Commit | Line | Data |
---|---|---|
b97771fc | 1 | /* Lock files for editing. |
0b5538bd | 2 | Copyright (C) 1985, 1986, 1987, 1993, 1994, 1996, 1998, 1999, 2000, 2001, |
114f9c96 | 3 | 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010 |
8cabe764 | 4 | Free Software Foundation, Inc. |
8489eb67 RS |
5 | |
6 | This file is part of GNU Emacs. | |
7 | ||
9ec0b715 | 8 | GNU Emacs is free software: you can redistribute it and/or modify |
8489eb67 | 9 | it under the terms of the GNU General Public License as published by |
9ec0b715 GM |
10 | the Free Software Foundation, either version 3 of the License, or |
11 | (at your option) any later version. | |
8489eb67 RS |
12 | |
13 | GNU Emacs is distributed in the hope that it will be useful, | |
14 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
16 | GNU General Public License for more details. | |
17 | ||
18 | You should have received a copy of the GNU General Public License | |
9ec0b715 | 19 | along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>. */ |
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> |
d7306fe6 | 27 | #include <setjmp.h> |
bfb61299 | 28 | |
5b9c0a1d | 29 | #ifdef HAVE_PWD_H |
8489eb67 | 30 | #include <pwd.h> |
5b9c0a1d | 31 | #endif |
bfb61299 | 32 | |
8489eb67 | 33 | #include <sys/file.h> |
e5ef3cdf | 34 | #ifdef HAVE_FCNTL_H |
8489eb67 | 35 | #include <fcntl.h> |
e5ef3cdf | 36 | #endif |
8dbbc384 | 37 | #include <string.h> |
8489eb67 | 38 | |
dfcf069d AS |
39 | #ifdef HAVE_UNISTD_H |
40 | #include <unistd.h> | |
41 | #endif | |
42 | ||
f805a125 | 43 | #ifdef __FreeBSD__ |
f805a125 KH |
44 | #include <sys/sysctl.h> |
45 | #endif /* __FreeBSD__ */ | |
46 | ||
e5ef3cdf | 47 | #include <errno.h> |
e5ef3cdf | 48 | |
8489eb67 | 49 | #include "lisp.h" |
8489eb67 | 50 | #include "buffer.h" |
d2f6dae8 | 51 | #include "character.h" |
f4a4528d | 52 | #include "coding.h" |
9177d978 | 53 | #include "systime.h" |
8489eb67 | 54 | |
5f8d6a10 RS |
55 | /* The directory for writing temporary files. */ |
56 | ||
57 | Lisp_Object Vtemporary_file_directory; | |
58 | ||
8489eb67 | 59 | #ifdef CLASH_DETECTION |
e788eecc | 60 | |
c6d09b8d | 61 | #ifdef HAVE_UTMP_H |
e788eecc | 62 | #include <utmp.h> |
c6d09b8d | 63 | #endif |
77e544a4 | 64 | |
fa5c314d RS |
65 | #if !defined (S_ISLNK) && defined (S_IFLNK) |
66 | #define S_ISLNK(m) (((m) & S_IFMT) == S_IFLNK) | |
67 | #endif | |
68 | ||
a48de9b2 PE |
69 | /* A file whose last-modified time is just after the most recent boot. |
70 | Define this to be NULL to disable checking for this file. */ | |
71 | #ifndef BOOT_TIME_FILE | |
72 | #define BOOT_TIME_FILE "/var/run/random-seed" | |
73 | #endif | |
74 | ||
77e544a4 RS |
75 | #ifndef WTMP_FILE |
76 | #define WTMP_FILE "/var/log/wtmp" | |
77 | #endif | |
177c0ea7 | 78 | |
8dbbc384 RS |
79 | /* The strategy: to lock a file FN, create a symlink .#FN in FN's |
80 | directory, with link data `user@host.pid'. This avoids a single | |
81 | mount (== failure) point for lock files. | |
82 | ||
83 | When the host in the lock data is the current host, we can check if | |
84 | the pid is valid with kill. | |
177c0ea7 | 85 | |
8dbbc384 RS |
86 | Otherwise, we could look at a separate file that maps hostnames to |
87 | reboot times to see if the remote pid can possibly be valid, since we | |
88 | don't want Emacs to have to communicate via pipes or sockets or | |
89 | whatever to other processes, either locally or remotely; rms says | |
90 | that's too unreliable. Hence the separate file, which could | |
91 | theoretically be updated by daemons running separately -- but this | |
92 | whole idea is unimplemented; in practice, at least in our | |
