2 * Copyright (c) 1998,1999 Adrian Sun (asun@zoology.washington.edu)
3 * All Rights Reserved. See COPYRIGHT for more information.
5 * Because fcntl locks are
6 * process-oriented, we need to keep around a list of file descriptors
7 * that refer to the same file.
9 * TODO: fix the race when reading/writing.
10 * keep a pool of both locks and reference counters around so that
11 * we can save on mallocs. we should also use a tree to keep things
17 #endif /* HAVE_CONFIG_H */
19 #include <atalk/adouble.h>
20 #include <atalk/logger.h>
21 #include <atalk/compat.h>
22 #include <atalk/errchk.h>
23 #include <atalk/util.h>
34 static const char *shmdstrfromoff(off_t off)
37 case AD_FILELOCK_OPEN_WR:
38 return "OPEN_WR_DATA";
39 case AD_FILELOCK_OPEN_RD:
40 return "OPEN_RD_DATA";
41 case AD_FILELOCK_RSRC_OPEN_WR:
42 return "OPEN_WR_RSRC";
43 case AD_FILELOCK_RSRC_OPEN_RD:
44 return "OPEN_RD_RSRC";
45 case AD_FILELOCK_DENY_WR:
46 return "DENY_WR_DATA";
47 case AD_FILELOCK_DENY_RD:
48 return "DENY_RD_DATA";
49 case AD_FILELOCK_RSRC_DENY_WR:
50 return "DENY_WR_RSRC";
51 case AD_FILELOCK_RSRC_DENY_RD:
52 return "DENY_RD_RSRC";
53 case AD_FILELOCK_OPEN_NONE:
54 return "OPEN_NONE_DATA";
55 case AD_FILELOCK_RSRC_OPEN_NONE:
56 return "OPEN_NONE_RSRC";
62 /* ----------------------- */
63 static int set_lock(int fd, int cmd, struct flock *lock)
67 LOG(log_debug, logtype_default, "set_lock(fd: %d, %s, %s, off: %jd (%s), len: %jd): BEGIN",
68 fd, cmd == F_SETLK ? "F_SETLK" : "F_GETLK",
69 lock->l_type == F_RDLCK ? "F_RDLCK" : lock->l_type == F_WRLCK ? "F_WRLCK" : "F_UNLCK",
70 (intmax_t)lock->l_start,
71 shmdstrfromoff(lock->l_start),
72 (intmax_t)lock->l_len);
75 /* We assign fd = -2 for symlinks -> do nothing */
77 lock->l_type = F_UNLCK;
81 EC_NEG1( fcntl(fd, cmd, lock) );
87 /* ----------------------- */
88 static int XLATE_FCNTL_LOCK(int type)
101 /* ----------------------- */
102 static int OVERLAP(off_t a, off_t alen, off_t b, off_t blen)
104 return (!alen && a <= b) ||
106 ( (a + alen > b) && (b + blen > a) );
109 /* allocation for lock regions. we allocate aggressively and shrink
110 * only in large chunks. */
111 #define ARRAY_BLOCK_SIZE 10
112 #define ARRAY_FREE_DELTA 100
114 /* remove a lock and compact space if necessary */
115 static void adf_freelock(struct ad_fd *ad, const int i)
117 adf_lock_t *lock = ad->adf_lock + i;
119 if (--(*lock->refcount) < 1) {
120 free(lock->refcount);
121 lock->lock.l_type = F_UNLCK;
122 set_lock(ad->adf_fd, F_SETLK, &lock->lock); /* unlock */
127 /* move another lock into the empty space */
128 if (i < ad->adf_lockcount) {
129 memcpy(lock, lock + ad->adf_lockcount - i, sizeof(adf_lock_t));
132 /* free extra cruft if we go past a boundary. we always want to
133 * keep at least some stuff around for allocations. this wastes
134 * a bit of space to save time on reallocations. */
135 if ((ad->adf_lockmax > ARRAY_FREE_DELTA) &&
136 (ad->adf_lockcount + ARRAY_FREE_DELTA < ad->adf_lockmax)) {
137 struct adf_lock_t *tmp;
139 tmp = (struct adf_lock_t *)
140 realloc(ad->adf_lock, sizeof(adf_lock_t)*
141 (ad->adf_lockcount + ARRAY_FREE_DELTA));
144 ad->adf_lockmax = ad->adf_lockcount + ARRAY_FREE_DELTA;
150 /* this needs to deal with the following cases:
151 * 1) free all UNIX byterange lock from any fork
152 * 2) free all locks of the requested fork
154 * i converted to using arrays of locks. everytime a lock
155 * gets removed, we shift all of the locks down.
