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>
33 /* ----------------------- */
34 static int set_lock(int fd, int cmd, struct flock *lock)
38 LOG(log_debug, logtype_default, "set_lock(%s, %s, off: %jd, len: %jd): BEGIN",
39 cmd == F_SETLK ? "F_SETLK" : "F_GETLK",
40 lock->l_type == F_RDLCK ? "F_RDLCK" : lock->l_type == F_WRLCK ? "F_WRLCK" : "F_UNLCK",
41 (intmax_t)lock->l_start, (intmax_t)lock->l_len);
44 /* We assign fd = -2 for symlinks -> do nothing */
46 lock->l_type = F_UNLCK;
50 EC_NEG1_LOGSTR( fcntl(fd, cmd, lock),
51 "set_lock: %s", strerror(errno));
57 /* ----------------------- */
58 static int XLATE_FCNTL_LOCK(int type)
71 /* ----------------------- */
72 static int OVERLAP(off_t a, off_t alen, off_t b, off_t blen)
74 return (!alen && a <= b) ||
76 ( (a + alen > b) && (b + blen > a) );
79 /* allocation for lock regions. we allocate aggressively and shrink
80 * only in large chunks. */
81 #define ARRAY_BLOCK_SIZE 10
82 #define ARRAY_FREE_DELTA 100
84 /* remove a lock and compact space if necessary */
85 static void adf_freelock(struct ad_fd *ad, const int i)
87 adf_lock_t *lock = ad->adf_lock + i;
89 if (--(*lock->refcount) < 1) {
91 lock->lock.l_type = F_UNLCK;
92 set_lock(ad->adf_fd, F_SETLK, &lock->lock); /* unlock */
97 /* move another lock into the empty space */
98 if (i < ad->adf_lockcount) {
99 memcpy(lock, lock + ad->adf_lockcount - i, sizeof(adf_lock_t));
102 /* free extra cruft if we go past a boundary. we always want to
103 * keep at least some stuff around for allocations. this wastes
104 * a bit of space to save time on reallocations. */
105 if ((ad->adf_lockmax > ARRAY_FREE_DELTA) &&
106 (ad->adf_lockcount + ARRAY_FREE_DELTA < ad->adf_lockmax)) {
107 struct adf_lock_t *tmp;
109 tmp = (struct adf_lock_t *)
110 realloc(ad->adf_lock, sizeof(adf_lock_t)*
111 (ad->adf_lockcount + ARRAY_FREE_DELTA));
114 ad->adf_lockmax = ad->adf_lockcount + ARRAY_FREE_DELTA;
120 /* this needs to deal with the following cases:
121 * 1) fork is the only user of the lock
122 * 2) fork shares a read lock with another open fork
124 * i converted to using arrays of locks. everytime a lock
125 * gets removed, we shift all of the locks down.
127 static void adf_unlock(struct ad_fd *ad, const int fork)
129 adf_lock_t *lock = ad->adf_lock;
132 for (i = 0; i < ad->adf_lockcount; i++) {
134 if (lock[i].user == fork) {
135 /* we're really going to delete this lock. note: read locks
136 are the only ones that allow refcounts > 1 */
138 i--; /* we shifted things down, so we need to backtrack */
139 /* unlikely but realloc may have change adf_lock */
145 /* relock any byte lock that overlaps off/len. unlock everything
147 static void adf_relockrange(struct ad_fd *ad, int fd, off_t off, off_t len)
149 adf_lock_t *lock = ad->adf_lock;
152 for (i = 0; i < ad->adf_lockcount; i++) {
153 if (OVERLAP(off, len, lock[i].lock.l_start, lock[i].lock.l_len))
154 set_lock(fd, F_SETLK, &lock[i].lock);
159 /* find a byte lock that overlaps off/len for a particular open fork */
160 static int adf_findlock(struct ad_fd *ad,
161 const int fork, const int type,
165 adf_lock_t *lock = ad->adf_lock;
168 for (i = 0; i < ad->adf_lockcount; i++) {
169 if ((((type & ADLOCK_RD) && (lock[i].lock.l_type == F_RDLCK)) ||
170 ((type & ADLOCK_WR) && (lock[i].lock.l_type == F_WRLCK))) &&
171 (lock[i].user == fork) &&
172 OVERLAP(off, len, lock[i].lock.l_start, lock[i].lock.l_len)) {
180 /* search other fork lock lists */
181 static int adf_findxlock(struct ad_fd *ad,
182 const int fork, const int type,
186 adf_lock_t *lock = ad->adf_lock;
189 for (i = 0; i < ad->adf_lockcount; i++) {
190 if ((((type & ADLOCK_RD) && (lock[i].lock.l_type == F_RDLCK))
192 ((type & ADLOCK_WR) && (lock[i].lock.l_type == F_WRLCK)))
194 (lock[i].user != fork)
196 OVERLAP(off, len, lock[i].lock.l_start, lock[i].lock.l_len))
202 /* okay, this needs to do the following:
203 * 1) check current list of locks. error on conflict.
