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 | |
9177d978 RS |
120 | extern Lisp_Object Vshell_file_name; |
121 | ||
2f2500ef | 122 | #ifdef BOOT_TIME |
f57e2426 | 123 | static void get_boot_time_1 (char *, int); |
2f2500ef DL |
124 | #endif |
125 | ||
15e88d21 | 126 | static time_t |
971de7fb | 127 | get_boot_time (void) |
15e88d21 | 128 | { |
9d2818d6 | 129 | #if defined (BOOT_TIME) |
9177d978 | 130 | int counter; |
2decc5a9 | 131 | #endif |
15e88d21 | 132 | |
b97771fc | 133 | if (boot_time_initialized) |
15e88d21 | 134 | return boot_time; |
b97771fc | 135 | boot_time_initialized = 1; |
15e88d21 | 136 | |
f805a125 KH |
137 | #if defined (CTL_KERN) && defined (KERN_BOOTTIME) |
138 | { | |
139 | int mib[2]; | |
140 | size_t size; | |
141 | struct timeval boottime_val; | |
142 | ||
143 | mib[0] = CTL_KERN; | |
144 | mib[1] = KERN_BOOTTIME; | |
145 | size = sizeof (boottime_val); | |
146 | ||
147 | if (sysctl (mib, 2, &boottime_val, &size, NULL, 0) >= 0) | |
148 | { | |
149 | boot_time = boottime_val.tv_sec; | |
150 | return boot_time; | |
151 | } | |
152 | } | |
153 | #endif /* defined (CTL_KERN) && defined (KERN_BOOTTIME) */ | |
9177d978 | 154 | |
a48de9b2 PE |
155 | if (BOOT_TIME_FILE) |
156 | { | |
157 | struct stat st; | |
158 | if (stat (BOOT_TIME_FILE, &st) == 0) | |
159 | { | |
160 | boot_time = st.st_mtime; | |
161 | return boot_time; | |
162 | } | |
163 | } | |
164 | ||
9d2818d6 | 165 | #if defined (BOOT_TIME) |
b97771fc RS |
166 | #ifndef CANNOT_DUMP |
167 | /* The utmp routines maintain static state. | |
168 | Don't touch that state unless we are initialized, | |
169 | since it might not survive dumping. */ | |
170 | if (! initialized) | |
171 | return boot_time; | |
172 | #endif /* not CANNOT_DUMP */ | |
173 | ||
174 | /* Try to get boot time from utmp before wtmp, | |
175 | since utmp is typically much smaller than wtmp. | |
176 | Passing a null pointer causes get_boot_time_1 | |
177 | to inspect the default file, namely utmp. */ | |
178 | get_boot_time_1 ((char *) 0, 0); | |
179 | if (boot_time) | |
180 | return boot_time; | |
181 | ||
9177d978 | 182 | /* Try to get boot time from the current wtmp file. */ |
b97771fc | 183 | get_boot_time_1 (WTMP_FILE, 1); |
9177d978 RS |
184 | |
185 | /* If we did not find a boot time in wtmp, look at wtmp, and so on. */ | |
b97771fc | 186 | for (counter = 0; counter < 20 && ! boot_time; counter++) |
9177d978 RS |
187 | { |
188 | char cmd_string[100]; | |
189 | Lisp_Object tempname, filename; | |
190 | int delete_flag = 0; | |
191 | ||
192 | filename = Qnil; | |
193 | ||
77e544a4 | 194 | sprintf (cmd_string, "%s.%d", WTMP_FILE, counter); |
9177d978 | 195 | tempname = build_string (cmd_string); |
29a2adb0 | 196 | if (! NILP (Ffile_exists_p (tempname))) |
9177d978 RS |
197 | filename = tempname; |
198 | else | |
199 | { | |
77e544a4 | 200 | sprintf (cmd_string, "%s.%d.gz", WTMP_FILE, counter); |
9177d978 RS |
201 | tempname = build_string (cmd_string); |
