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]; | |
5f8d6a10 RS |
206 | tempname = Fexpand_file_name (build_string ("wtmp"), |
207 | Vtemporary_file_directory); | |
208 | tempname = Fmake_temp_name (tempname); | |
9177d978 RS |
209 | args[0] = Vshell_file_name; |
210 | args[1] = Qnil; | |
211 | args[2] = Qnil; | |
212 | args[3] = Qnil; | |
213 | args[4] = build_string ("-c"); | |
77e544a4 RS |
214 | sprintf (cmd_string, "gunzip < %s.%d.gz > %s", |
215 | WTMP_FILE, counter, XSTRING (tempname)->data); | |
9177d978 RS |
216 | args[5] = build_string (cmd_string); |
217 | Fcall_process (6, args); | |
218 | filename = tempname; | |
219 | delete_flag = 1; | |
220 | } | |
221 | } | |
222 | ||
223 | if (! NILP (filename)) | |
224 | { | |
b97771fc | 225 | get_boot_time_1 (XSTRING (filename)->data, 1); |
9177d978 RS |
226 | if (delete_flag) |
227 | unlink (XSTRING (filename)->data); | |
228 | } | |
229 | } | |
230 | ||
231 | return boot_time; | |
232 | #else | |
233 | return 0; | |
234 | #endif | |
235 | } | |
236 | ||
e9f22ced | 237 | #ifdef BOOT_TIME |
9177d978 RS |
238 | /* Try to get the boot time from wtmp file FILENAME. |
239 | This succeeds if that file contains a reboot record. | |
9177d978 | 240 | |
b97771fc RS |
241 | If FILENAME is zero, use the same file as before; |
242 | if no FILENAME has ever been specified, this is the utmp file. | |
243 | Use the newest reboot record if NEWEST is nonzero, | |
244 | the first reboot record otherwise. | |
245 | Ignore all reboot records on or before BOOT_TIME. | |
246 | Success is indicated by setting BOOT_TIME to a larger value. */ | |
247 | ||
2f2500ef | 248 | void |
b97771fc | 249 | get_boot_time_1 (filename, newest) |
9177d978 | 250 | char *filename; |
b97771fc | 251 | int newest; |
9177d978 RS |
252 | { |
253 | struct utmp ut, *utp; | |
77e544a4 RS |
254 | int desc; |
255 | ||
b97771fc RS |
256 | if (filename) |
257 | { | |
258 | /* On some versions of IRIX, opening a nonexistent file name | |
259 | is likely to crash in the utmp routines. */ | |
68c45bf0 | 260 | desc = emacs_open (filename, O_RDONLY, 0); |
b97771fc RS |
261 | if (desc < 0) |
262 | return; | |
263 | ||
68c45bf0 | 264 | emacs_close (desc); |
b97771fc RS |
265 | |
266 | utmpname (filename); | |
267 | } | |
9177d978 | 268 | |
c321b190 | 269 | setutent (); |
b97771fc | 270 | |
c321b190 RS |
271 | while (1) |
272 | { | |
273 | /* Find the next reboot record. */ | |
274 | ut.ut_type = BOOT_TIME; | |
275 | utp = getutid (&ut); | |
276 | if (! utp) | |
277 | break; | |
278 | /* Compare reboot times and use the newest one. */ | |
279 | if (utp->ut_time > boot_time) | |
b97771fc RS |
280 | { |
281 | boot_time = utp->ut_time; | |
282 | if (! newest) | |
283 | break; | |
284 | } | |
c321b190 RS |
285 | /* Advance on element in the file |
286 | so that getutid won't repeat the same one. */ | |
287 | utp = getutent (); | |
288 | if (! utp) | |
289 | break; | |
290 | } | |
