 306 | { |
8dbbc384 RS |
307 | if (owner->pid == getpid ()) |
308 | ret = 2; /* We own it. */ | |
72dcef0e | 309 | else if (owner->pid > 0 |
15e88d21 RS |
310 | && (kill (owner->pid, 0) >= 0 || errno == EPERM) |
311 | && (owner->boot_time == 0 | |
312 | || owner->boot_time == get_boot_time ())) | |
8dbbc384 | 313 | ret = 1; /* An existing process on this machine owns it. */ |
8dbbc384 RS |
314 | /* The owner process is dead or has a strange pid (<=0), so try to |
315 | zap the lockfile. */ | |
72dcef0e | 316 | else if (unlink (lfname) < 0) |
8dbbc384 | 317 | ret = -1; |
72dcef0e RS |
318 | else |
319 | ret = 0; | |
32676c08 | 320 | } |
8dbbc384 RS |
321 | else |
322 | { /* If we wanted to support the check for stale locks on remote machines, | |
323 | here's where we'd do it. */ | |
324 | ret = 1; | |
325 | } | |
326 | ||
327 | /* Avoid garbage. */ | |
328 | if (local_owner || ret <= 0) | |
329 | { | |
330 | FREE_LOCK_INFO (*owner); | |
331 | } | |
332 | return ret; | |
32676c08 JB |
333 | } |
334 | ||
8dbbc384 RS |
335 | \f |
336 | /* Lock the lock named LFNAME if possible. | |
337 | Return 0 in that case. | |
338 | Return positive if some other process owns the lock, and info about | |
339 | that process in CLASHER. | |
340 | Return -1 if cannot lock for any other reason. */ | |
8489eb67 | 341 | |
8dbbc384 RS |
342 | static int |
343 | lock_if_free (clasher, lfname) | |
344 | lock_info_type *clasher; | |
345 | register char *lfname; | |
346 | { | |
c6c0c4b1 | 347 | if (lock_file_1 (lfname, 0) == 0) |
8dbbc384 RS |
348 | { |
349 | int locker; | |
e0e0205b | 350 | |
8dbbc384 RS |
351 | if (errno != EEXIST) |
352 | return -1; | |
353 | ||
354 | locker = current_lock_owner (clasher, lfname); | |
355 | if (locker == 2) | |
356 | { | |
357 | FREE_LOCK_INFO (*clasher); | |
358 | return 0; /* We ourselves locked it. */ | |
359 | } | |
360 | else if (locker == 1) | |
361 | return 1; /* Someone else has it. */ | |
8dbbc384 | 362 | |
c6c0c4b1 | 363 | return -1; /* Something's wrong. */ |
8dbbc384 RS |
364 | } |
365 | return 0; | |
8489eb67 RS |
366 | } |
367 | ||
8dbbc384 | 368 | /* lock_file locks file FN, |
8489eb67 RS |
369 | meaning it serves notice on the world that you intend to edit that file. |
370 | This should be done only when about to modify a file-visiting | |
371 | buffer previously unmodified. | |
8dbbc384 | 372 | Do not (normally) call this for a buffer already modified, |
8489eb67 RS |
373 | as either the file is already locked, or the user has already |
374 | decided to go ahead without locking. | |
375 | ||
8dbbc384 | 376 | When this returns, either the lock is locked for us, |
8489eb67 RS |
377 | or the user has said to go ahead without locking. |
378 | ||
8dbbc384 | 379 | If the file is locked by someone else, this calls |
8489eb67 | 380 | ask-user-about-lock (a Lisp function) with two arguments, |
8dbbc384 | 381 | the file name and info about the user who did the locking. |
8489eb67 RS |
382 | This function can signal an error, or return t meaning |
383 | take away the lock, or return nil meaning ignore the lock. */ | |
