]>
Commit | Line | Data |
---|---|---|
021b6e45 JH |
1 | /* |
2 | * Copyright (c) 2005, Junio C Hamano | |
3 | */ | |
021b6e45 | 4 | #include "cache.h" |
697cc8ef | 5 | #include "lockfile.h" |
4a16d072 | 6 | #include "sigchain.h" |
021b6e45 | 7 | |
2091c506 | 8 | static struct lock_file *volatile lock_file_list; |
021b6e45 | 9 | |
013870cd | 10 | static void remove_lock_files(int skip_fclose) |
021b6e45 | 11 | { |
5e635e39 JH |
12 | pid_t me = getpid(); |
13 | ||
021b6e45 | 14 | while (lock_file_list) { |
013870cd MH |
15 | if (lock_file_list->owner == me) { |
16 | /* fclose() is not safe to call in a signal handler */ | |
17 | if (skip_fclose) | |
18 | lock_file_list->fp = NULL; | |
a1754bcc | 19 | rollback_lock_file(lock_file_list); |
013870cd | 20 | } |
021b6e45 JH |
21 | lock_file_list = lock_file_list->next; |
22 | } | |
23 | } | |
24 | ||
013870cd MH |
25 | static void remove_lock_files_on_exit(void) |
26 | { | |
27 | remove_lock_files(0); | |
28 | } | |
29 | ||
316683bd | 30 | static void remove_lock_files_on_signal(int signo) |
021b6e45 | 31 | { |
013870cd | 32 | remove_lock_files(1); |
4a16d072 | 33 | sigchain_pop(signo); |
021b6e45 JH |
34 | raise(signo); |
35 | } | |
36 | ||
5d5a7a67 | 37 | /* |
0c0d6e86 | 38 | * path = absolute or relative path name |
5d5a7a67 | 39 | * |
0c0d6e86 MH |
40 | * Remove the last path name element from path (leaving the preceding |
41 | * "/", if any). If path is empty or the root directory ("/"), set | |
42 | * path to the empty string. | |
5d5a7a67 | 43 | */ |
0c0d6e86 | 44 | static void trim_last_path_component(struct strbuf *path) |
5d5a7a67 | 45 | { |
0c0d6e86 | 46 | int i = path->len; |
5d5a7a67 BS |
47 | |
48 | /* back up past trailing slashes, if any */ | |
0c0d6e86 MH |
49 | while (i && path->buf[i - 1] == '/') |
50 | i--; | |
5d5a7a67 BS |
51 | |
52 | /* | |
0c0d6e86 MH |
53 | * then go backwards until a slash, or the beginning of the |
54 | * string | |
5d5a7a67 | 55 | */ |
0c0d6e86 MH |
56 | while (i && path->buf[i - 1] != '/') |
57 | i--; | |
58 | ||
59 | strbuf_setlen(path, i); | |
5d5a7a67 BS |
60 | } |
61 | ||
62 | ||
63 | /* We allow "recursive" symbolic links. Only within reason, though */ | |
64 | #define MAXDEPTH 5 | |
65 | ||
66 | /* | |
6cad8053 | 67 | * path contains a path that might be a symlink. |
5d5a7a67 | 68 | * |
6cad8053 MH |
69 | * If path is a symlink, attempt to overwrite it with a path to the |
70 | * real file or directory (which may or may not exist), following a | |
71 | * chain of symlinks if necessary. Otherwise, leave path unmodified. | |
5d5a7a67 | 72 | * |
6cad8053 MH |
73 | * This is a best-effort routine. If an error occurs, path will |
74 | * either be left unmodified or will name a different symlink in a | |
75 | * symlink chain that started with the original path. | |
5d5a7a67 | 76 | */ |
6cad8053 | 77 | static void resolve_symlink(struct strbuf *path) |
5d5a7a67 BS |
78 | { |
79 | int depth = MAXDEPTH; | |
5025d845 | 80 | static struct strbuf link = STRBUF_INIT; |
5d5a7a67 BS |