15e88d21 | 291 | endutent (); |
15e88d21 | 292 | } |
e9f22ced | 293 | #endif /* BOOT_TIME */ |
15e88d21 | 294 | \f |
8dbbc384 | 295 | /* Here is the structure that stores information about a lock. */ |
32676c08 | 296 | |
8dbbc384 RS |
297 | typedef struct |
298 | { | |
299 | char *user; | |
300 | char *host; | |
9005cb4f | 301 | unsigned long pid; |
15e88d21 | 302 | time_t boot_time; |
8dbbc384 | 303 | } lock_info_type; |
32676c08 | 304 | |
49b6d120 RS |
305 | /* When we read the info back, we might need this much more, |
306 | enough for decimal representation plus null. */ | |
307 | #define LOCK_PID_MAX (4 * sizeof (unsigned long)) | |
32676c08 | 308 | |
8dbbc384 RS |
309 | /* Free the two dynamically-allocated pieces in PTR. */ |
310 | #define FREE_LOCK_INFO(i) do { xfree ((i).user); xfree ((i).host); } while (0) | |
e31fbc7a | 311 | |
e31fbc7a | 312 | |
8dbbc384 | 313 | /* Write the name of the lock file for FN into LFNAME. Length will be |
c1355e1f GM |
314 | that of FN plus two more for the leading `.#' plus 1 for the |
315 | trailing period plus one for the digit after it plus one for the | |
316 | null. */ | |
7b92975f | 317 | #define MAKE_LOCK_NAME(lock, file) \ |
c1355e1f | 318 | (lock = (char *) alloca (STRING_BYTES (XSTRING (file)) + 2 + 1 + 1 + 1), \ |
8dbbc384 | 319 | fill_in_lock_file_name (lock, (file))) |
e31fbc7a | 320 | |
8dbbc384 RS |
321 | static void |
322 | fill_in_lock_file_name (lockfile, fn) | |
e31fbc7a RS |
323 | register char *lockfile; |
324 | register Lisp_Object fn; | |
325 | { | |
8dbbc384 | 326 | register char *p; |
c1355e1f GM |
327 | struct stat st; |
328 | int count = 0; | |
8dbbc384 RS |
329 | |
330 | strcpy (lockfile, XSTRING (fn)->data); | |
331 | ||
332 | /* Shift the nondirectory part of the file name (including the null) | |
333 | right two characters. Here is one of the places where we'd have to | |
334 | do something to support 14-character-max file names. */ | |
335 | for (p = lockfile + strlen (lockfile); p != lockfile && *p != '/'; p--) | |
336 | p[2] = *p; | |
e31fbc7a | 337 | |
8dbbc384 RS |
338 | /* Insert the `.#'. */ |
339 | p[1] = '.'; | |
340 | p[2] = '#'; | |
c1355e1f GM |
341 | |
342 | p = p + strlen (p); | |
343 | ||
344 | while (lstat (lockfile, &st) == 0 && !S_ISLNK (st.st_mode)) | |
345 | { | |
346 | if (count > 9) | |
347 | { | |
348 | *p = '\0'; | |
349 | return; | |
350 | } | |
351 | sprintf (p, ".%d", count++); | |
352 | } | |
8dbbc384 | 353 | } |
e31fbc7a | 354 | |
8dbbc384 RS |
355 | /* Lock the lock file named LFNAME. |
356 | If FORCE is nonzero, we do so even if it is already locked. | |
357 | Return 1 if successful, 0 if not. */ | |
e31fbc7a | 358 | |
8dbbc384 RS |
359 | static int |
360 | lock_file_1 (lfname, force) | |
361 | char *lfname; | |
362 | int force; | |
363 | { | |
364 | register int err; | |
bd26d5a3 | 365 | time_t boot_time; |
662c2ef2 RS |
366 | char *user_name; |
367 | char *host_name; | |