157 static void adf_unlock(struct adouble *ad, struct ad_fd *adf, const int fork, int unlckbrl)
159 adf_lock_t *lock = adf->adf_lock;
162 for (i = 0; i < adf->adf_lockcount; i++) {
163 if ((unlckbrl && lock[i].lock.l_start < AD_FILELOCK_BASE)
164 || lock[i].user == fork) {
165 /* we're really going to delete this lock. note: read locks
166 are the only ones that allow refcounts > 1 */
167 adf_freelock(adf, i);
168 /* we shifted things down, so we need to backtrack */
170 /* unlikely but realloc may have change adf_lock */
171 lock = adf->adf_lock;
176 /* relock any byte lock that overlaps off/len. unlock everything
178 static void adf_relockrange(struct ad_fd *ad, int fd, off_t off, off_t len)
180 adf_lock_t *lock = ad->adf_lock;
183 for (i = 0; i < ad->adf_lockcount; i++) {
184 if (OVERLAP(off, len, lock[i].lock.l_start, lock[i].lock.l_len))
185 set_lock(fd, F_SETLK, &lock[i].lock);
190 /* find a byte lock that overlaps off/len for a particular open fork */
191 static int adf_findlock(struct ad_fd *ad,
192 const int fork, const int type,
196 adf_lock_t *lock = ad->adf_lock;
199 for (i = 0; i < ad->adf_lockcount; i++) {
200 if ((((type & ADLOCK_RD) && (lock[i].lock.l_type == F_RDLCK)) ||
201 ((type & ADLOCK_WR) && (lock[i].lock.l_type == F_WRLCK))) &&
202 (lock[i].user == fork) &&
203 OVERLAP(off, len, lock[i].lock.l_start, lock[i].lock.l_len)) {
211 /* search other fork lock lists */
212 static int adf_findxlock(struct ad_fd *ad,
213 const int fork, const int type,
217 adf_lock_t *lock = ad->adf_lock;
220 for (i = 0; i < ad->adf_lockcount; i++) {
221 if ((((type & ADLOCK_RD) && (lock[i].lock.l_type == F_RDLCK))
223 ((type & ADLOCK_WR) && (lock[i].lock.l_type == F_WRLCK)))
225 (lock[i].user != fork)
227 OVERLAP(off, len, lock[i].lock.l_start, lock[i].lock.l_len))
233 /* okay, this needs to do the following:
234 * 1) check current list of locks. error on conflict.
235 * 2) apply the lock. error on conflict with another process.
236 * 3) update the list of locks this file has.
238 * NOTE: this treats synchronization locks a little differently. we
239 * do the following things for those:
240 * 1) if the header file exists, all the locks go in the beginning
242 * 2) if the header file doesn't exist, we stick the locks
243 * in the locations specified by AD_FILELOCK_RD/WR.
