1 /* alock.c - access lock library */
3 /* This work is part of OpenLDAP Software <http://www.openldap.org/>.
5 * Copyright 2005-2006 The OpenLDAP Foundation.
6 * Portions Copyright 2004-2005 Symas Corporation.
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted only as authorized by the OpenLDAP
13 * A copy of this license is available in the file LICENSE in the
14 * top-level directory of the distribution or, alternatively, at
15 * <http://www.OpenLDAP.org/license.html>.
18 * This work was initially developed by Matthew Backes at Symas
19 * Corporation for inclusion in OpenLDAP Software.
24 #if SLAPD_BDB || SLAPD_HDB
28 #include <ac/stdlib.h>
29 #include <ac/string.h>
30 #include <ac/unistd.h>
32 #include <ac/assert.h>
33 #include <sys/types.h>
41 #include <sys/locking.h>
46 alock_grab_lock ( int fd, int slot )
50 #if defined( HAVE_LOCKF )
51 res = lseek (fd, (off_t) (ALOCK_SLOT_SIZE * slot), SEEK_SET);
52 if (res == -1) return -1;
53 res = lockf (fd, F_LOCK, (off_t) ALOCK_SLOT_SIZE);
54 #elif defined( HAVE_FCNTL )
55 struct flock lock_info;
56 (void) memset ((void *) &lock_info, 0, sizeof (struct flock));
58 lock_info.l_type = F_WRLCK;
59 lock_info.l_whence = SEEK_SET;
60 lock_info.l_start = (off_t) (ALOCK_SLOT_SIZE * slot);
61 lock_info.l_len = (off_t) ALOCK_SLOT_SIZE;
63 res = fcntl (fd, F_SETLKW, &lock_info);
64 #elif defined( _WIN32 )
65 if( _lseek( fd, (ALOCK_SLOT_SIZE * slot), SEEK_SET ) < 0 )
68 * _lock will try for the lock once per second, returning EDEADLOCK
69 * after ten tries. We just loop until we either get the lock
70 * or some other error is returned.
72 while((res = _locking( fd, _LK_LOCK, ALOCK_SLOT_SIZE )) < 0 ) {
73 if( errno != EDEADLOCK )
77 # error alock needs lockf, fcntl, or _locking
80 assert (errno != EDEADLK);
87 alock_release_lock ( int fd, int slot )
91 #if defined( HAVE_LOCKF )
92 res = lseek (fd, (off_t) (ALOCK_SLOT_SIZE * slot), SEEK_SET);
93 if (res == -1) return -1;
94 res = lockf (fd, F_ULOCK, (off_t) ALOCK_SLOT_SIZE);
95 if (res == -1) return -1;
96 #elif defined ( HAVE_FCNTL )
97 struct flock lock_info;
98 (void) memset ((void *) &lock_info, 0, sizeof (struct flock));
100 lock_info.l_type = F_UNLCK;
101 lock_info.l_whence = SEEK_SET;
102 lock_info.l_start = (off_t) (ALOCK_SLOT_SIZE * slot);
103 lock_info.l_len = (off_t) ALOCK_SLOT_SIZE;
105 res = fcntl (fd, F_SETLKW, &lock_info);
106 if (res == -1) return -1;
107 #elif defined( _WIN32 )
108 res = _lseek (fd, (ALOCK_SLOT_SIZE * slot), SEEK_SET);
109 if (res == -1) return -1;
110 res = _locking( fd, _LK_UNLCK, ALOCK_SLOT_SIZE );
111 if (res == -1) return -1;
113 # error alock needs lockf, fcntl, or _locking
120 alock_test_lock ( int fd, int slot )
124 #if defined( HAVE_LOCKF )
125 res = lseek (fd, (off_t) (ALOCK_SLOT_SIZE * slot), SEEK_SET);
126 if (res == -1) return -1;
128 res = lockf (fd, F_TEST, (off_t) ALOCK_SLOT_SIZE);
130 if (errno == EACCES || errno == EAGAIN) {
136 #elif defined( HAVE_FCNTL )
137 struct flock lock_info;
138 (void) memset ((void *) &lock_info, 0, sizeof (struct flock));
140 lock_info.l_type = F_WRLCK;
141 lock_info.l_whence = SEEK_SET;
