Commit | Line | Data |
---|---|---|
b97771fc | 1 | /* Lock files for editing. |
73b0cd50 | 2 | Copyright (C) 1985-1987, 1993-1994, 1996, 1998-2011 |
8cabe764 | 3 | Free Software Foundation, Inc. |
8489eb67 RS |
4 | |
5 | This file is part of GNU Emacs. | |
6 | ||
9ec0b715 | 7 | GNU Emacs is free software: you can redistribute it and/or modify |
8489eb67 | 8 | it under the terms of the GNU General Public License as published by |
9ec0b715 GM |
9 | the Free Software Foundation, either version 3 of the License, or |
10 | (at your option) any later version. | |
8489eb67 RS |
11 | |
12 | GNU Emacs is distributed in the hope that it will be useful, | |
13 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
15 | GNU General Public License for more details. | |
16 | ||
17 | You should have received a copy of the GNU General Public License | |
9ec0b715 | 18 | along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>. */ |
8489eb67 RS |
19 | |
20 | ||
68c45bf0 | 21 | #include <config.h> |
8489eb67 RS |
22 | #include <sys/types.h> |
23 | #include <sys/stat.h> | |
dfcf069d | 24 | #include <signal.h> |
2decc5a9 | 25 | #include <stdio.h> |
d7306fe6 | 26 | #include <setjmp.h> |
bfb61299 | 27 | |
5b9c0a1d | 28 | #ifdef HAVE_PWD_H |
8489eb67 | 29 | #include <pwd.h> |
5b9c0a1d | 30 | #endif |
bfb61299 | 31 | |
8489eb67 | 32 | #include <sys/file.h> |
8489eb67 | 33 | #include <fcntl.h> |
dfcf069d | 34 | #include <unistd.h> |
dfcf069d | 35 | |
f805a125 | 36 | #ifdef __FreeBSD__ |
f805a125 KH |
37 | #include <sys/sysctl.h> |
38 | #endif /* __FreeBSD__ */ | |
39 | ||
e5ef3cdf | 40 | #include <errno.h> |
e5ef3cdf | 41 | |
8489eb67 | 42 | #include "lisp.h" |
8489eb67 | 43 | #include "buffer.h" |
d2f6dae8 | 44 | #include "character.h" |
f4a4528d | 45 | #include "coding.h" |
9177d978 | 46 | #include "systime.h" |
8489eb67 | 47 | |
8489eb67 | 48 | #ifdef CLASH_DETECTION |
e788eecc | 49 | |
c6d09b8d | 50 | #ifdef HAVE_UTMP_H |
e788eecc | 51 | #include <utmp.h> |
c6d09b8d | 52 | #endif |
77e544a4 | 53 | |
fa5c314d RS |
54 | #if !defined (S_ISLNK) && defined (S_IFLNK) |
55 | #define S_ISLNK(m) (((m) & S_IFMT) == S_IFLNK) | |
56 | #endif | |
57 | ||
a48de9b2 PE |
58 | /* A file whose last-modified time is just after the most recent boot. |
59 | Define this to be NULL to disable checking for this file. */ | |
60 | #ifndef BOOT_TIME_FILE | |
61 | #define BOOT_TIME_FILE "/var/run/random-seed" | |
62 | #endif | |
63 | ||
77e544a4 RS |
64 | #ifndef WTMP_FILE |
65 | #define WTMP_FILE "/var/log/wtmp" | |
66 | #endif | |
177c0ea7 | 67 | |
8dbbc384 RS |
68 | /* The strategy: to lock a file FN, create a symlink .#FN in FN's |
69 | directory, with link data `user@host.pid'. This avoids a single | |
70 | mount (== failure) point for lock files. | |
71 | ||
72 | When the host in the lock data is the current host, we can check if | |
73 | the pid is valid with kill. | |
177c0ea7 | 74 | |
8dbbc384 RS |
75 | Otherwise, we could look at a separate file that maps hostnames to |
76 | reboot times to see if the remote pid can possibly be valid, since we | |
77 | don't want Emacs to have to communicate via pipes or sockets or | |
78 | whatever to other processes, either locally or remotely; rms says | |
79 | that's too unreliable. Hence the separate file, which could | |
80 | theoretically be updated by daemons running separately -- but this | |
81 | whole idea is unimplemented; in practice, at least in our | |
1c4f857c | 82 | environment, it seems such stale locks arise fairly infrequently, and |
8dbbc384 RS |
83 | Emacs' standard methods of dealing with clashes suffice. |
84 | ||