202 | if (! NILP (Ffile_exists_p (tempname))) | |
203 | { | |
204 | Lisp_Object args[6]; | |
f1d367aa GM |
205 | |
206 | /* The utmp functions on mescaline.gnu.org accept only | |
207 | file names up to 8 characters long. Choose a 2 | |
208 | character long prefix, and call make_temp_file with | |
209 | second arg non-zero, so that it will add not more | |
210 | than 6 characters to the prefix. */ | |
211 | tempname = Fexpand_file_name (build_string ("wt"), | |
5f8d6a10 | 212 | Vtemporary_file_directory); |
f1d367aa | 213 | tempname = make_temp_name (tempname, 1); |
9177d978 RS |
214 | args[0] = Vshell_file_name; |
215 | args[1] = Qnil; | |
216 | args[2] = Qnil; | |
217 | args[3] = Qnil; | |
218 | args[4] = build_string ("-c"); | |
77e544a4 | 219 | sprintf (cmd_string, "gunzip < %s.%d.gz > %s", |
d5db4077 | 220 | WTMP_FILE, counter, SDATA (tempname)); |
9177d978 RS |
221 | args[5] = build_string (cmd_string); |
222 | Fcall_process (6, args); | |
223 | filename = tempname; | |
224 | delete_flag = 1; | |
225 | } | |
226 | } | |
227 | ||
228 | if (! NILP (filename)) | |
229 | { | |
d5db4077 | 230 | get_boot_time_1 (SDATA (filename), 1); |
9177d978 | 231 | if (delete_flag) |
d5db4077 | 232 | unlink (SDATA (filename)); |
9177d978 RS |
233 | } |
234 | } | |
235 | ||
236 | return boot_time; | |
237 | #else | |
238 | return 0; | |
239 | #endif | |
240 | } | |
241 | ||
e9f22ced | 242 | #ifdef BOOT_TIME |
9177d978 RS |
243 | /* Try to get the boot time from wtmp file FILENAME. |
244 | This succeeds if that file contains a reboot record. | |
9177d978 | 245 | |
b97771fc RS |
246 | If FILENAME is zero, use the same file as before; |
247 | if no FILENAME has ever been specified, this is the utmp file. | |
248 | Use the newest reboot record if NEWEST is nonzero, | |
249 | the first reboot record otherwise. | |
250 | Ignore all reboot records on or before BOOT_TIME. | |
251 | Success is indicated by setting BOOT_TIME to a larger value. */ | |
252 | ||
2f2500ef | 253 | void |
971de7fb | 254 | get_boot_time_1 (char *filename, int newest) |
9177d978 RS |
255 | { |
256 | struct utmp ut, *utp; | |
77e544a4 RS |
257 | int desc; |
258 | ||
b97771fc RS |
259 | if (filename) |
260 | { | |
261 | /* On some versions of IRIX, opening a nonexistent file name | |
262 | is likely to crash in the utmp routines. */ | |
68c45bf0 | 263 | desc = emacs_open (filename, O_RDONLY, 0); |
b97771fc RS |
264 | if (desc < 0) |
265 | return; | |
266 | ||
68c45bf0 | 267 | emacs_close (desc); |
b97771fc RS |
268 | |
269 | utmpname (filename); | |
270 | } | |
9177d978 | 271 | |
c321b190 | 272 | setutent (); |
b97771fc | 273 | |
c321b190 RS |
274 | while (1) |
275 | { | |
276 | /* Find the next reboot record. */ | |
277 | ut.ut_type = BOOT_TIME; | |
278 | utp = getutid (&ut); | |
279 | if (! utp) | |
280 | break; | |
281 | /* Compare reboot times and use the newest one. */ | |
282 | if (utp->ut_time > boot_time) | |
b97771fc RS |
283 | { |
