Commit | Line | Data |
---|---|---|
b97771fc RS |
1 | /* Lock files for editing. |
2 | Copyright (C) 1985, 86, 87, 93, 94, 96, 98, 1999 Free Software Foundation, Inc. | |
8489eb67 RS |
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 | |
32676c08 | 8 | the Free Software Foundation; either version 2, or (at your option) |
8489eb67 RS |
9 | 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; see the file COPYING. If not, write to | |
3b7ad313 EN |
18 | the Free Software Foundation, Inc., 59 Temple Place - Suite 330, |
19 | Boston, MA 02111-1307, USA. */ | |
8489eb67 RS |
20 | |
21 | ||
68c45bf0 | 22 | #include <config.h> |
8489eb67 RS |
23 | #include <sys/types.h> |
24 | #include <sys/stat.h> | |
dfcf069d | 25 | #include <signal.h> |
2decc5a9 | 26 | #include <stdio.h> |
bfb61299 JB |
27 | |
28 | #ifdef VMS | |
b350a838 | 29 | #include "vms-pwd.h" |
bfb61299 | 30 | #else |
8489eb67 | 31 | #include <pwd.h> |
8dbbc384 | 32 | #endif /* not VMS */ |
bfb61299 | 33 | |
8489eb67 RS |
34 | #include <sys/file.h> |
35 | #ifdef USG | |
36 | #include <fcntl.h> | |
8dbbc384 | 37 | #include <string.h> |
8489eb67 RS |
38 | #endif /* USG */ |
39 | ||
dfcf069d AS |
40 | #ifdef HAVE_UNISTD_H |
41 | #include <unistd.h> | |
42 | #endif | |
43 | ||
f805a125 KH |
44 | #ifdef __FreeBSD__ |
45 | #include <sys/time.h> | |
46 | #include <sys/types.h> | |
47 | #include <sys/sysctl.h> | |
48 | #endif /* __FreeBSD__ */ | |
49 | ||
8489eb67 | 50 | #include "lisp.h" |
8489eb67 | 51 | #include "buffer.h" |
f4a4528d RS |
52 | #include "charset.h" |
53 | #include "coding.h" | |
9177d978 | 54 | #include "systime.h" |
8489eb67 | 55 | |
15e88d21 | 56 | #include <time.h> |
8dbbc384 RS |
57 | #include <errno.h> |
58 | #ifndef errno | |
8489eb67 | 59 | extern int errno; |
79941276 RS |
60 | #endif |
61 | ||
5f8d6a10 RS |
62 | /* The directory for writing temporary files. */ |
63 | ||
64 | Lisp_Object Vtemporary_file_directory; | |
65 | ||
8489eb67 | 66 | #ifdef CLASH_DETECTION |
e788eecc KH |
67 | |
68 | #include <utmp.h> | |
77e544a4 | 69 | |
a48de9b2 PE |
70 | /* A file whose last-modified time is just after the most recent boot. |
71 | Define this to be NULL to disable checking for this file. */ | |
72 | #ifndef BOOT_TIME_FILE | |
73 | #define BOOT_TIME_FILE "/var/run/random-seed" | |
74 | #endif | |
75 | ||
77e544a4 RS |
76 | #ifndef WTMP_FILE |
77 | #define WTMP_FILE "/var/log/wtmp" | |
78 | #endif | |
8489eb67 | 79 | |
8dbbc384 RS |
80 | /* The strategy: to lock a file FN, create a symlink .#FN in FN's |
81 | directory, with link data `user@host.pid'. This avoids a single | |
82 | mount (== failure) point for lock files. | |
83 | ||
84 | When the host in the lock data is the current host, we can check if | |
85 | the pid is valid with kill. | |
86 | ||
87 | Otherwise, we could look at a separate file that maps hostnames to | |
88 | reboot times to see if the remote pid can possibly be valid, since we | |
89 | don't want Emacs to have to communicate via pipes or sockets or | |
90 | whatever to other processes, either locally or remotely; rms says | |
91 | that's too unreliable. Hence the separate file, which could | |
92 | theoretically be updated by daemons running separately -- but this | |
93 | whole idea is unimplemented; in practice, at least in our | |
1c4f857c | 94 | environment, it seems such stale locks arise fairly infrequently, and |
8dbbc384 RS |
95 | Emacs' standard methods of dealing with clashes suffice. |
96 | ||
97 | We use symlinks instead of normal files because (1) they can be | |