1c4f857c | 93 | environment, it seems such stale locks arise fairly infrequently, and |
8dbbc384 RS |
94 | Emacs' standard methods of dealing with clashes suffice. |
95 | ||
96 | We use symlinks instead of normal files because (1) they can be | |
97 | stored more efficiently on the filesystem, since the kernel knows | |
98 | they will be small, and (2) all the info about the lock can be read | |
99 | in a single system call (readlink). Although we could use regular | |
1c4f857c | 100 | files to be useful on old systems lacking symlinks, nowadays |
8dbbc384 RS |
101 | virtually all such systems are probably single-user anyway, so it |
102 | didn't seem worth the complication. | |
177c0ea7 | 103 | |
8dbbc384 RS |
104 | Similarly, we don't worry about a possible 14-character limit on |
105 | file names, because those are all the same systems that don't have | |
106 | symlinks. | |
177c0ea7 | 107 | |
8dbbc384 RS |
108 | This is compatible with the locking scheme used by Interleaf (which |
109 | has contributed this implementation for Emacs), and was designed by | |
110 | Ethan Jacobson, Kimbo Mundy, and others. | |
177c0ea7 | 111 | |
8dbbc384 | 112 | --karl@cs.umb.edu/karl@hq.ileaf.com. */ |
8489eb67 | 113 | |
8dbbc384 | 114 | \f |
15e88d21 RS |
115 | /* Return the time of the last system boot. */ |
116 | ||
117 | static time_t boot_time; | |
b97771fc | 118 | static int boot_time_initialized; |
15e88d21 | 119 | |
2f2500ef | 120 | #ifdef BOOT_TIME |
f57e2426 | 121 | static void get_boot_time_1 (char *, int); |
2f2500ef DL |
122 | #endif |
123 | ||
15e88d21 | 124 | static time_t |
971de7fb | 125 | get_boot_time (void) |
15e88d21 | 126 | { |
9d2818d6 | 127 | #if defined (BOOT_TIME) |
9177d978 | 128 | int counter; |
2decc5a9 | 129 | #endif |
15e88d21 | 130 | |
b97771fc | 131 | if (boot_time_initialized) |
15e88d21 | 132 | return boot_time; |
b97771fc | 133 | boot_time_initialized = 1; |
15e88d21 | 134 | |
f805a125 KH |
135 | #if defined (CTL_KERN) && defined (KERN_BOOTTIME) |
136 | { | |
137 | int mib[2]; | |
138 | size_t size; | |
139 | struct timeval boottime_val; | |
140 | ||
141 | mib[0] = CTL_KERN; | |
142 | mib[1] = KERN_BOOTTIME; | |
143 | size = sizeof (boottime_val); | |
144 | ||
145 | if (sysctl (mib, 2, &boottime_val, &size, NULL, 0) >= 0) | |
146 | { | |
147 | boot_time = boottime_val.tv_sec; | |
148 | return boot_time; | |
149 | } | |
150 | } | |
151 | #endif /* defined (CTL_KERN) && defined (KERN_BOOTTIME) */ | |
9177d978 | 152 | |
a48de9b2 PE |
153 | if (BOOT_TIME_FILE) |
154 | { | |
155 | struct stat st; | |
156 | if (stat (BOOT_TIME_FILE, &st) == 0) | |
157 | { | |
158 | boot_time = st.st_mtime; | |
159 | return boot_time; | |
160 | } | |
161 | } | |
162 | ||
9d2818d6 | 163 | #if defined (BOOT_TIME) |
b97771fc RS |
164 | #ifndef CANNOT_DUMP |
165 | /* The utmp routines maintain static state. | |
166 | Don't touch that state unless we are initialized, | |
167 | since it might not survive dumping. */ | |
168 | if (! initialized) | |
169 | return boot_time; | |
170 | #endif /* not CANNOT_DUMP */ | |
171 | ||
172 | /* Try to get boot time from utmp before wtmp, | |
173 | since utmp is typically much smaller than wtmp. | |
174 | Passing a null pointer causes get_boot_time_1 | |
175 | to inspect the default file, namely utmp. */ | |
176 | get_boot_time_1 ((char *) 0, 0); | |
177 | if (boot_time) | |
178 | return boot_time; | |
179 | ||
9177d978 | 180 | /* Try to get boot time from the current wtmp file. */ |
b97771fc | 181 | get_boot_time_1 (WTMP_FILE, 1); |
9177d978 RS |
182 | |
183 | /* If we did not find a boot time in wtmp, look at wtmp, and so on. */ | |
b97771fc | 184 | for (counter = 0; counter < 20 && ! boot_time; counter++) |