204 * 2) apply the lock. error on conflict with another process.
205 * 3) update the list of locks this file has.
207 * NOTE: this treats synchronization locks a little differently. we
208 * do the following things for those:
209 * 1) if the header file exists, all the locks go in the beginning
211 * 2) if the header file doesn't exist, we stick the locks
212 * in the locations specified by AD_FILELOCK_RD/WR.
214 #define LOCK_DATA_WR (0)
215 #define LOCK_DATA_RD (1)
216 #define LOCK_RSRC_WR (2)
217 #define LOCK_RSRC_RD (3)
219 #define LOCK_RSRC_DRD (4)
220 #define LOCK_RSRC_DWR (5)
221 #define LOCK_DATA_DRD (6)
222 #define LOCK_DATA_DWR (7)
224 #define LOCK_RSRC_NONE (8)
225 #define LOCK_DATA_NONE (9)
228 translate a data fork lock to an offset
231 static off_t df2off(off_t off)
234 if (off == AD_FILELOCK_OPEN_WR)
235 start = LOCK_DATA_WR;
236 else if (off == AD_FILELOCK_OPEN_RD)
237 start = LOCK_DATA_RD;
238 else if (off == AD_FILELOCK_DENY_RD)
239 start = LOCK_DATA_DRD;
240 else if (off == AD_FILELOCK_DENY_WR)
241 start = LOCK_DATA_DWR;
242 else if (off == AD_FILELOCK_OPEN_NONE)
243 start = LOCK_DATA_NONE;
248 translate a resource fork lock to an offset
251 static off_t hf2off(off_t off)
254 if (off == AD_FILELOCK_OPEN_WR)
255 start = LOCK_RSRC_WR;
256 else if (off == AD_FILELOCK_OPEN_RD)
257 start = LOCK_RSRC_RD;
258 else if (off == AD_FILELOCK_DENY_RD)
259 start = LOCK_RSRC_DRD;
260 else if (off == AD_FILELOCK_DENY_WR)
261 start = LOCK_RSRC_DWR;
262 else if (off == AD_FILELOCK_OPEN_NONE)
263 start = LOCK_RSRC_NONE;
268 translate a resource fork lock to an offset
270 static off_t rf2off(off_t off)
273 if (off == AD_FILELOCK_OPEN_WR)
274 start = AD_FILELOCK_RSRC_OPEN_WR;
275 else if (off == AD_FILELOCK_OPEN_RD)
276 start = AD_FILELOCK_RSRC_OPEN_RD;
277 else if (off == AD_FILELOCK_DENY_RD)
278 start = AD_FILELOCK_RSRC_DENY_RD;
279 else if (off == AD_FILELOCK_DENY_WR)
280 start = AD_FILELOCK_RSRC_DENY_WR;
281 else if (off == AD_FILELOCK_OPEN_NONE)
282 start = AD_FILELOCK_RSRC_OPEN_NONE;
289 * (1) Test against our own locks array
290 * (2) Test fcntl lock, locks from other processes
292 * @param adf (r) handle
293 * @param off (r) offset
294 * @param len (r) lenght
296 * @returns 1 if there's an existing lock, 0 if there's no lock,
297 * -1 in case any error occured
299 static int testlock(const struct ad_fd *adf, off_t off, off_t len)
307 plock = adf->adf_lock;
308 lock.l_whence = SEEK_SET;
311 /* (1) Do we have a lock ? */
312 for (i = 0; i < adf->adf_lockcount; i++) {
313 if (OVERLAP(lock.l_start, 1, plock[i].lock.l_start, plock[i].lock.l_len))
317 /* (2) Does another process have a lock? */
318 lock.l_type = (adf->adf_flags & O_RDWR) ? F_WRLCK : F_RDLCK;
320 if (set_lock(adf->adf_fd, F_GETLK, &lock) < 0) {
