Commit | Line | Data |
---|---|---|
b97771fc | 1 | /* Lock files for editing. |
63680feb | 2 | Copyright (C) 1985, 86, 87, 93, 94, 96, 98, 1999, 2000, 2001 |
4fa09beb | 3 | Free Software Foundation, Inc. |
8489eb67 RS |
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 | |
32676c08 | 9 | the Free Software Foundation; either version 2, or (at your option) |
8489eb67 RS |
10 | 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; see the file COPYING. If not, write to | |
3b7ad313 EN |
19 | the Free Software Foundation, Inc., 59 Temple Place - Suite 330, |
20 | Boston, MA 02111-1307, USA. */ | |
8489eb67 RS |
21 | |
22 | ||
68c45bf0 | 23 | #include <config.h> |
8489eb67 RS |
24 | #include <sys/types.h> |
25 | #include <sys/stat.h> | |
dfcf069d | 26 | #include <signal.h> |
2decc5a9 | 27 | #include <stdio.h> |
bfb61299 JB |
28 | |
29 | #ifdef VMS | |
b350a838 | 30 | #include "vms-pwd.h" |
bfb61299 | 31 | #else |
8489eb67 | 32 | #include <pwd.h> |
8dbbc384 | 33 | #endif /* not VMS */ |
bfb61299 | 34 | |
8489eb67 | 35 | #include <sys/file.h> |
e5ef3cdf | 36 | #ifdef HAVE_FCNTL_H |
8489eb67 | 37 | #include <fcntl.h> |
e5ef3cdf DL |
38 | #endif |
39 | #ifdef HAVE_STRING_H | |
8dbbc384 | 40 | #include <string.h> |
e5ef3cdf | 41 | #endif |
8489eb67 | 42 | |
dfcf069d AS |
43 | #ifdef HAVE_UNISTD_H |
44 | #include <unistd.h> | |
45 | #endif | |
46 | ||
f805a125 | 47 | #ifdef __FreeBSD__ |
f805a125 KH |
48 | #include <sys/sysctl.h> |
49 | #endif /* __FreeBSD__ */ | |
50 | ||
e5ef3cdf DL |
51 | #include <errno.h> |
52 | #ifndef errno | |
53 | extern int errno; | |
54 | #endif | |
55 | ||
8489eb67 | 56 | #include "lisp.h" |
8489eb67 | 57 | #include "buffer.h" |
d2f6dae8 | 58 | #include "character.h" |
f4a4528d RS |
59 | #include "charset.h" |
60 | #include "coding.h" | |
9177d978 | 61 | #include "systime.h" |
8489eb67 | 62 | |
5f8d6a10 RS |
63 | /* The directory for writing temporary files. */ |
64 | ||
65 | Lisp_Object Vtemporary_file_directory; | |
66 | ||
8489eb67 | 67 | #ifdef CLASH_DETECTION |
e788eecc KH |
68 | |
69 | #include <utmp.h> | |
77e544a4 | 70 | |
fa5c314d RS |
71 | #if !defined (S_ISLNK) && defined (S_IFLNK) |
72 | #define S_ISLNK(m) (((m) & S_IFMT) == S_IFLNK) | |
73 | #endif | |
74 | ||
a48de9b2 PE |
75 | /* A file whose last-modified time is just after the most recent boot. |
76 | Define this to be NULL to disable checking for this file. */ | |
77 | #ifndef BOOT_TIME_FILE | |
78 | #define BOOT_TIME_FILE "/var/run/random-seed" | |
79 | #endif | |
80 | ||
77e544a4 RS |
81 | #ifndef WTMP_FILE |
82 | #define WTMP_FILE "/var/log/wtmp" | |
83 | #endif | |
8489eb67 | 84 | |
8dbbc384 RS |
85 | /* The strategy: to lock a file FN, create a symlink .#FN in FN's |
86 | directory, with link data `user@host.pid'. This avoids a single | |
87 | mount (== failure) point for lock files. | |
88 | ||
89 | When the host in the lock data is the current host, we can check if | |
90 | the pid is valid with kill. | |
91 | ||
92 | Otherwise, we could look at a separate file that maps hostnames to | |
93 | reboot times to see if the remote pid can possibly be valid, since we | |
94 | don't want Emacs to have to communicate via pipes or sockets or | |
95 | whatever to other processes, either locally or remotely; rms says | |
96 | that's too unreliable. Hence the separate file, which could | |
97 | theoretically be updated by daemons running separately -- but this | |
98 | whole idea is unimplemented; in practice, at least in our | |
1c4f857c | 99 | environment, it seems such stale locks arise fairly infrequently, and |
8dbbc384 RS |
100 | Emacs' standard methods of dealing with clashes suffice. |
