Commit | Line | Data |
---|---|---|
b97771fc | 1 | /* Lock files for editing. |
0b5538bd | 2 | Copyright (C) 1985, 1986, 1987, 1993, 1994, 1996, 1998, 1999, 2000, 2001, |
49f70d46 | 3 | 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012 |
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 DL |
36 | #endif |
37 | #ifdef HAVE_STRING_H | |
8dbbc384 | 38 | #include <string.h> |
e5ef3cdf | 39 | #endif |
8489eb67 | 40 | |
dfcf069d AS |
41 | #ifdef HAVE_UNISTD_H |
42 | #include <unistd.h> | |
43 | #endif | |
44 | ||
f805a125 | 45 | #ifdef __FreeBSD__ |
f805a125 KH |
46 | #include <sys/sysctl.h> |
47 | #endif /* __FreeBSD__ */ | |
48 | ||
e5ef3cdf DL |
49 | #include <errno.h> |
50 | #ifndef errno | |
51 | extern int errno; | |
52 | #endif | |
53 | ||
8489eb67 | 54 | #include "lisp.h" |
8489eb67 | 55 | #include "buffer.h" |
d2f6dae8 | 56 | #include "character.h" |
f4a4528d | 57 | #include "coding.h" |
9177d978 | 58 | #include "systime.h" |
8489eb67 | 59 | |
5f8d6a10 RS |
60 | /* The directory for writing temporary files. */ |
61 | ||
62 | Lisp_Object Vtemporary_file_directory; | |
63 | ||
8489eb67 | 64 | #ifdef CLASH_DETECTION |
e788eecc | 65 | |
c6d09b8d | 66 | #ifdef HAVE_UTMP_H |
e788eecc | 67 | #include <utmp.h> |
c6d09b8d | 68 | #endif |
77e544a4 | 69 | |
fa5c314d RS |
70 | #if !defined (S_ISLNK) && defined (S_IFLNK) |
71 | #define S_ISLNK(m) (((m) & S_IFMT) == S_IFLNK) | |
72 | #endif | |
73 | ||
a48de9b2 PE |
74 | /* A file whose last-modified time is just after the most recent boot. |
75 | Define this to be NULL to disable checking for this file. */ | |
76 | #ifndef BOOT_TIME_FILE | |
77 | #define BOOT_TIME_FILE "/var/run/random-seed" | |
78 | #endif | |
79 | ||
77e544a4 RS |
80 | #ifndef WTMP_FILE |
81 | #define WTMP_FILE "/var/log/wtmp" | |
82 | #endif | |
177c0ea7 | 83 | |
8dbbc384 RS |
84 | /* The strategy: to lock a file FN, create a symlink .#FN in FN's |
85 | directory, with link data `user@host.pid'. This avoids a single | |
86 | mount (== failure) point for lock files. | |
87 | ||
88 | When the host in the lock data is the current host, we can check if | |
89 | the pid is valid with kill. | |
177c0ea7 | 90 | |
8dbbc384 RS |
91 | Otherwise, we could look at a separate file that maps hostnames to |
92 | reboot times to see if the remote pid can possibly be valid, since we | |
93 | don't want Emacs to have to communicate via pipes or sockets or | |
94 | whatever to other processes, either locally or remotely; rms says | |
95 | that's too unreliable. Hence the separate file, which could | |
96 | theoretically be updated by daemons running separately -- but this | |
97 | whole idea is unimplemented; in practice, at least in our | |
1c4f857c | 98 | environment, it seems such stale locks arise fairly infrequently, and |
8dbbc384 RS |
99 | Emacs' standard methods of dealing with clashes suffice. |
100 | ||
101 | We use symlinks instead of normal files because (1) they can be | |
102 | stored more efficiently on the filesystem, since the kernel knows | |
103 | they will be small, and (2) all the info about the lock can be read | |
104 | in a single system call (readlink). Although we could use regular | |
1c4f857c | 105 | files to be useful on old systems lacking symlinks, nowadays |
8dbbc384 RS |
106 | virtually all such systems are probably single-user anyway, so it |
107 | didn't seem worth the complication. | |
177c0ea7 | 108 | |
8dbbc384 RS |
109 | Similarly, we don't worry about a possible 14-character limit on |
110 | file names, because those are all the same systems that don't have | |
111 | symlinks. | |