98 | stored more efficiently on the filesystem, since the kernel knows | |
99 | they will be small, and (2) all the info about the lock can be read | |
100 | in a single system call (readlink). Although we could use regular | |
1c4f857c | 101 | files to be useful on old systems lacking symlinks, nowadays |
8dbbc384 RS |
102 | virtually all such systems are probably single-user anyway, so it |
103 | didn't seem worth the complication. | |
104 | ||
105 | Similarly, we don't worry about a possible 14-character limit on | |
106 | file names, because those are all the same systems that don't have | |
107 | symlinks. | |
108 | ||
109 | This is compatible with the locking scheme used by Interleaf (which | |
110 | has contributed this implementation for Emacs), and was designed by | |
111 | Ethan Jacobson, Kimbo Mundy, and others. | |
112 | ||
113 | --karl@cs.umb.edu/karl@hq.ileaf.com. */ | |
8489eb67 | 114 | |
8dbbc384 | 115 | \f |
15e88d21 RS |
116 | /* Return the time of the last system boot. */ |
117 | ||
118 | static time_t boot_time; | |
b97771fc | 119 | static int boot_time_initialized; |
15e88d21 | 120 | |
9177d978 RS |
121 | extern Lisp_Object Vshell_file_name; |
122 | ||
2f2500ef DL |
123 | #ifdef BOOT_TIME |
124 | static void get_boot_time_1 P_ ((char *, int)); | |
125 | #endif | |
126 | ||
15e88d21 RS |
127 | static time_t |
128 | get_boot_time () | |
129 | { | |
2decc5a9 | 130 | #if defined (BOOT_TIME) && ! defined (NO_WTMP_FILE) |
9177d978 | 131 | int counter; |
2decc5a9 | 132 | #endif |
15e88d21 | 133 | |
b97771fc | 134 | if (boot_time_initialized) |
15e88d21 | 135 | return boot_time; |
b97771fc | 136 | boot_time_initialized = 1; |
15e88d21 | 137 | |
f805a125 KH |
138 | #if defined (CTL_KERN) && defined (KERN_BOOTTIME) |
139 | { | |
140 | int mib[2]; | |
141 | size_t size; | |
142 | struct timeval boottime_val; | |
143 | ||
144 | mib[0] = CTL_KERN; | |
145 | mib[1] = KERN_BOOTTIME; | |
146 | size = sizeof (boottime_val); | |
147 | ||
148 | if (sysctl (mib, 2, &boottime_val, &size, NULL, 0) >= 0) | |
149 | { | |
150 | boot_time = boottime_val.tv_sec; | |
151 | return boot_time; | |
152 | } | |
153 | } | |
154 | #endif /* defined (CTL_KERN) && defined (KERN_BOOTTIME) */ | |
9177d978 | 155 | |
a48de9b2 PE |
156 | if (BOOT_TIME_FILE) |
157 | { | |
158 | struct stat st; | |
159 | if (stat (BOOT_TIME_FILE, &st) == 0) | |
160 | { | |
161 | boot_time = st.st_mtime; | |
162 | return boot_time; | |
163 | } | |
164 | } | |
165 | ||
c6fd1dc4 | 166 | #if defined (BOOT_TIME) && ! defined (NO_WTMP_FILE) |
b97771fc RS |
167 | #ifndef CANNOT_DUMP |
168 | /* The utmp routines maintain static state. | |
169 | Don't touch that state unless we are initialized, | |
170 | since it might not survive dumping. */ | |
171 | if (! initialized) | |
172 | return boot_time; | |
173 | #endif /* not CANNOT_DUMP */ | |
174 | ||
175 | /* Try to get boot time from utmp before wtmp, | |
176 | since utmp is typically much smaller than wtmp. | |
177 | Passing a null pointer causes get_boot_time_1 | |
178 | to inspect the default file, namely utmp. */ | |
179 | get_boot_time_1 ((char *) 0, 0); | |
180 | if (boot_time) | |
181 | return boot_time; | |
182 | ||
9177d978 | 183 | /* Try to get boot time from the current wtmp file. */ |
b97771fc | 184 | get_boot_time_1 (WTMP_FILE, 1); |
9177d978 RS |
185 | |
186 | /* If we did not find a boot time in wtmp, look at wtmp, and so on. */ | |
b97771fc | 187 | for (counter = 0; counter < 20 && ! boot_time; counter++) |
9177d978 RS |
188 | { |
189 | char cmd_string[100]; | |
190 | Lisp_Object tempname, filename; | |