101 | ||
102 | We use symlinks instead of normal files because (1) they can be | |
103 | stored more efficiently on the filesystem, since the kernel knows | |
104 | they will be small, and (2) all the info about the lock can be read | |
105 | in a single system call (readlink). Although we could use regular | |
1c4f857c | 106 | files to be useful on old systems lacking symlinks, nowadays |
8dbbc384 RS |
107 | virtually all such systems are probably single-user anyway, so it |
108 | didn't seem worth the complication. | |
109 | ||
110 | Similarly, we don't worry about a possible 14-character limit on | |
111 | file names, because those are all the same systems that don't have | |
112 | symlinks. | |
113 | ||
114 | This is compatible with the locking scheme used by Interleaf (which | |
115 | has contributed this implementation for Emacs), and was designed by | |
116 | Ethan Jacobson, Kimbo Mundy, and others. | |
117 | ||
118 | --karl@cs.umb.edu/karl@hq.ileaf.com. */ | |
8489eb67 | 119 | |
8dbbc384 | 120 | \f |
15e88d21 RS |
121 | /* Return the time of the last system boot. */ |
122 | ||
123 | static time_t boot_time; | |
b97771fc | 124 | static int boot_time_initialized; |
15e88d21 | 125 | |
9177d978 RS |
126 | extern Lisp_Object Vshell_file_name; |
127 | ||
2f2500ef DL |
128 | #ifdef BOOT_TIME |
129 | static void get_boot_time_1 P_ ((char *, int)); | |
130 | #endif | |
131 | ||
15e88d21 RS |
132 | static time_t |
133 | get_boot_time () | |
134 | { | |
2decc5a9 | 135 | #if defined (BOOT_TIME) && ! defined (NO_WTMP_FILE) |
9177d978 | 136 | int counter; |
2decc5a9 | 137 | #endif |
15e88d21 | 138 | |
b97771fc | 139 | if (boot_time_initialized) |
15e88d21 | 140 | return boot_time; |
b97771fc | 141 | boot_time_initialized = 1; |
15e88d21 | 142 | |
f805a125 KH |
143 | #if defined (CTL_KERN) && defined (KERN_BOOTTIME) |
144 | { | |
145 | int mib[2]; | |
146 | size_t size; | |
147 | struct timeval boottime_val; | |
148 | ||
149 | mib[0] = CTL_KERN; | |
150 | mib[1] = KERN_BOOTTIME; | |
151 | size = sizeof (boottime_val); | |
152 | ||
153 | if (sysctl (mib, 2, &boottime_val, &size, NULL, 0) >= 0) | |
154 | { | |
155 | boot_time = boottime_val.tv_sec; | |
156 | return boot_time; | |
157 | } | |
158 | } | |
159 | #endif /* defined (CTL_KERN) && defined (KERN_BOOTTIME) */ | |
9177d978 | 160 | |
a48de9b2 PE |
161 | if (BOOT_TIME_FILE) |
162 | { | |
163 | struct stat st; | |
164 | if (stat (BOOT_TIME_FILE, &st) == 0) | |
165 | { | |
166 | boot_time = st.st_mtime; | |
167 | return boot_time; | |
168 | } | |
169 | } | |
170 | ||
c6fd1dc4 | 171 | #if defined (BOOT_TIME) && ! defined (NO_WTMP_FILE) |
b97771fc RS |
172 | #ifndef CANNOT_DUMP |
173 | /* The utmp routines maintain static state. | |
174 | Don't touch that state unless we are initialized, | |
175 | since it might not survive dumping. */ | |
176 | if (! initialized) | |
177 | return boot_time; | |
178 | #endif /* not CANNOT_DUMP */ | |
179 | ||
180 | /* Try to get boot time from utmp before wtmp, | |
181 | since utmp is typically much smaller than wtmp. | |
182 | Passing a null pointer causes get_boot_time_1 | |
183 | to inspect the default file, namely utmp. */ | |
184 | get_boot_time_1 ((char *) 0, 0); | |
185 | if (boot_time) | |
186 | return boot_time; | |
187 | ||
9177d978 | 188 | /* Try to get boot time from the current wtmp file. */ |
b97771fc | 189 | get_boot_time_1 (WTMP_FILE, 1); |
9177d978 RS |
190 | |
191 | /* If we did not find a boot time in wtmp, look at wtmp, and so on. */ | |
b97771fc | 192 | for (counter = 0; counter < 20 && ! boot_time; counter++) |
9177d978 RS |
193 | { |
194 | char cmd_string[100]; | |
