Commit | Line | Data |
---|---|---|
b97771fc | 1 | /* Lock files for editing. |
ab422c4d PE |
2 | Copyright (C) 1985-1987, 1993-1994, 1996, 1998-2013 Free Software |
3 | 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> |
bfb61299 | 26 | |
5b9c0a1d | 27 | #ifdef HAVE_PWD_H |
8489eb67 | 28 | #include <pwd.h> |
5b9c0a1d | 29 | #endif |
bfb61299 | 30 | |
8489eb67 | 31 | #include <sys/file.h> |
8489eb67 | 32 | #include <fcntl.h> |
dfcf069d | 33 | #include <unistd.h> |
dfcf069d | 34 | |
f805a125 | 35 | #ifdef __FreeBSD__ |
f805a125 KH |
36 | #include <sys/sysctl.h> |
37 | #endif /* __FreeBSD__ */ | |
38 | ||
e5ef3cdf | 39 | #include <errno.h> |
e5ef3cdf | 40 | |
8489eb67 | 41 | #include "lisp.h" |
d2f6dae8 | 42 | #include "character.h" |
e5560ff7 | 43 | #include "buffer.h" |
f4a4528d | 44 | #include "coding.h" |
9177d978 | 45 | #include "systime.h" |
343a2aef EZ |
46 | #ifdef WINDOWSNT |
47 | #include "w32.h" /* for dostounix_filename */ | |
48 | #endif | |
8489eb67 | 49 | |
8489eb67 | 50 | #ifdef CLASH_DETECTION |
e788eecc | 51 | |
c6d09b8d | 52 | #ifdef HAVE_UTMP_H |
e788eecc | 53 | #include <utmp.h> |
c6d09b8d | 54 | #endif |
77e544a4 | 55 | |
a48de9b2 PE |
56 | /* A file whose last-modified time is just after the most recent boot. |
57 | Define this to be NULL to disable checking for this file. */ | |
58 | #ifndef BOOT_TIME_FILE | |
59 | #define BOOT_TIME_FILE "/var/run/random-seed" | |
60 | #endif | |
61 | ||
77e544a4 RS |
62 | #ifndef WTMP_FILE |
63 | #define WTMP_FILE "/var/log/wtmp" | |
64 | #endif | |
177c0ea7 | 65 | |
8dbbc384 RS |
66 | /* The strategy: to lock a file FN, create a symlink .#FN in FN's |
67 | directory, with link data `user@host.pid'. This avoids a single | |
68 | mount (== failure) point for lock files. | |
69 | ||
70 | When the host in the lock data is the current host, we can check if | |
71 | the pid is valid with kill. | |
177c0ea7 | 72 | |
8dbbc384 RS |
73 | Otherwise, we could look at a separate file that maps hostnames to |
74 | reboot times to see if the remote pid can possibly be valid, since we | |
75 | don't want Emacs to have to communicate via pipes or sockets or | |
76 | whatever to other processes, either locally or remotely; rms says | |
77 | that's too unreliable. Hence the separate file, which could | |
78 | theoretically be updated by daemons running separately -- but this | |
79 | whole idea is unimplemented; in practice, at least in our | |
1c4f857c | 80 | environment, it seems such stale locks arise fairly infrequently, and |
8dbbc384 RS |
81 | Emacs' standard methods of dealing with clashes suffice. |
82 | ||
83 | We use symlinks instead of normal files because (1) they can be | |
84 | stored more efficiently on the filesystem, since the kernel knows | |
85 | they will be small, and (2) all the info about the lock can be read | |
86 | in a single system call (readlink). Although we could use regular | |
1c4f857c | 87 | files to be useful on old systems lacking symlinks, nowadays |
8dbbc384 RS |
88 | virtually all such systems are probably single-user anyway, so it |
89 | didn't seem worth the complication. | |
177c0ea7 | 90 | |
8dbbc384 RS |
91 | Similarly, we don't worry about a possible 14-character limit on |
92 | file names, because those are all the same systems that don't have | |
93 | symlinks. | |
177c0ea7 | 94 | |
8dbbc384 RS |
95 | This is compatible with the locking scheme used by Interleaf (which |
96 | has contributed this implementation for Emacs), and was designed by | |
97 | Ethan Jacobson, Kimbo Mundy, and others. | |
177c0ea7 | 98 | |
8dbbc384 | 99 | --karl@cs.umb.edu/karl@hq.ileaf.com. */ |
8489eb67 | 100 | |
8dbbc384 | 101 | \f |
15e88d21 RS |
102 | /* Return the time of the last system boot. */ |
103 | ||
104 | static time_t boot_time; | |
f75d7a91 | 105 | static bool boot_time_initialized; |