284 | boot_time = utp->ut_time; | |
285 | if (! newest) | |
286 | break; | |
287 | } | |
c321b190 RS |
288 | /* Advance on element in the file |
289 | so that getutid won't repeat the same one. */ | |
290 | utp = getutent (); | |
291 | if (! utp) | |
292 | break; | |
293 | } | |
15e88d21 | 294 | endutent (); |
15e88d21 | 295 | } |
e9f22ced | 296 | #endif /* BOOT_TIME */ |
15e88d21 | 297 | \f |
8dbbc384 | 298 | /* Here is the structure that stores information about a lock. */ |
32676c08 | 299 | |
8dbbc384 RS |
300 | typedef struct |
301 | { | |
302 | char *user; | |
303 | char *host; | |
9005cb4f | 304 | unsigned long pid; |
15e88d21 | 305 | time_t boot_time; |
8dbbc384 | 306 | } lock_info_type; |
32676c08 | 307 | |
49b6d120 RS |
308 | /* When we read the info back, we might need this much more, |
309 | enough for decimal representation plus null. */ | |
310 | #define LOCK_PID_MAX (4 * sizeof (unsigned long)) | |
32676c08 | 311 | |
8dbbc384 RS |
312 | /* Free the two dynamically-allocated pieces in PTR. */ |
313 | #define FREE_LOCK_INFO(i) do { xfree ((i).user); xfree ((i).host); } while (0) | |
e31fbc7a | 314 | |
e31fbc7a | 315 | |
8dbbc384 | 316 | /* Write the name of the lock file for FN into LFNAME. Length will be |
c1355e1f GM |
317 | that of FN plus two more for the leading `.#' plus 1 for the |
318 | trailing period plus one for the digit after it plus one for the | |
319 | null. */ | |
7b92975f | 320 | #define MAKE_LOCK_NAME(lock, file) \ |
d5db4077 | 321 | (lock = (char *) alloca (SBYTES (file) + 2 + 1 + 1 + 1), \ |
8dbbc384 | 322 | fill_in_lock_file_name (lock, (file))) |
e31fbc7a | 323 | |
8dbbc384 | 324 | static void |
971de7fb | 325 | fill_in_lock_file_name (register char *lockfile, register Lisp_Object fn) |
e31fbc7a | 326 | { |
8dbbc384 | 327 | register char *p; |
c1355e1f GM |
328 | struct stat st; |
329 | int count = 0; | |
8dbbc384 | 330 | |
d5db4077 | 331 | strcpy (lockfile, SDATA (fn)); |
8dbbc384 RS |
332 | |
333 | /* Shift the nondirectory part of the file name (including the null) | |
334 | right two characters. Here is one of the places where we'd have to | |
335 | do something to support 14-character-max file names. */ | |
336 | for (p = lockfile + strlen (lockfile); p != lockfile && *p != '/'; p--) | |
337 | p[2] = *p; | |
177c0ea7 | 338 | |
8dbbc384 RS |
339 | /* Insert the `.#'. */ |
340 | p[1] = '.'; | |
341 | p[2] = '#'; | |
c1355e1f GM |
342 | |
343 | p = p + strlen (p); | |
344 | ||
345 | while (lstat (lockfile, &st) == 0 && !S_ISLNK (st.st_mode)) | |
346 | { | |
347 | if (count > 9) | |
348 | { | |
349 | *p = '\0'; | |
350 | return; | |
351 | } | |
352 | sprintf (p, ".%d", count++); | |
353 | } | |
8dbbc384 | 354 | } |
e31fbc7a | 355 | |
8dbbc384 RS |
356 | /* Lock the lock file named LFNAME. |
357 | If FORCE is nonzero, we do so even if it is already locked. | |
358 | Return 1 if successful, 0 if not. */ | |
e31fbc7a | 359 | |
8dbbc384 | 360 | static int |