191 | int delete_flag = 0; | |
192 | ||
193 | filename = Qnil; | |
194 | ||
77e544a4 | 195 | sprintf (cmd_string, "%s.%d", WTMP_FILE, counter); |
9177d978 | 196 | tempname = build_string (cmd_string); |
29a2adb0 | 197 | if (! NILP (Ffile_exists_p (tempname))) |
9177d978 RS |
198 | filename = tempname; |
199 | else | |
200 | { | |
77e544a4 | 201 | sprintf (cmd_string, "%s.%d.gz", WTMP_FILE, counter); |
9177d978 RS |
202 | tempname = build_string (cmd_string); |
203 | if (! NILP (Ffile_exists_p (tempname))) | |
204 | { | |
205 | Lisp_Object args[6]; | |
f1d367aa GM |
206 | |
207 | /* The utmp functions on mescaline.gnu.org accept only | |
208 | file names up to 8 characters long. Choose a 2 | |
209 | character long prefix, and call make_temp_file with | |
210 | second arg non-zero, so that it will add not more | |
211 | than 6 characters to the prefix. */ | |
212 | tempname = Fexpand_file_name (build_string ("wt"), | |
5f8d6a10 | 213 | Vtemporary_file_directory); |
f1d367aa | 214 | tempname = make_temp_name (tempname, 1); |
9177d978 RS |
215 | args[0] = Vshell_file_name; |
216 | args[1] = Qnil; | |
217 | args[2] = Qnil; | |
218 | args[3] = Qnil; | |
219 | args[4] = build_string ("-c"); | |
77e544a4 RS |
220 | sprintf (cmd_string, "gunzip < %s.%d.gz > %s", |
221 | WTMP_FILE, counter, XSTRING (tempname)->data); | |
9177d978 RS |
222 | args[5] = build_string (cmd_string); |
223 | Fcall_process (6, args); | |
224 | filename = tempname; | |
225 | delete_flag = 1; | |
226 | } | |
227 | } | |
228 | ||
229 | if (! NILP (filename)) | |
230 | { | |
b97771fc | 231 | get_boot_time_1 (XSTRING (filename)->data, 1); |
9177d978 RS |
232 | if (delete_flag) |
233 | unlink (XSTRING (filename)->data); | |
234 | } | |
235 | } | |
236 | ||
237 | return boot_time; | |
238 | #else | |
239 | return 0; | |
240 | #endif | |
241 | } | |
242 | ||
e9f22ced | 243 | #ifdef BOOT_TIME |
9177d978 RS |
244 | /* Try to get the boot time from wtmp file FILENAME. |
245 | This succeeds if that file contains a reboot record. | |
9177d978 | 246 | |
b97771fc RS |
247 | If FILENAME is zero, use the same file as before; |
248 | if no FILENAME has ever been specified, this is the utmp file. | |
249 | Use the newest reboot record if NEWEST is nonzero, | |
250 | the first reboot record otherwise. | |
251 | Ignore all reboot records on or before BOOT_TIME. | |
252 | Success is indicated by setting BOOT_TIME to a larger value. */ | |
253 | ||
2f2500ef | 254 | void |
b97771fc | 255 | get_boot_time_1 (filename, newest) |
9177d978 | 256 | char *filename; |
b97771fc | 257 | int newest; |
9177d978 RS |
258 | { |
259 | struct utmp ut, *utp; | |
77e544a4 RS |
260 | int desc; |
261 | ||
b97771fc RS |
262 | if (filename) |
263 | { | |
264 | /* On some versions of IRIX, opening a nonexistent file name | |
265 | is likely to crash in the utmp routines. */ | |
68c45bf0 | 266 | desc = emacs_open (filename, O_RDONLY, 0); |
b97771fc RS |
267 | if (desc < 0) |
268 | return; | |
269 | ||
68c45bf0 | 270 | emacs_close (desc); |
b97771fc RS |
271 | |
272 | utmpname (filename); | |
273 | } | |
9177d978 | 274 | |
c321b190 | 275 | setutent (); |
b97771fc | 276 | |
c321b190 RS |
277 | while (1) |
278 | { | |
279 | /* Find the next reboot record. */ | |
280 | ut.ut_type = BOOT_TIME; | |
281 | utp = getutid (&ut); | |
282 | if (! utp) | |
283 | break; | |
284 | /* Compare reboot times and use the newest one. */ | |
285 | if (utp->ut_time > boot_time) | |
b97771fc RS |
286 | { |
287 | boot_time = utp->ut_time; | |
288 | if (! newest) | |
289 | break; | |
290 | } | |