321 /* is that kind of error possible ?*/
322 return (errno == EACCES || errno == EAGAIN) ? 1 : -1;
325 if (lock.l_type == F_UNLCK) {
331 static uint16_t ad_openforks_v2(struct adouble *ad, uint16_t attrbits)
337 if (!(attrbits & (ATTRBIT_DOPEN | ATTRBIT_ROPEN))) {
339 /* XXX know the locks layout:
340 AD_FILELOCK_OPEN_WR is first
341 and use it for merging requests
343 if (ad_meta_fileno(ad) != -1) {
344 /* there's a resource fork test the four bytes for
345 * data RW/RD and fork RW/RD locks in one request
352 /* no resource fork, only data RD/RW may exist */
353 adf = &ad->ad_data_fork;
354 off = AD_FILELOCK_OPEN_WR;
357 if (!testlock(adf, off, len))
360 /* either there's a lock or we already know one
363 if (!(attrbits & ATTRBIT_DOPEN)) {
364 if (ad_meta_fileno(ad) != -1) {
369 adf = &ad->ad_data_fork;
370 off = AD_FILELOCK_OPEN_WR;
372 ret = testlock(adf, off, 2) > 0? ATTRBIT_DOPEN : 0;
375 if (!(attrbits & ATTRBIT_ROPEN)) {
376 if (ad_meta_fileno(ad) != -1) {
379 ret |= testlock(adf, off, 2) > 0? ATTRBIT_ROPEN : 0;
386 /* test for sharemode locks, adouble:ea stores them on the datafork */
387 static uint16_t ad_openforks_ea(struct adouble *ad, uint16_t attrbits)
394 if (ad_data_fileno(ad) == -1)
397 if (!(attrbits & (ATTRBIT_DOPEN | ATTRBIT_ROPEN))) {
398 /* Test all 4 locks at once */
399 off = AD_FILELOCK_OPEN_WR;
401 if (testlock(&ad->ad_data_fork, off, len) == 0)
405 /* either there's a lock or we already know one fork is open */
407 if (!(attrbits & ATTRBIT_DOPEN)) {
408 off = AD_FILELOCK_OPEN_WR;
409 ret = testlock(&ad->ad_data_fork, off, 2) > 0 ? ATTRBIT_DOPEN : 0;
412 if (!(attrbits & ATTRBIT_ROPEN)) {
413 off = AD_FILELOCK_RSRC_OPEN_WR;
414 ret |= testlock(&ad->ad_data_fork, off, 2) > 0? ATTRBIT_ROPEN : 0;
420 static int ad_testlock_v2(struct adouble *ad, int eid, const off_t off)
426 if (eid == ADEID_DFORK) {
427 adf = &ad->ad_data_fork;
428 if (ad_meta_fileno(ad) != -1) {
430 lock_offset = df2off(off);
433 if (ad_meta_fileno(ad) == -1) {
434 /* there's no resource fork. return no lock */
438 lock_offset = hf2off(off);
440 return testlock(adf, lock_offset, 1);
443 static int ad_testlock_ea(struct adouble *ad, int eid, const off_t off)
447 if (eid == ADEID_DFORK) {
450 lock_offset = rf2off(off);
452 return testlock(&ad->ad_data_fork, lock_offset, 1);
455 #define LTYPE2STRBUFSIZ 128
456 static const char *locktypetostr(int type)
459 static char buf[LTYPE2STRBUFSIZ];
464 strlcat(buf, "CLR", LTYPE2STRBUFSIZ);
468 if (type & ADLOCK_RD) {
470 strlcat(buf, "|", LTYPE2STRBUFSIZ);
471 strlcat(buf, "RD", LTYPE2STRBUFSIZ);
474 if (type & ADLOCK_WR) {
476 strlcat(buf, "|", LTYPE2STRBUFSIZ);
477 strlcat(buf, "WR", LTYPE2STRBUFSIZ);
480 if (type & ADLOCK_UPGRADE) {
482 strlcat(buf, "|", LTYPE2STRBUFSIZ);