247 translate a resource fork lock to an offset
249 static off_t rf2off(off_t off)
252 if (off == AD_FILELOCK_OPEN_WR)
253 start = AD_FILELOCK_RSRC_OPEN_WR;
254 else if (off == AD_FILELOCK_OPEN_RD)
255 start = AD_FILELOCK_RSRC_OPEN_RD;
256 else if (off == AD_FILELOCK_DENY_RD)
257 start = AD_FILELOCK_RSRC_DENY_RD;
258 else if (off == AD_FILELOCK_DENY_WR)
259 start = AD_FILELOCK_RSRC_DENY_WR;
260 else if (off == AD_FILELOCK_OPEN_NONE)
261 start = AD_FILELOCK_RSRC_OPEN_NONE;
268 * (1) Test against our own locks array
269 * (2) Test fcntl lock, locks from other processes
271 * @param adf (r) handle
272 * @param off (r) offset
273 * @param len (r) lenght
275 * @returns 1 if there's an existing lock, 0 if there's no lock,
276 * -1 in case any error occured
278 static int testlock(const struct ad_fd *adf, off_t off, off_t len)
286 plock = adf->adf_lock;
287 lock.l_whence = SEEK_SET;
290 /* (1) Do we have a lock ? */
291 for (i = 0; i < adf->adf_lockcount; i++) {
292 if (OVERLAP(lock.l_start, 1, plock[i].lock.l_start, plock[i].lock.l_len))
296 /* (2) Does another process have a lock? */
297 lock.l_type = (adf->adf_flags & O_RDWR) ? F_WRLCK : F_RDLCK;
299 if (set_lock(adf->adf_fd, F_GETLK, &lock) < 0) {
300 /* is that kind of error possible ?*/
301 return (errno == EACCES || errno == EAGAIN) ? 1 : -1;
304 if (lock.l_type == F_UNLCK) {
310 #define LTYPE2STRBUFSIZ 128
311 static const char *locktypetostr(int type)
314 static char buf[LTYPE2STRBUFSIZ];
319 strlcat(buf, "CLR", LTYPE2STRBUFSIZ);
323 if (type & ADLOCK_RD) {
325 strlcat(buf, "|", LTYPE2STRBUFSIZ);
326 strlcat(buf, "RD", LTYPE2STRBUFSIZ);
329 if (type & ADLOCK_WR) {
331 strlcat(buf, "|", LTYPE2STRBUFSIZ);
332 strlcat(buf, "WR", LTYPE2STRBUFSIZ);
335 if (type & ADLOCK_UPGRADE) {
337 strlcat(buf, "|", LTYPE2STRBUFSIZ);
338 strlcat(buf, "UPG", LTYPE2STRBUFSIZ);
341 if (type & ADLOCK_FILELOCK) {
343 strlcat(buf, "|", LTYPE2STRBUFSIZ);
344 strlcat(buf, "FILELOCK", LTYPE2STRBUFSIZ);
351 /******************************************************************************
353 ******************************************************************************/
355 int ad_lock(struct adouble *ad, uint32_t eid, int locktype, off_t off, off_t len, int fork)
363 int ret = 0, fcntl_lock_err = 0;
365 LOG(log_debug, logtype_default, "ad_lock(\"%s\", %s, %s, off: %jd (%s), len: %jd): BEGIN",
366 ad->ad_m_name ? ad->ad_m_name : "???",
367 eid == ADEID_DFORK ? "data" : "reso",
368 locktypetostr(locktype),
373 if ((locktype & ADLOCK_FILELOCK) && (len != 1))
374 AFP_PANIC("lock API error");
378 if (eid == ADEID_DFORK) {
379 adf = &ad->ad_data_fork;
382 if (type & ADLOCK_FILELOCK) {
383 adf = &ad->ad_data_fork;
384 lock.l_start = rf2off(off);
387 lock.l_start = off + ad_getentryoff(ad, ADEID_RFORK);
391 /* NOTE: we can't write lock a read-only file. on those, we just
392 * make sure that we have a read lock set. that way, we at least prevent
393 * someone else from really setting a deny read/write on the file.
395 if (!(adf->adf_flags & O_RDWR) && (type & ADLOCK_WR)) {
396 type = (type & ~ADLOCK_WR) | ADLOCK_RD;
399 lock.l_type = XLATE_FCNTL_LOCK(type & ADLOCK_MASK);
400 lock.l_whence = SEEK_SET;
403 /* byte_lock(len=-1) lock whole file */
404 if (len == BYTELOCK_MAX) {
405 lock.l_len -= lock.l_start; /* otherwise EOVERFLOW error */
408 /* see if it's locked by another fork.