81 | |
82 | while (depth--) { | |
6cad8053 | 83 | if (strbuf_readlink(&link, path->buf, path->len) < 0) |
5025d845 | 84 | break; |
5d5a7a67 | 85 | |
6cad8053 | 86 | if (is_absolute_path(link.buf)) |
5d5a7a67 | 87 | /* absolute path simply replaces p */ |
6cad8053 | 88 | strbuf_reset(path); |
0c0d6e86 | 89 | else |
5d5a7a67 | 90 | /* |
5025d845 | 91 | * link is a relative path, so replace the |
5d5a7a67 BS |
92 | * last element of p with it. |
93 | */ | |
0c0d6e86 | 94 | trim_last_path_component(path); |
6cad8053 MH |
95 | |
96 | strbuf_addbuf(path, &link); | |
5d5a7a67 | 97 | } |
5025d845 | 98 | strbuf_reset(&link); |
5d5a7a67 BS |
99 | } |
100 | ||
447ff1bf | 101 | /* Make sure errno contains a meaningful value on error */ |
acd3b9ec | 102 | static int lock_file(struct lock_file *lk, const char *path, int flags) |
021b6e45 | 103 | { |
6cad8053 | 104 | size_t pathlen = strlen(path); |
2fbd4f92 | 105 | |
04e57d4d MH |
106 | if (!lock_file_list) { |
107 | /* One-time initialization */ | |
316683bd | 108 | sigchain_push_common(remove_lock_files_on_signal); |
013870cd | 109 | atexit(remove_lock_files_on_exit); |
04e57d4d MH |
110 | } |
111 | ||
707103fd MH |
112 | if (lk->active) |
113 | die("BUG: cannot lock_file(\"%s\") using active struct lock_file", | |
114 | path); | |
04e57d4d MH |
115 | if (!lk->on_list) { |
116 | /* Initialize *lk and add it to lock_file_list: */ | |
117 | lk->fd = -1; | |
013870cd | 118 | lk->fp = NULL; |
707103fd | 119 | lk->active = 0; |
04e57d4d | 120 | lk->owner = 0; |
6cad8053 | 121 | strbuf_init(&lk->filename, pathlen + LOCK_SUFFIX_LEN); |
04e57d4d MH |
122 | lk->next = lock_file_list; |
123 | lock_file_list = lk; | |
124 | lk->on_list = 1; | |
cf6950d3 MH |
125 | } else if (lk->filename.len) { |
126 | /* This shouldn't happen, but better safe than sorry. */ | |
127 | die("BUG: lock_file(\"%s\") called with improperly-reset lock_file object", | |
128 | path); | |
04e57d4d MH |
129 | } |
130 | ||
fa137f67 NTND |
131 | if (flags & LOCK_NO_DEREF) { |
132 | strbuf_add_absolute_path(&lk->filename, path); | |
133 | } else { | |
134 | struct strbuf resolved_path = STRBUF_INIT; | |
135 | ||
136 | strbuf_add(&resolved_path, path, pathlen); | |
137 | resolve_symlink(&resolved_path); | |
138 | strbuf_add_absolute_path(&lk->filename, resolved_path.buf); | |
139 | strbuf_release(&resolved_path); | |
140 | } | |
141 | ||
cf6950d3 MH |
142 | strbuf_addstr(&lk->filename, LOCK_SUFFIX); |
143 | lk->fd = open(lk->filename.buf, O_RDWR | O_CREAT | O_EXCL, 0666); | |
e31e949b | 144 | if (lk->fd < 0) { |
cf6950d3 | 145 | strbuf_reset(&lk->filename); |
2fbd4f92 | 146 | return -1; |
447ff1bf | 147 | } |
e31e949b | 148 | lk->owner = getpid(); |
707103fd | 149 | lk->active = 1; |
cf6950d3 | 150 | if (adjust_shared_perm(lk->filename.buf)) { |
e31e949b | 151 | int save_errno = errno; |
cf6950d3 | 152 | error("cannot fix permission bits on %s", lk->filename.buf); |
e31e949b MH |
153 | rollback_lock_file(lk); |
154 | errno = save_errno; | |
155 | return -1; | |