c321b190 RS |
291 | /* Advance on element in the file |
292 | so that getutid won't repeat the same one. */ | |
293 | utp = getutent (); | |
294 | if (! utp) | |
295 | break; | |
296 | } | |
15e88d21 | 297 | endutent (); |
15e88d21 | 298 | } |
e9f22ced | 299 | #endif /* BOOT_TIME */ |
15e88d21 | 300 | \f |
8dbbc384 | 301 | /* Here is the structure that stores information about a lock. */ |
32676c08 | 302 | |
8dbbc384 RS |
303 | typedef struct |
304 | { | |
305 | char *user; | |
306 | char *host; | |
9005cb4f | 307 | unsigned long pid; |
15e88d21 | 308 | time_t boot_time; |
8dbbc384 | 309 | } lock_info_type; |
32676c08 | 310 | |
49b6d120 RS |
311 | /* When we read the info back, we might need this much more, |
312 | enough for decimal representation plus null. */ | |
313 | #define LOCK_PID_MAX (4 * sizeof (unsigned long)) | |
32676c08 | 314 | |
8dbbc384 RS |
315 | /* Free the two dynamically-allocated pieces in PTR. */ |
316 | #define FREE_LOCK_INFO(i) do { xfree ((i).user); xfree ((i).host); } while (0) | |
e31fbc7a | 317 | |
e31fbc7a | 318 | |
8dbbc384 | 319 | /* Write the name of the lock file for FN into LFNAME. Length will be |
c1355e1f GM |
320 | that of FN plus two more for the leading `.#' plus 1 for the |
321 | trailing period plus one for the digit after it plus one for the | |
322 | null. */ | |
7b92975f | 323 | #define MAKE_LOCK_NAME(lock, file) \ |
c1355e1f | 324 | (lock = (char *) alloca (STRING_BYTES (XSTRING (file)) + 2 + 1 + 1 + 1), \ |
8dbbc384 | 325 | fill_in_lock_file_name (lock, (file))) |
e31fbc7a | 326 | |
8dbbc384 RS |
327 | static void |
328 | fill_in_lock_file_name (lockfile, fn) | |
e31fbc7a RS |
329 | register char *lockfile; |
330 | register Lisp_Object fn; | |
331 | { | |
8dbbc384 | 332 | register char *p; |
c1355e1f GM |
333 | struct stat st; |
334 | int count = 0; | |
8dbbc384 RS |
335 | |
336 | strcpy (lockfile, XSTRING (fn)->data); | |
337 | ||
338 | /* Shift the nondirectory part of the file name (including the null) | |
339 | right two characters. Here is one of the places where we'd have to | |
340 | do something to support 14-character-max file names. */ | |
341 | for (p = lockfile + strlen (lockfile); p != lockfile && *p != '/'; p--) | |
342 | p[2] = *p; | |
e31fbc7a | 343 | |
8dbbc384 RS |
344 | /* Insert the `.#'. */ |
345 | p[1] = '.'; | |
346 | p[2] = '#'; | |
c1355e1f GM |
347 | |
348 | p = p + strlen (p); | |
349 | ||
350 | while (lstat (lockfile, &st) == 0 && !S_ISLNK (st.st_mode)) | |
351 | { | |
352 | if (count > 9) | |
353 | { | |
354 | *p = '\0'; | |
355 | return; | |
356 | } | |
357 | sprintf (p, ".%d", count++); | |
358 | } | |
8dbbc384 | 359 | } |
e31fbc7a | 360 | |
8dbbc384 RS |
361 | /* Lock the lock file named LFNAME. |
362 | If FORCE is nonzero, we do so even if it is already locked. | |
363 | Return 1 if successful, 0 if not. */ | |
e31fbc7a | 364 | |
8dbbc384 RS |
365 | static int |
366 | lock_file_1 (lfname, force) | |
367 | char *lfname; | |
368 | int force; | |
369 | { | |
370 | register int err; | |
bd26d5a3 | 371 | time_t boot_time; |
662c2ef2 RS |
372 | char *user_name; |
373 | char *host_name; | |
374 | char *lock_info_str; | |
375 | ||
376 | if (STRINGP (Fuser_login_name (Qnil))) | |
266d7a00 | 377 | user_name = (char *)XSTRING (Fuser_login_name (Qnil))->data; |
662c2ef2 RS |
378 | else |
379 | user_name = ""; | |
380 | if (STRINGP (Fsystem_name ())) | |
266d7a00 | 381 | host_name = (char *)XSTRING (Fsystem_name ())->data; |
662c2ef2 RS |
382 | else |
383 | host_name = ""; | |
266d7a00 | 384 | lock_info_str = (char *)alloca (strlen (user_name) + strlen (host_name) |