195 | Lisp_Object tempname, filename; | |
196 | int delete_flag = 0; | |
197 | ||
198 | filename = Qnil; | |
199 | ||
77e544a4 | 200 | sprintf (cmd_string, "%s.%d", WTMP_FILE, counter); |
9177d978 | 201 | tempname = build_string (cmd_string); |
29a2adb0 | 202 | if (! NILP (Ffile_exists_p (tempname))) |
9177d978 RS |
203 | filename = tempname; |
204 | else | |
205 | { | |
77e544a4 | 206 | sprintf (cmd_string, "%s.%d.gz", WTMP_FILE, counter); |
9177d978 RS |
207 | tempname = build_string (cmd_string); |
208 | if (! NILP (Ffile_exists_p (tempname))) | |
209 | { | |
210 | Lisp_Object args[6]; | |
f1d367aa GM |
211 | |
212 | /* The utmp functions on mescaline.gnu.org accept only | |
213 | file names up to 8 characters long. Choose a 2 | |
214 | character long prefix, and call make_temp_file with | |
215 | second arg non-zero, so that it will add not more | |
216 | than 6 characters to the prefix. */ | |
217 | tempname = Fexpand_file_name (build_string ("wt"), | |
5f8d6a10 | 218 | Vtemporary_file_directory); |
f1d367aa | 219 | tempname = make_temp_name (tempname, 1); |
9177d978 RS |
220 | args[0] = Vshell_file_name; |
221 | args[1] = Qnil; | |
222 | args[2] = Qnil; | |
223 | args[3] = Qnil; | |
224 | args[4] = build_string ("-c"); | |
77e544a4 RS |
225 | sprintf (cmd_string, "gunzip < %s.%d.gz > %s", |
226 | WTMP_FILE, counter, XSTRING (tempname)->data); | |
9177d978 RS |
227 | args[5] = build_string (cmd_string); |
228 | Fcall_process (6, args); | |
229 | filename = tempname; | |
230 | delete_flag = 1; | |
231 | } | |
232 | } | |
233 | ||
234 | if (! NILP (filename)) | |
235 | { | |
b97771fc | 236 | get_boot_time_1 (XSTRING (filename)->data, 1); |
9177d978 RS |
237 | if (delete_flag) |
238 | unlink (XSTRING (filename)->data); | |
239 | } | |
240 | } | |
241 | ||
242 | return boot_time; | |
243 | #else | |
244 | return 0; | |
245 | #endif | |
246 | } | |
247 | ||
e9f22ced | 248 | #ifdef BOOT_TIME |
9177d978 RS |
249 | /* Try to get the boot time from wtmp file FILENAME. |
250 | This succeeds if that file contains a reboot record. | |
9177d978 | 251 | |
b97771fc RS |
252 | If FILENAME is zero, use the same file as before; |
253 | if no FILENAME has ever been specified, this is the utmp file. | |
254 | Use the newest reboot record if NEWEST is nonzero, | |
255 | the first reboot record otherwise. | |
256 | Ignore all reboot records on or before BOOT_TIME. | |
257 | Success is indicated by setting BOOT_TIME to a larger value. */ | |
258 | ||
2f2500ef | 259 | void |
b97771fc | 260 | get_boot_time_1 (filename, newest) |
9177d978 | 261 | char *filename; |
b97771fc | 262 | int newest; |
9177d978 RS |
263 | { |
264 | struct utmp ut, *utp; | |
77e544a4 RS |
265 | int desc; |
266 | ||
b97771fc RS |
267 | if (filename) |
268 | { | |
269 | /* On some versions of IRIX, opening a nonexistent file name | |
270 | is likely to crash in the utmp routines. */ | |
68c45bf0 | 271 | desc = emacs_open (filename, O_RDONLY, 0); |
b97771fc RS |
272 | if (desc < 0) |
273 | return; | |
274 | ||
68c45bf0 | 275 | emacs_close (desc); |
b97771fc RS |
276 | |
277 | utmpname (filename); | |
278 | } | |
9177d978 | 279 | |
c321b190 | 280 | setutent (); |
b97771fc | 281 | |
c321b190 RS |
282 | while (1) |
283 | { | |
284 | /* Find the next reboot record. */ | |
285 | ut.ut_type = BOOT_TIME; | |
286 | utp = getutid (&ut); | |
287 | if (! utp) | |
288 | break; | |
289 | /* Compare reboot times and use the newest one. */ | |
290 | if (utp->ut_time > boot_time) | |
b97771fc RS |
291 | { |
292 | boot_time = utp->ut_time; | |
293 | if (! newest) | |
294 | break; | |
295 | } | |
c321b190 RS |