15e88d21 | 106 | |
2f2500ef | 107 | #ifdef BOOT_TIME |
f75d7a91 | 108 | static void get_boot_time_1 (const char *, bool); |
2f2500ef DL |
109 | #endif |
110 | ||
15e88d21 | 111 | static time_t |
971de7fb | 112 | get_boot_time (void) |
15e88d21 | 113 | { |
9d2818d6 | 114 | #if defined (BOOT_TIME) |
9177d978 | 115 | int counter; |
2decc5a9 | 116 | #endif |
15e88d21 | 117 | |
b97771fc | 118 | if (boot_time_initialized) |
15e88d21 | 119 | return boot_time; |
b97771fc | 120 | boot_time_initialized = 1; |
15e88d21 | 121 | |
f805a125 KH |
122 | #if defined (CTL_KERN) && defined (KERN_BOOTTIME) |
123 | { | |
124 | int mib[2]; | |
125 | size_t size; | |
126 | struct timeval boottime_val; | |
127 | ||
128 | mib[0] = CTL_KERN; | |
129 | mib[1] = KERN_BOOTTIME; | |
130 | size = sizeof (boottime_val); | |
131 | ||
132 | if (sysctl (mib, 2, &boottime_val, &size, NULL, 0) >= 0) | |
133 | { | |
134 | boot_time = boottime_val.tv_sec; | |
135 | return boot_time; | |
136 | } | |
137 | } | |
138 | #endif /* defined (CTL_KERN) && defined (KERN_BOOTTIME) */ | |
9177d978 | 139 | |
a48de9b2 PE |
140 | if (BOOT_TIME_FILE) |
141 | { | |
142 | struct stat st; | |
143 | if (stat (BOOT_TIME_FILE, &st) == 0) | |
144 | { | |
145 | boot_time = st.st_mtime; | |
146 | return boot_time; | |
147 | } | |
148 | } | |
149 | ||
9d2818d6 | 150 | #if defined (BOOT_TIME) |
b97771fc RS |
151 | #ifndef CANNOT_DUMP |
152 | /* The utmp routines maintain static state. | |
153 | Don't touch that state unless we are initialized, | |
154 | since it might not survive dumping. */ | |
155 | if (! initialized) | |
156 | return boot_time; | |
157 | #endif /* not CANNOT_DUMP */ | |
158 | ||
159 | /* Try to get boot time from utmp before wtmp, | |
160 | since utmp is typically much smaller than wtmp. | |
161 | Passing a null pointer causes get_boot_time_1 | |
162 | to inspect the default file, namely utmp. */ | |
163 | get_boot_time_1 ((char *) 0, 0); | |
164 | if (boot_time) | |
165 | return boot_time; | |
166 | ||
9177d978 | 167 | /* Try to get boot time from the current wtmp file. */ |
b97771fc | 168 | get_boot_time_1 (WTMP_FILE, 1); |
9177d978 RS |
169 | |
170 | /* If we did not find a boot time in wtmp, look at wtmp, and so on. */ | |
b97771fc | 171 | for (counter = 0; counter < 20 && ! boot_time; counter++) |
9177d978 | 172 | { |
882f0d81 | 173 | char cmd_string[sizeof WTMP_FILE ".19.gz"]; |
9177d978 | 174 | Lisp_Object tempname, filename; |
f75d7a91 | 175 | bool delete_flag = 0; |
9177d978 RS |
176 | |
177 | filename = Qnil; | |
178 | ||
a8290ec3 DA |
179 | tempname = make_formatted_string |
180 | (cmd_string, "%s.%d", WTMP_FILE, counter); | |
29a2adb0 | 181 | if (! NILP (Ffile_exists_p (tempname))) |
9177d978 RS |
182 | filename = tempname; |
183 | else | |
184 | { | |
a8290ec3 DA |
185 | tempname = make_formatted_string (cmd_string, "%s.%d.gz", |
186 | WTMP_FILE, counter); | |
9177d978 RS |
187 | if (! NILP (Ffile_exists_p (tempname))) |
188 | { | |
189 | Lisp_Object args[6]; | |
f1d367aa GM |
190 | |
191 | /* The utmp functions on mescaline.gnu.org accept only | |
192 | file names up to 8 characters long. Choose a 2 | |
193 | character long prefix, and call make_temp_file with | |
194 | second arg non-zero, so that it will add not more | |
195 | than 6 characters to the prefix. */ | |
882f0d81 | 196 | filename = Fexpand_file_name (build_string ("wt"), |
5f8d6a10 | 197 | Vtemporary_file_directory); |
882f0d81 PE |
198 | filename = make_temp_name (filename, 1); |
199 | args[0] = build_string ("gzip"); | |
9177d978 | 200 | args[1] = Qnil; |
882f0d81 | 201 | args[2] = list2 (QCfile, filename); |
9177d978 | 202 | args[3] = Qnil; |
882f0d81 PE |
203 | args[4] = build_string ("-cd"); |
204 | args[5] = tempname; | |
9177d978 | 205 | Fcall_process (6, args); |
9177d978 RS |