9177d978 RS |
185 | { |
186 | char cmd_string[100]; | |
187 | Lisp_Object tempname, filename; | |
188 | int delete_flag = 0; | |
189 | ||
190 | filename = Qnil; | |
191 | ||
77e544a4 | 192 | sprintf (cmd_string, "%s.%d", WTMP_FILE, counter); |
9177d978 | 193 | tempname = build_string (cmd_string); |
29a2adb0 | 194 | if (! NILP (Ffile_exists_p (tempname))) |
9177d978 RS |
195 | filename = tempname; |
196 | else | |
197 | { | |
77e544a4 | 198 | sprintf (cmd_string, "%s.%d.gz", WTMP_FILE, counter); |
9177d978 RS |
199 | tempname = build_string (cmd_string); |
200 | if (! NILP (Ffile_exists_p (tempname))) | |
201 | { | |
202 | Lisp_Object args[6]; | |
f1d367aa GM |
203 | |
204 | /* The utmp functions on mescaline.gnu.org accept only | |
205 | file names up to 8 characters long. Choose a 2 | |
206 | character long prefix, and call make_temp_file with | |
207 | second arg non-zero, so that it will add not more | |
208 | than 6 characters to the prefix. */ | |
209 | tempname = Fexpand_file_name (build_string ("wt"), | |
5f8d6a10 | 210 | Vtemporary_file_directory); |
f1d367aa | 211 | tempname = make_temp_name (tempname, 1); |
9177d978 RS |
212 | args[0] = Vshell_file_name; |
213 | args[1] = Qnil; | |
214 | args[2] = Qnil; | |
215 | args[3] = Qnil; | |
216 | args[4] = build_string ("-c"); | |
77e544a4 | 217 | sprintf (cmd_string, "gunzip < %s.%d.gz > %s", |
d5db4077 | 218 | WTMP_FILE, counter, SDATA (tempname)); |
9177d978 RS |
219 | args[5] = build_string (cmd_string); |
220 | Fcall_process (6, args); | |
221 | filename = tempname; | |
222 | delete_flag = 1; | |
223 | } | |
224 | } | |
225 | ||
226 | if (! NILP (filename)) | |
227 | { | |
d5db4077 | 228 | get_boot_time_1 (SDATA (filename), 1); |
9177d978 | 229 | if (delete_flag) |
d5db4077 | 230 | unlink (SDATA (filename)); |
9177d978 RS |
231 | } |
232 | } | |
233 | ||
234 | return boot_time; | |
235 | #else | |
236 | return 0; | |
237 | #endif | |
238 | } | |
239 | ||
e9f22ced | 240 | #ifdef BOOT_TIME |
9177d978 RS |
241 | /* Try to get the boot time from wtmp file FILENAME. |
242 | This succeeds if that file contains a reboot record. | |
9177d978 | 243 | |
b97771fc RS |
244 | If FILENAME is zero, use the same file as before; |
245 | if no FILENAME has ever been specified, this is the utmp file. | |
246 | Use the newest reboot record if NEWEST is nonzero, | |
247 | the first reboot record otherwise. | |
248 | Ignore all reboot records on or before BOOT_TIME. | |
249 | Success is indicated by setting BOOT_TIME to a larger value. */ | |
250 | ||
2f2500ef | 251 | void |
971de7fb | 252 | get_boot_time_1 (char *filename, int newest) |
9177d978 RS |
253 | { |
254 | struct utmp ut, *utp; | |
77e544a4 RS |
255 | int desc; |
256 | ||
b97771fc RS |
257 | if (filename) |
258 | { | |
259 | /* On some versions of IRIX, opening a nonexistent file name | |
260 | is likely to crash in the utmp routines. */ | |
68c45bf0 | 261 | desc = emacs_open (filename, O_RDONLY, 0); |
b97771fc RS |
262 | if (desc < 0) |
263 | return; | |
264 | ||
68c45bf0 | 265 | emacs_close (desc); |
b97771fc RS |
266 | |
267 | utmpname (filename); | |
268 | } | |
9177d978 | 269 | |
c321b190 | 270 | setutent (); |
b97771fc | 271 | |
c321b190 RS |
272 | while (1) |
273 | { | |
274 | /* Find the next reboot record. */ | |
275 | ut.ut_type = BOOT_TIME; | |
276 | utp = getutid (&ut); | |
277 | if (! utp) | |
278 | break; | |
279 | /* Compare reboot times and use the newest one. */ | |
280 | if (utp->ut_time > boot_time) | |
b97771fc RS |
281 | { |
282 | boot_time = utp->ut_time; | |
283 | if (! newest) | |
284 | break; | |
285 | } | |
c321b190 RS |