409 * NOTE: this guarantees that any existing locks must be at most
410 * read locks. we use ADLOCK_WR/RD because F_RD/WRLCK aren't
411 * guaranteed to be ORable. */
412 if (adf_findxlock(adf, fork, ADLOCK_WR |
413 ((type & ADLOCK_WR) ? ADLOCK_RD : 0),
414 lock.l_start, lock.l_len) > -1) {
420 /* look for any existing lock that we may have */
421 i = adf_findlock(adf, fork, ADLOCK_RD | ADLOCK_WR, lock.l_start, lock.l_len);
422 adflock = (i < 0) ? NULL : adf->adf_lock + i;
424 /* here's what we check for:
425 1) we're trying to re-lock a lock, but we didn't specify an update.
426 2) we're trying to free only part of a lock.
427 3) we're trying to free a non-existent lock. */
428 if ( (!adflock && (lock.l_type == F_UNLCK))
431 && !(type & ADLOCK_UPGRADE)
432 && ((lock.l_type != F_UNLCK)
433 || (adflock->lock.l_start != lock.l_start)
434 || (adflock->lock.l_len != lock.l_len) ))
442 /* now, update our list of locks */
444 if (lock.l_type == F_UNLCK) {
445 adf_freelock(adf, i);
449 /* attempt to lock the file. */
450 if (set_lock(adf->adf_fd, F_SETLK, &lock) < 0) {
455 /* we upgraded this lock. */
456 if (adflock && (type & ADLOCK_UPGRADE)) {
457 memcpy(&adflock->lock, &lock, sizeof(lock));
461 /* it wasn't an upgrade */
463 if (lock.l_type == F_RDLCK) {
464 oldlock = adf_findxlock(adf, fork, ADLOCK_RD, lock.l_start, lock.l_len);
467 /* no more space. this will also happen if lockmax == lockcount == 0 */
468 if (adf->adf_lockmax == adf->adf_lockcount) {
469 adf_lock_t *tmp = (adf_lock_t *)
470 realloc(adf->adf_lock, sizeof(adf_lock_t)*
471 (adf->adf_lockmax + ARRAY_BLOCK_SIZE));
473 ret = fcntl_lock_err = -1;
477 adf->adf_lockmax += ARRAY_BLOCK_SIZE;
479 adflock = adf->adf_lock + adf->adf_lockcount;
482 memcpy(&adflock->lock, &lock, sizeof(lock));
483 adflock->user = fork;
485 adflock->refcount = (adf->adf_lock + oldlock)->refcount;
486 } else if ((adflock->refcount = calloc(1, sizeof(int))) == NULL) {
487 ret = fcntl_lock_err = 1;
491 (*adflock->refcount)++;
492 adf->adf_lockcount++;
496 if (fcntl_lock_err != 0) {
497 lock.l_type = F_UNLCK;
498 set_lock(adf->adf_fd, F_SETLK, &lock);
501 LOG(log_debug, logtype_default, "ad_lock: END: %d", ret);
505 int ad_tmplock(struct adouble *ad, uint32_t eid, int locktype, off_t off, off_t len, int fork)
512 LOG(log_debug, logtype_default, "ad_tmplock(\"%s\", %s, %s, off: %jd (%s), len: %jd): BEGIN",
513 ad->ad_m_name ? ad->ad_m_name : "???",
514 eid == ADEID_DFORK ? "data" : "reso",
515 locktypetostr(locktype),
523 if (eid == ADEID_DFORK) {
524 adf = &ad->ad_data_fork;
526 adf = &ad->ad_resource_fork;
527 if (adf->adf_fd == -1) {
528 /* there's no resource fork. return success */
532 /* if ADLOCK_FILELOCK we want a lock from offset 0
533 * it's used when deleting a file:
534 * in open we put read locks on meta datas
535 * in delete a write locks on the whole file
536 * so if the file is open by somebody else it fails
538 if (!(type & ADLOCK_FILELOCK))
539 lock.l_start += ad_getentryoff(ad, eid);
542 if (!(adf->adf_flags & O_RDWR) && (type & ADLOCK_WR)) {
543 type = (type & ~ADLOCK_WR) | ADLOCK_RD;
546 lock.l_type = XLATE_FCNTL_LOCK(type & ADLOCK_MASK);
547 lock.l_whence = SEEK_SET;
550 /* see if it's locked by another fork. */
551 if (fork && adf_findxlock(adf, fork,
552 ADLOCK_WR | ((type & ADLOCK_WR) ? ADLOCK_RD : 0),
553 lock.l_start, lock.l_len) > -1) {
559 /* okay, we might have ranges byte-locked. we need to make sure that
560 * we restore the appropriate ranges once we're done. so, we check
561 * for overlap on an unlock and relock.