368 | char *lock_info_str; | |
369 | ||
370 | if (STRINGP (Fuser_login_name (Qnil))) | |
266d7a00 | 371 | user_name = (char *)XSTRING (Fuser_login_name (Qnil))->data; |
662c2ef2 RS |
372 | else |
373 | user_name = ""; | |
374 | if (STRINGP (Fsystem_name ())) | |
266d7a00 | 375 | host_name = (char *)XSTRING (Fsystem_name ())->data; |
662c2ef2 RS |
376 | else |
377 | host_name = ""; | |
266d7a00 | 378 | lock_info_str = (char *)alloca (strlen (user_name) + strlen (host_name) |
15e88d21 | 379 | + LOCK_PID_MAX + 5); |
8dbbc384 | 380 | |
bd26d5a3 RS |
381 | boot_time = get_boot_time (); |
382 | if (boot_time) | |
383 | sprintf (lock_info_str, "%s@%s.%lu:%lu", user_name, host_name, | |
384 | (unsigned long) getpid (), (unsigned long) boot_time); | |
385 | else | |
386 | sprintf (lock_info_str, "%s@%s.%lu", user_name, host_name, | |
387 | (unsigned long) getpid ()); | |
8dbbc384 RS |
388 | |
389 | err = symlink (lock_info_str, lfname); | |
390 | if (errno == EEXIST && force) | |
e31fbc7a | 391 | { |
8dbbc384 RS |
392 | unlink (lfname); |
393 | err = symlink (lock_info_str, lfname); | |
e31fbc7a | 394 | } |
e31fbc7a | 395 | |
8dbbc384 RS |
396 | return err == 0; |
397 | } | |
e31fbc7a | 398 | |
9177d978 | 399 | /* Return 1 if times A and B are no more than one second apart. */ |
32676c08 | 400 | |
9177d978 RS |
401 | int |
402 | within_one_second (a, b) | |
403 | time_t a, b; | |
404 | { | |
405 | return (a - b >= -1 && a - b <= 1); | |
406 | } | |
8dbbc384 RS |
407 | \f |
408 | /* Return 0 if nobody owns the lock file LFNAME or the lock is obsolete, | |
409 | 1 if another process owns it (and set OWNER (if non-null) to info), | |
410 | 2 if the current process owns it, | |
411 | or -1 if something is wrong with the locking mechanism. */ | |
e31fbc7a | 412 | |
8dbbc384 RS |
413 | static int |
414 | current_lock_owner (owner, lfname) | |
415 | lock_info_type *owner; | |
416 | char *lfname; | |
32676c08 | 417 | { |
8dbbc384 RS |
418 | #ifndef index |
419 | extern char *rindex (), *index (); | |
420 | #endif | |
5f8d6a10 | 421 | int len, ret; |
8dbbc384 | 422 | int local_owner = 0; |
15e88d21 | 423 | char *at, *dot, *colon; |
8dbbc384 RS |
424 | char *lfinfo = 0; |
425 | int bufsize = 50; | |
426 | /* Read arbitrarily-long contents of symlink. Similar code in | |
427 | file-symlink-p in fileio.c. */ | |
428 | do | |
429 | { | |
430 | bufsize *= 2; | |
431 | lfinfo = (char *) xrealloc (lfinfo, bufsize); | |
432 | len = readlink (lfname, lfinfo, bufsize); | |
433 | } | |
434 | while (len >= bufsize); | |
435 | ||
436 | /* If nonexistent lock file, all is well; otherwise, got strange error. */ | |
437 | if (len == -1) | |
438 | { | |
439 | xfree (lfinfo); | |
440 | return errno == ENOENT ? 0 : -1; | |
441 | } | |
32676c08 | 442 | |
8dbbc384 RS |
443 | /* Link info exists, so `len' is its length. Null terminate. */ |
444 | lfinfo[len] = 0; | |
445 | ||
446 | /* Even if the caller doesn't want the owner info, we still have to | |