971de7fb | 361 | lock_file_1 (char *lfname, int force) |
8dbbc384 RS |
362 | { |
363 | register int err; | |
bd26d5a3 | 364 | time_t boot_time; |
662c2ef2 RS |
365 | char *user_name; |
366 | char *host_name; | |
367 | char *lock_info_str; | |
368 | ||
4ba93ac0 AS |
369 | /* Call this first because it can GC. */ |
370 | boot_time = get_boot_time (); | |
371 | ||
662c2ef2 | 372 | if (STRINGP (Fuser_login_name (Qnil))) |
d5db4077 | 373 | user_name = (char *)SDATA (Fuser_login_name (Qnil)); |
662c2ef2 RS |
374 | else |
375 | user_name = ""; | |
376 | if (STRINGP (Fsystem_name ())) | |
d5db4077 | 377 | host_name = (char *)SDATA (Fsystem_name ()); |
662c2ef2 RS |
378 | else |
379 | host_name = ""; | |
266d7a00 | 380 | lock_info_str = (char *)alloca (strlen (user_name) + strlen (host_name) |
4ba93ac0 | 381 | + LOCK_PID_MAX + 30); |
8dbbc384 | 382 | |
bd26d5a3 RS |
383 | if (boot_time) |
384 | sprintf (lock_info_str, "%s@%s.%lu:%lu", user_name, host_name, | |
385 | (unsigned long) getpid (), (unsigned long) boot_time); | |
386 | else | |
387 | sprintf (lock_info_str, "%s@%s.%lu", user_name, host_name, | |
177c0ea7 | 388 | (unsigned long) getpid ()); |
8dbbc384 RS |
389 | |
390 | err = symlink (lock_info_str, lfname); | |
391 | if (errno == EEXIST && force) | |
e31fbc7a | 392 | { |
8dbbc384 RS |
393 | unlink (lfname); |
394 | err = symlink (lock_info_str, lfname); | |
e31fbc7a | 395 | } |
e31fbc7a | 396 | |
8dbbc384 RS |
397 | return err == 0; |
398 | } | |
e31fbc7a | 399 | |
9177d978 | 400 | /* Return 1 if times A and B are no more than one second apart. */ |
32676c08 | 401 | |
9177d978 | 402 | int |
971de7fb | 403 | within_one_second (time_t a, time_t b) |
9177d978 RS |
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 | 413 | static int |
971de7fb | 414 | current_lock_owner (lock_info_type *owner, char *lfname) |
32676c08 | 415 | { |
8dbbc384 | 416 | #ifndef index |
971de7fb | 417 | extern char *rindex (const char *, int), *index (const char *, int); |
8dbbc384 | 418 | #endif |
5f8d6a10 | 419 | int len, ret; |
8dbbc384 | 420 | int local_owner = 0; |
15e88d21 | 421 | char *at, *dot, *colon; |
8dbbc384 RS |
422 | char *lfinfo = 0; |
423 | int bufsize = 50; | |
424 | /* Read arbitrarily-long contents of symlink. Similar code in | |
425 | file-symlink-p in fileio.c. */ | |
426 | do | |
427 | { | |
428 | bufsize *= 2; | |
429 | lfinfo = (char *) xrealloc (lfinfo, bufsize); | |
620c4704 | 430 | errno = 0; |
8dbbc384 | 431 | len = readlink (lfname, lfinfo, bufsize); |
b6e97b0a GM |
432 | #ifdef ERANGE |
433 | /* HP-UX reports ERANGE if the buffer is too small. */ | |
434 | if (len == -1 && errno == ERANGE) | |
63680feb | 435 | len = bufsize; |
b6e97b0a | 436 | #endif |
8dbbc384 RS |
437 | } |
438 | while (len >= bufsize); | |
177c0ea7 | 439 | |
8dbbc384 RS |
440 | /* If nonexistent lock file, all is well; otherwise, got strange error. */ |
441 | if (len == -1) | |
442 | { | |
443 | xfree (lfinfo); | |
444 | return errno == ENOENT ? 0 : -1; | |