483 strlcat(buf, "UPG", LTYPE2STRBUFSIZ);
486 if (type & ADLOCK_FILELOCK) {
488 strlcat(buf, "|", LTYPE2STRBUFSIZ);
489 strlcat(buf, "FILELOCK", LTYPE2STRBUFSIZ);
496 /******************************************************************************
498 ******************************************************************************/
500 int ad_lock(struct adouble *ad, uint32_t eid, int locktype, off_t off, off_t len, int fork)
509 LOG(log_debug, logtype_default, "ad_lock(\"%s\", %s, %s, off: %jd, len: %jd): BEGIN",
510 ad->ad_m_name ? ad->ad_m_name : "???",
511 eid == ADEID_DFORK ? "data" : "reso",
512 locktypetostr(locktype), (intmax_t)off, (intmax_t)len);
514 if ((locktype & ADLOCK_FILELOCK) && (len != 1))
521 if (eid == ADEID_DFORK) {
522 adf = &ad->ad_data_fork;
523 if ((ad->ad_vers == AD_VERSION2) && (type & ADLOCK_FILELOCK)) {
524 if (ad_meta_fileno(ad) != -1) { /* META */
526 lock.l_start = df2off(off);
530 switch (ad->ad_vers) {
532 if (ad_meta_fileno(ad) == -1 || ad_reso_fileno(ad) == -1) {
533 /* there's no meta data. return a lock error
534 * otherwise if a second process is able to create it
535 * locks are a mess. */
539 if (type & ADLOCK_FILELOCK) {
540 adf = ad->ad_mdp; /* either resource or meta data (set in ad_open) */
541 lock.l_start = hf2off(off);
543 /* we really want the resource fork it's a byte lock */
544 adf = &ad->ad_resource_fork;
545 lock.l_start += ad_getentryoff(ad, eid);
550 if (type & ADLOCK_FILELOCK) {
551 adf = &ad->ad_data_fork;
552 lock.l_start = rf2off(off);
558 lock.l_start= ADEDOFF_RFORK_OSX + off;
568 /* NOTE: we can't write lock a read-only file. on those, we just
569 * make sure that we have a read lock set. that way, we at least prevent
570 * someone else from really setting a deny read/write on the file.
572 if (!(adf->adf_flags & O_RDWR) && (type & ADLOCK_WR)) {
573 type = (type & ~ADLOCK_WR) | ADLOCK_RD;
576 lock.l_type = XLATE_FCNTL_LOCK(type & ADLOCK_MASK);
577 lock.l_whence = SEEK_SET;
580 /* byte_lock(len=-1) lock whole file */
581 if (len == BYTELOCK_MAX) {
582 lock.l_len -= lock.l_start; /* otherwise EOVERFLOW error */
585 /* see if it's locked by another fork.
586 * NOTE: this guarantees that any existing locks must be at most
587 * read locks. we use ADLOCK_WR/RD because F_RD/WRLCK aren't
588 * guaranteed to be ORable. */
589 if (adf_findxlock(adf, fork, ADLOCK_WR |
590 ((type & ADLOCK_WR) ? ADLOCK_RD : 0),
591 lock.l_start, lock.l_len) > -1) {
596 /* look for any existing lock that we may have */
597 i = adf_findlock(adf, fork, ADLOCK_RD | ADLOCK_WR, lock.l_start, lock.l_len);
598 adflock = (i < 0) ? NULL : adf->adf_lock + i;
600 /* here's what we check for:
601 1) we're trying to re-lock a lock, but we didn't specify an update.
602 2) we're trying to free only part of a lock.