177c0ea7 | 112 | |
8dbbc384 RS |
113 | This is compatible with the locking scheme used by Interleaf (which |
114 | has contributed this implementation for Emacs), and was designed by | |
115 | Ethan Jacobson, Kimbo Mundy, and others. | |
177c0ea7 | 116 | |
8dbbc384 | 117 | --karl@cs.umb.edu/karl@hq.ileaf.com. */ |
8489eb67 | 118 | |
8dbbc384 | 119 | \f |
15e88d21 RS |
120 | /* Return the time of the last system boot. */ |
121 | ||
122 | static time_t boot_time; | |
b97771fc | 123 | static int boot_time_initialized; |
15e88d21 | 124 | |
9177d978 RS |
125 | extern Lisp_Object Vshell_file_name; |
126 | ||
2f2500ef DL |
127 | #ifdef BOOT_TIME |
128 | static void get_boot_time_1 P_ ((char *, int)); | |
129 | #endif | |
130 | ||
15e88d21 RS |
131 | static time_t |
132 | get_boot_time () | |
133 | { | |
9d2818d6 | 134 | #if defined (BOOT_TIME) |
9177d978 | 135 | int counter; |
2decc5a9 | 136 | #endif |
15e88d21 | 137 | |
b97771fc | 138 | if (boot_time_initialized) |
15e88d21 | 139 | return boot_time; |
b97771fc | 140 | boot_time_initialized = 1; |
15e88d21 | 141 | |
f805a125 KH |
142 | #if defined (CTL_KERN) && defined (KERN_BOOTTIME) |
143 | { | |
144 | int mib[2]; | |
145 | size_t size; | |
146 | struct timeval boottime_val; | |
147 | ||
148 | mib[0] = CTL_KERN; | |
149 | mib[1] = KERN_BOOTTIME; | |
150 | size = sizeof (boottime_val); | |
151 | ||
152 | if (sysctl (mib, 2, &boottime_val, &size, NULL, 0) >= 0) | |
153 | { | |
154 | boot_time = boottime_val.tv_sec; | |
155 | return boot_time; | |
156 | } | |
157 | } | |
158 | #endif /* defined (CTL_KERN) && defined (KERN_BOOTTIME) */ | |
9177d978 | 159 | |
a48de9b2 PE |
160 | if (BOOT_TIME_FILE) |
161 | { | |
162 | struct stat st; | |
163 | if (stat (BOOT_TIME_FILE, &st) == 0) | |
164 | { | |
165 | boot_time = st.st_mtime; | |
166 | return boot_time; | |
167 | } | |
168 | } | |
169 | ||
9d2818d6 | 170 | #if defined (BOOT_TIME) |
b97771fc RS |
171 | #ifndef CANNOT_DUMP |
172 | /* The utmp routines maintain static state. | |
173 | Don't touch that state unless we are initialized, | |
174 | since it might not survive dumping. */ | |
175 | if (! initialized) | |
176 | return boot_time; | |
177 | #endif /* not CANNOT_DUMP */ | |
178 | ||
179 | /* Try to get boot time from utmp before wtmp, | |
180 | since utmp is typically much smaller than wtmp. | |
181 | Passing a null pointer causes get_boot_time_1 | |
182 | to inspect the default file, namely utmp. */ | |
183 | get_boot_time_1 ((char *) 0, 0); | |
184 | if (boot_time) | |
185 | return boot_time; | |
186 | ||
9177d978 | 187 | /* Try to get boot time from the current wtmp file. */ |
b97771fc | 188 | get_boot_time_1 (WTMP_FILE, 1); |
9177d978 RS |
189 | |
190 | /* If we did not find a boot time in wtmp, look at wtmp, and so on. */ | |
b97771fc | 191 | for (counter = 0; counter < 20 && ! boot_time; counter++) |
9177d978 RS |
192 | { |
193 | char cmd_string[100]; | |
194 | Lisp_Object tempname, filename; | |
195 | int delete_flag = 0; | |
196 | ||
197 | filename = Qnil; | |
198 | ||
77e544a4 | 199 | sprintf (cmd_string, "%s.%d", WTMP_FILE, counter); |
9177d978 | 200 | tempname = build_string (cmd_string); |
29a2adb0 | 201 | if (! NILP (Ffile_exists_p (tempname))) |
9177d978 RS |
202 | filename = tempname; |
203 | else | |
204 | { | |
77e544a4 | 205 | sprintf (cmd_string, "%s.%d.gz", WTMP_FILE, counter); |
9177d978 RS |
206 | tempname = build_string (cmd_string); |
207 | if (! NILP (Ffile_exists_p (tempname))) | |
208 | { | |
209 | Lisp_Object args[6]; | |
f1d367aa GM |
210 | |
211 | /* The utmp functions on mescaline.gnu.org accept only | |