445 | } | |
32676c08 | 446 | |
8dbbc384 RS |
447 | /* Link info exists, so `len' is its length. Null terminate. */ |
448 | lfinfo[len] = 0; | |
177c0ea7 | 449 | |
8dbbc384 RS |
450 | /* Even if the caller doesn't want the owner info, we still have to |
451 | read it to determine return value, so allocate it. */ | |
452 | if (!owner) | |
453 | { | |
3609a53b | 454 | owner = (lock_info_type *) alloca (sizeof (lock_info_type)); |
8dbbc384 RS |
455 | local_owner = 1; |
456 | } | |
177c0ea7 | 457 | |
15e88d21 | 458 | /* Parse USER@HOST.PID:BOOT_TIME. If can't parse, return -1. */ |
50624218 JR |
459 | /* The USER is everything before the last @. */ |
460 | at = rindex (lfinfo, '@'); | |
8dbbc384 | 461 | dot = rindex (lfinfo, '.'); |
15e88d21 RS |
462 | if (!at || !dot) |
463 | { | |
464 | xfree (lfinfo); | |
465 | return -1; | |
466 | } | |
8dbbc384 RS |
467 | len = at - lfinfo; |
468 | owner->user = (char *) xmalloc (len + 1); | |
469 | strncpy (owner->user, lfinfo, len); | |
470 | owner->user[len] = 0; | |
177c0ea7 | 471 | |
15e88d21 | 472 | /* The PID is everything from the last `.' to the `:'. */ |
8dbbc384 | 473 | owner->pid = atoi (dot + 1); |
15e88d21 RS |
474 | colon = dot; |
475 | while (*colon && *colon != ':') | |
476 | colon++; | |
477 | /* After the `:', if there is one, comes the boot time. */ | |
478 | if (*colon == ':') | |
479 | owner->boot_time = atoi (colon + 1); | |
480 | else | |
481 | owner->boot_time = 0; | |
32676c08 | 482 | |
8dbbc384 RS |
483 | /* The host is everything in between. */ |
484 | len = dot - at - 1; | |
485 | owner->host = (char *) xmalloc (len + 1); | |
486 | strncpy (owner->host, at + 1, len); | |
487 | owner->host[len] = 0; | |
32676c08 | 488 | |
8dbbc384 RS |
489 | /* We're done looking at the link info. */ |
490 | xfree (lfinfo); | |
177c0ea7 | 491 | |
8dbbc384 | 492 | /* On current host? */ |
662c2ef2 | 493 | if (STRINGP (Fsystem_name ()) |
d5db4077 | 494 | && strcmp (owner->host, SDATA (Fsystem_name ())) == 0) |
32676c08 | 495 | { |
8dbbc384 RS |
496 | if (owner->pid == getpid ()) |
497 | ret = 2; /* We own it. */ | |
72dcef0e | 498 | else if (owner->pid > 0 |
15e88d21 RS |
499 | && (kill (owner->pid, 0) >= 0 || errno == EPERM) |
500 | && (owner->boot_time == 0 | |
9177d978 | 501 | || within_one_second (owner->boot_time, get_boot_time ()))) |
8dbbc384 | 502 | ret = 1; /* An existing process on this machine owns it. */ |
8dbbc384 RS |
503 | /* The owner process is dead or has a strange pid (<=0), so try to |
504 | zap the lockfile. */ | |
72dcef0e | 505 | else if (unlink (lfname) < 0) |
8dbbc384 | 506 | ret = -1; |
72dcef0e RS |
507 | else |
508 | ret = 0; | |
32676c08 | 509 | } |
8dbbc384 RS |
510 | else |
511 | { /* If we wanted to support the check for stale locks on remote machines, | |
512 | here's where we'd do it. */ | |
513 | ret = 1; | |
514 | } | |
177c0ea7 | 515 | |
8dbbc384 RS |
516 | /* Avoid garbage. */ |
517 | if (local_owner || ret <= 0) | |