15e88d21 | 385 | + LOCK_PID_MAX + 5); |
8dbbc384 | 386 | |
bd26d5a3 RS |
387 | boot_time = get_boot_time (); |
388 | if (boot_time) | |
389 | sprintf (lock_info_str, "%s@%s.%lu:%lu", user_name, host_name, | |
390 | (unsigned long) getpid (), (unsigned long) boot_time); | |
391 | else | |
392 | sprintf (lock_info_str, "%s@%s.%lu", user_name, host_name, | |
393 | (unsigned long) getpid ()); | |
8dbbc384 RS |
394 | |
395 | err = symlink (lock_info_str, lfname); | |
396 | if (errno == EEXIST && force) | |
e31fbc7a | 397 | { |
8dbbc384 RS |
398 | unlink (lfname); |
399 | err = symlink (lock_info_str, lfname); | |
e31fbc7a | 400 | } |
e31fbc7a | 401 | |
8dbbc384 RS |
402 | return err == 0; |
403 | } | |
e31fbc7a | 404 | |
9177d978 | 405 | /* Return 1 if times A and B are no more than one second apart. */ |
32676c08 | 406 | |
9177d978 RS |
407 | int |
408 | within_one_second (a, b) | |
409 | time_t a, b; | |
410 | { | |
411 | return (a - b >= -1 && a - b <= 1); | |
412 | } | |
8dbbc384 RS |
413 | \f |
414 | /* Return 0 if nobody owns the lock file LFNAME or the lock is obsolete, | |
415 | 1 if another process owns it (and set OWNER (if non-null) to info), | |
416 | 2 if the current process owns it, | |
417 | or -1 if something is wrong with the locking mechanism. */ | |
e31fbc7a | 418 | |
8dbbc384 RS |
419 | static int |
420 | current_lock_owner (owner, lfname) | |
421 | lock_info_type *owner; | |
422 | char *lfname; | |
32676c08 | 423 | { |
8dbbc384 RS |
424 | #ifndef index |
425 | extern char *rindex (), *index (); | |
426 | #endif | |
5f8d6a10 | 427 | int len, ret; |
8dbbc384 | 428 | int local_owner = 0; |
15e88d21 | 429 | char *at, *dot, *colon; |
8dbbc384 RS |
430 | char *lfinfo = 0; |
431 | int bufsize = 50; | |
432 | /* Read arbitrarily-long contents of symlink. Similar code in | |
433 | file-symlink-p in fileio.c. */ | |
434 | do | |
435 | { | |
436 | bufsize *= 2; | |
437 | lfinfo = (char *) xrealloc (lfinfo, bufsize); | |
438 | len = readlink (lfname, lfinfo, bufsize); | |
439 | } | |
440 | while (len >= bufsize); | |
441 | ||
442 | /* If nonexistent lock file, all is well; otherwise, got strange error. */ | |
443 | if (len == -1) | |
444 | { | |
445 | xfree (lfinfo); | |
446 | return errno == ENOENT ? 0 : -1; | |
447 | } | |
32676c08 | 448 | |
8dbbc384 RS |
449 | /* Link info exists, so `len' is its length. Null terminate. */ |
450 | lfinfo[len] = 0; | |
451 | ||
452 | /* Even if the caller doesn't want the owner info, we still have to | |
453 | read it to determine return value, so allocate it. */ | |
454 | if (!owner) | |
455 | { | |
3609a53b | 456 | owner = (lock_info_type *) alloca (sizeof (lock_info_type)); |
8dbbc384 RS |
457 | local_owner = 1; |
458 | } | |
459 | ||
15e88d21 | 460 | /* Parse USER@HOST.PID:BOOT_TIME. If can't parse, return -1. */ |
8dbbc384 RS |
461 | /* The USER is everything before the first @. */ |
462 | at = index (lfinfo, '@'); | |
463 | dot = rindex (lfinfo, '.'); | |
15e88d21 RS |
464 | if (!at || !dot) |
465 | { | |
466 | xfree (lfinfo); | |
467 | return -1; | |
468 | } | |
8dbbc384 RS |
469 | len = at - lfinfo; |
470 | owner->user = (char *) xmalloc (len + 1); | |
471 | strncpy (owner->user, lfinfo, len); | |
472 | owner->user[len] = 0; | |
473 | ||
15e88d21 | 474 | /* The PID is everything from the last `.' to the `:'. */ |
8dbbc384 | 475 | owner->pid = atoi (dot + 1); |
15e88d21 RS |
476 | colon = dot; |
477 | while (*colon && *colon != ':') | |
478 | colon++; | |
479 | /* After the `:', if there is one, comes the boot time. */ | |