212 | file names up to 8 characters long. Choose a 2 | |
213 | character long prefix, and call make_temp_file with | |
214 | second arg non-zero, so that it will add not more | |
215 | than 6 characters to the prefix. */ | |
216 | tempname = Fexpand_file_name (build_string ("wt"), | |
5f8d6a10 | 217 | Vtemporary_file_directory); |
f1d367aa | 218 | tempname = make_temp_name (tempname, 1); |
9177d978 RS |
219 | args[0] = Vshell_file_name; |
220 | args[1] = Qnil; | |
221 | args[2] = Qnil; | |
222 | args[3] = Qnil; | |
223 | args[4] = build_string ("-c"); | |
77e544a4 | 224 | sprintf (cmd_string, "gunzip < %s.%d.gz > %s", |
d5db4077 | 225 | WTMP_FILE, counter, SDATA (tempname)); |
9177d978 RS |
226 | args[5] = build_string (cmd_string); |
227 | Fcall_process (6, args); | |
228 | filename = tempname; | |
229 | delete_flag = 1; | |
230 | } | |
231 | } | |
232 | ||
233 | if (! NILP (filename)) | |
234 | { | |
d5db4077 | 235 | get_boot_time_1 (SDATA (filename), 1); |
9177d978 | 236 | if (delete_flag) |
d5db4077 | 237 | unlink (SDATA (filename)); |
9177d978 RS |
238 | } |
239 | } | |
240 | ||
241 | return boot_time; | |
242 | #else | |
243 | return 0; | |
244 | #endif | |
245 | } | |
246 | ||
e9f22ced | 247 | #ifdef BOOT_TIME |
9177d978 RS |
248 | /* Try to get the boot time from wtmp file FILENAME. |
249 | This succeeds if that file contains a reboot record. | |
9177d978 | 250 | |
b97771fc RS |
251 | If FILENAME is zero, use the same file as before; |
252 | if no FILENAME has ever been specified, this is the utmp file. | |
253 | Use the newest reboot record if NEWEST is nonzero, | |
254 | the first reboot record otherwise. | |
255 | Ignore all reboot records on or before BOOT_TIME. | |
256 | Success is indicated by setting BOOT_TIME to a larger value. */ | |
257 | ||
2f2500ef | 258 | void |
b97771fc | 259 | get_boot_time_1 (filename, newest) |
9177d978 | 260 | char *filename; |
b97771fc | 261 | int newest; |
9177d978 RS |
262 | { |
263 | struct utmp ut, *utp; | |
77e544a4 RS |
264 | int desc; |
265 | ||
b97771fc RS |
266 | if (filename) |
267 | { | |
268 | /* On some versions of IRIX, opening a nonexistent file name | |
269 | is likely to crash in the utmp routines. */ | |
68c45bf0 | 270 | desc = emacs_open (filename, O_RDONLY, 0); |
b97771fc RS |
271 | if (desc < 0) |
272 | return; | |
273 | ||
68c45bf0 | 274 | emacs_close (desc); |
b97771fc RS |
275 | |
276 | utmpname (filename); | |
277 | } | |
9177d978 | 278 | |
c321b190 | 279 | setutent (); |
b97771fc | 280 | |
c321b190 RS |
281 | while (1) |
282 | { | |
283 | /* Find the next reboot record. */ | |
284 | ut.ut_type = BOOT_TIME; | |
285 | utp = getutid (&ut); | |
286 | if (! utp) | |
287 | break; | |
288 | /* Compare reboot times and use the newest one. */ | |
289 | if (utp->ut_time > boot_time) | |
b97771fc RS |
290 | { |
291 | boot_time = utp->ut_time; | |
292 | if (! newest) | |
293 | break; | |
294 | } | |
c321b190 RS |
295 | /* Advance on element in the file |
296 | so that getutid won't repeat the same one. */ | |
297 | utp = getutent (); | |
298 | if (! utp) | |
299 | break; | |
300 | } | |
15e88d21 | 301 | endutent (); |
15e88d21 | 302 | } |
e9f22ced | 303 | #endif /* BOOT_TIME */ |
15e88d21 | 304 | \f |
8dbbc384 | 305 | /* Here is the structure that stores information about a lock. */ |
32676c08 | 306 | |
8dbbc384 RS |
307 | typedef struct |
308 | { | |
309 | char *user; | |
310 | char *host; | |
9005cb4f | 311 | unsigned long pid; |
15e88d21 | 312 | time_t boot_time; |
8dbbc384 | 313 | } lock_info_type; |
32676c08 | 314 | |
49b6d120 RS |