206 | delete_flag = 1; |
207 | } | |
208 | } | |
209 | ||
210 | if (! NILP (filename)) | |
211 | { | |
42a5b22f | 212 | get_boot_time_1 (SSDATA (filename), 1); |
9177d978 | 213 | if (delete_flag) |
42a5b22f | 214 | unlink (SSDATA (filename)); |
9177d978 RS |
215 | } |
216 | } | |
217 | ||
218 | return boot_time; | |
219 | #else | |
220 | return 0; | |
221 | #endif | |
222 | } | |
223 | ||
e9f22ced | 224 | #ifdef BOOT_TIME |
9177d978 RS |
225 | /* Try to get the boot time from wtmp file FILENAME. |
226 | This succeeds if that file contains a reboot record. | |
9177d978 | 227 | |
b97771fc RS |
228 | If FILENAME is zero, use the same file as before; |
229 | if no FILENAME has ever been specified, this is the utmp file. | |
f75d7a91 | 230 | Use the newest reboot record if NEWEST, |
b97771fc RS |
231 | the first reboot record otherwise. |
232 | Ignore all reboot records on or before BOOT_TIME. | |
233 | Success is indicated by setting BOOT_TIME to a larger value. */ | |
234 | ||
2f2500ef | 235 | void |
f75d7a91 | 236 | get_boot_time_1 (const char *filename, bool newest) |
9177d978 RS |
237 | { |
238 | struct utmp ut, *utp; | |
77e544a4 RS |
239 | int desc; |
240 | ||
b97771fc RS |
241 | if (filename) |
242 | { | |
243 | /* On some versions of IRIX, opening a nonexistent file name | |
244 | is likely to crash in the utmp routines. */ | |
68c45bf0 | 245 | desc = emacs_open (filename, O_RDONLY, 0); |
b97771fc RS |
246 | if (desc < 0) |
247 | return; | |
248 | ||
68c45bf0 | 249 | emacs_close (desc); |
b97771fc RS |
250 | |
251 | utmpname (filename); | |
252 | } | |
9177d978 | 253 | |
c321b190 | 254 | setutent (); |
b97771fc | 255 | |
c321b190 RS |
256 | while (1) |
257 | { | |
258 | /* Find the next reboot record. */ | |
259 | ut.ut_type = BOOT_TIME; | |
260 | utp = getutid (&ut); | |
261 | if (! utp) | |
262 | break; | |
263 | /* Compare reboot times and use the newest one. */ | |
264 | if (utp->ut_time > boot_time) | |
b97771fc RS |
265 | { |
266 | boot_time = utp->ut_time; | |
267 | if (! newest) | |
268 | break; | |
269 | } | |
c321b190 RS |
270 | /* Advance on element in the file |
271 | so that getutid won't repeat the same one. */ | |
272 | utp = getutent (); | |
273 | if (! utp) | |
274 | break; | |
275 | } | |
15e88d21 | 276 | endutent (); |
15e88d21 | 277 | } |
e9f22ced | 278 | #endif /* BOOT_TIME */ |
15e88d21 | 279 | \f |
8dbbc384 | 280 | /* Here is the structure that stores information about a lock. */ |
32676c08 | 281 | |
8dbbc384 RS |
282 | typedef struct |
283 | { | |
284 | char *user; | |
285 | char *host; | |
882f0d81 | 286 | pid_t pid; |
15e88d21 | 287 | time_t boot_time; |
8dbbc384 | 288 | } lock_info_type; |
32676c08 | 289 | |
8dbbc384 RS |
290 | /* Free the two dynamically-allocated pieces in PTR. */ |
291 | #define FREE_LOCK_INFO(i) do { xfree ((i).user); xfree ((i).host); } while (0) | |
e31fbc7a | 292 | |
e31fbc7a | 293 | |
343a2aef EZ |
294 | /* Write the name of the lock file for FNAME into LOCKNAME. Length |
295 | will be that of FN plus two more for the leading `.#' plus 1 for | |
296 | the trailing period plus one for the digit after it plus one for | |
297 | the null. */ | |
298 | #define MAKE_LOCK_NAME(LOCKNAME, FNAME) \ | |
299 | (LOCKNAME = alloca (SBYTES (FNAME) + 2 + 1 + 1 + 1), \ | |
300 | fill_in_lock_file_name (LOCKNAME, (FNAME))) | |
301 | ||
302 | #ifdef WINDOWSNT | |
303 | /* 256 chars for user, 1024 chars for host, 10 digits for each of 2 int's. */ | |
304 | #define MAX_LFINFO (256 + 1024 + 10 + 10 + 2) | |
305 | /* min size: .@PID */ | |
306 | #define IS_LOCK_FILE(ST) (MAX_LFINFO >= (ST).st_size && (ST).st_size >= 3) | |
307 | #else | |
308 | #define IS_LOCK_FILE(ST) S_ISLNK ((ST).st_mode) | |
309 | #endif | |
e31fbc7a | 310 | |
8dbbc384 | 311 | static void |
971de7fb | 312 | fill_in_lock_file_name (register char *lockfile, register Lisp_Object fn) |