142 lock_info.l_start = (off_t) (ALOCK_SLOT_SIZE * slot);
143 lock_info.l_len = (off_t) ALOCK_SLOT_SIZE;
145 res = fcntl (fd, F_GETLK, &lock_info);
146 if (res == -1) return -1;
148 if (lock_info.l_type != F_UNLCK) return ALOCK_LOCKED;
149 #elif defined( _WIN32 )
150 res = _lseek (fd, (ALOCK_SLOT_SIZE * slot), SEEK_SET);
151 if (res == -1) return -1;
152 res = _locking( fd, _LK_NBLCK, ALOCK_SLOT_SIZE );
153 _locking( fd, _LK_UNLCK, ALOCK_SLOT_SIZE );
155 if( errno == EACCES ) {
162 # error alock needs lockf, fcntl, or _locking
168 /* Read a 64bit LE value */
169 static unsigned long int
170 alock_read_iattr ( unsigned char * bufptr )
172 unsigned long int val = 0;
175 assert (bufptr != NULL);
177 bufptr += sizeof (unsigned long int);
178 for (count=0; count <= sizeof (unsigned long int); ++count) {
180 val += (unsigned long int) *bufptr--;
186 /* Write a 64bit LE value */
188 alock_write_iattr ( unsigned char * bufptr,
189 unsigned long int val )
193 assert (bufptr != NULL);
195 for (count=0; count < 8; ++count) {
196 *bufptr++ = (unsigned char) (val & 0xff);
202 alock_read_slot ( alock_info_t * info,
203 alock_slot_t * slot_data )
205 unsigned char slotbuf [ALOCK_SLOT_SIZE];
206 int res, size, size_total, err;
208 assert (info != NULL);
209 assert (slot_data != NULL);
210 assert (info->al_slot > 0);
212 res = lseek (info->al_fd,
213 (off_t) (ALOCK_SLOT_SIZE * info->al_slot),
215 if (res == -1) return -1;
218 while (size_total < ALOCK_SLOT_SIZE) {
219 size = read (info->al_fd,
220 slotbuf + size_total,
221 ALOCK_SLOT_SIZE - size_total);
222 if (size == 0) return -1;
225 if (err != EINTR && err != EAGAIN) return -1;
231 if (alock_read_iattr (slotbuf) != ALOCK_MAGIC) {
234 slot_data->al_lock = alock_read_iattr (slotbuf+8);
235 slot_data->al_stamp = alock_read_iattr (slotbuf+16);
236 slot_data->al_pid = alock_read_iattr (slotbuf+24);
238 if (slot_data->al_appname) free (slot_data->al_appname);
239 slot_data->al_appname = calloc (1, ALOCK_MAX_APPNAME);
240 strncpy (slot_data->al_appname, (char *)slotbuf+32, ALOCK_MAX_APPNAME-1);
241 (slot_data->al_appname) [ALOCK_MAX_APPNAME-1] = '\0';
247 alock_write_slot ( alock_info_t * info,
248 alock_slot_t * slot_data )
250 unsigned char slotbuf [ALOCK_SLOT_SIZE];
251 int res, size, size_total, err;
253 assert (info != NULL);
254 assert (slot_data != NULL);
255 assert (info->al_slot > 0);
257 (void) memset ((void *) slotbuf, 0, ALOCK_SLOT_SIZE);
259 alock_write_iattr (slotbuf, ALOCK_MAGIC);
260 assert (alock_read_iattr (slotbuf) == ALOCK_MAGIC);
261 alock_write_iattr (slotbuf+8, slot_data->al_lock);
262 alock_write_iattr (slotbuf+16, slot_data->al_stamp);
263 alock_write_iattr (slotbuf+24, slot_data->al_pid);
265 strncpy ((char *)slotbuf+32, slot_data->al_appname, ALOCK_MAX_APPNAME-1);
266 slotbuf[ALOCK_SLOT_SIZE-1] = '\0';
268 res = lseek (info->al_fd,
269 (off_t) (ALOCK_SLOT_SIZE * info->al_slot),
271 if (res == -1) return -1;
274 while (size_total < ALOCK_SLOT_SIZE) {
275 size = write (info->al_fd,
276 slotbuf + size_total,
277 ALOCK_SLOT_SIZE - size_total);
278 if (size == 0) return -1;
281 if (err != EINTR && err != EAGAIN) return -1;