315 | /* When we read the info back, we might need this much more, |
316 | enough for decimal representation plus null. */ | |
317 | #define LOCK_PID_MAX (4 * sizeof (unsigned long)) | |
32676c08 | 318 | |
8dbbc384 RS |
319 | /* Free the two dynamically-allocated pieces in PTR. */ |
320 | #define FREE_LOCK_INFO(i) do { xfree ((i).user); xfree ((i).host); } while (0) | |
e31fbc7a | 321 | |
e31fbc7a | 322 | |
8dbbc384 | 323 | /* Write the name of the lock file for FN into LFNAME. Length will be |
c1355e1f GM |
324 | that of FN plus two more for the leading `.#' plus 1 for the |
325 | trailing period plus one for the digit after it plus one for the | |
326 | null. */ | |
7b92975f | 327 | #define MAKE_LOCK_NAME(lock, file) \ |
d5db4077 | 328 | (lock = (char *) alloca (SBYTES (file) + 2 + 1 + 1 + 1), \ |
8dbbc384 | 329 | fill_in_lock_file_name (lock, (file))) |
e31fbc7a | 330 | |
8dbbc384 RS |
331 | static void |
332 | fill_in_lock_file_name (lockfile, fn) | |
e31fbc7a RS |
333 | register char *lockfile; |
334 | register Lisp_Object fn; | |
335 | { | |
8dbbc384 | 336 | register char *p; |
c1355e1f GM |
337 | struct stat st; |
338 | int count = 0; | |
8dbbc384 | 339 | |
d5db4077 | 340 | strcpy (lockfile, SDATA (fn)); |
8dbbc384 RS |
341 | |
342 | /* Shift the nondirectory part of the file name (including the null) | |
343 | right two characters. Here is one of the places where we'd have to | |
344 | do something to support 14-character-max file names. */ | |
345 | for (p = lockfile + strlen (lockfile); p != lockfile && *p != '/'; p--) | |
346 | p[2] = *p; | |
177c0ea7 | 347 | |
8dbbc384 RS |
348 | /* Insert the `.#'. */ |
349 | p[1] = '.'; | |
350 | p[2] = '#'; | |
c1355e1f GM |
351 | |
352 | p = p + strlen (p); | |
353 | ||
354 | while (lstat (lockfile, &st) == 0 && !S_ISLNK (st.st_mode)) | |
355 | { | |
356 | if (count > 9) | |
357 | { | |
358 | *p = '\0'; | |
359 | return; | |
360 | } | |
361 | sprintf (p, ".%d", count++); | |
362 | } | |
8dbbc384 | 363 | } |
e31fbc7a | 364 | |
8dbbc384 RS |
365 | /* Lock the lock file named LFNAME. |
366 | If FORCE is nonzero, we do so even if it is already locked. | |
367 | Return 1 if successful, 0 if not. */ | |
e31fbc7a | 368 | |
8dbbc384 RS |
369 | static int |
370 | lock_file_1 (lfname, force) | |
177c0ea7 | 371 | char *lfname; |
8dbbc384 RS |
372 | int force; |
373 | { | |
374 | register int err; | |
bd26d5a3 | 375 | time_t boot_time; |
662c2ef2 RS |
376 | char *user_name; |
377 | char *host_name; | |
378 | char *lock_info_str; | |
379 | ||
4ba93ac0 AS |
380 | /* Call this first because it can GC. */ |
381 | boot_time = get_boot_time (); | |
382 | ||
662c2ef2 | 383 | if (STRINGP (Fuser_login_name (Qnil))) |
d5db4077 | 384 | user_name = (char *)SDATA (Fuser_login_name (Qnil)); |
662c2ef2 RS |
385 | else |
386 | user_name = ""; | |
387 | if (STRINGP (Fsystem_name ())) | |
d5db4077 | 388 | host_name = (char *)SDATA (Fsystem_name ()); |
662c2ef2 RS |
389 | else |
390 | host_name = ""; | |
266d7a00 | 391 | lock_info_str = (char *)alloca (strlen (user_name) + strlen (host_name) |
4ba93ac0 | 392 | + LOCK_PID_MAX + 30); |
8dbbc384 | 393 | |
bd26d5a3 RS |
394 | if (boot_time) |
395 | sprintf (lock_info_str, "%s@%s.%lu:%lu", user_name, host_name, | |
396 | (unsigned long) getpid (), (unsigned long) boot_time); | |
397 | else | |
398 | sprintf (lock_info_str, "%s@%s.%lu", user_name, host_name, | |
177c0ea7 | 399 | (unsigned long) getpid ()); |
8dbbc384 RS |
400 | |
401 | err = symlink (lock_info_str, lfname); | |
402 | if (errno == EEXIST && force) | |
e31fbc7a | 403 | { |
8dbbc384 RS |