85 | We use symlinks instead of normal files because (1) they can be | |
86 | stored more efficiently on the filesystem, since the kernel knows | |
87 | they will be small, and (2) all the info about the lock can be read | |
88 | in a single system call (readlink). Although we could use regular | |
1c4f857c | 89 | files to be useful on old systems lacking symlinks, nowadays |
8dbbc384 RS |
90 | virtually all such systems are probably single-user anyway, so it |
91 | didn't seem worth the complication. | |
177c0ea7 | 92 | |
8dbbc384 RS |
93 | Similarly, we don't worry about a possible 14-character limit on |
94 | file names, because those are all the same systems that don't have | |
95 | symlinks. | |
177c0ea7 | 96 | |
8dbbc384 RS |
97 | This is compatible with the locking scheme used by Interleaf (which |
98 | has contributed this implementation for Emacs), and was designed by | |
99 | Ethan Jacobson, Kimbo Mundy, and others. | |
177c0ea7 | 100 | |
8dbbc384 | 101 | --karl@cs.umb.edu/karl@hq.ileaf.com. */ |
8489eb67 | 102 | |
8dbbc384 | 103 | \f |
15e88d21 RS |
104 | /* Return the time of the last system boot. */ |
105 | ||
106 | static time_t boot_time; | |
b97771fc | 107 | static int boot_time_initialized; |
15e88d21 | 108 | |
2f2500ef | 109 | #ifdef BOOT_TIME |
8ea90aa3 | 110 | static void get_boot_time_1 (const char *, int); |
2f2500ef DL |
111 | #endif |
112 | ||
15e88d21 | 113 | static time_t |
971de7fb | 114 | get_boot_time (void) |
15e88d21 | 115 | { |
9d2818d6 | 116 | #if defined (BOOT_TIME) |
9177d978 | 117 | int counter; |
2decc5a9 | 118 | #endif |
15e88d21 | 119 | |
b97771fc | 120 | if (boot_time_initialized) |
15e88d21 | 121 | return boot_time; |
b97771fc | 122 | boot_time_initialized = 1; |
15e88d21 | 123 | |
f805a125 KH |
124 | #if defined (CTL_KERN) && defined (KERN_BOOTTIME) |
125 | { | |
126 | int mib[2]; | |
127 | size_t size; | |
128 | struct timeval boottime_val; | |
129 | ||
130 | mib[0] = CTL_KERN; | |
131 | mib[1] = KERN_BOOTTIME; | |
132 | size = sizeof (boottime_val); | |
133 | ||
134 | if (sysctl (mib, 2, &boottime_val, &size, NULL, 0) >= 0) | |
135 | { | |
136 | boot_time = boottime_val.tv_sec; | |
137 | return boot_time; | |
138 | } | |
139 | } | |
140 | #endif /* defined (CTL_KERN) && defined (KERN_BOOTTIME) */ | |
9177d978 | 141 | |
a48de9b2 PE |
142 | if (BOOT_TIME_FILE) |
143 | { | |
144 | struct stat st; | |
145 | if (stat (BOOT_TIME_FILE, &st) == 0) | |
146 | { | |
147 | boot_time = st.st_mtime; | |
148 | return boot_time; | |
149 | } | |
150 | } | |
151 | ||
9d2818d6 | 152 | #if defined (BOOT_TIME) |
b97771fc RS |
153 | #ifndef CANNOT_DUMP |
154 | /* The utmp routines maintain static state. | |
155 | Don't touch that state unless we are initialized, | |
156 | since it might not survive dumping. */ | |
157 | if (! initialized) | |
158 | return boot_time; | |
159 | #endif /* not CANNOT_DUMP */ | |
160 | ||
161 | /* Try to get boot time from utmp before wtmp, | |
162 | since utmp is typically much smaller than wtmp. | |
163 | Passing a null pointer causes get_boot_time_1 | |
164 | to inspect the default file, namely utmp. */ | |
165 | get_boot_time_1 ((char *) 0, 0); | |
166 | if (boot_time) | |
167 | return boot_time; | |
168 | ||
9177d978 | 169 | /* Try to get boot time from the current wtmp file. */ |
b97771fc | 170 | get_boot_time_1 (WTMP_FILE, 1); |
9177d978 RS |
171 | |
172 | /* If we did not find a boot time in wtmp, look at wtmp, and so on. */ | |
b97771fc | 173 | for (counter = 0; counter < 20 && ! boot_time; counter++) |
9177d978 RS |
174 | { |
175 | char cmd_string[100]; | |
176 | Lisp_Object tempname, filename; | |
177 | int delete_flag = 0; | |
178 | ||