296 | /* Advance on element in the file |
297 | so that getutid won't repeat the same one. */ | |
298 | utp = getutent (); | |
299 | if (! utp) | |
300 | break; | |
301 | } | |
15e88d21 | 302 | endutent (); |
15e88d21 | 303 | } |
e9f22ced | 304 | #endif /* BOOT_TIME */ |
15e88d21 | 305 | \f |
8dbbc384 | 306 | /* Here is the structure that stores information about a lock. */ |
32676c08 | 307 | |
8dbbc384 RS |
308 | typedef struct |
309 | { | |
310 | char *user; | |
311 | char *host; | |
9005cb4f | 312 | unsigned long pid; |
15e88d21 | 313 | time_t boot_time; |
8dbbc384 | 314 | } lock_info_type; |
32676c08 | 315 | |
49b6d120 RS |
316 | /* When we read the info back, we might need this much more, |
317 | enough for decimal representation plus null. */ | |
318 | #define LOCK_PID_MAX (4 * sizeof (unsigned long)) | |
32676c08 | 319 | |
8dbbc384 RS |
320 | /* Free the two dynamically-allocated pieces in PTR. */ |
321 | #define FREE_LOCK_INFO(i) do { xfree ((i).user); xfree ((i).host); } while (0) | |
e31fbc7a | 322 | |
e31fbc7a | 323 | |
8dbbc384 | 324 | /* Write the name of the lock file for FN into LFNAME. Length will be |
c1355e1f GM |
325 | that of FN plus two more for the leading `.#' plus 1 for the |
326 | trailing period plus one for the digit after it plus one for the | |
327 | null. */ | |
7b92975f | 328 | #define MAKE_LOCK_NAME(lock, file) \ |
c1355e1f | 329 | (lock = (char *) alloca (STRING_BYTES (XSTRING (file)) + 2 + 1 + 1 + 1), \ |
8dbbc384 | 330 | fill_in_lock_file_name (lock, (file))) |
e31fbc7a | 331 | |
8dbbc384 RS |
332 | static void |
333 | fill_in_lock_file_name (lockfile, fn) | |
e31fbc7a RS |
334 | register char *lockfile; |
335 | register Lisp_Object fn; | |
336 | { | |
8dbbc384 | 337 | register char *p; |
c1355e1f GM |
338 | struct stat st; |
339 | int count = 0; | |
8dbbc384 RS |
340 | |
341 | strcpy (lockfile, XSTRING (fn)->data); | |
342 | ||
343 | /* Shift the nondirectory part of the file name (including the null) | |
344 | right two characters. Here is one of the places where we'd have to | |
345 | do something to support 14-character-max file names. */ | |
346 | for (p = lockfile + strlen (lockfile); p != lockfile && *p != '/'; p--) | |
347 | p[2] = *p; | |
e31fbc7a | 348 | |
8dbbc384 RS |
349 | /* Insert the `.#'. */ |
350 | p[1] = '.'; | |
351 | p[2] = '#'; | |
c1355e1f GM |
352 | |
353 | p = p + strlen (p); | |
354 | ||
355 | while (lstat (lockfile, &st) == 0 && !S_ISLNK (st.st_mode)) | |
356 | { | |
357 | if (count > 9) | |
358 | { | |
359 | *p = '\0'; | |
360 | return; | |
361 | } | |
362 | sprintf (p, ".%d", count++); | |
363 | } | |
8dbbc384 | 364 | } |
e31fbc7a | 365 | |
8dbbc384 RS |
366 | /* Lock the lock file named LFNAME. |
367 | If FORCE is nonzero, we do so even if it is already locked. | |
368 | Return 1 if successful, 0 if not. */ | |
e31fbc7a | 369 | |
8dbbc384 RS |
370 | static int |
371 | lock_file_1 (lfname, force) | |
372 | char *lfname; | |
373 | int force; | |
374 | { | |
375 | register int err; | |
bd26d5a3 | 376 | time_t boot_time; |
662c2ef2 RS |
377 | char *user_name; |
378 | char *host_name; | |
379 | char *lock_info_str; | |
380 | ||
381 | if (STRINGP (Fuser_login_name (Qnil))) | |
266d7a00 | 382 | user_name = (char *)XSTRING (Fuser_login_name (Qnil))->data; |
662c2ef2 RS |
383 | else |
384 | user_name = ""; | |
385 | if (STRINGP (Fsystem_name ())) | |
266d7a00 | 386 | host_name = (char *)XSTRING (Fsystem_name ())->data; |
662c2ef2 RS |
387 | else |
388 | host_name = ""; | |
266d7a00 | 389 | lock_info_str = (char *)alloca (strlen (user_name) + strlen (host_name) |
15e88d21 | 390 | + LOCK_PID_MAX + 5); |
8dbbc384 | 391 | |