518 | { | |
519 | FREE_LOCK_INFO (*owner); | |
520 | } | |
521 | return ret; | |
32676c08 JB |
522 | } |
523 | ||
8dbbc384 RS |
524 | \f |
525 | /* Lock the lock named LFNAME if possible. | |
526 | Return 0 in that case. | |
527 | Return positive if some other process owns the lock, and info about | |
528 | that process in CLASHER. | |
529 | Return -1 if cannot lock for any other reason. */ | |
8489eb67 | 530 | |
8dbbc384 | 531 | static int |
971de7fb | 532 | lock_if_free (lock_info_type *clasher, register char *lfname) |
8dbbc384 | 533 | { |
cfc01fa7 | 534 | while (lock_file_1 (lfname, 0) == 0) |
8dbbc384 RS |
535 | { |
536 | int locker; | |
e0e0205b | 537 | |
8dbbc384 RS |
538 | if (errno != EEXIST) |
539 | return -1; | |
177c0ea7 | 540 | |
8dbbc384 RS |
541 | locker = current_lock_owner (clasher, lfname); |
542 | if (locker == 2) | |
543 | { | |
544 | FREE_LOCK_INFO (*clasher); | |
545 | return 0; /* We ourselves locked it. */ | |
546 | } | |
547 | else if (locker == 1) | |
548 | return 1; /* Someone else has it. */ | |
5df0b2fa | 549 | else if (locker == -1) |
ae1ef097 | 550 | return -1; /* current_lock_owner returned strange error. */ |
8dbbc384 | 551 | |
cfc01fa7 | 552 | /* We deleted a stale lock; try again to lock the file. */ |
8dbbc384 RS |
553 | } |
554 | return 0; | |
8489eb67 RS |
555 | } |
556 | ||
8dbbc384 | 557 | /* lock_file locks file FN, |
8489eb67 RS |
558 | meaning it serves notice on the world that you intend to edit that file. |
559 | This should be done only when about to modify a file-visiting | |
560 | buffer previously unmodified. | |
8dbbc384 | 561 | Do not (normally) call this for a buffer already modified, |
8489eb67 RS |
562 | as either the file is already locked, or the user has already |
563 | decided to go ahead without locking. | |
564 | ||
8dbbc384 | 565 | When this returns, either the lock is locked for us, |
8489eb67 RS |
566 | or the user has said to go ahead without locking. |
567 | ||
8dbbc384 | 568 | If the file is locked by someone else, this calls |
8489eb67 | 569 | ask-user-about-lock (a Lisp function) with two arguments, |
8dbbc384 | 570 | the file name and info about the user who did the locking. |
8489eb67 RS |
571 | This function can signal an error, or return t meaning |
572 | take away the lock, or return nil meaning ignore the lock. */ | |
573 | ||
8489eb67 | 574 | void |
971de7fb | 575 | lock_file (Lisp_Object fn) |
8489eb67 | 576 | { |
f4a4528d | 577 | register Lisp_Object attack, orig_fn, encoded_fn; |
8dbbc384 RS |
578 | register char *lfname, *locker; |
579 | lock_info_type lock_info; | |
3edc33a4 | 580 | struct gcpro gcpro1; |
8489eb67 | 581 | |
33bae690 RS |
582 | /* Don't do locking while dumping Emacs. |
583 | Uncompressing wtmp files uses call-process, which does not work | |
584 | in an uninitialized Emacs. */ | |
585 | if (! NILP (Vpurify_flag)) | |
586 | return; | |
587 | ||
5383bc6d | 588 | orig_fn = fn; |
8af8a9ca | 589 | GCPRO1 (fn); |