480 | if (*colon == ':') | |
481 | owner->boot_time = atoi (colon + 1); | |
482 | else | |
483 | owner->boot_time = 0; | |
32676c08 | 484 | |
8dbbc384 RS |
485 | /* The host is everything in between. */ |
486 | len = dot - at - 1; | |
487 | owner->host = (char *) xmalloc (len + 1); | |
488 | strncpy (owner->host, at + 1, len); | |
489 | owner->host[len] = 0; | |
32676c08 | 490 | |
8dbbc384 RS |
491 | /* We're done looking at the link info. */ |
492 | xfree (lfinfo); | |
493 | ||
494 | /* On current host? */ | |
662c2ef2 RS |
495 | if (STRINGP (Fsystem_name ()) |
496 | && strcmp (owner->host, XSTRING (Fsystem_name ())->data) == 0) | |
32676c08 | 497 | { |
8dbbc384 RS |
498 | if (owner->pid == getpid ()) |
499 | ret = 2; /* We own it. */ | |
72dcef0e | 500 | else if (owner->pid > 0 |
15e88d21 RS |
501 | && (kill (owner->pid, 0) >= 0 || errno == EPERM) |
502 | && (owner->boot_time == 0 | |
9177d978 | 503 | || within_one_second (owner->boot_time, get_boot_time ()))) |
8dbbc384 | 504 | ret = 1; /* An existing process on this machine owns it. */ |
8dbbc384 RS |
505 | /* The owner process is dead or has a strange pid (<=0), so try to |
506 | zap the lockfile. */ | |
72dcef0e | 507 | else if (unlink (lfname) < 0) |
8dbbc384 | 508 | ret = -1; |
72dcef0e RS |
509 | else |
510 | ret = 0; | |
32676c08 | 511 | } |
8dbbc384 RS |
512 | else |
513 | { /* If we wanted to support the check for stale locks on remote machines, | |
514 | here's where we'd do it. */ | |
515 | ret = 1; | |
516 | } | |
517 | ||
518 | /* Avoid garbage. */ | |
519 | if (local_owner || ret <= 0) | |
520 | { | |
521 | FREE_LOCK_INFO (*owner); | |
522 | } | |
523 | return ret; | |
32676c08 JB |
524 | } |
525 | ||
8dbbc384 RS |
526 | \f |
527 | /* Lock the lock named LFNAME if possible. | |
528 | Return 0 in that case. | |
529 | Return positive if some other process owns the lock, and info about | |
530 | that process in CLASHER. | |
531 | Return -1 if cannot lock for any other reason. */ | |
8489eb67 | 532 | |
8dbbc384 RS |
533 | static int |
534 | lock_if_free (clasher, lfname) | |
535 | lock_info_type *clasher; | |
536 | register char *lfname; | |
537 | { | |
cfc01fa7 | 538 | while (lock_file_1 (lfname, 0) == 0) |
8dbbc384 RS |
539 | { |
540 | int locker; | |
e0e0205b | 541 | |
8dbbc384 RS |
542 | if (errno != EEXIST) |
543 | return -1; | |
544 | ||
545 | locker = current_lock_owner (clasher, lfname); | |
546 | if (locker == 2) | |
547 | { | |
548 | FREE_LOCK_INFO (*clasher); | |
549 | return 0; /* We ourselves locked it. */ | |
550 | } | |
551 | else if (locker == 1) | |
552 | return 1; /* Someone else has it. */ | |
5df0b2fa | 553 | else if (locker == -1) |
ae1ef097 | 554 | return -1; /* current_lock_owner returned strange error. */ |
8dbbc384 | 555 | |
cfc01fa7 | 556 | /* We deleted a stale lock; try again to lock the file. */ |
8dbbc384 RS |
557 | } |
558 | return 0; | |
8489eb67 RS |
559 | } |
560 | ||
8dbbc384 | 561 | /* lock_file locks file FN, |
8489eb67 RS |
562 | meaning it serves notice on the world that you intend to edit that file. |
563 | This should be done only when about to modify a file-visiting | |
564 | buffer previously unmodified. | |
8dbbc384 | 565 | Do not (normally) call this for a buffer already modified, |
8489eb67 RS |
566 | as either the file is already locked, or the user has already |
567 | decided to go ahead without locking. | |
568 | ||
8dbbc384 | 569 | When this returns, either the lock is locked for us, |
8489eb67 RS |
570 | or the user has said to go ahead without locking. |
571 | ||