404 | unlink (lfname); |
405 | err = symlink (lock_info_str, lfname); | |
e31fbc7a | 406 | } |
e31fbc7a | 407 | |
8dbbc384 RS |
408 | return err == 0; |
409 | } | |
e31fbc7a | 410 | |
9177d978 | 411 | /* Return 1 if times A and B are no more than one second apart. */ |
32676c08 | 412 | |
9177d978 RS |
413 | int |
414 | within_one_second (a, b) | |
415 | time_t a, b; | |
416 | { | |
417 | return (a - b >= -1 && a - b <= 1); | |
418 | } | |
8dbbc384 RS |
419 | \f |
420 | /* Return 0 if nobody owns the lock file LFNAME or the lock is obsolete, | |
421 | 1 if another process owns it (and set OWNER (if non-null) to info), | |
422 | 2 if the current process owns it, | |
423 | or -1 if something is wrong with the locking mechanism. */ | |
e31fbc7a | 424 | |
8dbbc384 RS |
425 | static int |
426 | current_lock_owner (owner, lfname) | |
427 | lock_info_type *owner; | |
428 | char *lfname; | |
32676c08 | 429 | { |
8dbbc384 RS |
430 | #ifndef index |
431 | extern char *rindex (), *index (); | |
432 | #endif | |
5f8d6a10 | 433 | int len, ret; |
8dbbc384 | 434 | int local_owner = 0; |
15e88d21 | 435 | char *at, *dot, *colon; |
8dbbc384 RS |
436 | char *lfinfo = 0; |
437 | int bufsize = 50; | |
438 | /* Read arbitrarily-long contents of symlink. Similar code in | |
439 | file-symlink-p in fileio.c. */ | |
440 | do | |
441 | { | |
442 | bufsize *= 2; | |
443 | lfinfo = (char *) xrealloc (lfinfo, bufsize); | |
620c4704 | 444 | errno = 0; |
8dbbc384 | 445 | len = readlink (lfname, lfinfo, bufsize); |
b6e97b0a GM |
446 | #ifdef ERANGE |
447 | /* HP-UX reports ERANGE if the buffer is too small. */ | |
448 | if (len == -1 && errno == ERANGE) | |
63680feb | 449 | len = bufsize; |
b6e97b0a | 450 | #endif |
8dbbc384 RS |
451 | } |
452 | while (len >= bufsize); | |
177c0ea7 | 453 | |
8dbbc384 RS |
454 | /* If nonexistent lock file, all is well; otherwise, got strange error. */ |
455 | if (len == -1) | |
456 | { | |
457 | xfree (lfinfo); | |
458 | return errno == ENOENT ? 0 : -1; | |
459 | } | |
32676c08 | 460 | |
8dbbc384 RS |
461 | /* Link info exists, so `len' is its length. Null terminate. */ |
462 | lfinfo[len] = 0; | |
177c0ea7 | 463 | |
8dbbc384 RS |
464 | /* Even if the caller doesn't want the owner info, we still have to |
465 | read it to determine return value, so allocate it. */ | |
466 | if (!owner) | |
467 | { | |
3609a53b | 468 | owner = (lock_info_type *) alloca (sizeof (lock_info_type)); |
8dbbc384 RS |
469 | local_owner = 1; |
470 | } | |
177c0ea7 | 471 | |
15e88d21 | 472 | /* Parse USER@HOST.PID:BOOT_TIME. If can't parse, return -1. */ |
50624218 JR |
473 | /* The USER is everything before the last @. */ |
474 | at = rindex (lfinfo, '@'); | |
8dbbc384 | 475 | dot = rindex (lfinfo, '.'); |
15e88d21 RS |
476 | if (!at || !dot) |
477 | { | |
478 | xfree (lfinfo); | |
479 | return -1; | |
480 | } | |
8dbbc384 RS |
481 | len = at - lfinfo; |
482 | owner->user = (char *) xmalloc (len + 1); | |
483 | strncpy (owner->user, lfinfo, len); | |
484 | owner->user[len] = 0; | |
177c0ea7 | 485 | |
15e88d21 | 486 | /* The PID is everything from the last `.' to the `:'. */ |
8dbbc384 | 487 | owner->pid = atoi (dot + 1); |
15e88d21 RS |
488 | colon = dot; |
489 | while (*colon && *colon != ':') | |
490 | colon++; | |
491 | /* After the `:', if there is one, comes the boot time. */ | |
492 | if (*colon == ':') | |
493 | owner->boot_time = atoi (colon + 1); | |
494 | else | |
495 | owner->boot_time = 0; | |
32676c08 | 496 | |
8dbbc384 RS |
497 | /* The host is everything in between. */ |
498 | len = dot - at - 1; | |
499 | owner->host = (char *) xmalloc (len + 1); | |