286 | /* Advance on element in the file |
287 | so that getutid won't repeat the same one. */ | |
288 | utp = getutent (); | |
289 | if (! utp) | |
290 | break; | |
291 | } | |
15e88d21 | 292 | endutent (); |
15e88d21 | 293 | } |
e9f22ced | 294 | #endif /* BOOT_TIME */ |
15e88d21 | 295 | \f |
8dbbc384 | 296 | /* Here is the structure that stores information about a lock. */ |
32676c08 | 297 | |
8dbbc384 RS |
298 | typedef struct |
299 | { | |
300 | char *user; | |
301 | char *host; | |
9005cb4f | 302 | unsigned long pid; |
15e88d21 | 303 | time_t boot_time; |
8dbbc384 | 304 | } lock_info_type; |
32676c08 | 305 | |
49b6d120 RS |
306 | /* When we read the info back, we might need this much more, |
307 | enough for decimal representation plus null. */ | |
308 | #define LOCK_PID_MAX (4 * sizeof (unsigned long)) | |
32676c08 | 309 | |
8dbbc384 RS |
310 | /* Free the two dynamically-allocated pieces in PTR. */ |
311 | #define FREE_LOCK_INFO(i) do { xfree ((i).user); xfree ((i).host); } while (0) | |
e31fbc7a | 312 | |
e31fbc7a | 313 | |
8dbbc384 | 314 | /* Write the name of the lock file for FN into LFNAME. Length will be |
c1355e1f GM |
315 | that of FN plus two more for the leading `.#' plus 1 for the |
316 | trailing period plus one for the digit after it plus one for the | |
317 | null. */ | |
7b92975f | 318 | #define MAKE_LOCK_NAME(lock, file) \ |
d5db4077 | 319 | (lock = (char *) alloca (SBYTES (file) + 2 + 1 + 1 + 1), \ |
8dbbc384 | 320 | fill_in_lock_file_name (lock, (file))) |
e31fbc7a | 321 | |
8dbbc384 | 322 | static void |
971de7fb | 323 | fill_in_lock_file_name (register char *lockfile, register Lisp_Object fn) |
e31fbc7a | 324 | { |
8dbbc384 | 325 | register char *p; |
c1355e1f GM |
326 | struct stat st; |
327 | int count = 0; | |
8dbbc384 | 328 | |
d5db4077 | 329 | strcpy (lockfile, SDATA (fn)); |
8dbbc384 RS |
330 | |
331 | /* Shift the nondirectory part of the file name (including the null) | |
332 | right two characters. Here is one of the places where we'd have to | |
333 | do something to support 14-character-max file names. */ | |
334 | for (p = lockfile + strlen (lockfile); p != lockfile && *p != '/'; p--) | |
335 | p[2] = *p; | |
177c0ea7 | 336 | |
8dbbc384 RS |
337 | /* Insert the `.#'. */ |
338 | p[1] = '.'; | |
339 | p[2] = '#'; | |
c1355e1f GM |
340 | |
341 | p = p + strlen (p); | |
342 | ||
343 | while (lstat (lockfile, &st) == 0 && !S_ISLNK (st.st_mode)) | |
344 | { | |
345 | if (count > 9) | |
346 | { | |
347 | *p = '\0'; | |
348 | return; | |
349 | } | |
350 | sprintf (p, ".%d", count++); | |
351 | } | |
8dbbc384 | 352 | } |
e31fbc7a | 353 | |
8dbbc384 RS |
354 | /* Lock the lock file named LFNAME. |
355 | If FORCE is nonzero, we do so even if it is already locked. | |
356 | Return 1 if successful, 0 if not. */ | |
e31fbc7a | 357 | |
8dbbc384 | 358 | static int |
971de7fb | 359 | lock_file_1 (char *lfname, int force) |
8dbbc384 RS |
360 | { |
361 | register int err; | |
bd26d5a3 | 362 | time_t boot_time; |
662c2ef2 RS |
363 | char *user_name; |
364 | char *host_name; | |
365 | char *lock_info_str; | |
366 | ||
4ba93ac0 AS |
367 | /* Call this first because it can GC. */ |
368 | boot_time = get_boot_time (); | |
369 | ||
662c2ef2 | 370 | if (STRINGP (Fuser_login_name (Qnil))) |
d5db4077 | 371 | user_name = (char *)SDATA (Fuser_login_name (Qnil)); |
662c2ef2 RS |
372 | else |
373 | user_name = ""; | |
374 | if (STRINGP (Fsystem_name ())) | |
d5db4077 | 375 | host_name = (char *)SDATA (Fsystem_name ()); |
662c2ef2 RS |
376 | else |
377 | host_name = ""; | |
266d7a00 | 378 | lock_info_str = (char *)alloca (strlen (user_name) + strlen (host_name) |
4ba93ac0 | 379 | + LOCK_PID_MAX + 30); |