bd26d5a3 RS |
392 | boot_time = get_boot_time (); |
393 | if (boot_time) | |
394 | sprintf (lock_info_str, "%s@%s.%lu:%lu", user_name, host_name, | |
395 | (unsigned long) getpid (), (unsigned long) boot_time); | |
396 | else | |
397 | sprintf (lock_info_str, "%s@%s.%lu", user_name, host_name, | |
398 | (unsigned long) getpid ()); | |
8dbbc384 RS |
399 | |
400 | err = symlink (lock_info_str, lfname); | |
401 | if (errno == EEXIST && force) | |
e31fbc7a | 402 | { |
8dbbc384 RS |
403 | unlink (lfname); |
404 | err = symlink (lock_info_str, lfname); | |
e31fbc7a | 405 | } |
e31fbc7a | 406 | |
8dbbc384 RS |
407 | return err == 0; |
408 | } | |
e31fbc7a | 409 | |
9177d978 | 410 | /* Return 1 if times A and B are no more than one second apart. */ |
32676c08 | 411 | |
9177d978 RS |
412 | int |
413 | within_one_second (a, b) | |
414 | time_t a, b; | |
415 | { | |
416 | return (a - b >= -1 && a - b <= 1); | |
417 | } | |
8dbbc384 RS |
418 | \f |
419 | /* Return 0 if nobody owns the lock file LFNAME or the lock is obsolete, | |
420 | 1 if another process owns it (and set OWNER (if non-null) to info), | |
421 | 2 if the current process owns it, | |
422 | or -1 if something is wrong with the locking mechanism. */ | |
e31fbc7a | 423 | |
8dbbc384 RS |
424 | static int |
425 | current_lock_owner (owner, lfname) | |
426 | lock_info_type *owner; | |
427 | char *lfname; | |
32676c08 | 428 | { |
8dbbc384 RS |
429 | #ifndef index |
430 | extern char *rindex (), *index (); | |
431 | #endif | |
5f8d6a10 | 432 | int len, ret; |
8dbbc384 | 433 | int local_owner = 0; |
15e88d21 | 434 | char *at, *dot, *colon; |
8dbbc384 RS |
435 | char *lfinfo = 0; |
436 | int bufsize = 50; | |
437 | /* Read arbitrarily-long contents of symlink. Similar code in | |
438 | file-symlink-p in fileio.c. */ | |
439 | do | |
440 | { | |
441 | bufsize *= 2; | |
442 | lfinfo = (char *) xrealloc (lfinfo, bufsize); | |
620c4704 | 443 | errno = 0; |
8dbbc384 | 444 | len = readlink (lfname, lfinfo, bufsize); |
b6e97b0a GM |
445 | #ifdef ERANGE |
446 | /* HP-UX reports ERANGE if the buffer is too small. */ | |
447 | if (len == -1 && errno == ERANGE) | |
63680feb | 448 | len = bufsize; |
b6e97b0a | 449 | #endif |
8dbbc384 RS |
450 | } |
451 | while (len >= bufsize); | |
452 | ||
453 | /* If nonexistent lock file, all is well; otherwise, got strange error. */ | |
454 | if (len == -1) | |
455 | { | |
456 | xfree (lfinfo); | |
457 | return errno == ENOENT ? 0 : -1; | |
458 | } | |
32676c08 | 459 | |
8dbbc384 RS |
460 | /* Link info exists, so `len' is its length. Null terminate. */ |
461 | lfinfo[len] = 0; | |
462 | ||
463 | /* Even if the caller doesn't want the owner info, we still have to | |
464 | read it to determine return value, so allocate it. */ | |
465 | if (!owner) | |
466 | { | |
3609a53b | 467 | owner = (lock_info_type *) alloca (sizeof (lock_info_type)); |
8dbbc384 RS |
468 | local_owner = 1; |
469 | } | |
470 | ||
15e88d21 | 471 | /* Parse USER@HOST.PID:BOOT_TIME. If can't parse, return -1. */ |
8dbbc384 RS |
472 | /* The USER is everything before the first @. */ |
473 | at = index (lfinfo, '@'); | |
474 | dot = rindex (lfinfo, '.'); | |
15e88d21 RS |
475 | if (!at || !dot) |
476 | { | |
477 | xfree (lfinfo); | |
478 | return -1; | |
479 | } | |
8dbbc384 RS |
480 | len = at - lfinfo; |
481 | owner->user = (char *) xmalloc (len + 1); | |
482 | strncpy (owner->user, lfinfo, len); | |
483 | owner->user[len] = 0; | |
484 | ||
15e88d21 | 485 | /* The PID is everything from the last `.' to the `:'. */ |
8dbbc384 | 486 | owner->pid = atoi (dot + 1); |
15e88d21 RS |
487 | colon = dot; |
488 | while (*colon && *colon != ':') | |