179 | filename = Qnil; | |
180 | ||
77e544a4 | 181 | sprintf (cmd_string, "%s.%d", WTMP_FILE, counter); |
9177d978 | 182 | tempname = build_string (cmd_string); |
29a2adb0 | 183 | if (! NILP (Ffile_exists_p (tempname))) |
9177d978 RS |
184 | filename = tempname; |
185 | else | |
186 | { | |
77e544a4 | 187 | sprintf (cmd_string, "%s.%d.gz", WTMP_FILE, counter); |
9177d978 RS |
188 | tempname = build_string (cmd_string); |
189 | if (! NILP (Ffile_exists_p (tempname))) | |
190 | { | |
191 | Lisp_Object args[6]; | |
f1d367aa GM |
192 | |
193 | /* The utmp functions on mescaline.gnu.org accept only | |
194 | file names up to 8 characters long. Choose a 2 | |
195 | character long prefix, and call make_temp_file with | |
196 | second arg non-zero, so that it will add not more | |
197 | than 6 characters to the prefix. */ | |
198 | tempname = Fexpand_file_name (build_string ("wt"), | |
5f8d6a10 | 199 | Vtemporary_file_directory); |
f1d367aa | 200 | tempname = make_temp_name (tempname, 1); |
9177d978 RS |
201 | args[0] = Vshell_file_name; |
202 | args[1] = Qnil; | |
203 | args[2] = Qnil; | |
204 | args[3] = Qnil; | |
205 | args[4] = build_string ("-c"); | |
77e544a4 | 206 | sprintf (cmd_string, "gunzip < %s.%d.gz > %s", |
d5db4077 | 207 | WTMP_FILE, counter, SDATA (tempname)); |
9177d978 RS |
208 | args[5] = build_string (cmd_string); |
209 | Fcall_process (6, args); | |
210 | filename = tempname; | |
211 | delete_flag = 1; | |
212 | } | |
213 | } | |
214 | ||
215 | if (! NILP (filename)) | |
216 | { | |
42a5b22f | 217 | get_boot_time_1 (SSDATA (filename), 1); |
9177d978 | 218 | if (delete_flag) |
42a5b22f | 219 | unlink (SSDATA (filename)); |
9177d978 RS |
220 | } |
221 | } | |
222 | ||
223 | return boot_time; | |
224 | #else | |
225 | return 0; | |
226 | #endif | |
227 | } | |
228 | ||
e9f22ced | 229 | #ifdef BOOT_TIME |
9177d978 RS |
230 | /* Try to get the boot time from wtmp file FILENAME. |
231 | This succeeds if that file contains a reboot record. | |
9177d978 | 232 | |
b97771fc RS |
233 | If FILENAME is zero, use the same file as before; |
234 | if no FILENAME has ever been specified, this is the utmp file. | |
235 | Use the newest reboot record if NEWEST is nonzero, | |
236 | the first reboot record otherwise. | |
237 | Ignore all reboot records on or before BOOT_TIME. | |
238 | Success is indicated by setting BOOT_TIME to a larger value. */ | |
239 | ||
2f2500ef | 240 | void |
8ea90aa3 | 241 | get_boot_time_1 (const char *filename, int newest) |
9177d978 RS |
242 | { |
243 | struct utmp ut, *utp; | |
77e544a4 RS |
244 | int desc; |
245 | ||
b97771fc RS |
246 | if (filename) |
247 | { | |
248 | /* On some versions of IRIX, opening a nonexistent file name | |
249 | is likely to crash in the utmp routines. */ | |
68c45bf0 | 250 | desc = emacs_open (filename, O_RDONLY, 0); |
b97771fc RS |
251 | if (desc < 0) |
252 | return; | |
253 | ||
68c45bf0 | 254 | emacs_close (desc); |
b97771fc RS |
255 | |
256 | utmpname (filename); | |
257 | } | |
9177d978 | 258 | |
c321b190 | 259 | setutent (); |
b97771fc | 260 | |
c321b190 RS |
261 | while (1) |
262 | { | |
263 | /* Find the next reboot record. */ | |
264 | ut.ut_type = BOOT_TIME; | |
265 | utp = getutid (&ut); | |
266 | if (! utp) | |
267 | break; | |
268 | /* Compare reboot times and use the newest one. */ | |
269 | if (utp->ut_time > boot_time) | |
b97771fc RS |
270 | { |
271 | boot_time = utp->ut_time; | |
272 | if (! newest) | |
273 | break; | |
274 | } | |
c321b190 RS |
275 | /* Advance on element in the file |
276 | so that getutid won't repeat the same one. */ | |
277 | utp = getutent (); | |
278 | if (! utp) | |
279 | break; | |