8dbbc384 | 380 | |
bd26d5a3 RS |
381 | if (boot_time) |
382 | sprintf (lock_info_str, "%s@%s.%lu:%lu", user_name, host_name, | |
383 | (unsigned long) getpid (), (unsigned long) boot_time); | |
384 | else | |
385 | sprintf (lock_info_str, "%s@%s.%lu", user_name, host_name, | |
177c0ea7 | 386 | (unsigned long) getpid ()); |
8dbbc384 RS |
387 | |
388 | err = symlink (lock_info_str, lfname); | |
389 | if (errno == EEXIST && force) | |
e31fbc7a | 390 | { |
8dbbc384 RS |
391 | unlink (lfname); |
392 | err = symlink (lock_info_str, lfname); | |
e31fbc7a | 393 | } |
e31fbc7a | 394 | |
8dbbc384 RS |
395 | return err == 0; |
396 | } | |
e31fbc7a | 397 | |
9177d978 | 398 | /* Return 1 if times A and B are no more than one second apart. */ |
32676c08 | 399 | |
9177d978 | 400 | int |
971de7fb | 401 | within_one_second (time_t a, time_t b) |
9177d978 RS |
402 | { |
403 | return (a - b >= -1 && a - b <= 1); | |
404 | } | |
8dbbc384 RS |
405 | \f |
406 | /* Return 0 if nobody owns the lock file LFNAME or the lock is obsolete, | |
407 | 1 if another process owns it (and set OWNER (if non-null) to info), | |
408 | 2 if the current process owns it, | |
409 | or -1 if something is wrong with the locking mechanism. */ | |
e31fbc7a | 410 | |
8dbbc384 | 411 | static int |
971de7fb | 412 | current_lock_owner (lock_info_type *owner, char *lfname) |
32676c08 | 413 | { |
5f8d6a10 | 414 | int len, ret; |
8dbbc384 | 415 | int local_owner = 0; |
15e88d21 | 416 | char *at, *dot, *colon; |
8dbbc384 RS |
417 | char *lfinfo = 0; |
418 | int bufsize = 50; | |
419 | /* Read arbitrarily-long contents of symlink. Similar code in | |
420 | file-symlink-p in fileio.c. */ | |
421 | do | |
422 | { | |
423 | bufsize *= 2; | |
424 | lfinfo = (char *) xrealloc (lfinfo, bufsize); | |
620c4704 | 425 | errno = 0; |
8dbbc384 | 426 | len = readlink (lfname, lfinfo, bufsize); |
b6e97b0a GM |
427 | #ifdef ERANGE |
428 | /* HP-UX reports ERANGE if the buffer is too small. */ | |
429 | if (len == -1 && errno == ERANGE) | |
63680feb | 430 | len = bufsize; |
b6e97b0a | 431 | #endif |
8dbbc384 RS |
432 | } |
433 | while (len >= bufsize); | |
177c0ea7 | 434 | |
8dbbc384 RS |
435 | /* If nonexistent lock file, all is well; otherwise, got strange error. */ |
436 | if (len == -1) | |
437 | { | |
438 | xfree (lfinfo); | |
439 | return errno == ENOENT ? 0 : -1; | |
440 | } | |
32676c08 | 441 | |
8dbbc384 RS |
442 | /* Link info exists, so `len' is its length. Null terminate. */ |
443 | lfinfo[len] = 0; | |
177c0ea7 | 444 | |
8dbbc384 RS |
445 | /* Even if the caller doesn't want the owner info, we still have to |
446 | read it to determine return value, so allocate it. */ | |
447 | if (!owner) | |
448 | { | |
3609a53b | 449 | owner = (lock_info_type *) alloca (sizeof (lock_info_type)); |
8dbbc384 RS |
450 | local_owner = 1; |
451 | } | |
177c0ea7 | 452 | |
15e88d21 | 453 | /* Parse USER@HOST.PID:BOOT_TIME. If can't parse, return -1. */ |
50624218 | 454 | /* The USER is everything before the last @. */ |
8966b757 AS |
455 | at = strrchr (lfinfo, '@'); |
456 | dot = strrchr (lfinfo, '.'); | |
15e88d21 RS |
457 | if (!at || !dot) |
458 | { | |
459 | xfree (lfinfo); | |
460 | return -1; | |
461 | } | |
8dbbc384 RS |
462 | len = at - lfinfo; |
463 | owner->user = (char *) xmalloc (len + 1); | |
464 | strncpy (owner->user, lfinfo, len); | |
465 | owner->user[len] = 0; | |
177c0ea7 | 466 | |
15e88d21 | 467 | /* The PID is everything from the last `.' to the `:'. */ |
8dbbc384 | 468 | owner->pid = atoi (dot + 1); |
15e88d21 RS |
469 | colon = dot; |
470 | while (*colon && *colon != ':') | |
471 | colon++; | |
472 | /* After the `:', if there is one, comes the boot time. */ | |