e31fbc7a | 313 | { |
c293e30c | 314 | ptrdiff_t length = SBYTES (fn); |
8dbbc384 | 315 | register char *p; |
c1355e1f GM |
316 | struct stat st; |
317 | int count = 0; | |
8dbbc384 | 318 | |
42a5b22f | 319 | strcpy (lockfile, SSDATA (fn)); |
8dbbc384 RS |
320 | |
321 | /* Shift the nondirectory part of the file name (including the null) | |
322 | right two characters. Here is one of the places where we'd have to | |
323 | do something to support 14-character-max file names. */ | |
c293e30c | 324 | for (p = lockfile + length; p != lockfile && *p != '/'; p--) |
8dbbc384 | 325 | p[2] = *p; |
177c0ea7 | 326 | |
8dbbc384 RS |
327 | /* Insert the `.#'. */ |
328 | p[1] = '.'; | |
329 | p[2] = '#'; | |
c1355e1f | 330 | |
1938d88c | 331 | p = lockfile + length + 2; |
c1355e1f | 332 | |
343a2aef | 333 | while (lstat (lockfile, &st) == 0 && !IS_LOCK_FILE (st)) |
c1355e1f GM |
334 | { |
335 | if (count > 9) | |
336 | { | |
337 | *p = '\0'; | |
338 | return; | |
339 | } | |
340 | sprintf (p, ".%d", count++); | |
341 | } | |
8dbbc384 | 342 | } |
e31fbc7a | 343 | |
343a2aef EZ |
344 | static int |
345 | create_lock_file (char *lfname, char *lock_info_str, bool force) | |
346 | { | |
347 | int err; | |
348 | ||
349 | #ifdef WINDOWSNT | |
350 | /* Symlinks are supported only by latest versions of Windows, and | |
351 | creating them is a privileged operation that often triggers UAC | |
352 | elevation prompts. Therefore, instead of using symlinks, we | |
353 | create a regular file with the lock info written as its | |
354 | contents. */ | |
355 | { | |
356 | int fd = emacs_open (lfname, O_WRONLY | O_BINARY | O_CREAT | O_EXCL, | |
357 | S_IREAD | S_IWRITE); | |
358 | ||
359 | if (fd < 0 && errno == EEXIST && force) | |
360 | fd = emacs_open (lfname, O_WRONLY | O_BINARY | O_TRUNC, | |
361 | S_IREAD | S_IWRITE); | |
362 | if (fd >= 0) | |
363 | { | |
364 | ssize_t lock_info_len = strlen (lock_info_str); | |
365 | ||
366 | err = 0; | |
367 | if (emacs_write (fd, lock_info_str, lock_info_len) != lock_info_len) | |
368 | err = -1; | |
369 | if (emacs_close (fd)) | |
370 | err = -1; | |
371 | } | |
372 | else | |
373 | err = -1; | |
374 | } | |
375 | #else | |
376 | err = symlink (lock_info_str, lfname); | |
377 | if (errno == EEXIST && force) | |
378 | { | |
379 | unlink (lfname); | |
380 | err = symlink (lock_info_str, lfname); | |
381 | } | |
382 | #endif | |
383 | ||
384 | return err; | |
385 | } | |
386 | ||
8dbbc384 | 387 | /* Lock the lock file named LFNAME. |
f75d7a91 PE |
388 | If FORCE, do so even if it is already locked. |
389 | Return true if successful. */ | |
e31fbc7a | 390 | |
f75d7a91 PE |
391 | static bool |
392 | lock_file_1 (char *lfname, bool force) | |
8dbbc384 | 393 | { |
98c6f1e3 | 394 | int err; |
b5cd1905 PE |
395 | int symlink_errno; |
396 | USE_SAFE_ALLOCA; | |
662c2ef2 | 397 | |
4ba93ac0 | 398 | /* Call this first because it can GC. */ |
98c6f1e3 PE |
399 | printmax_t boot = get_boot_time (); |
400 | ||
401 | Lisp_Object luser_name = Fuser_login_name (Qnil); | |
402 | char const *user_name = STRINGP (luser_name) ? SSDATA (luser_name) : ""; | |
403 | Lisp_Object lhost_name = Fsystem_name (); | |
404 | char const *host_name = STRINGP (lhost_name) ? SSDATA (lhost_name) : ""; | |
405 | ptrdiff_t lock_info_size = (strlen (user_name) + strlen (host_name) | |
406 | + 2 * INT_STRLEN_BOUND (printmax_t) | |
407 | + sizeof "@.:"); | |
408 | char *lock_info_str = SAFE_ALLOCA (lock_info_size); | |
409 | printmax_t pid = getpid (); | |
8dbbc384 | 410 | |
b5cd1905 PE |
411 | esprintf (lock_info_str, boot ? "%s@%s.%"pMd":%"pMd : "%s@%s.%"pMd, |
412 | user_name, host_name, pid, boot); | |
343a2aef | 413 | err = create_lock_file (lfname, lock_info_str, force); |
e31fbc7a | 414 | |
b5cd1905 PE |
415 | symlink_errno = errno; |