280 | } | |
15e88d21 | 281 | endutent (); |
15e88d21 | 282 | } |
e9f22ced | 283 | #endif /* BOOT_TIME */ |
15e88d21 | 284 | \f |
8dbbc384 | 285 | /* Here is the structure that stores information about a lock. */ |
32676c08 | 286 | |
8dbbc384 RS |
287 | typedef struct |
288 | { | |
289 | char *user; | |
290 | char *host; | |
9005cb4f | 291 | unsigned long pid; |
15e88d21 | 292 | time_t boot_time; |
8dbbc384 | 293 | } lock_info_type; |
32676c08 | 294 | |
49b6d120 RS |
295 | /* When we read the info back, we might need this much more, |
296 | enough for decimal representation plus null. */ | |
297 | #define LOCK_PID_MAX (4 * sizeof (unsigned long)) | |
32676c08 | 298 | |
8dbbc384 RS |
299 | /* Free the two dynamically-allocated pieces in PTR. */ |
300 | #define FREE_LOCK_INFO(i) do { xfree ((i).user); xfree ((i).host); } while (0) | |
e31fbc7a | 301 | |
e31fbc7a | 302 | |
8dbbc384 | 303 | /* Write the name of the lock file for FN into LFNAME. Length will be |
c1355e1f GM |
304 | that of FN plus two more for the leading `.#' plus 1 for the |
305 | trailing period plus one for the digit after it plus one for the | |
306 | null. */ | |
7b92975f | 307 | #define MAKE_LOCK_NAME(lock, file) \ |
d5db4077 | 308 | (lock = (char *) alloca (SBYTES (file) + 2 + 1 + 1 + 1), \ |
8dbbc384 | 309 | fill_in_lock_file_name (lock, (file))) |
e31fbc7a | 310 | |
8dbbc384 | 311 | static void |
971de7fb | 312 | fill_in_lock_file_name (register char *lockfile, register Lisp_Object fn) |
e31fbc7a | 313 | { |
8dbbc384 | 314 | register char *p; |
c1355e1f GM |
315 | struct stat st; |
316 | int count = 0; | |
8dbbc384 | 317 | |
42a5b22f | 318 | strcpy (lockfile, SSDATA (fn)); |
8dbbc384 RS |
319 | |
320 | /* Shift the nondirectory part of the file name (including the null) | |
321 | right two characters. Here is one of the places where we'd have to | |
322 | do something to support 14-character-max file names. */ | |
323 | for (p = lockfile + strlen (lockfile); p != lockfile && *p != '/'; p--) | |
324 | p[2] = *p; | |
177c0ea7 | 325 | |
8dbbc384 RS |
326 | /* Insert the `.#'. */ |
327 | p[1] = '.'; | |
328 | p[2] = '#'; | |
c1355e1f GM |
329 | |
330 | p = p + strlen (p); | |
331 | ||
332 | while (lstat (lockfile, &st) == 0 && !S_ISLNK (st.st_mode)) | |
333 | { | |
334 | if (count > 9) | |
335 | { | |
336 | *p = '\0'; | |
337 | return; | |
338 | } | |
339 | sprintf (p, ".%d", count++); | |
340 | } | |
8dbbc384 | 341 | } |
e31fbc7a | 342 | |
8dbbc384 RS |
343 | /* Lock the lock file named LFNAME. |
344 | If FORCE is nonzero, we do so even if it is already locked. | |
345 | Return 1 if successful, 0 if not. */ | |
e31fbc7a | 346 | |
8dbbc384 | 347 | static int |
971de7fb | 348 | lock_file_1 (char *lfname, int force) |
8dbbc384 RS |
349 | { |
350 | register int err; | |
bd26d5a3 | 351 | time_t boot_time; |
8ea90aa3 DN |
352 | const char *user_name; |
353 | const char *host_name; | |
662c2ef2 RS |
354 | char *lock_info_str; |
355 | ||
4ba93ac0 AS |
356 | /* Call this first because it can GC. */ |
357 | boot_time = get_boot_time (); | |
358 | ||
662c2ef2 | 359 | if (STRINGP (Fuser_login_name (Qnil))) |
51b59d79 | 360 | user_name = SSDATA (Fuser_login_name (Qnil)); |
662c2ef2 RS |
361 | else |
362 | user_name = ""; | |
363 | if (STRINGP (Fsystem_name ())) | |
51b59d79 | 364 | host_name = SSDATA (Fsystem_name ()); |
662c2ef2 RS |
365 | else |
366 | host_name = ""; | |
266d7a00 | 367 | lock_info_str = (char *)alloca (strlen (user_name) + strlen (host_name) |
4ba93ac0 | 368 | + LOCK_PID_MAX + 30); |
8dbbc384 | 369 | |
bd26d5a3 RS |
370 | if (boot_time) |
371 | sprintf (lock_info_str, "%s@%s.%lu:%lu", user_name, host_name, | |