500 | strncpy (owner->host, at + 1, len); | |
501 | owner->host[len] = 0; | |
32676c08 | 502 | |
8dbbc384 RS |
503 | /* We're done looking at the link info. */ |
504 | xfree (lfinfo); | |
177c0ea7 | 505 | |
8dbbc384 | 506 | /* On current host? */ |
662c2ef2 | 507 | if (STRINGP (Fsystem_name ()) |
d5db4077 | 508 | && strcmp (owner->host, SDATA (Fsystem_name ())) == 0) |
32676c08 | 509 | { |
8dbbc384 RS |
510 | if (owner->pid == getpid ()) |
511 | ret = 2; /* We own it. */ | |
72dcef0e | 512 | else if (owner->pid > 0 |
15e88d21 RS |
513 | && (kill (owner->pid, 0) >= 0 || errno == EPERM) |
514 | && (owner->boot_time == 0 | |
9177d978 | 515 | || within_one_second (owner->boot_time, get_boot_time ()))) |
8dbbc384 | 516 | ret = 1; /* An existing process on this machine owns it. */ |
8dbbc384 RS |
517 | /* The owner process is dead or has a strange pid (<=0), so try to |
518 | zap the lockfile. */ | |
72dcef0e | 519 | else if (unlink (lfname) < 0) |
8dbbc384 | 520 | ret = -1; |
72dcef0e RS |
521 | else |
522 | ret = 0; | |
32676c08 | 523 | } |
8dbbc384 RS |
524 | else |
525 | { /* If we wanted to support the check for stale locks on remote machines, | |
526 | here's where we'd do it. */ | |
527 | ret = 1; | |
528 | } | |
177c0ea7 | 529 | |
8dbbc384 RS |
530 | /* Avoid garbage. */ |
531 | if (local_owner || ret <= 0) | |
532 | { | |
533 | FREE_LOCK_INFO (*owner); | |
534 | } | |
535 | return ret; | |
32676c08 JB |
536 | } |
537 | ||
8dbbc384 RS |
538 | \f |
539 | /* Lock the lock named LFNAME if possible. | |
540 | Return 0 in that case. | |
541 | Return positive if some other process owns the lock, and info about | |
542 | that process in CLASHER. | |
543 | Return -1 if cannot lock for any other reason. */ | |
8489eb67 | 544 | |
8dbbc384 RS |
545 | static int |
546 | lock_if_free (clasher, lfname) | |
547 | lock_info_type *clasher; | |
177c0ea7 | 548 | register char *lfname; |
8dbbc384 | 549 | { |
cfc01fa7 | 550 | while (lock_file_1 (lfname, 0) == 0) |
8dbbc384 RS |
551 | { |
552 | int locker; | |
e0e0205b | 553 | |
8dbbc384 RS |
554 | if (errno != EEXIST) |
555 | return -1; | |
177c0ea7 | 556 | |
8dbbc384 RS |
557 | locker = current_lock_owner (clasher, lfname); |
558 | if (locker == 2) | |
559 | { | |
560 | FREE_LOCK_INFO (*clasher); | |
561 | return 0; /* We ourselves locked it. */ | |
562 | } | |
563 | else if (locker == 1) | |
564 | return 1; /* Someone else has it. */ | |
5df0b2fa | 565 | else if (locker == -1) |
ae1ef097 | 566 | return -1; /* current_lock_owner returned strange error. */ |
8dbbc384 | 567 | |
cfc01fa7 | 568 | /* We deleted a stale lock; try again to lock the file. */ |
8dbbc384 RS |
569 | } |
570 | return 0; | |
8489eb67 RS |
571 | } |
572 | ||
8dbbc384 | 573 | /* lock_file locks file FN, |
8489eb67 RS |
574 | meaning it serves notice on the world that you intend to edit that file. |
575 | This should be done only when about to modify a file-visiting | |
576 | buffer previously unmodified. | |
8dbbc384 | 577 | Do not (normally) call this for a buffer already modified, |
8489eb67 RS |
578 | as either the file is already locked, or the user has already |
579 | decided to go ahead without locking. | |
580 | ||
8dbbc384 | 581 | When this returns, either the lock is locked for us, |
8489eb67 RS |
582 | or the user has said to go ahead without locking. |
583 | ||
8dbbc384 | 584 | If the file is locked by someone else, this calls |
8489eb67 | 585 | ask-user-about-lock (a Lisp function) with two arguments, |
8dbbc384 | 586 | the file name and info about the user who did the locking. |
8489eb67 RS |