416 | SAFE_FREE (); | |
417 | errno = symlink_errno; | |
8dbbc384 RS |
418 | return err == 0; |
419 | } | |
e31fbc7a | 420 | |
f75d7a91 | 421 | /* Return true if times A and B are no more than one second apart. */ |
32676c08 | 422 | |
f75d7a91 | 423 | static bool |
971de7fb | 424 | within_one_second (time_t a, time_t b) |
9177d978 RS |
425 | { |
426 | return (a - b >= -1 && a - b <= 1); | |
427 | } | |
8dbbc384 | 428 | \f |
343a2aef EZ |
429 | static Lisp_Object |
430 | read_lock_data (char *lfname) | |
431 | { | |
432 | #ifndef WINDOWSNT | |
433 | return emacs_readlinkat (AT_FDCWD, lfname); | |
434 | #else | |
435 | int fd = emacs_open (lfname, O_RDONLY | O_BINARY, S_IREAD); | |
436 | ssize_t nbytes; | |
437 | char lfinfo[MAX_LFINFO + 1]; | |
438 | ||
439 | if (fd < 0) | |
440 | return Qnil; | |
441 | ||
442 | nbytes = emacs_read (fd, lfinfo, MAX_LFINFO); | |
443 | emacs_close (fd); | |
444 | ||
445 | if (nbytes > 0) | |
446 | { | |
447 | lfinfo[nbytes] = '\0'; | |
448 | return build_string (lfinfo); | |
449 | } | |
450 | else | |
451 | return Qnil; | |
452 | #endif | |
453 | } | |
454 | ||
8dbbc384 RS |
455 | /* Return 0 if nobody owns the lock file LFNAME or the lock is obsolete, |
456 | 1 if another process owns it (and set OWNER (if non-null) to info), | |
457 | 2 if the current process owns it, | |
458 | or -1 if something is wrong with the locking mechanism. */ | |
e31fbc7a | 459 | |
8dbbc384 | 460 | static int |
971de7fb | 461 | current_lock_owner (lock_info_type *owner, char *lfname) |
32676c08 | 462 | { |
d1fdcab7 | 463 | int ret; |
882f0d81 PE |
464 | ptrdiff_t len; |
465 | lock_info_type local_owner; | |
466 | intmax_t n; | |
15e88d21 | 467 | char *at, *dot, *colon; |
343a2aef | 468 | Lisp_Object lfinfo_object = read_lock_data (lfname); |
8654f9d7 PE |
469 | char *lfinfo; |
470 | struct gcpro gcpro1; | |
177c0ea7 | 471 | |
8dbbc384 | 472 | /* If nonexistent lock file, all is well; otherwise, got strange error. */ |
8654f9d7 | 473 | if (NILP (lfinfo_object)) |
d1fdcab7 | 474 | return errno == ENOENT ? 0 : -1; |
8654f9d7 | 475 | lfinfo = SSDATA (lfinfo_object); |
177c0ea7 | 476 | |
8dbbc384 | 477 | /* Even if the caller doesn't want the owner info, we still have to |
882f0d81 | 478 | read it to determine return value. */ |
8dbbc384 | 479 | if (!owner) |
882f0d81 | 480 | owner = &local_owner; |
177c0ea7 | 481 | |
15e88d21 | 482 | /* Parse USER@HOST.PID:BOOT_TIME. If can't parse, return -1. */ |
50624218 | 483 | /* The USER is everything before the last @. */ |
8966b757 AS |
484 | at = strrchr (lfinfo, '@'); |
485 | dot = strrchr (lfinfo, '.'); | |
15e88d21 | 486 | if (!at || !dot) |
8654f9d7 | 487 | return -1; |
8dbbc384 | 488 | len = at - lfinfo; |
8654f9d7 | 489 | GCPRO1 (lfinfo_object); |
23f86fce | 490 | owner->user = xmalloc (len + 1); |
882f0d81 | 491 | memcpy (owner->user, lfinfo, len); |
8dbbc384 | 492 | owner->user[len] = 0; |
177c0ea7 | 493 | |
15e88d21 | 494 | /* The PID is everything from the last `.' to the `:'. */ |
882f0d81 PE |
495 | errno = 0; |
496 | n = strtoimax (dot + 1, NULL, 10); | |
497 | owner->pid = | |
498 | ((0 <= n && n <= TYPE_MAXIMUM (pid_t) | |
499 | && (TYPE_MAXIMUM (pid_t) < INTMAX_MAX || errno != ERANGE)) | |
500 | ? n : 0); | |
501 | ||
502 | colon = strchr (dot + 1, ':'); | |
15e88d21 | 503 | /* After the `:', if there is one, comes the boot time. */ |
882f0d81 PE |
504 | n = 0; |
505 | if (colon) | |
506 | { | |
507 | errno = 0; | |
508 | n = strtoimax (colon + 1, NULL, 10); | |
509 | } | |
510 | owner->boot_time = | |
511 | ((0 <= n && n <= TYPE_MAXIMUM (time_t) | |
512 | && (TYPE_MAXIMUM (time_t) < INTMAX_MAX || errno != ERANGE)) | |
513 | ? n : 0); | |
32676c08 | 514 | |
8dbbc384 RS |
515 | /* The host is everything in between. */ |
516 | len = dot - at - 1; | |