473 | if (*colon == ':') | |
474 | owner->boot_time = atoi (colon + 1); | |
475 | else | |
476 | owner->boot_time = 0; | |
32676c08 | 477 | |
8dbbc384 RS |
478 | /* The host is everything in between. */ |
479 | len = dot - at - 1; | |
480 | owner->host = (char *) xmalloc (len + 1); | |
481 | strncpy (owner->host, at + 1, len); | |
482 | owner->host[len] = 0; | |
32676c08 | 483 | |
8dbbc384 RS |
484 | /* We're done looking at the link info. */ |
485 | xfree (lfinfo); | |
177c0ea7 | 486 | |
8dbbc384 | 487 | /* On current host? */ |
662c2ef2 | 488 | if (STRINGP (Fsystem_name ()) |
d5db4077 | 489 | && strcmp (owner->host, SDATA (Fsystem_name ())) == 0) |
32676c08 | 490 | { |
8dbbc384 RS |
491 | if (owner->pid == getpid ()) |
492 | ret = 2; /* We own it. */ | |
72dcef0e | 493 | else if (owner->pid > 0 |
15e88d21 RS |
494 | && (kill (owner->pid, 0) >= 0 || errno == EPERM) |
495 | && (owner->boot_time == 0 | |
9177d978 | 496 | || within_one_second (owner->boot_time, get_boot_time ()))) |
8dbbc384 | 497 | ret = 1; /* An existing process on this machine owns it. */ |
8dbbc384 RS |
498 | /* The owner process is dead or has a strange pid (<=0), so try to |
499 | zap the lockfile. */ | |
72dcef0e | 500 | else if (unlink (lfname) < 0) |
8dbbc384 | 501 | ret = -1; |
72dcef0e RS |
502 | else |
503 | ret = 0; | |
32676c08 | 504 | } |
8dbbc384 RS |
505 | else |
506 | { /* If we wanted to support the check for stale locks on remote machines, | |
507 | here's where we'd do it. */ | |
508 | ret = 1; | |
509 | } | |
177c0ea7 | 510 | |
8dbbc384 RS |
511 | /* Avoid garbage. */ |
512 | if (local_owner || ret <= 0) | |
513 | { | |
514 | FREE_LOCK_INFO (*owner); | |
515 | } | |
516 | return ret; | |
32676c08 JB |
517 | } |
518 | ||
8dbbc384 RS |
519 | \f |
520 | /* Lock the lock named LFNAME if possible. | |
521 | Return 0 in that case. | |
522 | Return positive if some other process owns the lock, and info about | |
523 | that process in CLASHER. | |
524 | Return -1 if cannot lock for any other reason. */ | |
8489eb67 | 525 | |
8dbbc384 | 526 | static int |
971de7fb | 527 | lock_if_free (lock_info_type *clasher, register char *lfname) |
8dbbc384 | 528 | { |
cfc01fa7 | 529 | while (lock_file_1 (lfname, 0) == 0) |
8dbbc384 RS |
530 | { |
531 | int locker; | |
e0e0205b | 532 | |
8dbbc384 RS |
533 | if (errno != EEXIST) |
534 | return -1; | |
177c0ea7 | 535 | |
8dbbc384 RS |
536 | locker = current_lock_owner (clasher, lfname); |
537 | if (locker == 2) | |
538 | { | |
539 | FREE_LOCK_INFO (*clasher); | |
540 | return 0; /* We ourselves locked it. */ | |
541 | } | |
542 | else if (locker == 1) | |
543 | return 1; /* Someone else has it. */ | |
5df0b2fa | 544 | else if (locker == -1) |
ae1ef097 | 545 | return -1; /* current_lock_owner returned strange error. */ |
8dbbc384 | 546 | |
cfc01fa7 | 547 | /* We deleted a stale lock; try again to lock the file. */ |
8dbbc384 RS |
548 | } |
549 | return 0; | |
8489eb67 RS |
550 | } |
551 | ||
8dbbc384 | 552 | /* lock_file locks file FN, |
8489eb67 RS |
553 | meaning it serves notice on the world that you intend to edit that file. |
554 | This should be done only when about to modify a file-visiting | |
555 | buffer previously unmodified. | |
8dbbc384 | 556 | Do not (normally) call this for a buffer already modified, |
8489eb67 RS |
557 | as either the file is already locked, or the user has already |
558 | decided to go ahead without locking. | |
559 | ||
8dbbc384 | 560 | When this returns, either the lock is locked for us, |
8489eb67 RS |
561 | or the user has said to go ahead without locking. |
562 | ||
8dbbc384 | 563 | If the file is locked by someone else, this calls |