8dbbc384 | 572 | If the file is locked by someone else, this calls |
8489eb67 | 573 | ask-user-about-lock (a Lisp function) with two arguments, |
8dbbc384 | 574 | the file name and info about the user who did the locking. |
8489eb67 RS |
575 | This function can signal an error, or return t meaning |
576 | take away the lock, or return nil meaning ignore the lock. */ | |
577 | ||
8489eb67 RS |
578 | void |
579 | lock_file (fn) | |
eb4b1c05 | 580 | Lisp_Object fn; |
8489eb67 | 581 | { |
f4a4528d | 582 | register Lisp_Object attack, orig_fn, encoded_fn; |
8dbbc384 RS |
583 | register char *lfname, *locker; |
584 | lock_info_type lock_info; | |
3edc33a4 | 585 | struct gcpro gcpro1; |
8489eb67 | 586 | |
33bae690 RS |
587 | /* Don't do locking while dumping Emacs. |
588 | Uncompressing wtmp files uses call-process, which does not work | |
589 | in an uninitialized Emacs. */ | |
590 | if (! NILP (Vpurify_flag)) | |
591 | return; | |
592 | ||
5383bc6d | 593 | orig_fn = fn; |
8af8a9ca | 594 | GCPRO1 (fn); |
1e89de84 | 595 | fn = Fexpand_file_name (fn, Qnil); |
f4a4528d | 596 | encoded_fn = ENCODE_FILE (fn); |
1e89de84 | 597 | |
8dbbc384 | 598 | /* Create the name of the lock-file for file fn */ |
f4a4528d | 599 | MAKE_LOCK_NAME (lfname, encoded_fn); |
8489eb67 | 600 | |
32676c08 JB |
601 | /* See if this file is visited and has changed on disk since it was |
602 | visited. */ | |
8489eb67 | 603 | { |
a57bc488 | 604 | register Lisp_Object subject_buf; |
3036594f | 605 | |
5383bc6d | 606 | subject_buf = get_truename_buffer (orig_fn); |
3036594f | 607 | |
265a9e55 JB |
608 | if (!NILP (subject_buf) |
609 | && NILP (Fverify_visited_file_modtime (subject_buf)) | |
610 | && !NILP (Ffile_exists_p (fn))) | |
8489eb67 | 611 | call1 (intern ("ask-user-about-supersession-threat"), fn); |
3036594f | 612 | |
8489eb67 | 613 | } |
8af8a9ca | 614 | UNGCPRO; |
8489eb67 RS |
615 | |
616 | /* Try to lock the lock. */ | |
8dbbc384 RS |
617 | if (lock_if_free (&lock_info, lfname) <= 0) |
618 | /* Return now if we have locked it, or if lock creation failed */ | |
8489eb67 RS |
619 | return; |
620 | ||
621 | /* Else consider breaking the lock */ | |
266d7a00 RS |
622 | locker = (char *) alloca (strlen (lock_info.user) + strlen (lock_info.host) |
623 | + LOCK_PID_MAX + 9); | |
79e51eeb | 624 | sprintf (locker, "%s@%s (pid %lu)", lock_info.user, lock_info.host, |
8dbbc384 RS |
625 | lock_info.pid); |
626 | FREE_LOCK_INFO (lock_info); | |
627 | ||
628 | attack = call2 (intern ("ask-user-about-lock"), fn, build_string (locker)); | |
265a9e55 | 629 | if (!NILP (attack)) |
8489eb67 RS |
630 | /* User says take the lock */ |
631 | { | |
8dbbc384 | 632 | lock_file_1 (lfname, 1); |
8489eb67 RS |
633 | return; |
634 | } | |
635 | /* User says ignore the lock */ | |
636 | } | |
637 | ||
8489eb67 RS |
638 | void |
639 | unlock_file (fn) | |
640 | register Lisp_Object fn; | |
641 | { | |
642 | register char *lfname; | |
643 | ||
1e89de84 | 644 | fn = Fexpand_file_name (fn, Qnil); |
88eace34 | 645 | fn = ENCODE_FILE (fn); |
1e89de84 | 646 | |
7b92975f | 647 | MAKE_LOCK_NAME (lfname, fn); |
8489eb67 | 648 | |
8dbbc384 | 649 | if (current_lock_owner (0, lfname) == 2) |
8489eb67 | 650 | unlink (lfname); |
8489eb67 RS |
651 | } |
652 | ||
653 | void | |
654 | unlock_all_files () | |
655 | { | |
656 | register Lisp_Object tail; | |
657 | register struct buffer *b; | |
658 | ||
03699b14 | 659 | for (tail = Vbuffer_alist; GC_CONSP (tail); tail = XCDR (tail)) |
8489eb67 | 660 | { |
03699b14 | 661 | b = XBUFFER (XCDR (XCAR (tail))); |