372 | (unsigned long) getpid (), (unsigned long) boot_time); | |
373 | else | |
374 | sprintf (lock_info_str, "%s@%s.%lu", user_name, host_name, | |
177c0ea7 | 375 | (unsigned long) getpid ()); |
8dbbc384 RS |
376 | |
377 | err = symlink (lock_info_str, lfname); | |
378 | if (errno == EEXIST && force) | |
e31fbc7a | 379 | { |
8dbbc384 RS |
380 | unlink (lfname); |
381 | err = symlink (lock_info_str, lfname); | |
e31fbc7a | 382 | } |
e31fbc7a | 383 | |
8dbbc384 RS |
384 | return err == 0; |
385 | } | |
e31fbc7a | 386 | |
9177d978 | 387 | /* Return 1 if times A and B are no more than one second apart. */ |
32676c08 | 388 | |
9177d978 | 389 | int |
971de7fb | 390 | within_one_second (time_t a, time_t b) |
9177d978 RS |
391 | { |
392 | return (a - b >= -1 && a - b <= 1); | |
393 | } | |
8dbbc384 RS |
394 | \f |
395 | /* Return 0 if nobody owns the lock file LFNAME or the lock is obsolete, | |
396 | 1 if another process owns it (and set OWNER (if non-null) to info), | |
397 | 2 if the current process owns it, | |
398 | or -1 if something is wrong with the locking mechanism. */ | |
e31fbc7a | 399 | |
8dbbc384 | 400 | static int |
971de7fb | 401 | current_lock_owner (lock_info_type *owner, char *lfname) |
32676c08 | 402 | { |
5f8d6a10 | 403 | int len, ret; |
8dbbc384 | 404 | int local_owner = 0; |
15e88d21 | 405 | char *at, *dot, *colon; |
8dbbc384 RS |
406 | char *lfinfo = 0; |
407 | int bufsize = 50; | |
408 | /* Read arbitrarily-long contents of symlink. Similar code in | |
409 | file-symlink-p in fileio.c. */ | |
410 | do | |
411 | { | |
412 | bufsize *= 2; | |
413 | lfinfo = (char *) xrealloc (lfinfo, bufsize); | |
620c4704 | 414 | errno = 0; |
8dbbc384 | 415 | len = readlink (lfname, lfinfo, bufsize); |
b6e97b0a GM |
416 | #ifdef ERANGE |
417 | /* HP-UX reports ERANGE if the buffer is too small. */ | |
418 | if (len == -1 && errno == ERANGE) | |
63680feb | 419 | len = bufsize; |
b6e97b0a | 420 | #endif |
8dbbc384 RS |
421 | } |
422 | while (len >= bufsize); | |
177c0ea7 | 423 | |
8dbbc384 RS |
424 | /* If nonexistent lock file, all is well; otherwise, got strange error. */ |
425 | if (len == -1) | |
426 | { | |
427 | xfree (lfinfo); | |
428 | return errno == ENOENT ? 0 : -1; | |
429 | } | |
32676c08 | 430 | |
8dbbc384 RS |
431 | /* Link info exists, so `len' is its length. Null terminate. */ |
432 | lfinfo[len] = 0; | |
177c0ea7 | 433 | |
8dbbc384 RS |
434 | /* Even if the caller doesn't want the owner info, we still have to |
435 | read it to determine return value, so allocate it. */ | |
436 | if (!owner) | |
437 | { | |
3609a53b | 438 | owner = (lock_info_type *) alloca (sizeof (lock_info_type)); |
8dbbc384 RS |
439 | local_owner = 1; |
440 | } | |
177c0ea7 | 441 | |
15e88d21 | 442 | /* Parse USER@HOST.PID:BOOT_TIME. If can't parse, return -1. */ |
50624218 | 443 | /* The USER is everything before the last @. */ |
8966b757 AS |
444 | at = strrchr (lfinfo, '@'); |
445 | dot = strrchr (lfinfo, '.'); | |
15e88d21 RS |
446 | if (!at || !dot) |
447 | { | |
448 | xfree (lfinfo); | |
449 | return -1; | |
450 | } | |
8dbbc384 RS |
451 | len = at - lfinfo; |
452 | owner->user = (char *) xmalloc (len + 1); | |
453 | strncpy (owner->user, lfinfo, len); | |
454 | owner->user[len] = 0; | |
177c0ea7 | 455 | |
15e88d21 | 456 | /* The PID is everything from the last `.' to the `:'. */ |
8dbbc384 | 457 | owner->pid = atoi (dot + 1); |
15e88d21 RS |
458 | colon = dot; |
459 | while (*colon && *colon != ':') | |
460 | colon++; | |
461 | /* After the `:', if there is one, comes the boot time. */ | |
462 | if (*colon == ':') | |
463 | owner->boot_time = atoi (colon + 1); | |