489 | colon++; | |
490 | /* After the `:', if there is one, comes the boot time. */ | |
491 | if (*colon == ':') | |
492 | owner->boot_time = atoi (colon + 1); | |
493 | else | |
494 | owner->boot_time = 0; | |
32676c08 | 495 | |
8dbbc384 RS |
496 | /* The host is everything in between. */ |
497 | len = dot - at - 1; | |
498 | owner->host = (char *) xmalloc (len + 1); | |
499 | strncpy (owner->host, at + 1, len); | |
500 | owner->host[len] = 0; | |
32676c08 | 501 | |
8dbbc384 RS |
502 | /* We're done looking at the link info. */ |
503 | xfree (lfinfo); | |
504 | ||
505 | /* On current host? */ | |
662c2ef2 RS |
506 | if (STRINGP (Fsystem_name ()) |
507 | && strcmp (owner->host, XSTRING (Fsystem_name ())->data) == 0) | |
32676c08 | 508 | { |
8dbbc384 RS |
509 | if (owner->pid == getpid ()) |
510 | ret = 2; /* We own it. */ | |
72dcef0e | 511 | else if (owner->pid > 0 |
15e88d21 RS |
512 | && (kill (owner->pid, 0) >= 0 || errno == EPERM) |
513 | && (owner->boot_time == 0 | |
9177d978 | 514 | || within_one_second (owner->boot_time, get_boot_time ()))) |
8dbbc384 | 515 | ret = 1; /* An existing process on this machine owns it. */ |
8dbbc384 RS |
516 | /* The owner process is dead or has a strange pid (<=0), so try to |
517 | zap the lockfile. */ | |
72dcef0e | 518 | else if (unlink (lfname) < 0) |
8dbbc384 | 519 | ret = -1; |
72dcef0e RS |
520 | else |
521 | ret = 0; | |
32676c08 | 522 | } |
8dbbc384 RS |
523 | else |
524 | { /* If we wanted to support the check for stale locks on remote machines, | |
525 | here's where we'd do it. */ | |
526 | ret = 1; | |
527 | } | |
528 | ||
529 | /* Avoid garbage. */ | |
530 | if (local_owner || ret <= 0) | |
531 | { | |
532 | FREE_LOCK_INFO (*owner); | |
533 | } | |
534 | return ret; | |
32676c08 JB |
535 | } |
536 | ||
8dbbc384 RS |
537 | \f |
538 | /* Lock the lock named LFNAME if possible. | |
539 | Return 0 in that case. | |
540 | Return positive if some other process owns the lock, and info about | |
541 | that process in CLASHER. | |
542 | Return -1 if cannot lock for any other reason. */ | |
8489eb67 | 543 | |
8dbbc384 RS |
544 | static int |
545 | lock_if_free (clasher, lfname) | |
546 | lock_info_type *clasher; | |
547 | register char *lfname; | |
548 | { | |
cfc01fa7 | 549 | while (lock_file_1 (lfname, 0) == 0) |
8dbbc384 RS |
550 | { |
551 | int locker; | |
e0e0205b | 552 | |
8dbbc384 RS |
553 | if (errno != EEXIST) |
554 | return -1; | |
555 | ||
556 | locker = current_lock_owner (clasher, lfname); | |
557 | if (locker == 2) | |
558 | { | |
559 | FREE_LOCK_INFO (*clasher); | |
560 | return 0; /* We ourselves locked it. */ | |
561 | } | |
562 | else if (locker == 1) | |
563 | return 1; /* Someone else has it. */ | |
5df0b2fa | 564 | else if (locker == -1) |
ae1ef097 | 565 | return -1; /* current_lock_owner returned strange error. */ |
8dbbc384 | 566 | |
cfc01fa7 | 567 | /* We deleted a stale lock; try again to lock the file. */ |
8dbbc384 RS |
568 | } |
569 | return 0; | |
8489eb67 RS |
570 | } |
571 | ||
8dbbc384 | 572 | /* lock_file locks file FN, |
8489eb67 RS |
573 | meaning it serves notice on the world that you intend to edit that file. |
574 | This should be done only when about to modify a file-visiting | |
575 | buffer previously unmodified. | |
8dbbc384 | 576 | Do not (normally) call this for a buffer already modified, |
8489eb67 RS |
577 | as either the file is already locked, or the user has already |
578 | decided to go ahead without locking. | |
579 | ||
8dbbc384 | 580 | When this returns, either the lock is locked for us, |
8489eb67 RS |
581 | or the user has said to go ahead without locking. |