447 | read it to determine return value, so allocate it. */ | |
448 | if (!owner) | |
449 | { | |
3609a53b | 450 | owner = (lock_info_type *) alloca (sizeof (lock_info_type)); |
8dbbc384 RS |
451 | local_owner = 1; |
452 | } | |
453 | ||
15e88d21 | 454 | /* Parse USER@HOST.PID:BOOT_TIME. If can't parse, return -1. */ |
8dbbc384 RS |
455 | /* The USER is everything before the first @. */ |
456 | at = index (lfinfo, '@'); | |
457 | dot = rindex (lfinfo, '.'); | |
15e88d21 RS |
458 | if (!at || !dot) |
459 | { | |
460 | xfree (lfinfo); | |
461 | return -1; | |
462 | } | |
8dbbc384 RS |
463 | len = at - lfinfo; |
464 | owner->user = (char *) xmalloc (len + 1); | |
465 | strncpy (owner->user, lfinfo, len); | |
466 | owner->user[len] = 0; | |
467 | ||
15e88d21 | 468 | /* The PID is everything from the last `.' to the `:'. */ |
8dbbc384 | 469 | owner->pid = atoi (dot + 1); |
15e88d21 RS |
470 | colon = dot; |
471 | while (*colon && *colon != ':') | |
472 | colon++; | |
473 | /* After the `:', if there is one, comes the boot time. */ | |
474 | if (*colon == ':') | |
475 | owner->boot_time = atoi (colon + 1); | |
476 | else | |
477 | owner->boot_time = 0; | |
32676c08 | 478 | |
8dbbc384 RS |
479 | /* The host is everything in between. */ |
480 | len = dot - at - 1; | |
481 | owner->host = (char *) xmalloc (len + 1); | |
482 | strncpy (owner->host, at + 1, len); | |
483 | owner->host[len] = 0; | |
32676c08 | 484 | |
8dbbc384 RS |
485 | /* We're done looking at the link info. */ |
486 | xfree (lfinfo); | |
487 | ||
488 | /* On current host? */ | |
662c2ef2 RS |
489 | if (STRINGP (Fsystem_name ()) |
490 | && strcmp (owner->host, XSTRING (Fsystem_name ())->data) == 0) | |
32676c08 | 491 | { |
8dbbc384 RS |
492 | if (owner->pid == getpid ()) |
493 | ret = 2; /* We own it. */ | |
72dcef0e | 494 | else if (owner->pid > 0 |
15e88d21 RS |
495 | && (kill (owner->pid, 0) >= 0 || errno == EPERM) |
496 | && (owner->boot_time == 0 | |
9177d978 | 497 | || within_one_second (owner->boot_time, get_boot_time ()))) |
8dbbc384 | 498 | ret = 1; /* An existing process on this machine owns it. */ |
8dbbc384 RS |
499 | /* The owner process is dead or has a strange pid (<=0), so try to |
500 | zap the lockfile. */ | |
72dcef0e | 501 | else if (unlink (lfname) < 0) |
8dbbc384 | 502 | ret = -1; |
72dcef0e RS |
503 | else |
504 | ret = 0; | |
32676c08 | 505 | } |
8dbbc384 RS |
506 | else |
507 | { /* If we wanted to support the check for stale locks on remote machines, | |
508 | here's where we'd do it. */ | |
509 | ret = 1; | |
510 | } | |
511 | ||
512 | /* Avoid garbage. */ | |
513 | if (local_owner || ret <= 0) | |
514 | { | |
515 | FREE_LOCK_INFO (*owner); | |
516 | } | |
517 | return ret; | |
32676c08 JB |
518 | } |
519 | ||
8dbbc384 RS |
520 | \f |
521 | /* Lock the lock named LFNAME if possible. | |
522 | Return 0 in that case. | |
523 | Return positive if some other process owns the lock, and info about | |