23f86fce | 517 | owner->host = xmalloc (len + 1); |
882f0d81 | 518 | memcpy (owner->host, at + 1, len); |
8dbbc384 | 519 | owner->host[len] = 0; |
32676c08 | 520 | |
8dbbc384 | 521 | /* We're done looking at the link info. */ |
8654f9d7 | 522 | UNGCPRO; |
177c0ea7 | 523 | |
8dbbc384 | 524 | /* On current host? */ |
662c2ef2 | 525 | if (STRINGP (Fsystem_name ()) |
42a5b22f | 526 | && strcmp (owner->host, SSDATA (Fsystem_name ())) == 0) |
32676c08 | 527 | { |
8dbbc384 RS |
528 | if (owner->pid == getpid ()) |
529 | ret = 2; /* We own it. */ | |
72dcef0e | 530 | else if (owner->pid > 0 |
15e88d21 RS |
531 | && (kill (owner->pid, 0) >= 0 || errno == EPERM) |
532 | && (owner->boot_time == 0 | |
9177d978 | 533 | || within_one_second (owner->boot_time, get_boot_time ()))) |
8dbbc384 | 534 | ret = 1; /* An existing process on this machine owns it. */ |
8dbbc384 RS |
535 | /* The owner process is dead or has a strange pid (<=0), so try to |
536 | zap the lockfile. */ | |
72dcef0e | 537 | else if (unlink (lfname) < 0) |
8dbbc384 | 538 | ret = -1; |
72dcef0e RS |
539 | else |
540 | ret = 0; | |
32676c08 | 541 | } |
8dbbc384 RS |
542 | else |
543 | { /* If we wanted to support the check for stale locks on remote machines, | |
544 | here's where we'd do it. */ | |
545 | ret = 1; | |
546 | } | |
177c0ea7 | 547 | |
8dbbc384 | 548 | /* Avoid garbage. */ |
882f0d81 | 549 | if (owner == &local_owner || ret <= 0) |
8dbbc384 RS |
550 | { |
551 | FREE_LOCK_INFO (*owner); | |
552 | } | |
553 | return ret; | |
32676c08 JB |
554 | } |
555 | ||
8dbbc384 RS |
556 | \f |
557 | /* Lock the lock named LFNAME if possible. | |
558 | Return 0 in that case. | |
559 | Return positive if some other process owns the lock, and info about | |
560 | that process in CLASHER. | |
561 | Return -1 if cannot lock for any other reason. */ | |
8489eb67 | 562 | |
8dbbc384 | 563 | static int |
971de7fb | 564 | lock_if_free (lock_info_type *clasher, register char *lfname) |
8dbbc384 | 565 | { |
f75d7a91 | 566 | while (! lock_file_1 (lfname, 0)) |
8dbbc384 RS |
567 | { |
568 | int locker; | |
e0e0205b | 569 | |
8dbbc384 RS |
570 | if (errno != EEXIST) |
571 | return -1; | |
177c0ea7 | 572 | |
8dbbc384 RS |
573 | locker = current_lock_owner (clasher, lfname); |
574 | if (locker == 2) | |
575 | { | |
576 | FREE_LOCK_INFO (*clasher); | |
577 | return 0; /* We ourselves locked it. */ | |
578 | } | |
579 | else if (locker == 1) | |
580 | return 1; /* Someone else has it. */ | |
5df0b2fa | 581 | else if (locker == -1) |
ae1ef097 | 582 | return -1; /* current_lock_owner returned strange error. */ |
8dbbc384 | 583 | |
cfc01fa7 | 584 | /* We deleted a stale lock; try again to lock the file. */ |
8dbbc384 RS |
585 | } |
586 | return 0; | |
8489eb67 RS |
587 | } |
588 | ||
8dbbc384 | 589 | /* lock_file locks file FN, |
8489eb67 RS |
590 | meaning it serves notice on the world that you intend to edit that file. |
591 | This should be done only when about to modify a file-visiting | |
592 | buffer previously unmodified. | |
8dbbc384 | 593 | Do not (normally) call this for a buffer already modified, |
8489eb67 RS |
594 | as either the file is already locked, or the user has already |
595 | decided to go ahead without locking. | |
596 | ||
8dbbc384 | 597 | When this returns, either the lock is locked for us, |
8489eb67 RS |
598 | or the user has said to go ahead without locking. |
599 | ||
8dbbc384 | 600 | If the file is locked by someone else, this calls |
8489eb67 | 601 | ask-user-about-lock (a Lisp function) with two arguments, |
8dbbc384 | 602 | the file name and info about the user who did the locking. |
8489eb67 RS |
603 | This function can signal an error, or return t meaning |
604 | take away the lock, or return nil meaning ignore the lock. */ | |
605 | ||
8489eb67 | 606 | void |
971de7fb | 607 | lock_file (Lisp_Object fn) |