582 | ||
8dbbc384 | 583 | If the file is locked by someone else, this calls |
8489eb67 | 584 | ask-user-about-lock (a Lisp function) with two arguments, |
8dbbc384 | 585 | the file name and info about the user who did the locking. |
8489eb67 RS |
586 | This function can signal an error, or return t meaning |
587 | take away the lock, or return nil meaning ignore the lock. */ | |
588 | ||
8489eb67 RS |
589 | void |
590 | lock_file (fn) | |
eb4b1c05 | 591 | Lisp_Object fn; |
8489eb67 | 592 | { |
f4a4528d | 593 | register Lisp_Object attack, orig_fn, encoded_fn; |
8dbbc384 RS |
594 | register char *lfname, *locker; |
595 | lock_info_type lock_info; | |
3edc33a4 | 596 | struct gcpro gcpro1; |
8489eb67 | 597 | |
33bae690 RS |
598 | /* Don't do locking while dumping Emacs. |
599 | Uncompressing wtmp files uses call-process, which does not work | |
600 | in an uninitialized Emacs. */ | |
601 | if (! NILP (Vpurify_flag)) | |
602 | return; | |
603 | ||
5383bc6d | 604 | orig_fn = fn; |
8af8a9ca | 605 | GCPRO1 (fn); |
1e89de84 | 606 | fn = Fexpand_file_name (fn, Qnil); |
f4a4528d | 607 | encoded_fn = ENCODE_FILE (fn); |
1e89de84 | 608 | |
8dbbc384 | 609 | /* Create the name of the lock-file for file fn */ |
f4a4528d | 610 | MAKE_LOCK_NAME (lfname, encoded_fn); |
8489eb67 | 611 | |
32676c08 JB |
612 | /* See if this file is visited and has changed on disk since it was |
613 | visited. */ | |
8489eb67 | 614 | { |
a57bc488 | 615 | register Lisp_Object subject_buf; |
3036594f | 616 | |
5383bc6d | 617 | subject_buf = get_truename_buffer (orig_fn); |
3036594f | 618 | |
265a9e55 JB |
619 | if (!NILP (subject_buf) |
620 | && NILP (Fverify_visited_file_modtime (subject_buf)) | |
621 | && !NILP (Ffile_exists_p (fn))) | |
8489eb67 | 622 | call1 (intern ("ask-user-about-supersession-threat"), fn); |
3036594f | 623 | |
8489eb67 | 624 | } |
8af8a9ca | 625 | UNGCPRO; |
8489eb67 RS |
626 | |
627 | /* Try to lock the lock. */ | |
8dbbc384 RS |
628 | if (lock_if_free (&lock_info, lfname) <= 0) |
629 | /* Return now if we have locked it, or if lock creation failed */ | |
8489eb67 RS |
630 | return; |
631 | ||
632 | /* Else consider breaking the lock */ | |
266d7a00 RS |
633 | locker = (char *) alloca (strlen (lock_info.user) + strlen (lock_info.host) |
634 | + LOCK_PID_MAX + 9); | |
79e51eeb | 635 | sprintf (locker, "%s@%s (pid %lu)", lock_info.user, lock_info.host, |
8dbbc384 RS |
636 | lock_info.pid); |
637 | FREE_LOCK_INFO (lock_info); | |
638 | ||
639 | attack = call2 (intern ("ask-user-about-lock"), fn, build_string (locker)); | |
265a9e55 | 640 | if (!NILP (attack)) |
8489eb67 RS |
641 | /* User says take the lock */ |
642 | { | |
8dbbc384 | 643 | lock_file_1 (lfname, 1); |
8489eb67 RS |
644 | return; |
645 | } | |
646 | /* User says ignore the lock */ | |
647 | } | |
648 | ||
8489eb67 RS |
649 | void |
650 | unlock_file (fn) | |
651 | register Lisp_Object fn; | |
652 | { | |
653 | register char *lfname; | |
654 | ||
1e89de84 | 655 | fn = Fexpand_file_name (fn, Qnil); |
88eace34 | 656 | fn = ENCODE_FILE (fn); |
1e89de84 | 657 | |
7b92975f | 658 | MAKE_LOCK_NAME (lfname, fn); |
8489eb67 | 659 | |
8dbbc384 | 660 | if (current_lock_owner (0, lfname) == 2) |
8489eb67 | 661 | unlink (lfname); |
8489eb67 RS |
662 | } |
663 | ||
664 | void | |
665 | unlock_all_files () | |
666 | { | |
667 | register Lisp_Object tail; | |
668 | register struct buffer *b; | |
669 | ||
03699b14 | 670 | for (tail = Vbuffer_alist; GC_CONSP (tail); tail = XCDR (tail)) |
8489eb67 | 671 | { |
03699b14 | 672 | b = XBUFFER (XCDR (XCAR (tail))); |
5757b805 | 673 | if (STRINGP (b->file_truename) && BUF_SAVE_MODIFF (b) < BUF_MODIFF (b)) |