524 | that process in CLASHER. | |
525 | Return -1 if cannot lock for any other reason. */ | |
8489eb67 | 526 | |
8dbbc384 RS |
527 | static int |
528 | lock_if_free (clasher, lfname) | |
529 | lock_info_type *clasher; | |
530 | register char *lfname; | |
531 | { | |
cfc01fa7 | 532 | while (lock_file_1 (lfname, 0) == 0) |
8dbbc384 RS |
533 | { |
534 | int locker; | |
e0e0205b | 535 | |
8dbbc384 RS |
536 | if (errno != EEXIST) |
537 | return -1; | |
538 | ||
539 | locker = current_lock_owner (clasher, lfname); | |
540 | if (locker == 2) | |
541 | { | |
542 | FREE_LOCK_INFO (*clasher); | |
543 | return 0; /* We ourselves locked it. */ | |
544 | } | |
545 | else if (locker == 1) | |
546 | return 1; /* Someone else has it. */ | |
5df0b2fa | 547 | else if (locker == -1) |
ae1ef097 | 548 | return -1; /* current_lock_owner returned strange error. */ |
8dbbc384 | 549 | |
cfc01fa7 | 550 | /* We deleted a stale lock; try again to lock the file. */ |
8dbbc384 RS |
551 | } |
552 | return 0; | |
8489eb67 RS |
553 | } |
554 | ||
8dbbc384 | 555 | /* lock_file locks file FN, |
8489eb67 RS |
556 | meaning it serves notice on the world that you intend to edit that file. |
557 | This should be done only when about to modify a file-visiting | |
558 | buffer previously unmodified. | |
8dbbc384 | 559 | Do not (normally) call this for a buffer already modified, |
8489eb67 RS |
560 | as either the file is already locked, or the user has already |
561 | decided to go ahead without locking. | |
562 | ||
8dbbc384 | 563 | When this returns, either the lock is locked for us, |
8489eb67 RS |
564 | or the user has said to go ahead without locking. |
565 | ||
8dbbc384 | 566 | If the file is locked by someone else, this calls |
8489eb67 | 567 | ask-user-about-lock (a Lisp function) with two arguments, |
8dbbc384 | 568 | the file name and info about the user who did the locking. |
8489eb67 RS |
569 | This function can signal an error, or return t meaning |
570 | take away the lock, or return nil meaning ignore the lock. */ | |
571 | ||
8489eb67 RS |
572 | void |
573 | lock_file (fn) | |
eb4b1c05 | 574 | Lisp_Object fn; |
8489eb67 | 575 | { |
f4a4528d | 576 | register Lisp_Object attack, orig_fn, encoded_fn; |
8dbbc384 RS |
577 | register char *lfname, *locker; |
578 | lock_info_type lock_info; | |
3edc33a4 | 579 | struct gcpro gcpro1; |
8489eb67 | 580 | |
33bae690 RS |
581 | /* Don't do locking while dumping Emacs. |
582 | Uncompressing wtmp files uses call-process, which does not work | |
583 | in an uninitialized Emacs. */ | |
584 | if (! NILP (Vpurify_flag)) | |
585 | return; | |
586 | ||
5383bc6d | 587 | orig_fn = fn; |
8af8a9ca | 588 | GCPRO1 (fn); |
1e89de84 | 589 | fn = Fexpand_file_name (fn, Qnil); |
f4a4528d | 590 | encoded_fn = ENCODE_FILE (fn); |
1e89de84 | 591 | |
8dbbc384 | 592 | /* Create the name of the lock-file for file fn */ |
f4a4528d | 593 | MAKE_LOCK_NAME (lfname, encoded_fn); |