603 3) we're trying to free a non-existent lock. */
604 if ( (!adflock && (lock.l_type == F_UNLCK))
607 && !(type & ADLOCK_UPGRADE)
608 && ((lock.l_type != F_UNLCK)
609 || (adflock->lock.l_start != lock.l_start)
610 || (adflock->lock.l_len != lock.l_len) ))
617 /* now, update our list of locks */
619 if (lock.l_type == F_UNLCK) {
620 adf_freelock(adf, i);
624 /* attempt to lock the file. */
625 if (set_lock(adf->adf_fd, F_SETLK, &lock) < 0)
628 /* we upgraded this lock. */
629 if (adflock && (type & ADLOCK_UPGRADE)) {
630 memcpy(&adflock->lock, &lock, sizeof(lock));
634 /* it wasn't an upgrade */
636 if (lock.l_type == F_RDLCK) {
637 oldlock = adf_findxlock(adf, fork, ADLOCK_RD, lock.l_start, lock.l_len);
640 /* no more space. this will also happen if lockmax == lockcount == 0 */
641 if (adf->adf_lockmax == adf->adf_lockcount) {
642 adf_lock_t *tmp = (adf_lock_t *)
643 realloc(adf->adf_lock, sizeof(adf_lock_t)*
644 (adf->adf_lockmax + ARRAY_BLOCK_SIZE));
648 adf->adf_lockmax += ARRAY_BLOCK_SIZE;
650 adflock = adf->adf_lock + adf->adf_lockcount;
653 memcpy(&adflock->lock, &lock, sizeof(lock));
654 adflock->user = fork;
656 adflock->refcount = (adf->adf_lock + oldlock)->refcount;
657 } else if ((adflock->refcount = calloc(1, sizeof(int))) == NULL) {
661 (*adflock->refcount)++;
662 adf->adf_lockcount++;
666 lock.l_type = F_UNLCK;
667 set_lock(adf->adf_fd, F_SETLK, &lock);
671 /* -------------------------
673 int ad_tmplock(struct adouble *ad, const uint32_t eid, const int locktype,
674 const off_t off, const off_t len, const int fork)
683 if (eid == ADEID_DFORK) {
684 adf = &ad->ad_data_fork;
687 adf = &ad->ad_resource_fork;
688 if (adf->adf_fd == -1) {
689 /* there's no resource fork. return success */
692 /* if ADLOCK_FILELOCK we want a lock from offset 0
693 * it's used when deleting a file:
694 * in open we put read locks on meta datas
695 * in delete a write locks on the whole file
696 * so if the file is open by somebody else it fails
698 if (!(type & ADLOCK_FILELOCK))
699 lock.l_start += ad_getentryoff(ad, eid);
702 if (!(adf->adf_flags & O_RDWR) && (type & ADLOCK_WR)) {
703 type = (type & ~ADLOCK_WR) | ADLOCK_RD;
706 lock.l_type = XLATE_FCNTL_LOCK(type & ADLOCK_MASK);
707 lock.l_whence = SEEK_SET;
710 /* see if it's locked by another fork. */
711 if (fork && adf_findxlock(adf, fork,
712 ADLOCK_WR | ((type & ADLOCK_WR) ? ADLOCK_RD : 0),
713 lock.l_start, lock.l_len) > -1) {
718 /* okay, we might have ranges byte-locked. we need to make sure that
719 * we restore the appropriate ranges once we're done. so, we check
720 * for overlap on an unlock and relock.
721 * XXX: in the future, all the byte locks will be sorted and contiguous.
722 * we just want to upgrade all the locks and then downgrade them
724 err = set_lock(adf->adf_fd, F_SETLK, &lock);
725 if (!err && (lock.l_type == F_UNLCK))
726 adf_relockrange(adf, adf->adf_fd, lock.l_start, len);
731 /* --------------------- */
732 void ad_unlock(struct adouble *ad, const int fork)
734 if (ad_data_fileno(ad) != -1) {
735 adf_unlock(&ad->ad_data_fork, fork);
737 if (ad_reso_fileno(ad) != -1) {
738 adf_unlock(&ad->ad_resource_fork, fork);
743 * Test for a share mode lock
745 * @param ad (rw) handle
746 * @param eid (r) datafork or ressource fork
747 * @param off (r) sharemode lock to test
749 * @returns 1 if there's an existing lock, 0 if there's no lock,
750 * -1 in case any error occured
752 int ad_testlock(struct adouble *ad, int eid, const off_t off)
754 switch (ad->ad_vers) {
756 return ad_testlock_v2(ad, eid, off);
758 return ad_testlock_ea(ad, eid, off);
765 * Return if a file is open by another process.
767 * Optimized for the common case:
768 * - there's no locks held by another process (clients)
769 * - or we already know the answer and don't need to test (attrbits)
771 * @param ad (rw) handle
772 * @param attrbits (r) forks opened by us
773 * @returns bitflags ATTRBIT_DOPEN | ATTRBIT_ROPEN if
774 * other process has fork of file opened
776 uint16_t ad_openforks(struct adouble *ad, uint16_t attrbits)
778 switch (ad->ad_vers) {
780 return ad_openforks_v2(ad, attrbits);
782 return ad_openforks_ea(ad, attrbits);