8489eb67 | 608 | { |
f4a4528d | 609 | register Lisp_Object attack, orig_fn, encoded_fn; |
8dbbc384 | 610 | register char *lfname, *locker; |
b5cd1905 | 611 | ptrdiff_t locker_size; |
8dbbc384 | 612 | lock_info_type lock_info; |
a81d11a3 | 613 | printmax_t pid; |
3edc33a4 | 614 | struct gcpro gcpro1; |
b5cd1905 | 615 | USE_SAFE_ALLOCA; |
8489eb67 | 616 | |
836d29b3 DA |
617 | /* Don't do locking if the user has opted out. */ |
618 | if (! create_lockfiles) | |
619 | return; | |
620 | ||
33bae690 RS |
621 | /* Don't do locking while dumping Emacs. |
622 | Uncompressing wtmp files uses call-process, which does not work | |
623 | in an uninitialized Emacs. */ | |
624 | if (! NILP (Vpurify_flag)) | |
625 | return; | |
626 | ||
5383bc6d | 627 | orig_fn = fn; |
8af8a9ca | 628 | GCPRO1 (fn); |
1e89de84 | 629 | fn = Fexpand_file_name (fn, Qnil); |
343a2aef EZ |
630 | #ifdef WINDOWSNT |
631 | /* Ensure we have only '/' separators, to avoid problems with | |
632 | looking (inside fill_in_lock_file_name) for backslashes in file | |
633 | names encoded by some DBCS codepage. */ | |
634 | dostounix_filename (SSDATA (fn), 1); | |
635 | #endif | |
f4a4528d | 636 | encoded_fn = ENCODE_FILE (fn); |
1e89de84 | 637 | |
8dbbc384 | 638 | /* Create the name of the lock-file for file fn */ |
f4a4528d | 639 | MAKE_LOCK_NAME (lfname, encoded_fn); |
8489eb67 | 640 | |
32676c08 JB |
641 | /* See if this file is visited and has changed on disk since it was |
642 | visited. */ | |
8489eb67 | 643 | { |
a57bc488 | 644 | register Lisp_Object subject_buf; |
3036594f | 645 | |
5383bc6d | 646 | subject_buf = get_truename_buffer (orig_fn); |
3036594f | 647 | |
265a9e55 JB |
648 | if (!NILP (subject_buf) |
649 | && NILP (Fverify_visited_file_modtime (subject_buf)) | |
650 | && !NILP (Ffile_exists_p (fn))) | |
8489eb67 | 651 | call1 (intern ("ask-user-about-supersession-threat"), fn); |
3036594f | 652 | |
8489eb67 | 653 | } |
8af8a9ca | 654 | UNGCPRO; |
8489eb67 RS |
655 | |
656 | /* Try to lock the lock. */ | |
8dbbc384 RS |
657 | if (lock_if_free (&lock_info, lfname) <= 0) |
658 | /* Return now if we have locked it, or if lock creation failed */ | |
8489eb67 RS |
659 | return; |
660 | ||
661 | /* Else consider breaking the lock */ | |
b5cd1905 PE |
662 | locker_size = (strlen (lock_info.user) + strlen (lock_info.host) |
663 | + INT_STRLEN_BOUND (printmax_t) | |
664 | + sizeof "@ (pid )"); | |
98c6f1e3 | 665 | locker = SAFE_ALLOCA (locker_size); |
882f0d81 | 666 | pid = lock_info.pid; |
b5cd1905 PE |
667 | esprintf (locker, "%s@%s (pid %"pMd")", |
668 | lock_info.user, lock_info.host, pid); | |
8dbbc384 | 669 | FREE_LOCK_INFO (lock_info); |
177c0ea7 | 670 | |
8dbbc384 | 671 | attack = call2 (intern ("ask-user-about-lock"), fn, build_string (locker)); |
b5cd1905 | 672 | SAFE_FREE (); |
265a9e55 | 673 | if (!NILP (attack)) |
8489eb67 RS |
674 | /* User says take the lock */ |
675 | { | |
8dbbc384 | 676 | lock_file_1 (lfname, 1); |
8489eb67 RS |
677 | return; |
678 | } | |
679 | /* User says ignore the lock */ | |
680 | } | |
681 | ||
8489eb67 | 682 | void |
971de7fb | 683 | unlock_file (register Lisp_Object fn) |
8489eb67 RS |
684 | { |
685 | register char *lfname; | |
686 | ||
1e89de84 | 687 | fn = Fexpand_file_name (fn, Qnil); |
88eace34 | 688 | fn = ENCODE_FILE (fn); |
1e89de84 | 689 | |
7b92975f | 690 | MAKE_LOCK_NAME (lfname, fn); |
8489eb67 | 691 | |
8dbbc384 | 692 | if (current_lock_owner (0, lfname) == 2) |
8489eb67 | 693 | unlink (lfname); |
8489eb67 RS |
694 | } |
695 | ||
696 | void | |
971de7fb | 697 | unlock_all_files (void) |
8489eb67 RS |
698 | { |
699 | register Lisp_Object tail; | |
700 | register struct buffer *b; | |
701 | ||
8e50cc2d | 702 | for (tail = Vbuffer_alist; CONSP (tail); tail = XCDR (tail)) |
8489eb67 | 703 | { |
03699b14 | 704 | b = XBUFFER (XCDR (XCAR (tail))); |