8489eb67 | 564 | ask-user-about-lock (a Lisp function) with two arguments, |
8dbbc384 | 565 | the file name and info about the user who did the locking. |
8489eb67 RS |
566 | This function can signal an error, or return t meaning |
567 | take away the lock, or return nil meaning ignore the lock. */ | |
568 | ||
8489eb67 | 569 | void |
971de7fb | 570 | lock_file (Lisp_Object fn) |
8489eb67 | 571 | { |
f4a4528d | 572 | register Lisp_Object attack, orig_fn, encoded_fn; |
8dbbc384 RS |
573 | register char *lfname, *locker; |
574 | lock_info_type lock_info; | |
3edc33a4 | 575 | struct gcpro gcpro1; |
8489eb67 | 576 | |
33bae690 RS |
577 | /* Don't do locking while dumping Emacs. |
578 | Uncompressing wtmp files uses call-process, which does not work | |
579 | in an uninitialized Emacs. */ | |
580 | if (! NILP (Vpurify_flag)) | |
581 | return; | |
582 | ||
5383bc6d | 583 | orig_fn = fn; |
8af8a9ca | 584 | GCPRO1 (fn); |
1e89de84 | 585 | fn = Fexpand_file_name (fn, Qnil); |
f4a4528d | 586 | encoded_fn = ENCODE_FILE (fn); |
1e89de84 | 587 | |
8dbbc384 | 588 | /* Create the name of the lock-file for file fn */ |
f4a4528d | 589 | MAKE_LOCK_NAME (lfname, encoded_fn); |
8489eb67 | 590 | |
32676c08 JB |
591 | /* See if this file is visited and has changed on disk since it was |
592 | visited. */ | |
8489eb67 | 593 | { |
a57bc488 | 594 | register Lisp_Object subject_buf; |
3036594f | 595 | |
5383bc6d | 596 | subject_buf = get_truename_buffer (orig_fn); |
3036594f | 597 | |
265a9e55 JB |
598 | if (!NILP (subject_buf) |
599 | && NILP (Fverify_visited_file_modtime (subject_buf)) | |
600 | && !NILP (Ffile_exists_p (fn))) | |
8489eb67 | 601 | call1 (intern ("ask-user-about-supersession-threat"), fn); |
3036594f | 602 | |
8489eb67 | 603 | } |
8af8a9ca | 604 | UNGCPRO; |
8489eb67 RS |
605 | |
606 | /* Try to lock the lock. */ | |
8dbbc384 RS |
607 | if (lock_if_free (&lock_info, lfname) <= 0) |
608 | /* Return now if we have locked it, or if lock creation failed */ | |
8489eb67 RS |
609 | return; |
610 | ||
611 | /* Else consider breaking the lock */ | |
266d7a00 RS |
612 | locker = (char *) alloca (strlen (lock_info.user) + strlen (lock_info.host) |
613 | + LOCK_PID_MAX + 9); | |
79e51eeb | 614 | sprintf (locker, "%s@%s (pid %lu)", lock_info.user, lock_info.host, |
8dbbc384 RS |
615 | lock_info.pid); |
616 | FREE_LOCK_INFO (lock_info); | |
177c0ea7 | 617 | |
8dbbc384 | 618 | attack = call2 (intern ("ask-user-about-lock"), fn, build_string (locker)); |
265a9e55 | 619 | if (!NILP (attack)) |
8489eb67 RS |
620 | /* User says take the lock */ |
621 | { | |
8dbbc384 | 622 | lock_file_1 (lfname, 1); |
8489eb67 RS |
623 | return; |
624 | } | |
625 | /* User says ignore the lock */ | |
626 | } | |
627 | ||
8489eb67 | 628 | void |
971de7fb | 629 | unlock_file (register Lisp_Object fn) |
8489eb67 RS |
630 | { |
631 | register char *lfname; | |
632 | ||
1e89de84 | 633 | fn = Fexpand_file_name (fn, Qnil); |
88eace34 | 634 | fn = ENCODE_FILE (fn); |
1e89de84 | 635 | |
7b92975f | 636 | MAKE_LOCK_NAME (lfname, fn); |
8489eb67 | 637 | |
8dbbc384 | 638 | if (current_lock_owner (0, lfname) == 2) |
8489eb67 | 639 | unlink (lfname); |
8489eb67 RS |
640 | } |
641 | ||
642 | void | |
971de7fb | 643 | unlock_all_files (void) |
8489eb67 RS |
644 | { |
645 | register Lisp_Object tail; | |
646 | register struct buffer *b; | |
647 | ||
8e50cc2d | 648 | for (tail = Vbuffer_alist; CONSP (tail); tail = XCDR (tail)) |
8489eb67 | 649 | { |
03699b14 | 650 | b = XBUFFER (XCDR (XCAR (tail))); |
5757b805 | 651 | if (STRINGP (b->file_truename) && BUF_SAVE_MODIFF (b) < BUF_MODIFF (b)) |
1c343051 | 652 | { |
4fa09beb | 653 | unlock_file(b->file_truename); |