8489eb67 | 594 | |
32676c08 JB |
595 | /* See if this file is visited and has changed on disk since it was |
596 | visited. */ | |
8489eb67 | 597 | { |
a57bc488 | 598 | register Lisp_Object subject_buf; |
3036594f | 599 | |
5383bc6d | 600 | subject_buf = get_truename_buffer (orig_fn); |
3036594f | 601 | |
265a9e55 JB |
602 | if (!NILP (subject_buf) |
603 | && NILP (Fverify_visited_file_modtime (subject_buf)) | |
604 | && !NILP (Ffile_exists_p (fn))) | |
8489eb67 | 605 | call1 (intern ("ask-user-about-supersession-threat"), fn); |
3036594f | 606 | |
8489eb67 | 607 | } |
8af8a9ca | 608 | UNGCPRO; |
8489eb67 RS |
609 | |
610 | /* Try to lock the lock. */ | |
8dbbc384 RS |
611 | if (lock_if_free (&lock_info, lfname) <= 0) |
612 | /* Return now if we have locked it, or if lock creation failed */ | |
8489eb67 RS |
613 | return; |
614 | ||
615 | /* Else consider breaking the lock */ | |
266d7a00 RS |
616 | locker = (char *) alloca (strlen (lock_info.user) + strlen (lock_info.host) |
617 | + LOCK_PID_MAX + 9); | |
79e51eeb | 618 | sprintf (locker, "%s@%s (pid %lu)", lock_info.user, lock_info.host, |
8dbbc384 RS |
619 | lock_info.pid); |
620 | FREE_LOCK_INFO (lock_info); | |
621 | ||
622 | attack = call2 (intern ("ask-user-about-lock"), fn, build_string (locker)); | |
265a9e55 | 623 | if (!NILP (attack)) |
8489eb67 RS |
624 | /* User says take the lock */ |
625 | { | |
8dbbc384 | 626 | lock_file_1 (lfname, 1); |
8489eb67 RS |
627 | return; |
628 | } | |
629 | /* User says ignore the lock */ | |
630 | } | |
631 | ||
8489eb67 RS |
632 | void |
633 | unlock_file (fn) | |
634 | register Lisp_Object fn; | |
635 | { | |
636 | register char *lfname; | |
637 | ||
1e89de84 | 638 | fn = Fexpand_file_name (fn, Qnil); |
88eace34 | 639 | fn = ENCODE_FILE (fn); |
1e89de84 | 640 | |
7b92975f | 641 | MAKE_LOCK_NAME (lfname, fn); |
8489eb67 | 642 | |
8dbbc384 | 643 | if (current_lock_owner (0, lfname) == 2) |
8489eb67 | 644 | unlink (lfname); |
8489eb67 RS |
645 | } |
646 | ||
647 | void | |
648 | unlock_all_files () | |
649 | { | |
650 | register Lisp_Object tail; | |
651 | register struct buffer *b; | |
652 | ||
03699b14 | 653 | for (tail = Vbuffer_alist; GC_CONSP (tail); tail = XCDR (tail)) |
8489eb67 | 654 | { |
03699b14 | 655 | b = XBUFFER (XCDR (XCAR (tail))); |
5757b805 | 656 | if (STRINGP (b->file_truename) && BUF_SAVE_MODIFF (b) < BUF_MODIFF (b)) |
1c343051 KH |
657 | { |
658 | register char *lfname; | |
659 | ||
660 | MAKE_LOCK_NAME (lfname, b->file_truename); | |
661 | ||
662 | if (current_lock_owner (0, lfname) == 2) | |
663 | unlink (lfname); | |
664 | } | |
8489eb67 RS |
665 | } |
666 | } | |
8489eb67 RS |
667 | \f |
668 | DEFUN ("lock-buffer", Flock_buffer, Slock_buffer, | |
669 | 0, 1, 0, | |
670 | "Lock FILE, if current buffer is modified.\n\ | |
671 | FILE defaults to current buffer's visited file,\n\ | |
672 | or else nothing is done if current buffer isn't visiting a file.") | |
e9319ef2 EN |