291 alock_query_slot ( alock_info_t * info )
294 alock_slot_t slot_data;
296 assert (info != NULL);
297 assert (info->al_slot > 0);
299 (void) memset ((void *) &slot_data, 0, sizeof (alock_slot_t));
300 alock_read_slot (info, &slot_data);
302 if (slot_data.al_appname != NULL) free (slot_data.al_appname);
303 slot_data.al_appname = NULL;
305 nosave = slot_data.al_lock & ALOCK_NOSAVE;
307 if ((slot_data.al_lock & ALOCK_SMASK) == ALOCK_UNLOCKED)
308 return slot_data.al_lock;
310 res = alock_test_lock (info->al_fd, info->al_slot);
311 if (res < 0) return -1;
313 if ((slot_data.al_lock & ALOCK_SMASK) == ALOCK_UNIQUE) {
314 return slot_data.al_lock;
316 return ALOCK_LOCKED | nosave;
320 return ALOCK_DIRTY | nosave;
324 alock_open ( alock_info_t * info,
325 const char * appname,
330 alock_info_t scan_info;
331 alock_slot_t slot_data;
334 int dirty_count, live_count, nosave;
336 assert (info != NULL);
337 assert (appname != NULL);
338 assert (envdir != NULL);
339 assert ((locktype & ALOCK_SMASK) >= 1 && (locktype & ALOCK_SMASK) <= 2);
341 slot_data.al_lock = locktype;
342 slot_data.al_stamp = time(NULL);
343 slot_data.al_pid = getpid();
344 slot_data.al_appname = calloc (1, ALOCK_MAX_APPNAME);
345 strncpy (slot_data.al_appname, appname, ALOCK_MAX_APPNAME-1);
346 slot_data.al_appname [ALOCK_MAX_APPNAME-1] = '\0';
348 filename = calloc (1, strlen (envdir) + strlen ("/alock") + 1);
349 strcpy (filename, envdir);
350 strcat (filename, "/alock");
351 info->al_fd = open (filename, O_CREAT|O_RDWR, 0666);
353 if (info->al_fd < 0) {
354 free (slot_data.al_appname);
355 return ALOCK_UNSTABLE;
359 res = alock_grab_lock (info->al_fd, 0);
362 free (slot_data.al_appname);
363 return ALOCK_UNSTABLE;
366 res = fstat (info->al_fd, &statbuf);
369 free (slot_data.al_appname);
370 return ALOCK_UNSTABLE;
373 max_slot = (statbuf.st_size + ALOCK_SLOT_SIZE - 1) / ALOCK_SLOT_SIZE;
377 scan_info.al_fd = info->al_fd;
378 for (scan_info.al_slot = 1;
379 scan_info.al_slot < max_slot;
380 ++ scan_info.al_slot) {
381 if (scan_info.al_slot != info->al_slot) {
382 res = alock_query_slot (&scan_info);
384 if (res & ALOCK_NOSAVE) {
385 nosave = ALOCK_NOSAVE;
388 if (res == ALOCK_UNLOCKED
389 && info->al_slot == 0) {
390 info->al_slot = scan_info.al_slot;
392 } else if (res == ALOCK_LOCKED) {
395 } else if (res == ALOCK_UNIQUE
396 && locktype == ALOCK_UNIQUE) {
398 free (slot_data.al_appname);
401 } else if (res == ALOCK_DIRTY) {
404 } else if (res == -1) {
406 free (slot_data.al_appname);
407 return ALOCK_UNSTABLE;
413 if (dirty_count && live_count) {
415 free (slot_data.al_appname);
416 return ALOCK_UNSTABLE;
419 if (info->al_slot == 0) info->al_slot = max_slot + 1;
420 res = alock_grab_lock (info->al_fd,
424 free (slot_data.al_appname);
425 return ALOCK_UNSTABLE;
427 res = alock_write_slot (info, &slot_data);
428 free (slot_data.al_appname);
431 return ALOCK_UNSTABLE;
434 res = alock_release_lock (info->al_fd, 0);
437 return ALOCK_UNSTABLE;
440 if (dirty_count) return ALOCK_RECOVER | nosave;
441 return ALOCK_CLEAN | nosave;
445 alock_scan ( alock_info_t * info )
448 alock_info_t scan_info;
450 int dirty_count, live_count, nosave;