384 | ||
8489eb67 RS |
385 | void |
386 | lock_file (fn) | |
eb4b1c05 | 387 | Lisp_Object fn; |
8489eb67 | 388 | { |
f4a4528d | 389 | register Lisp_Object attack, orig_fn, encoded_fn; |
8dbbc384 RS |
390 | register char *lfname, *locker; |
391 | lock_info_type lock_info; | |
8489eb67 | 392 | |
5383bc6d | 393 | orig_fn = fn; |
1e89de84 | 394 | fn = Fexpand_file_name (fn, Qnil); |
f4a4528d | 395 | encoded_fn = ENCODE_FILE (fn); |
1e89de84 | 396 | |
8dbbc384 | 397 | /* Create the name of the lock-file for file fn */ |
f4a4528d | 398 | MAKE_LOCK_NAME (lfname, encoded_fn); |
8489eb67 | 399 | |
32676c08 JB |
400 | /* See if this file is visited and has changed on disk since it was |
401 | visited. */ | |
8489eb67 | 402 | { |
a57bc488 | 403 | register Lisp_Object subject_buf; |
eb4b1c05 | 404 | struct gcpro gcpro1; |
3036594f | 405 | |
5383bc6d | 406 | subject_buf = get_truename_buffer (orig_fn); |
3036594f RS |
407 | GCPRO1 (fn); |
408 | ||
265a9e55 JB |
409 | if (!NILP (subject_buf) |
410 | && NILP (Fverify_visited_file_modtime (subject_buf)) | |
411 | && !NILP (Ffile_exists_p (fn))) | |
8489eb67 | 412 | call1 (intern ("ask-user-about-supersession-threat"), fn); |
3036594f RS |
413 | |
414 | UNGCPRO; | |
8489eb67 RS |
415 | } |
416 | ||
417 | /* Try to lock the lock. */ | |
8dbbc384 RS |
418 | if (lock_if_free (&lock_info, lfname) <= 0) |
419 | /* Return now if we have locked it, or if lock creation failed */ | |
8489eb67 RS |
420 | return; |
421 | ||
422 | /* Else consider breaking the lock */ | |
266d7a00 RS |
423 | locker = (char *) alloca (strlen (lock_info.user) + strlen (lock_info.host) |
424 | + LOCK_PID_MAX + 9); | |
79e51eeb | 425 | sprintf (locker, "%s@%s (pid %lu)", lock_info.user, lock_info.host, |
8dbbc384 RS |
426 | lock_info.pid); |
427 | FREE_LOCK_INFO (lock_info); | |
428 | ||
429 | attack = call2 (intern ("ask-user-about-lock"), fn, build_string (locker)); | |
265a9e55 | 430 | if (!NILP (attack)) |
8489eb67 RS |
431 | /* User says take the lock */ |
432 | { | |
8dbbc384 | 433 | lock_file_1 (lfname, 1); |
8489eb67 RS |
434 | return; |
435 | } | |
436 | /* User says ignore the lock */ | |
437 | } | |
438 | ||
8489eb67 RS |
439 | void |
440 | unlock_file (fn) | |
441 | register Lisp_Object fn; | |
442 | { | |
443 | register char *lfname; | |
444 | ||
1e89de84 | 445 | fn = Fexpand_file_name (fn, Qnil); |
88eace34 | 446 | fn = ENCODE_FILE (fn); |
1e89de84 | 447 | |
7b92975f | 448 | MAKE_LOCK_NAME (lfname, fn); |
8489eb67 | 449 | |
8dbbc384 | 450 | if (current_lock_owner (0, lfname) == 2) |
8489eb67 | 451 | unlink (lfname); |
8489eb67 RS |
452 | } |
453 | ||
454 | void | |
455 | unlock_all_files () | |
456 | { | |
457 | register Lisp_Object tail; | |
458 | register struct buffer *b; | |
459 | ||
4e6c9d9e | 460 | for (tail = Vbuffer_alist; GC_CONSP (tail); tail = XCONS (tail)->cdr) |
8489eb67 RS |
461 | { |
462 | b = XBUFFER (XCONS (XCONS (tail)->car)->cdr); | |
5757b805 | 463 | if (STRINGP (b->file_truename) && BUF_SAVE_MODIFF (b) < BUF_MODIFF (b)) |
1c343051 KH |
464 | { |