021b6e45 | 156 | } |
4723ee99 | 157 | return lk->fd; |
021b6e45 JH |
158 | } |
159 | ||
044b6a9e MH |
160 | /* |
161 | * Constants defining the gaps between attempts to lock a file. The | |
162 | * first backoff period is approximately INITIAL_BACKOFF_MS | |
163 | * milliseconds. The longest backoff period is approximately | |
164 | * (BACKOFF_MAX_MULTIPLIER * INITIAL_BACKOFF_MS) milliseconds. | |
165 | */ | |
166 | #define INITIAL_BACKOFF_MS 1L | |
167 | #define BACKOFF_MAX_MULTIPLIER 1000 | |
168 | ||
169 | /* | |
170 | * Try locking path, retrying with quadratic backoff for at least | |
171 | * timeout_ms milliseconds. If timeout_ms is 0, try locking the file | |
172 | * exactly once. If timeout_ms is -1, try indefinitely. | |
173 | */ | |
174 | static int lock_file_timeout(struct lock_file *lk, const char *path, | |
175 | int flags, long timeout_ms) | |
176 | { | |
177 | int n = 1; | |
178 | int multiplier = 1; | |
a8a17756 | 179 | long remaining_ms = 0; |
044b6a9e MH |
180 | static int random_initialized = 0; |
181 | ||
182 | if (timeout_ms == 0) | |
183 | return lock_file(lk, path, flags); | |
184 | ||
185 | if (!random_initialized) { | |
1e9676ec | 186 | srand((unsigned int)getpid()); |
044b6a9e MH |
187 | random_initialized = 1; |
188 | } | |
189 | ||
a8a17756 JS |
190 | if (timeout_ms > 0) |
191 | remaining_ms = timeout_ms; | |
044b6a9e MH |
192 | |
193 | while (1) { | |
a8a17756 | 194 | long backoff_ms, wait_ms; |
044b6a9e MH |
195 | int fd; |
196 | ||
197 | fd = lock_file(lk, path, flags); | |
198 | ||
199 | if (fd >= 0) | |
200 | return fd; /* success */ | |
201 | else if (errno != EEXIST) | |
202 | return -1; /* failure other than lock held */ | |
a8a17756 | 203 | else if (timeout_ms > 0 && remaining_ms <= 0) |
044b6a9e MH |
204 | return -1; /* failure due to timeout */ |
205 | ||
206 | backoff_ms = multiplier * INITIAL_BACKOFF_MS; | |
207 | /* back off for between 0.75*backoff_ms and 1.25*backoff_ms */ | |
a8a17756 | 208 | wait_ms = (750 + rand() % 500) * backoff_ms / 1000; |
30f8160d | 209 | sleep_millisec(wait_ms); |
a8a17756 | 210 | remaining_ms -= wait_ms; |
044b6a9e MH |
211 | |
212 | /* Recursion: (n+1)^2 = n^2 + 2n + 1 */ | |
213 | multiplier += 2*n + 1; | |
214 | if (multiplier > BACKOFF_MAX_MULTIPLIER) | |
215 | multiplier = BACKOFF_MAX_MULTIPLIER; | |
216 | else | |
217 | n++; | |
218 | } | |
219 | } | |
220 | ||
6af926e8 | 221 | void unable_to_lock_message(const char *path, int err, struct strbuf *buf) |
e43a6fd3 | 222 | { |
bdfd739d | 223 | if (err == EEXIST) { |
6af926e8 | 224 | strbuf_addf(buf, "Unable to create '%s.lock': %s.\n\n" |
e43a6fd3 MM |
225 | "If no other git process is currently running, this probably means a\n" |
226 | "git process crashed in this repository earlier. Make sure no other git\n" | |
227 | "process is running and remove the file manually to continue.", | |
e2a57aac | 228 | absolute_path(path), strerror(err)); |
1b018fd9 | 229 | } else |
6af926e8 | 230 | strbuf_addf(buf, "Unable to create '%s.lock': %s", |