1e89de84 | 590 | fn = Fexpand_file_name (fn, Qnil); |
f4a4528d | 591 | encoded_fn = ENCODE_FILE (fn); |
1e89de84 | 592 | |
8dbbc384 | 593 | /* Create the name of the lock-file for file fn */ |
f4a4528d | 594 | MAKE_LOCK_NAME (lfname, encoded_fn); |
8489eb67 | 595 | |
32676c08 JB |
596 | /* See if this file is visited and has changed on disk since it was |
597 | visited. */ | |
8489eb67 | 598 | { |
a57bc488 | 599 | register Lisp_Object subject_buf; |
3036594f | 600 | |
5383bc6d | 601 | subject_buf = get_truename_buffer (orig_fn); |
3036594f | 602 | |
265a9e55 JB |
603 | if (!NILP (subject_buf) |
604 | && NILP (Fverify_visited_file_modtime (subject_buf)) | |
605 | && !NILP (Ffile_exists_p (fn))) | |
8489eb67 | 606 | call1 (intern ("ask-user-about-supersession-threat"), fn); |
3036594f | 607 | |
8489eb67 | 608 | } |
8af8a9ca | 609 | UNGCPRO; |
8489eb67 RS |
610 | |
611 | /* Try to lock the lock. */ | |
8dbbc384 RS |
612 | if (lock_if_free (&lock_info, lfname) <= 0) |
613 | /* Return now if we have locked it, or if lock creation failed */ | |
8489eb67 RS |
614 | return; |
615 | ||
616 | /* Else consider breaking the lock */ | |
266d7a00 RS |
617 | locker = (char *) alloca (strlen (lock_info.user) + strlen (lock_info.host) |
618 | + LOCK_PID_MAX + 9); | |
79e51eeb | 619 | sprintf (locker, "%s@%s (pid %lu)", lock_info.user, lock_info.host, |
8dbbc384 RS |
620 | lock_info.pid); |
621 | FREE_LOCK_INFO (lock_info); | |
177c0ea7 | 622 | |
8dbbc384 | 623 | attack = call2 (intern ("ask-user-about-lock"), fn, build_string (locker)); |
265a9e55 | 624 | if (!NILP (attack)) |
8489eb67 RS |
625 | /* User says take the lock */ |
626 | { | |
8dbbc384 | 627 | lock_file_1 (lfname, 1); |
8489eb67 RS |
628 | return; |
629 | } | |
630 | /* User says ignore the lock */ | |
631 | } | |
632 | ||
8489eb67 | 633 | void |
971de7fb | 634 | unlock_file (register Lisp_Object fn) |
8489eb67 RS |
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 | |
971de7fb | 648 | unlock_all_files (void) |
8489eb67 RS |
649 | { |
650 | register Lisp_Object tail; | |
651 | register struct buffer *b; | |
652 | ||
8e50cc2d | 653 | for (tail = Vbuffer_alist; 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 | 657 | { |
4fa09beb | 658 | unlock_file(b->file_truename); |
1c343051 | 659 | } |
8489eb67 RS |
660 | } |
661 | } | |
8489eb67 RS |
662 | \f |
663 | DEFUN ("lock-buffer", Flock_buffer, Slock_buffer, | |
335c5470 PJ |
664 | 0, 1, 0, |
665 | doc: /* Lock FILE, if current buffer is modified. | |
666 | FILE defaults to current buffer's visited file, | |
667 | or else nothing is done if current buffer isn't visiting a file. */) | |
5842a27b | 668 | (Lisp_Object file) |
8489eb67 | 669 | { |
e9319ef2 EN |
670 | if (NILP (file)) |
671 | file = current_buffer->file_truename; | |
8489eb67 | 672 | else |
b7826503 | 673 | CHECK_STRING (file); |
6a140159 | 674 | if (SAVE_MODIFF < MODIFF |
e9319ef2 EN |
675 | && !NILP (file)) |
676 | lock_file (file); | |