465 | register char *lfname; | |
466 | ||
467 | MAKE_LOCK_NAME (lfname, b->file_truename); | |
468 | ||
469 | if (current_lock_owner (0, lfname) == 2) | |
470 | unlink (lfname); | |
471 | } | |
8489eb67 RS |
472 | } |
473 | } | |
8489eb67 RS |
474 | \f |
475 | DEFUN ("lock-buffer", Flock_buffer, Slock_buffer, | |
476 | 0, 1, 0, | |
477 | "Lock FILE, if current buffer is modified.\n\ | |
478 | FILE defaults to current buffer's visited file,\n\ | |
479 | or else nothing is done if current buffer isn't visiting a file.") | |
e9319ef2 EN |
480 | (file) |
481 | Lisp_Object file; | |
8489eb67 | 482 | { |
e9319ef2 EN |
483 | if (NILP (file)) |
484 | file = current_buffer->file_truename; | |
8489eb67 | 485 | else |
e9319ef2 | 486 | CHECK_STRING (file, 0); |
6a140159 | 487 | if (SAVE_MODIFF < MODIFF |
e9319ef2 EN |
488 | && !NILP (file)) |
489 | lock_file (file); | |
8489eb67 RS |
490 | return Qnil; |
491 | } | |
492 | ||
493 | DEFUN ("unlock-buffer", Funlock_buffer, Sunlock_buffer, | |
494 | 0, 0, 0, | |
495 | "Unlock the file visited in the current buffer,\n\ | |
496 | if it should normally be locked.") | |
497 | () | |
498 | { | |
6a140159 | 499 | if (SAVE_MODIFF < MODIFF |
5757b805 RS |
500 | && STRINGP (current_buffer->file_truename)) |
501 | unlock_file (current_buffer->file_truename); | |
8489eb67 RS |
502 | return Qnil; |
503 | } | |
504 | ||
8489eb67 RS |
505 | /* Unlock the file visited in buffer BUFFER. */ |
506 | ||
d07e0802 | 507 | void |
8489eb67 RS |
508 | unlock_buffer (buffer) |
509 | struct buffer *buffer; | |
510 | { | |
6a140159 | 511 | if (BUF_SAVE_MODIFF (buffer) < BUF_MODIFF (buffer) |
5757b805 RS |
512 | && STRINGP (buffer->file_truename)) |
513 | unlock_file (buffer->file_truename); | |
8489eb67 RS |
514 | } |
515 | ||
516 | DEFUN ("file-locked-p", Ffile_locked_p, Sfile_locked_p, 0, 1, 0, | |
517 | "Return nil if the FILENAME is not locked,\n\ | |
518 | t if it is locked by you, else a string of the name of the locker.") | |
e9319ef2 EN |
519 | (filename) |
520 | Lisp_Object filename; | |
8489eb67 | 521 | { |
8dbbc384 | 522 | Lisp_Object ret; |
8489eb67 RS |
523 | register char *lfname; |
524 | int owner; | |
8dbbc384 | 525 | lock_info_type locker; |
8489eb67 | 526 | |
e9319ef2 | 527 | filename = Fexpand_file_name (filename, Qnil); |
8489eb67 | 528 | |
e9319ef2 | 529 | MAKE_LOCK_NAME (lfname, filename); |
8489eb67 | 530 | |
8dbbc384 | 531 | owner = current_lock_owner (&locker, lfname); |
8489eb67 | 532 | if (owner <= 0) |
8dbbc384 RS |
533 | ret = Qnil; |
534 | else if (owner == 2) | |
535 | ret = Qt; | |
536 | else | |
537 | ret = build_string (locker.user); | |
538 | ||
539 | if (owner > 0) | |
540 | FREE_LOCK_INFO (locker); | |
541 | ||
542 | return ret; | |
8489eb67 | 543 | } |
32676c08 JB |
544 | \f |
545 | /* Initialization functions. */ | |
546 | ||
dfcf069d | 547 | void |
8489eb67 RS |
548 | syms_of_filelock () |
549 | { | |
550 | defsubr (&Sunlock_buffer); | |
551 | defsubr (&Slock_buffer); | |
552 | defsubr (&Sfile_locked_p); | |
553 | } | |
554 | ||
555 | #endif /* CLASH_DETECTION */ |