562 * XXX: in the future, all the byte locks will be sorted and contiguous.
563 * we just want to upgrade all the locks and then downgrade them
565 err = set_lock(adf->adf_fd, F_SETLK, &lock);
566 if (!err && (lock.l_type == F_UNLCK))
567 adf_relockrange(adf, adf->adf_fd, lock.l_start, len);
570 LOG(log_debug, logtype_default, "ad_tmplock: END: %d", err);
574 /* --------------------- */
575 void ad_unlock(struct adouble *ad, const int fork, int unlckbrl)
577 LOG(log_debug, logtype_default, "ad_unlock(\"%s\", unlckbrl: %d): BEGIN",
578 ad->ad_m_name ? ad->ad_m_name : "???", unlckbrl);
580 if (ad_data_fileno(ad) != -1) {
581 adf_unlock(ad, &ad->ad_data_fork, fork, unlckbrl);
583 if (ad_reso_fileno(ad) != -1) {
584 adf_unlock(ad, &ad->ad_resource_fork, fork, unlckbrl);
587 LOG(log_debug, logtype_default, "ad_unlock(\"%s\"): END", ad->ad_m_name ? ad->ad_m_name : "???");
591 * Test for a share mode lock
593 * @param ad (rw) handle
594 * @param eid (r) datafork or ressource fork
595 * @param off (r) sharemode lock to test
597 * @returns 1 if there's an existing lock, 0 if there's no lock,
598 * -1 in case any error occured
600 int ad_testlock(struct adouble *ad, int eid, const off_t off)
605 LOG(log_debug, logtype_default, "ad_testlock(\"%s\", %s, off: %jd (%s): BEGIN",
606 ad->ad_m_name ? ad->ad_m_name : "???",
607 eid == ADEID_DFORK ? "data" : "reso",
609 shmdstrfromoff(off));
611 if (eid == ADEID_DFORK) {
614 lock_offset = rf2off(off);
617 ret = testlock(&ad->ad_data_fork, lock_offset, 1);
619 LOG(log_debug, logtype_default, "ad_testlock: END: %d", ret);
624 * Return if a file is open by another process.
626 * Optimized for the common case:
627 * - there's no locks held by another process (clients)
628 * - or we already know the answer and don't need to test (attrbits)
630 * @param ad (rw) handle
631 * @param attrbits (r) forks opened by us
632 * @returns bitflags ATTRBIT_DOPEN | ATTRBIT_ROPEN if
633 * other process has fork of file opened
635 uint16_t ad_openforks(struct adouble *ad, uint16_t attrbits)
642 if (ad_data_fileno(ad) == -1)
645 if (!(attrbits & (ATTRBIT_DOPEN | ATTRBIT_ROPEN))) {
646 /* Test all 4 locks at once */
647 off = AD_FILELOCK_OPEN_WR;
649 if (testlock(&ad->ad_data_fork, off, len) == 0)
653 /* either there's a lock or we already know one fork is open */
655 if (!(attrbits & ATTRBIT_DOPEN)) {
656 off = AD_FILELOCK_OPEN_WR;
657 ret = testlock(&ad->ad_data_fork, off, 2) > 0 ? ATTRBIT_DOPEN : 0;
660 if (!(attrbits & ATTRBIT_ROPEN)) {
661 off = AD_FILELOCK_RSRC_OPEN_WR;
662 ret |= testlock(&ad->ad_data_fork, off, 2) > 0? ATTRBIT_ROPEN : 0;