e2a57aac | 231 | absolute_path(path), strerror(err)); |
1b018fd9 MV |
232 | } |
233 | ||
e197c218 | 234 | NORETURN void unable_to_lock_die(const char *path, int err) |
1b018fd9 | 235 | { |
6af926e8 RS |
236 | struct strbuf buf = STRBUF_INIT; |
237 | ||
238 | unable_to_lock_message(path, err, &buf); | |
239 | die("%s", buf.buf); | |
e43a6fd3 MM |
240 | } |
241 | ||
447ff1bf | 242 | /* This should return a meaningful errno on failure */ |
044b6a9e MH |
243 | int hold_lock_file_for_update_timeout(struct lock_file *lk, const char *path, |
244 | int flags, long timeout_ms) | |
40aaae88 | 245 | { |
044b6a9e | 246 | int fd = lock_file_timeout(lk, path, flags, timeout_ms); |
acd3b9ec | 247 | if (fd < 0 && (flags & LOCK_DIE_ON_ERROR)) |
e197c218 | 248 | unable_to_lock_die(path, errno); |
40aaae88 JH |
249 | return fd; |
250 | } | |
251 | ||
acd3b9ec | 252 | int hold_lock_file_for_append(struct lock_file *lk, const char *path, int flags) |
ea3cd5c7 DB |
253 | { |
254 | int fd, orig_fd; | |
255 | ||
acd3b9ec | 256 | fd = lock_file(lk, path, flags); |
ea3cd5c7 | 257 | if (fd < 0) { |
acd3b9ec | 258 | if (flags & LOCK_DIE_ON_ERROR) |
e197c218 | 259 | unable_to_lock_die(path, errno); |
ea3cd5c7 DB |
260 | return fd; |
261 | } | |
262 | ||
263 | orig_fd = open(path, O_RDONLY); | |
264 | if (orig_fd < 0) { | |
265 | if (errno != ENOENT) { | |
4d423a3e MH |
266 | int save_errno = errno; |
267 | ||
acd3b9ec | 268 | if (flags & LOCK_DIE_ON_ERROR) |
ea3cd5c7 | 269 | die("cannot open '%s' for copying", path); |
ebb8e380 | 270 | rollback_lock_file(lk); |
4d423a3e MH |
271 | error("cannot open '%s' for copying", path); |
272 | errno = save_errno; | |
273 | return -1; | |
ea3cd5c7 DB |
274 | } |
275 | } else if (copy_fd(orig_fd, fd)) { | |
4d423a3e MH |
276 | int save_errno = errno; |
277 | ||
acd3b9ec | 278 | if (flags & LOCK_DIE_ON_ERROR) |
00b7cbfc | 279 | die("failed to prepare '%s' for appending", path); |
b29763aa | 280 | close(orig_fd); |
ebb8e380 | 281 | rollback_lock_file(lk); |
4d423a3e | 282 | errno = save_errno; |
ea3cd5c7 | 283 | return -1; |
b29763aa SP |
284 | } else { |
285 | close(orig_fd); | |
ea3cd5c7 DB |
286 | } |
287 | return fd; | |
288 | } | |
289 | ||
013870cd MH |
290 | FILE *fdopen_lock_file(struct lock_file *lk, const char *mode) |
291 | { | |
292 | if (!lk->active) | |
293 | die("BUG: fdopen_lock_file() called for unlocked object"); | |
294 | if (lk->fp) | |
295 | die("BUG: fdopen_lock_file() called twice for file '%s'", lk->filename.buf); | |
296 | ||
297 | lk->fp = fdopen(lk->fd, mode); | |
298 | return lk->fp; | |
299 | } | |
300 | ||
ec38b4e4 MH |
301 | char *get_locked_file_path(struct lock_file *lk) |
302 | { | |
303 | if (!lk->active) | |
304 | die("BUG: get_locked_file_path() called for unlocked object"); | |
305 | if (lk->filename.len <= LOCK_SUFFIX_LEN) | |
306 | die("BUG: get_locked_file_path() called for malformed lock object"); | |
307 | return xmemdupz(lk->filename.buf, lk->filename.len - LOCK_SUFFIX_LEN); | |
308 | } | |
309 | ||
d6cf61bf BC |