177c0ea7 | 677 | return Qnil; |
8489eb67 RS |
678 | } |
679 | ||
680 | DEFUN ("unlock-buffer", Funlock_buffer, Sunlock_buffer, | |
335c5470 | 681 | 0, 0, 0, |
3bfb8921 RS |
682 | doc: /* Unlock the file visited in the current buffer. |
683 | If the buffer is not modified, this does nothing because the file | |
684 | should not be locked in that case. */) | |
5842a27b | 685 | (void) |
8489eb67 | 686 | { |
6a140159 | 687 | if (SAVE_MODIFF < MODIFF |
5757b805 RS |
688 | && STRINGP (current_buffer->file_truename)) |
689 | unlock_file (current_buffer->file_truename); | |
8489eb67 RS |
690 | return Qnil; |
691 | } | |
692 | ||
8489eb67 RS |
693 | /* Unlock the file visited in buffer BUFFER. */ |
694 | ||
d07e0802 | 695 | void |
971de7fb | 696 | unlock_buffer (struct buffer *buffer) |
8489eb67 | 697 | { |
6a140159 | 698 | if (BUF_SAVE_MODIFF (buffer) < BUF_MODIFF (buffer) |
5757b805 RS |
699 | && STRINGP (buffer->file_truename)) |
700 | unlock_file (buffer->file_truename); | |
8489eb67 RS |
701 | } |
702 | ||
8105cbf7 | 703 | DEFUN ("file-locked-p", Ffile_locked_p, Sfile_locked_p, 1, 1, 0, |
3bfb8921 RS |
704 | doc: /* Return a value indicating whether FILENAME is locked. |
705 | The value is nil if the FILENAME is not locked, | |
706 | t if it is locked by you, else a string saying which user has locked it. */) | |
5842a27b | 707 | (Lisp_Object filename) |
8489eb67 | 708 | { |
8dbbc384 | 709 | Lisp_Object ret; |
8489eb67 RS |
710 | register char *lfname; |
711 | int owner; | |
8dbbc384 | 712 | lock_info_type locker; |
8489eb67 | 713 | |
e9319ef2 | 714 | filename = Fexpand_file_name (filename, Qnil); |
8489eb67 | 715 | |
e9319ef2 | 716 | MAKE_LOCK_NAME (lfname, filename); |
8489eb67 | 717 | |
8dbbc384 | 718 | owner = current_lock_owner (&locker, lfname); |
8489eb67 | 719 | if (owner <= 0) |
8dbbc384 RS |
720 | ret = Qnil; |
721 | else if (owner == 2) | |
722 | ret = Qt; | |
723 | else | |
724 | ret = build_string (locker.user); | |
725 | ||
726 | if (owner > 0) | |
727 | FREE_LOCK_INFO (locker); | |
728 | ||
729 | return ret; | |
8489eb67 | 730 | } |
32676c08 JB |
731 | \f |
732 | /* Initialization functions. */ | |
733 | ||
a3fd58aa | 734 | void |
971de7fb | 735 | init_filelock (void) |
a3fd58aa KH |
736 | { |
737 | boot_time = 0; | |
b97771fc | 738 | boot_time_initialized = 0; |
a3fd58aa KH |
739 | } |
740 | ||
dfcf069d | 741 | void |
971de7fb | 742 | syms_of_filelock (void) |
8489eb67 | 743 | { |
5f8d6a10 | 744 | DEFVAR_LISP ("temporary-file-directory", &Vtemporary_file_directory, |
335c5470 | 745 | doc: /* The directory for writing temporary files. */); |
5f8d6a10 RS |
746 | Vtemporary_file_directory = Qnil; |
747 | ||
8489eb67 RS |
748 | defsubr (&Sunlock_buffer); |
749 | defsubr (&Slock_buffer); | |
750 | defsubr (&Sfile_locked_p); | |
751 | } | |
752 | ||
753 | #endif /* CLASH_DETECTION */ | |
6b61353c KH |
754 | |
755 | /* arch-tag: e062676d-50b2-4be0-ab96-197c81b181a1 | |
756 | (do not change this comment) */ |