1c343051 | 654 | } |
8489eb67 RS |
655 | } |
656 | } | |
8489eb67 RS |
657 | \f |
658 | DEFUN ("lock-buffer", Flock_buffer, Slock_buffer, | |
335c5470 PJ |
659 | 0, 1, 0, |
660 | doc: /* Lock FILE, if current buffer is modified. | |
661 | FILE defaults to current buffer's visited file, | |
662 | or else nothing is done if current buffer isn't visiting a file. */) | |
5842a27b | 663 | (Lisp_Object file) |
8489eb67 | 664 | { |
e9319ef2 EN |
665 | if (NILP (file)) |
666 | file = current_buffer->file_truename; | |
8489eb67 | 667 | else |
b7826503 | 668 | CHECK_STRING (file); |
6a140159 | 669 | if (SAVE_MODIFF < MODIFF |
e9319ef2 EN |
670 | && !NILP (file)) |
671 | lock_file (file); | |
177c0ea7 | 672 | return Qnil; |
8489eb67 RS |
673 | } |
674 | ||
675 | DEFUN ("unlock-buffer", Funlock_buffer, Sunlock_buffer, | |
335c5470 | 676 | 0, 0, 0, |
3bfb8921 RS |
677 | doc: /* Unlock the file visited in the current buffer. |
678 | If the buffer is not modified, this does nothing because the file | |
679 | should not be locked in that case. */) | |
5842a27b | 680 | (void) |
8489eb67 | 681 | { |
6a140159 | 682 | if (SAVE_MODIFF < MODIFF |
5757b805 RS |
683 | && STRINGP (current_buffer->file_truename)) |
684 | unlock_file (current_buffer->file_truename); | |
8489eb67 RS |
685 | return Qnil; |
686 | } | |
687 | ||
8489eb67 RS |
688 | /* Unlock the file visited in buffer BUFFER. */ |
689 | ||
d07e0802 | 690 | void |
971de7fb | 691 | unlock_buffer (struct buffer *buffer) |
8489eb67 | 692 | { |
6a140159 | 693 | if (BUF_SAVE_MODIFF (buffer) < BUF_MODIFF (buffer) |
5757b805 RS |
694 | && STRINGP (buffer->file_truename)) |
695 | unlock_file (buffer->file_truename); | |
8489eb67 RS |
696 | } |
697 | ||
8105cbf7 | 698 | DEFUN ("file-locked-p", Ffile_locked_p, Sfile_locked_p, 1, 1, 0, |
3bfb8921 RS |
699 | doc: /* Return a value indicating whether FILENAME is locked. |
700 | The value is nil if the FILENAME is not locked, | |
701 | t if it is locked by you, else a string saying which user has locked it. */) | |
5842a27b | 702 | (Lisp_Object filename) |
8489eb67 | 703 | { |
8dbbc384 | 704 | Lisp_Object ret; |
8489eb67 RS |
705 | register char *lfname; |
706 | int owner; | |
8dbbc384 | 707 | lock_info_type locker; |
8489eb67 | 708 | |
e9319ef2 | 709 | filename = Fexpand_file_name (filename, Qnil); |
8489eb67 | 710 | |
e9319ef2 | 711 | MAKE_LOCK_NAME (lfname, filename); |
8489eb67 | 712 | |
8dbbc384 | 713 | owner = current_lock_owner (&locker, lfname); |
8489eb67 | 714 | if (owner <= 0) |
8dbbc384 RS |
715 | ret = Qnil; |
716 | else if (owner == 2) | |
717 | ret = Qt; | |
718 | else | |
719 | ret = build_string (locker.user); | |
720 | ||
721 | if (owner > 0) | |
722 | FREE_LOCK_INFO (locker); | |
723 | ||
724 | return ret; | |
8489eb67 | 725 | } |
32676c08 JB |
726 | \f |
727 | /* Initialization functions. */ | |
728 | ||
a3fd58aa | 729 | void |
971de7fb | 730 | init_filelock (void) |
a3fd58aa KH |
731 | { |
732 | boot_time = 0; | |
b97771fc | 733 | boot_time_initialized = 0; |
a3fd58aa KH |
734 | } |
735 | ||
dfcf069d | 736 | void |
971de7fb | 737 | syms_of_filelock (void) |
8489eb67 | 738 | { |
5f8d6a10 | 739 | DEFVAR_LISP ("temporary-file-directory", &Vtemporary_file_directory, |
335c5470 | 740 | doc: /* The directory for writing temporary files. */); |
5f8d6a10 RS |
741 | Vtemporary_file_directory = Qnil; |
742 | ||
8489eb67 RS |
743 | defsubr (&Sunlock_buffer); |
744 | defsubr (&Slock_buffer); | |
745 | defsubr (&Sfile_locked_p); | |
746 | } | |
747 | ||
748 | #endif /* CLASH_DETECTION */ | |
6b61353c KH |
749 | |
750 | /* arch-tag: e062676d-50b2-4be0-ab96-197c81b181a1 | |
751 | (do not change this comment) */ |