452 assert (info != NULL);
454 scan_info.al_fd = info->al_fd;
456 res = alock_grab_lock (info->al_fd, 0);
459 return ALOCK_UNSTABLE;
462 res = fstat (info->al_fd, &statbuf);
465 return ALOCK_UNSTABLE;
468 max_slot = (statbuf.st_size + ALOCK_SLOT_SIZE - 1) / ALOCK_SLOT_SIZE;
472 for (scan_info.al_slot = 1;
473 scan_info.al_slot < max_slot;
474 ++ scan_info.al_slot) {
475 if (scan_info.al_slot != info->al_slot) {
476 res = alock_query_slot (&scan_info);
478 if (res & ALOCK_NOSAVE) {
479 nosave = ALOCK_NOSAVE;
483 if (res == ALOCK_LOCKED) {
486 } else if (res == ALOCK_DIRTY) {
489 } else if (res == -1) {
491 return ALOCK_UNSTABLE;
497 res = alock_release_lock (info->al_fd, 0);
500 return ALOCK_UNSTABLE;
506 return ALOCK_UNSTABLE;
508 return ALOCK_RECOVER | nosave;
512 return ALOCK_CLEAN | nosave;
516 alock_close ( alock_info_t * info )
518 alock_slot_t slot_data;
521 if ( !info->al_slot )
524 (void) memset ((void *) &slot_data, 0, sizeof(alock_slot_t));
526 res = alock_grab_lock (info->al_fd, 0);
529 return ALOCK_UNSTABLE;
532 /* mark our slot as clean */
533 res = alock_read_slot (info, &slot_data);
536 if (slot_data.al_appname != NULL)
537 free (slot_data.al_appname);
538 return ALOCK_UNSTABLE;
540 slot_data.al_lock = ALOCK_UNLOCKED | (slot_data.al_lock & ALOCK_NOSAVE);
541 res = alock_write_slot (info, &slot_data);
544 if (slot_data.al_appname != NULL)
545 free (slot_data.al_appname);
546 return ALOCK_UNSTABLE;
548 if (slot_data.al_appname != NULL) {
549 free (slot_data.al_appname);
550 slot_data.al_appname = NULL;
553 res = alock_release_lock (info->al_fd, info->al_slot);
556 return ALOCK_UNSTABLE;
558 res = alock_release_lock (info->al_fd, 0);
561 return ALOCK_UNSTABLE;
564 res = close (info->al_fd);
565 if (res == -1) return ALOCK_UNSTABLE;
571 alock_recover ( alock_info_t * info )
574 alock_slot_t slot_data;
575 alock_info_t scan_info;
578 assert (info != NULL);
580 scan_info.al_fd = info->al_fd;
582 (void) memset ((void *) &slot_data, 0, sizeof(alock_slot_t));
584 res = alock_grab_lock (info->al_fd, 0);
587 return ALOCK_UNSTABLE;
590 res = fstat (info->al_fd, &statbuf);
593 return ALOCK_UNSTABLE;
596 max_slot = (statbuf.st_size + ALOCK_SLOT_SIZE - 1) / ALOCK_SLOT_SIZE;
597 for (scan_info.al_slot = 1;
598 scan_info.al_slot < max_slot;
599 ++ scan_info.al_slot) {
600 if (scan_info.al_slot != info->al_slot) {
601 res = alock_query_slot (&scan_info) & ~ALOCK_NOSAVE;
603 if (res == ALOCK_LOCKED
604 || res == ALOCK_UNIQUE) {
605 /* recovery attempt on an active db? */
607 return ALOCK_UNSTABLE;
609 } else if (res == ALOCK_DIRTY) {
611 res = alock_read_slot (&scan_info, &slot_data);
614 return ALOCK_UNSTABLE;
616 slot_data.al_lock = ALOCK_UNLOCKED;
617 res = alock_write_slot (&scan_info, &slot_data);
620 if (slot_data.al_appname != NULL)
621 free (slot_data.al_appname);
622 return ALOCK_UNSTABLE;
624 if (slot_data.al_appname != NULL) {
625 free (slot_data.al_appname);
626 slot_data.al_appname = NULL;
629 } else if (res == -1) {
631 return ALOCK_UNSTABLE;
637 res = alock_release_lock (info->al_fd, 0);
640 return ALOCK_UNSTABLE;
646 #endif /* SLAPD_BDB || SLAPD_HDB */