464 | else | |
465 | owner->boot_time = 0; | |
32676c08 | 466 | |
8dbbc384 RS |
467 | /* The host is everything in between. */ |
468 | len = dot - at - 1; | |
469 | owner->host = (char *) xmalloc (len + 1); | |
470 | strncpy (owner->host, at + 1, len); | |
471 | owner->host[len] = 0; | |
32676c08 | 472 | |
8dbbc384 RS |
473 | /* We're done looking at the link info. */ |
474 | xfree (lfinfo); | |
177c0ea7 | 475 | |
8dbbc384 | 476 | /* On current host? */ |
662c2ef2 | 477 | if (STRINGP (Fsystem_name ()) |
42a5b22f | 478 | && strcmp (owner->host, SSDATA (Fsystem_name ())) == 0) |
32676c08 | 479 | { |
8dbbc384 RS |
480 | if (owner->pid == getpid ()) |
481 | ret = 2; /* We own it. */ | |
72dcef0e | 482 | else if (owner->pid > 0 |
15e88d21 RS |
483 | && (kill (owner->pid, 0) >= 0 || errno == EPERM) |
484 | && (owner->boot_time == 0 | |
9177d978 | 485 | || within_one_second (owner->boot_time, get_boot_time ()))) |
8dbbc384 | 486 | ret = 1; /* An existing process on this machine owns it. */ |
8dbbc384 RS |
487 | /* The owner process is dead or has a strange pid (<=0), so try to |
488 | zap the lockfile. */ | |
72dcef0e | 489 | else if (unlink (lfname) < 0) |
8dbbc384 | 490 | ret = -1; |
72dcef0e RS |
491 | else |
492 | ret = 0; | |
32676c08 | 493 | } |
8dbbc384 RS |
494 | else |
495 | { /* If we wanted to support the check for stale locks on remote machines, | |
496 | here's where we'd do it. */ | |
497 | ret = 1; | |
498 | } | |
177c0ea7 | 499 | |
8dbbc384 RS |
500 | /* Avoid garbage. */ |
501 | if (local_owner || ret <= 0) | |
502 | { | |
503 | FREE_LOCK_INFO (*owner); | |
504 | } | |
505 | return ret; | |
32676c08 JB |
506 | } |
507 | ||
8dbbc384 RS |
508 | \f |
509 | /* Lock the lock named LFNAME if possible. | |
510 | Return 0 in that case. | |
511 | Return positive if some other process owns the lock, and info about | |
512 | that process in CLASHER. | |
513 | Return -1 if cannot lock for any other reason. */ | |
8489eb67 | 514 | |
8dbbc384 | 515 | static int |
971de7fb | 516 | lock_if_free (lock_info_type *clasher, register char *lfname) |
8dbbc384 | 517 | { |
cfc01fa7 | 518 | while (lock_file_1 (lfname, 0) == 0) |
8dbbc384 RS |
519 | { |
520 | int locker; | |
e0e0205b | 521 | |
8dbbc384 RS |
522 | if (errno != EEXIST) |
523 | return -1; | |
177c0ea7 | 524 | |
8dbbc384 RS |
525 | locker = current_lock_owner (clasher, lfname); |
526 | if (locker == 2) | |
527 | { | |
528 | FREE_LOCK_INFO (*clasher); | |
529 | return 0; /* We ourselves locked it. */ | |
530 | } | |
531 | else if (locker == 1) | |
532 | return 1; /* Someone else has it. */ | |
5df0b2fa | 533 | else if (locker == -1) |
ae1ef097 | 534 | return -1; /* current_lock_owner returned strange error. */ |
8dbbc384 | 535 | |
cfc01fa7 | 536 | /* We deleted a stale lock; try again to lock the file. */ |
8dbbc384 RS |
537 | } |
538 | return 0; | |
8489eb67 RS |
539 | } |
540 | ||
8dbbc384 | 541 | /* lock_file locks file FN, |
8489eb67 RS |
542 | meaning it serves notice on the world that you intend to edit that file. |
543 | This should be done only when about to modify a file-visiting | |
544 | buffer previously unmodified. | |
8dbbc384 | 545 | Do not (normally) call this for a buffer already modified, |
8489eb67 RS |
546 | as either the file is already locked, or the user has already |
547 | decided to go ahead without locking. | |
548 | ||
8dbbc384 | 549 | When this returns, either the lock is locked for us, |
8489eb67 RS |
550 | or the user has said to go ahead without locking. |
551 | ||
8dbbc384 | 552 | If the file is locked by someone else, this calls |
8489eb67 | 553 | ask-user-about-lock (a Lisp function) with two arguments, |