673 | (file) |
674 | Lisp_Object file; | |
8489eb67 | 675 | { |
e9319ef2 EN |
676 | if (NILP (file)) |
677 | file = current_buffer->file_truename; | |
8489eb67 | 678 | else |
e9319ef2 | 679 | CHECK_STRING (file, 0); |
6a140159 | 680 | if (SAVE_MODIFF < MODIFF |
e9319ef2 EN |
681 | && !NILP (file)) |
682 | lock_file (file); | |
8489eb67 RS |
683 | return Qnil; |
684 | } | |
685 | ||
686 | DEFUN ("unlock-buffer", Funlock_buffer, Sunlock_buffer, | |
687 | 0, 0, 0, | |
688 | "Unlock the file visited in the current buffer,\n\ | |
689 | if it should normally be locked.") | |
690 | () | |
691 | { | |
6a140159 | 692 | if (SAVE_MODIFF < MODIFF |
5757b805 RS |
693 | && STRINGP (current_buffer->file_truename)) |
694 | unlock_file (current_buffer->file_truename); | |
8489eb67 RS |
695 | return Qnil; |
696 | } | |
697 | ||
8489eb67 RS |
698 | /* Unlock the file visited in buffer BUFFER. */ |
699 | ||
d07e0802 | 700 | void |
8489eb67 RS |
701 | unlock_buffer (buffer) |
702 | struct buffer *buffer; | |
703 | { | |
6a140159 | 704 | if (BUF_SAVE_MODIFF (buffer) < BUF_MODIFF (buffer) |
5757b805 RS |
705 | && STRINGP (buffer->file_truename)) |
706 | unlock_file (buffer->file_truename); | |
8489eb67 RS |
707 | } |
708 | ||
8105cbf7 | 709 | DEFUN ("file-locked-p", Ffile_locked_p, Sfile_locked_p, 1, 1, 0, |
8489eb67 RS |
710 | "Return nil if the FILENAME is not locked,\n\ |
711 | t if it is locked by you, else a string of the name of the locker.") | |
e9319ef2 EN |
712 | (filename) |
713 | Lisp_Object filename; | |
8489eb67 | 714 | { |
8dbbc384 | 715 | Lisp_Object ret; |
8489eb67 RS |
716 | register char *lfname; |
717 | int owner; | |
8dbbc384 | 718 | lock_info_type locker; |
8489eb67 | 719 | |
e9319ef2 | 720 | filename = Fexpand_file_name (filename, Qnil); |
8489eb67 | 721 | |
e9319ef2 | 722 | MAKE_LOCK_NAME (lfname, filename); |
8489eb67 | 723 | |
8dbbc384 | 724 | owner = current_lock_owner (&locker, lfname); |
8489eb67 | 725 | if (owner <= 0) |
8dbbc384 RS |
726 | ret = Qnil; |
727 | else if (owner == 2) | |
728 | ret = Qt; | |
729 | else | |
730 | ret = build_string (locker.user); | |
731 | ||
732 | if (owner > 0) | |
733 | FREE_LOCK_INFO (locker); | |
734 | ||
735 | return ret; | |
8489eb67 | 736 | } |
32676c08 JB |
737 | \f |
738 | /* Initialization functions. */ | |
739 | ||
a3fd58aa KH |
740 | void |
741 | init_filelock () | |
742 | { | |
743 | boot_time = 0; | |
b97771fc | 744 | boot_time_initialized = 0; |
a3fd58aa KH |
745 | } |
746 | ||
dfcf069d | 747 | void |
8489eb67 RS |
748 | syms_of_filelock () |
749 | { | |
5f8d6a10 RS |
750 | DEFVAR_LISP ("temporary-file-directory", &Vtemporary_file_directory, |
751 | "The directory for writing temporary files."); | |
752 | Vtemporary_file_directory = Qnil; | |
753 | ||
8489eb67 RS |
754 | defsubr (&Sunlock_buffer); |
755 | defsubr (&Slock_buffer); | |
756 | defsubr (&Sfile_locked_p); | |
757 | } | |
758 | ||
759 | #endif /* CLASH_DETECTION */ |