310 | int close_lock_file(struct lock_file *lk) |
311 | { | |
312 | int fd = lk->fd; | |
013870cd MH |
313 | FILE *fp = lk->fp; |
314 | int err; | |
419f0c0f MH |
315 | |
316 | if (fd < 0) | |
317 | return 0; | |
318 | ||
d6cf61bf | 319 | lk->fd = -1; |
013870cd MH |
320 | if (fp) { |
321 | lk->fp = NULL; | |
322 | ||
323 | /* | |
324 | * Note: no short-circuiting here; we want to fclose() | |
325 | * in any case! | |
326 | */ | |
327 | err = ferror(fp) | fclose(fp); | |
328 | } else { | |
329 | err = close(fd); | |
330 | } | |
331 | ||
332 | if (err) { | |
8e86c155 MH |
333 | int save_errno = errno; |
334 | rollback_lock_file(lk); | |
335 | errno = save_errno; | |
336 | return -1; | |
337 | } | |
013870cd | 338 | |
8e86c155 | 339 | return 0; |
d6cf61bf BC |
340 | } |
341 | ||
93dcaea2 JH |
342 | int reopen_lock_file(struct lock_file *lk) |
343 | { | |
344 | if (0 <= lk->fd) | |
345 | die(_("BUG: reopen a lockfile that is still open")); | |
707103fd | 346 | if (!lk->active) |
93dcaea2 | 347 | die(_("BUG: reopen a lockfile that has been committed")); |
cf6950d3 | 348 | lk->fd = open(lk->filename.buf, O_WRONLY); |
93dcaea2 JH |
349 | return lk->fd; |
350 | } | |
351 | ||
751baced | 352 | int commit_lock_file_to(struct lock_file *lk, const char *path) |
021b6e45 | 353 | { |
707103fd | 354 | if (!lk->active) |
751baced | 355 | die("BUG: attempt to commit unlocked object to \"%s\"", path); |
8a1c7533 | 356 | |
419f0c0f | 357 | if (close_lock_file(lk)) |
d6cf61bf | 358 | return -1; |
4f4713df | 359 | |
751baced | 360 | if (rename(lk->filename.buf, path)) { |
1b1648f4 MH |
361 | int save_errno = errno; |
362 | rollback_lock_file(lk); | |
363 | errno = save_errno; | |
d6cf61bf | 364 | return -1; |
1b1648f4 MH |
365 | } |
366 | ||
707103fd | 367 | lk->active = 0; |
cf6950d3 | 368 | strbuf_reset(&lk->filename); |
d6cf61bf | 369 | return 0; |
021b6e45 JH |
370 | } |
371 | ||
751baced | 372 | int commit_lock_file(struct lock_file *lk) |
30ca07a2 | 373 | { |
751baced MH |
374 | static struct strbuf result_file = STRBUF_INIT; |
375 | int err; | |
376 | ||
377 | if (!lk->active) | |
378 | die("BUG: attempt to commit unlocked object"); | |
379 | ||
380 | if (lk->filename.len <= LOCK_SUFFIX_LEN || | |
381 | strcmp(lk->filename.buf + lk->filename.len - LOCK_SUFFIX_LEN, LOCK_SUFFIX)) | |
382 | die("BUG: lockfile filename corrupt"); | |
383 | ||
384 | /* remove ".lock": */ | |
385 | strbuf_add(&result_file, lk->filename.buf, | |
386 | lk->filename.len - LOCK_SUFFIX_LEN); | |
387 | err = commit_lock_file_to(lk, result_file.buf); | |
388 | strbuf_reset(&result_file); | |
389 | return err; | |
30ca07a2 JH |
390 | } |
391 | ||
021b6e45 JH |
392 | void rollback_lock_file(struct lock_file *lk) |
393 | { | |
707103fd | 394 | if (!lk->active) |
9085f8e2 MH |
395 | return; |
396 | ||
8e86c155 | 397 | if (!close_lock_file(lk)) { |
cf6950d3 | 398 | unlink_or_warn(lk->filename.buf); |
707103fd | 399 | lk->active = 0; |
cf6950d3 | 400 | strbuf_reset(&lk->filename); |
4723ee99 | 401 | } |
021b6e45 | 402 | } |