8dbbc384 | 554 | the file name and info about the user who did the locking. |
8489eb67 RS |
555 | This function can signal an error, or return t meaning |
556 | take away the lock, or return nil meaning ignore the lock. */ | |
557 | ||
8489eb67 | 558 | void |
971de7fb | 559 | lock_file (Lisp_Object fn) |
8489eb67 | 560 | { |
f4a4528d | 561 | register Lisp_Object attack, orig_fn, encoded_fn; |
8dbbc384 RS |
562 | register char *lfname, *locker; |
563 | lock_info_type lock_info; | |
3edc33a4 | 564 | struct gcpro gcpro1; |
8489eb67 | 565 | |
33bae690 RS |
566 | /* Don't do locking while dumping Emacs. |
567 | Uncompressing wtmp files uses call-process, which does not work | |
568 | in an uninitialized Emacs. */ | |
569 | if (! NILP (Vpurify_flag)) | |
570 | return; | |
571 | ||
5383bc6d | 572 | orig_fn = fn; |
8af8a9ca | 573 | GCPRO1 (fn); |
1e89de84 | 574 | fn = Fexpand_file_name (fn, Qnil); |
f4a4528d | 575 | encoded_fn = ENCODE_FILE (fn); |
1e89de84 | 576 | |
8dbbc384 | 577 | /* Create the name of the lock-file for file fn */ |
f4a4528d | 578 | MAKE_LOCK_NAME (lfname, encoded_fn); |
8489eb67 | 579 | |
32676c08 JB |
580 | /* See if this file is visited and has changed on disk since it was |
581 | visited. */ | |
8489eb67 | 582 | { |
a57bc488 | 583 | register Lisp_Object subject_buf; |
3036594f | 584 | |
5383bc6d | 585 | subject_buf = get_truename_buffer (orig_fn); |
3036594f | 586 | |
265a9e55 JB |
587 | if (!NILP (subject_buf) |
588 | && NILP (Fverify_visited_file_modtime (subject_buf)) | |
589 | && !NILP (Ffile_exists_p (fn))) | |
8489eb67 | 590 | call1 (intern ("ask-user-about-supersession-threat"), fn); |
3036594f | 591 | |
8489eb67 | 592 | } |
8af8a9ca | 593 | UNGCPRO; |
8489eb67 RS |
594 | |
595 | /* Try to lock the lock. */ | |
8dbbc384 RS |
596 | if (lock_if_free (&lock_info, lfname) <= 0) |
597 | /* Return now if we have locked it, or if lock creation failed */ | |
8489eb67 RS |
598 | return; |
599 | ||
600 | /* Else consider breaking the lock */ | |
266d7a00 RS |
601 | locker = (char *) alloca (strlen (lock_info.user) + strlen (lock_info.host) |
602 | + LOCK_PID_MAX + 9); | |
79e51eeb | 603 | sprintf (locker, "%s@%s (pid %lu)", lock_info.user, lock_info.host, |
8dbbc384 RS |
604 | lock_info.pid); |
605 | FREE_LOCK_INFO (lock_info); | |
177c0ea7 | 606 | |
8dbbc384 | 607 | attack = call2 (intern ("ask-user-about-lock"), fn, build_string (locker)); |
265a9e55 | 608 | if (!NILP (attack)) |
8489eb67 RS |
609 | /* User says take the lock */ |
610 | { | |
8dbbc384 | 611 | lock_file_1 (lfname, 1); |
8489eb67 RS |
612 | return; |
613 | } | |
614 | /* User says ignore the lock */ | |
615 | } | |
616 | ||
8489eb67 | 617 | void |
971de7fb | 618 | unlock_file (register Lisp_Object fn) |
8489eb67 RS |
619 | { |
620 | register char *lfname; | |
621 | ||
1e89de84 | 622 | fn = Fexpand_file_name (fn, Qnil); |
88eace34 | 623 | fn = ENCODE_FILE (fn); |
1e89de84 | 624 | |
7b92975f | 625 | MAKE_LOCK_NAME (lfname, fn); |
8489eb67 | 626 | |
8dbbc384 | 627 | if (current_lock_owner (0, lfname) == 2) |
8489eb67 | 628 | unlink (lfname); |
8489eb67 RS |
629 | } |
630 | ||
631 | void | |
971de7fb | 632 | unlock_all_files (void) |
8489eb67 RS |
633 | { |
634 | register Lisp_Object tail; | |
635 | register struct buffer *b; | |
636 | ||
8e50cc2d | 637 | for (tail = Vbuffer_alist; CONSP (tail); tail = XCDR (tail)) |
8489eb67 | 638 | { |
03699b14 | 639 | b = XBUFFER (XCDR (XCAR (tail))); |
5d8ea120 | 640 | if (STRINGP (B_ (b, file_truename)) && BUF_SAVE_MODIFF (b) < BUF_MODIFF (b)) |
1c343051 | 641 | { |
5d8ea120 | 642 | unlock_file(B_ (b, file_truename)); |
1c343051 | 643 | } |