4b4deea2 | 705 | if (STRINGP (BVAR (b, file_truename)) && BUF_SAVE_MODIFF (b) < BUF_MODIFF (b)) |
1c343051 | 706 | { |
5e617bc2 | 707 | unlock_file (BVAR (b, file_truename)); |
1c343051 | 708 | } |
8489eb67 RS |
709 | } |
710 | } | |
8489eb67 RS |
711 | \f |
712 | DEFUN ("lock-buffer", Flock_buffer, Slock_buffer, | |
335c5470 PJ |
713 | 0, 1, 0, |
714 | doc: /* Lock FILE, if current buffer is modified. | |
715 | FILE defaults to current buffer's visited file, | |
716 | or else nothing is done if current buffer isn't visiting a file. */) | |
5842a27b | 717 | (Lisp_Object file) |
8489eb67 | 718 | { |
e9319ef2 | 719 | if (NILP (file)) |
4b4deea2 | 720 | file = BVAR (current_buffer, file_truename); |
8489eb67 | 721 | else |
b7826503 | 722 | CHECK_STRING (file); |
6a140159 | 723 | if (SAVE_MODIFF < MODIFF |
e9319ef2 EN |
724 | && !NILP (file)) |
725 | lock_file (file); | |
177c0ea7 | 726 | return Qnil; |
8489eb67 RS |
727 | } |
728 | ||
a7ca3326 | 729 | DEFUN ("unlock-buffer", Funlock_buffer, Sunlock_buffer, |
335c5470 | 730 | 0, 0, 0, |
3bfb8921 RS |
731 | doc: /* Unlock the file visited in the current buffer. |
732 | If the buffer is not modified, this does nothing because the file | |
733 | should not be locked in that case. */) | |
5842a27b | 734 | (void) |
8489eb67 | 735 | { |
6a140159 | 736 | if (SAVE_MODIFF < MODIFF |
4b4deea2 TT |
737 | && STRINGP (BVAR (current_buffer, file_truename))) |
738 | unlock_file (BVAR (current_buffer, file_truename)); | |
8489eb67 RS |
739 | return Qnil; |
740 | } | |
741 | ||
8489eb67 RS |
742 | /* Unlock the file visited in buffer BUFFER. */ |
743 | ||
d07e0802 | 744 | void |
971de7fb | 745 | unlock_buffer (struct buffer *buffer) |
8489eb67 | 746 | { |
6a140159 | 747 | if (BUF_SAVE_MODIFF (buffer) < BUF_MODIFF (buffer) |
4b4deea2 TT |
748 | && STRINGP (BVAR (buffer, file_truename))) |
749 | unlock_file (BVAR (buffer, file_truename)); | |
8489eb67 RS |
750 | } |
751 | ||
8105cbf7 | 752 | DEFUN ("file-locked-p", Ffile_locked_p, Sfile_locked_p, 1, 1, 0, |
3bfb8921 RS |
753 | doc: /* Return a value indicating whether FILENAME is locked. |
754 | The value is nil if the FILENAME is not locked, | |
755 | t if it is locked by you, else a string saying which user has locked it. */) | |
5842a27b | 756 | (Lisp_Object filename) |
8489eb67 | 757 | { |
8dbbc384 | 758 | Lisp_Object ret; |
8489eb67 RS |
759 | register char *lfname; |
760 | int owner; | |
8dbbc384 | 761 | lock_info_type locker; |
8489eb67 | 762 | |
e9319ef2 | 763 | filename = Fexpand_file_name (filename, Qnil); |
8489eb67 | 764 | |
e9319ef2 | 765 | MAKE_LOCK_NAME (lfname, filename); |
8489eb67 | 766 | |
8dbbc384 | 767 | owner = current_lock_owner (&locker, lfname); |
8489eb67 | 768 | if (owner <= 0) |
8dbbc384 RS |
769 | ret = Qnil; |
770 | else if (owner == 2) | |
771 | ret = Qt; | |
772 | else | |
773 | ret = build_string (locker.user); | |
774 | ||
775 | if (owner > 0) | |
776 | FREE_LOCK_INFO (locker); | |
777 | ||
778 | return ret; | |
8489eb67 | 779 | } |
a3fd58aa | 780 | |
ffe75e6b EZ |
781 | #endif /* CLASH_DETECTION */ |
782 | ||
dfcf069d | 783 | void |
971de7fb | 784 | syms_of_filelock (void) |
8489eb67 | 785 | { |
29208e82 | 786 | DEFVAR_LISP ("temporary-file-directory", Vtemporary_file_directory, |
335c5470 | 787 | doc: /* The directory for writing temporary files. */); |
5f8d6a10 RS |
788 | Vtemporary_file_directory = Qnil; |
789 | ||
836d29b3 DA |
790 | DEFVAR_BOOL ("create-lockfiles", create_lockfiles, |
791 | doc: /* Non-nil means use lockfiles to avoid editing collisions. */); | |
792 | create_lockfiles = 1; | |
793 | ||
ffe75e6b | 794 | #ifdef CLASH_DETECTION |
8489eb67 RS |
795 | defsubr (&Sunlock_buffer); |
796 | defsubr (&Slock_buffer); | |
797 | defsubr (&Sfile_locked_p); | |
ffe75e6b | 798 | #endif |
8489eb67 | 799 | } |