5757b805 | 662 | if (STRINGP (b->file_truename) && BUF_SAVE_MODIFF (b) < BUF_MODIFF (b)) |
1c343051 KH |
663 | { |
664 | register char *lfname; | |
665 | ||
666 | MAKE_LOCK_NAME (lfname, b->file_truename); | |
667 | ||
668 | if (current_lock_owner (0, lfname) == 2) | |
669 | unlink (lfname); | |
670 | } | |
8489eb67 RS |
671 | } |
672 | } | |
8489eb67 RS |
673 | \f |
674 | DEFUN ("lock-buffer", Flock_buffer, Slock_buffer, | |
675 | 0, 1, 0, | |
676 | "Lock FILE, if current buffer is modified.\n\ | |
677 | FILE defaults to current buffer's visited file,\n\ | |
678 | or else nothing is done if current buffer isn't visiting a file.") | |
e9319ef2 EN |
679 | (file) |
680 | Lisp_Object file; | |
8489eb67 | 681 | { |
e9319ef2 EN |
682 | if (NILP (file)) |
683 | file = current_buffer->file_truename; | |
8489eb67 | 684 | else |
e9319ef2 | 685 | CHECK_STRING (file, 0); |
6a140159 | 686 | if (SAVE_MODIFF < MODIFF |
e9319ef2 EN |
687 | && !NILP (file)) |
688 | lock_file (file); | |
8489eb67 RS |
689 | return Qnil; |
690 | } | |
691 | ||
692 | DEFUN ("unlock-buffer", Funlock_buffer, Sunlock_buffer, | |
693 | 0, 0, 0, | |
694 | "Unlock the file visited in the current buffer,\n\ | |
695 | if it should normally be locked.") | |
696 | () | |
697 | { | |
6a140159 | 698 | if (SAVE_MODIFF < MODIFF |
5757b805 RS |
699 | && STRINGP (current_buffer->file_truename)) |
700 | unlock_file (current_buffer->file_truename); | |
8489eb67 RS |
701 | return Qnil; |
702 | } | |
703 | ||
8489eb67 RS |
704 | /* Unlock the file visited in buffer BUFFER. */ |
705 | ||
d07e0802 | 706 | void |
8489eb67 RS |
707 | unlock_buffer (buffer) |
708 | struct buffer *buffer; | |
709 | { | |
6a140159 | 710 | if (BUF_SAVE_MODIFF (buffer) < BUF_MODIFF (buffer) |
5757b805 RS |
711 | && STRINGP (buffer->file_truename)) |
712 | unlock_file (buffer->file_truename); | |
8489eb67 RS |
713 | } |
714 | ||
8105cbf7 | 715 | DEFUN ("file-locked-p", Ffile_locked_p, Sfile_locked_p, 1, 1, 0, |
8489eb67 RS |
716 | "Return nil if the FILENAME is not locked,\n\ |
717 | t if it is locked by you, else a string of the name of the locker.") | |
e9319ef2 EN |
718 | (filename) |
719 | Lisp_Object filename; | |
8489eb67 | 720 | { |
8dbbc384 | 721 | Lisp_Object ret; |
8489eb67 RS |
722 | register char *lfname; |
723 | int owner; | |
8dbbc384 | 724 | lock_info_type locker; |
8489eb67 | 725 | |
e9319ef2 | 726 | filename = Fexpand_file_name (filename, Qnil); |
8489eb67 | 727 | |
e9319ef2 | 728 | MAKE_LOCK_NAME (lfname, filename); |
8489eb67 | 729 | |
8dbbc384 | 730 | owner = current_lock_owner (&locker, lfname); |
8489eb67 | 731 | if (owner <= 0) |
8dbbc384 RS |
732 | ret = Qnil; |
733 | else if (owner == 2) | |
734 | ret = Qt; | |
735 | else | |
736 | ret = build_string (locker.user); | |
737 | ||
738 | if (owner > 0) | |
739 | FREE_LOCK_INFO (locker); | |
740 | ||
741 | return ret; | |
8489eb67 | 742 | } |
32676c08 JB |
743 | \f |
744 | /* Initialization functions. */ | |
745 | ||
a3fd58aa KH |
746 | void |
747 | init_filelock () | |
748 | { | |
749 | boot_time = 0; | |
b97771fc | 750 | boot_time_initialized = 0; |
a3fd58aa KH |
751 | } |
752 | ||
dfcf069d | 753 | void |
8489eb67 RS |
754 | syms_of_filelock () |
755 | { | |
5f8d6a10 RS |
756 | DEFVAR_LISP ("temporary-file-directory", &Vtemporary_file_directory, |
757 | "The directory for writing temporary files."); | |
758 | Vtemporary_file_directory = Qnil; | |
759 | ||
8489eb67 RS |
760 | defsubr (&Sunlock_buffer); |
761 | defsubr (&Slock_buffer); | |
762 | defsubr (&Sfile_locked_p); | |
763 | } | |
764 | ||
765 | #endif /* CLASH_DETECTION */ |