587 | This function can signal an error, or return t meaning |
588 | take away the lock, or return nil meaning ignore the lock. */ | |
589 | ||
8489eb67 RS |
590 | void |
591 | lock_file (fn) | |
eb4b1c05 | 592 | Lisp_Object fn; |
8489eb67 | 593 | { |
f4a4528d | 594 | register Lisp_Object attack, orig_fn, encoded_fn; |
8dbbc384 RS |
595 | register char *lfname, *locker; |
596 | lock_info_type lock_info; | |
3edc33a4 | 597 | struct gcpro gcpro1; |
8489eb67 | 598 | |
33bae690 RS |
599 | /* Don't do locking while dumping Emacs. |
600 | Uncompressing wtmp files uses call-process, which does not work | |
601 | in an uninitialized Emacs. */ | |
602 | if (! NILP (Vpurify_flag)) | |
603 | return; | |
604 | ||
5383bc6d | 605 | orig_fn = fn; |
8af8a9ca | 606 | GCPRO1 (fn); |
1e89de84 | 607 | fn = Fexpand_file_name (fn, Qnil); |
f4a4528d | 608 | encoded_fn = ENCODE_FILE (fn); |
1e89de84 | 609 | |
8dbbc384 | 610 | /* Create the name of the lock-file for file fn */ |
f4a4528d | 611 | MAKE_LOCK_NAME (lfname, encoded_fn); |
8489eb67 | 612 | |
32676c08 JB |
613 | /* See if this file is visited and has changed on disk since it was |
614 | visited. */ | |
8489eb67 | 615 | { |
a57bc488 | 616 | register Lisp_Object subject_buf; |
3036594f | 617 | |
5383bc6d | 618 | subject_buf = get_truename_buffer (orig_fn); |
3036594f | 619 | |
265a9e55 JB |
620 | if (!NILP (subject_buf) |
621 | && NILP (Fverify_visited_file_modtime (subject_buf)) | |
622 | && !NILP (Ffile_exists_p (fn))) | |
8489eb67 | 623 | call1 (intern ("ask-user-about-supersession-threat"), fn); |
3036594f | 624 | |
8489eb67 | 625 | } |
8af8a9ca | 626 | UNGCPRO; |
8489eb67 RS |
627 | |
628 | /* Try to lock the lock. */ | |
8dbbc384 RS |
629 | if (lock_if_free (&lock_info, lfname) <= 0) |
630 | /* Return now if we have locked it, or if lock creation failed */ | |
8489eb67 RS |
631 | return; |
632 | ||
633 | /* Else consider breaking the lock */ | |
266d7a00 RS |
634 | locker = (char *) alloca (strlen (lock_info.user) + strlen (lock_info.host) |
635 | + LOCK_PID_MAX + 9); | |
79e51eeb | 636 | sprintf (locker, "%s@%s (pid %lu)", lock_info.user, lock_info.host, |
8dbbc384 RS |
637 | lock_info.pid); |
638 | FREE_LOCK_INFO (lock_info); | |
177c0ea7 | 639 | |
8dbbc384 | 640 | attack = call2 (intern ("ask-user-about-lock"), fn, build_string (locker)); |
265a9e55 | 641 | if (!NILP (attack)) |
8489eb67 RS |
642 | /* User says take the lock */ |
643 | { | |
8dbbc384 | 644 | lock_file_1 (lfname, 1); |
8489eb67 RS |
645 | return; |
646 | } | |
647 | /* User says ignore the lock */ | |
648 | } | |
649 | ||
8489eb67 RS |
650 | void |
651 | unlock_file (fn) | |
652 | register Lisp_Object fn; | |
653 | { | |
654 | register char *lfname; | |
655 | ||
1e89de84 | 656 | fn = Fexpand_file_name (fn, Qnil); |
88eace34 | 657 | fn = ENCODE_FILE (fn); |
1e89de84 | 658 | |
7b92975f | 659 | MAKE_LOCK_NAME (lfname, fn); |
8489eb67 | 660 | |
8dbbc384 | 661 | if (current_lock_owner (0, lfname) == 2) |
8489eb67 | 662 | unlink (lfname); |
8489eb67 RS |
663 | } |
664 | ||
665 | void | |
666 | unlock_all_files () | |
667 | { | |
668 | register Lisp_Object tail; | |
669 | register struct buffer *b; | |
670 | ||
8e50cc2d | 671 | for (tail = Vbuffer_alist; CONSP (tail); tail = XCDR (tail)) |
8489eb67 | 672 | { |
03699b14 | 673 | b = XBUFFER (XCDR (XCAR (tail))); |
5757b805 | 674 | if (STRINGP (b->file_truename) && BUF_SAVE_MODIFF (b) < BUF_MODIFF (b)) |
1c343051 | 675 | { |
4fa09beb | 676 | unlock_file(b->file_truename); |
1c343051 | 677 | } |
8489eb67 RS |
678 | } |
679 | } | |
8489eb67 RS |
680 | \f |