1c343051 | 674 | { |
4fa09beb | 675 | unlock_file(b->file_truename); |
1c343051 | 676 | } |
8489eb67 RS |
677 | } |
678 | } | |
8489eb67 RS |
679 | \f |
680 | DEFUN ("lock-buffer", Flock_buffer, Slock_buffer, | |
335c5470 PJ |
681 | 0, 1, 0, |
682 | doc: /* Lock FILE, if current buffer is modified. | |
683 | FILE defaults to current buffer's visited file, | |
684 | or else nothing is done if current buffer isn't visiting a file. */) | |
685 | (file) | |
e9319ef2 | 686 | Lisp_Object file; |
8489eb67 | 687 | { |
e9319ef2 EN |
688 | if (NILP (file)) |
689 | file = current_buffer->file_truename; | |
8489eb67 | 690 | else |
b7826503 | 691 | CHECK_STRING (file); |
6a140159 | 692 | if (SAVE_MODIFF < MODIFF |
e9319ef2 EN |
693 | && !NILP (file)) |
694 | lock_file (file); | |
8489eb67 RS |
695 | return Qnil; |
696 | } | |
697 | ||
698 | DEFUN ("unlock-buffer", Funlock_buffer, Sunlock_buffer, | |
335c5470 | 699 | 0, 0, 0, |
3bfb8921 RS |
700 | doc: /* Unlock the file visited in the current buffer. |
701 | If the buffer is not modified, this does nothing because the file | |
702 | should not be locked in that case. */) | |
335c5470 | 703 | () |
8489eb67 | 704 | { |
6a140159 | 705 | if (SAVE_MODIFF < MODIFF |
5757b805 RS |
706 | && STRINGP (current_buffer->file_truename)) |
707 | unlock_file (current_buffer->file_truename); | |
8489eb67 RS |
708 | return Qnil; |
709 | } | |
710 | ||
8489eb67 RS |
711 | /* Unlock the file visited in buffer BUFFER. */ |
712 | ||
d07e0802 | 713 | void |
8489eb67 RS |
714 | unlock_buffer (buffer) |
715 | struct buffer *buffer; | |
716 | { | |
6a140159 | 717 | if (BUF_SAVE_MODIFF (buffer) < BUF_MODIFF (buffer) |
5757b805 RS |
718 | && STRINGP (buffer->file_truename)) |
719 | unlock_file (buffer->file_truename); | |
8489eb67 RS |
720 | } |
721 | ||
8105cbf7 | 722 | DEFUN ("file-locked-p", Ffile_locked_p, Sfile_locked_p, 1, 1, 0, |
3bfb8921 RS |
723 | doc: /* Return a value indicating whether FILENAME is locked. |
724 | The value is nil if the FILENAME is not locked, | |
725 | t if it is locked by you, else a string saying which user has locked it. */) | |
335c5470 PJ |
726 | (filename) |
727 | Lisp_Object filename; | |
8489eb67 | 728 | { |
8dbbc384 | 729 | Lisp_Object ret; |
8489eb67 RS |
730 | register char *lfname; |
731 | int owner; | |
8dbbc384 | 732 | lock_info_type locker; |
8489eb67 | 733 | |
e9319ef2 | 734 | filename = Fexpand_file_name (filename, Qnil); |
8489eb67 | 735 | |
e9319ef2 | 736 | MAKE_LOCK_NAME (lfname, filename); |
8489eb67 | 737 | |
8dbbc384 | 738 | owner = current_lock_owner (&locker, lfname); |
8489eb67 | 739 | if (owner <= 0) |
8dbbc384 RS |
740 | ret = Qnil; |
741 | else if (owner == 2) | |
742 | ret = Qt; | |
743 | else | |
744 | ret = build_string (locker.user); | |
745 | ||
746 | if (owner > 0) | |
747 | FREE_LOCK_INFO (locker); | |
748 | ||
749 | return ret; | |
8489eb67 | 750 | } |
32676c08 JB |
751 | \f |
752 | /* Initialization functions. */ | |
753 | ||
a3fd58aa KH |
754 | void |
755 | init_filelock () | |
756 | { | |
757 | boot_time = 0; | |
b97771fc | 758 | boot_time_initialized = 0; |
a3fd58aa KH |
759 | } |
760 | ||
dfcf069d | 761 | void |
8489eb67 RS |
762 | syms_of_filelock () |
763 | { | |
5f8d6a10 | 764 | DEFVAR_LISP ("temporary-file-directory", &Vtemporary_file_directory, |
335c5470 | 765 | doc: /* The directory for writing temporary files. */); |
5f8d6a10 RS |
766 | Vtemporary_file_directory = Qnil; |
767 | ||
8489eb67 RS |
768 | defsubr (&Sunlock_buffer); |
769 | defsubr (&Slock_buffer); | |
770 | defsubr (&Sfile_locked_p); | |
771 | } | |
772 | ||
773 | #endif /* CLASH_DETECTION */ |