8489eb67 RS |
644 | } |
645 | } | |
8489eb67 RS |
646 | \f |
647 | DEFUN ("lock-buffer", Flock_buffer, Slock_buffer, | |
335c5470 PJ |
648 | 0, 1, 0, |
649 | doc: /* Lock FILE, if current buffer is modified. | |
650 | FILE defaults to current buffer's visited file, | |
651 | or else nothing is done if current buffer isn't visiting a file. */) | |
5842a27b | 652 | (Lisp_Object file) |
8489eb67 | 653 | { |
e9319ef2 | 654 | if (NILP (file)) |
5d8ea120 | 655 | file = B_ (current_buffer, file_truename); |
8489eb67 | 656 | else |
b7826503 | 657 | CHECK_STRING (file); |
6a140159 | 658 | if (SAVE_MODIFF < MODIFF |
e9319ef2 EN |
659 | && !NILP (file)) |
660 | lock_file (file); | |
177c0ea7 | 661 | return Qnil; |
8489eb67 RS |
662 | } |
663 | ||
664 | DEFUN ("unlock-buffer", Funlock_buffer, Sunlock_buffer, | |
335c5470 | 665 | 0, 0, 0, |
3bfb8921 RS |
666 | doc: /* Unlock the file visited in the current buffer. |
667 | If the buffer is not modified, this does nothing because the file | |
668 | should not be locked in that case. */) | |
5842a27b | 669 | (void) |
8489eb67 | 670 | { |
6a140159 | 671 | if (SAVE_MODIFF < MODIFF |
5d8ea120 TT |
672 | && STRINGP (B_ (current_buffer, file_truename))) |
673 | unlock_file (B_ (current_buffer, file_truename)); | |
8489eb67 RS |
674 | return Qnil; |
675 | } | |
676 | ||
8489eb67 RS |
677 | /* Unlock the file visited in buffer BUFFER. */ |
678 | ||
d07e0802 | 679 | void |
971de7fb | 680 | unlock_buffer (struct buffer *buffer) |
8489eb67 | 681 | { |
6a140159 | 682 | if (BUF_SAVE_MODIFF (buffer) < BUF_MODIFF (buffer) |
5d8ea120 TT |
683 | && STRINGP (B_ (buffer, file_truename))) |
684 | unlock_file (B_ (buffer, file_truename)); | |
8489eb67 RS |
685 | } |
686 | ||
8105cbf7 | 687 | DEFUN ("file-locked-p", Ffile_locked_p, Sfile_locked_p, 1, 1, 0, |
3bfb8921 RS |
688 | doc: /* Return a value indicating whether FILENAME is locked. |
689 | The value is nil if the FILENAME is not locked, | |
690 | t if it is locked by you, else a string saying which user has locked it. */) | |
5842a27b | 691 | (Lisp_Object filename) |
8489eb67 | 692 | { |
8dbbc384 | 693 | Lisp_Object ret; |
8489eb67 RS |
694 | register char *lfname; |
695 | int owner; | |
8dbbc384 | 696 | lock_info_type locker; |
8489eb67 | 697 | |
e9319ef2 | 698 | filename = Fexpand_file_name (filename, Qnil); |
8489eb67 | 699 | |
e9319ef2 | 700 | MAKE_LOCK_NAME (lfname, filename); |
8489eb67 | 701 | |
8dbbc384 | 702 | owner = current_lock_owner (&locker, lfname); |
8489eb67 | 703 | if (owner <= 0) |
8dbbc384 RS |
704 | ret = Qnil; |
705 | else if (owner == 2) | |
706 | ret = Qt; | |
707 | else | |
708 | ret = build_string (locker.user); | |
709 | ||
710 | if (owner > 0) | |
711 | FREE_LOCK_INFO (locker); | |
712 | ||
713 | return ret; | |
8489eb67 | 714 | } |
32676c08 JB |
715 | \f |
716 | /* Initialization functions. */ | |
717 | ||
a3fd58aa | 718 | void |
971de7fb | 719 | init_filelock (void) |
a3fd58aa KH |
720 | { |
721 | boot_time = 0; | |
b97771fc | 722 | boot_time_initialized = 0; |
a3fd58aa KH |
723 | } |
724 | ||
ffe75e6b EZ |
725 | #endif /* CLASH_DETECTION */ |
726 | ||
dfcf069d | 727 | void |
971de7fb | 728 | syms_of_filelock (void) |
8489eb67 | 729 | { |
29208e82 | 730 | DEFVAR_LISP ("temporary-file-directory", Vtemporary_file_directory, |
335c5470 | 731 | doc: /* The directory for writing temporary files. */); |
5f8d6a10 RS |
732 | Vtemporary_file_directory = Qnil; |
733 | ||
ffe75e6b | 734 | #ifdef CLASH_DETECTION |
8489eb67 RS |
735 | defsubr (&Sunlock_buffer); |
736 | defsubr (&Slock_buffer); | |
737 | defsubr (&Sfile_locked_p); | |
ffe75e6b | 738 | #endif |
8489eb67 | 739 | } |