681 | DEFUN ("lock-buffer", Flock_buffer, Slock_buffer, | |
335c5470 PJ |
682 | 0, 1, 0, |
683 | doc: /* Lock FILE, if current buffer is modified. | |
684 | FILE defaults to current buffer's visited file, | |
685 | or else nothing is done if current buffer isn't visiting a file. */) | |
686 | (file) | |
e9319ef2 | 687 | Lisp_Object file; |
8489eb67 | 688 | { |
e9319ef2 EN |
689 | if (NILP (file)) |
690 | file = current_buffer->file_truename; | |
8489eb67 | 691 | else |
b7826503 | 692 | CHECK_STRING (file); |
6a140159 | 693 | if (SAVE_MODIFF < MODIFF |
e9319ef2 EN |
694 | && !NILP (file)) |
695 | lock_file (file); | |
177c0ea7 | 696 | return Qnil; |
8489eb67 RS |
697 | } |
698 | ||
699 | DEFUN ("unlock-buffer", Funlock_buffer, Sunlock_buffer, | |
335c5470 | 700 | 0, 0, 0, |
3bfb8921 RS |
701 | doc: /* Unlock the file visited in the current buffer. |
702 | If the buffer is not modified, this does nothing because the file | |
703 | should not be locked in that case. */) | |
335c5470 | 704 | () |
8489eb67 | 705 | { |
6a140159 | 706 | if (SAVE_MODIFF < MODIFF |
5757b805 RS |
707 | && STRINGP (current_buffer->file_truename)) |
708 | unlock_file (current_buffer->file_truename); | |
8489eb67 RS |
709 | return Qnil; |
710 | } | |
711 | ||
8489eb67 RS |
712 | /* Unlock the file visited in buffer BUFFER. */ |
713 | ||
d07e0802 | 714 | void |
8489eb67 RS |
715 | unlock_buffer (buffer) |
716 | struct buffer *buffer; | |
717 | { | |
6a140159 | 718 | if (BUF_SAVE_MODIFF (buffer) < BUF_MODIFF (buffer) |
5757b805 RS |
719 | && STRINGP (buffer->file_truename)) |
720 | unlock_file (buffer->file_truename); | |
8489eb67 RS |
721 | } |
722 | ||
8105cbf7 | 723 | DEFUN ("file-locked-p", Ffile_locked_p, Sfile_locked_p, 1, 1, 0, |
3bfb8921 RS |
724 | doc: /* Return a value indicating whether FILENAME is locked. |
725 | The value is nil if the FILENAME is not locked, | |
726 | t if it is locked by you, else a string saying which user has locked it. */) | |
335c5470 PJ |
727 | (filename) |
728 | Lisp_Object filename; | |
8489eb67 | 729 | { |
8dbbc384 | 730 | Lisp_Object ret; |
8489eb67 RS |
731 | register char *lfname; |
732 | int owner; | |
8dbbc384 | 733 | lock_info_type locker; |
8489eb67 | 734 | |
e9319ef2 | 735 | filename = Fexpand_file_name (filename, Qnil); |
8489eb67 | 736 | |
e9319ef2 | 737 | MAKE_LOCK_NAME (lfname, filename); |
8489eb67 | 738 | |
8dbbc384 | 739 | owner = current_lock_owner (&locker, lfname); |
8489eb67 | 740 | if (owner <= 0) |
8dbbc384 RS |
741 | ret = Qnil; |
742 | else if (owner == 2) | |
743 | ret = Qt; | |
744 | else | |
745 | ret = build_string (locker.user); | |
746 | ||
747 | if (owner > 0) | |
748 | FREE_LOCK_INFO (locker); | |
749 | ||
750 | return ret; | |
8489eb67 | 751 | } |
32676c08 JB |
752 | \f |
753 | /* Initialization functions. */ | |
754 | ||
a3fd58aa KH |
755 | void |
756 | init_filelock () | |
757 | { | |
758 | boot_time = 0; | |
b97771fc | 759 | boot_time_initialized = 0; |
a3fd58aa KH |
760 | } |
761 | ||
dfcf069d | 762 | void |
8489eb67 RS |
763 | syms_of_filelock () |
764 | { | |
5f8d6a10 | 765 | DEFVAR_LISP ("temporary-file-directory", &Vtemporary_file_directory, |
335c5470 | 766 | doc: /* The directory for writing temporary files. */); |
5f8d6a10 RS |
767 | Vtemporary_file_directory = Qnil; |
768 | ||
8489eb67 RS |
769 | defsubr (&Sunlock_buffer); |
770 | defsubr (&Slock_buffer); | |
771 | defsubr (&Sfile_locked_p); | |
772 | } | |
773 | ||
774 | #endif /* CLASH_DETECTION */ | |
6b61353c KH |
775 | |
776 | /* arch-tag: e062676d-50b2-4be0-ab96-197c81b181a1 | |
777 | (do not change this comment) */ |