diff options
Diffstat (limited to '')
| -rw-r--r-- | common/check.c | 489 | ||||
| -rw-r--r-- | common/dump.c | 149 | ||||
| -rw-r--r-- | common/error.c | 74 | ||||
| -rw-r--r-- | common/freelist.c | 747 | ||||
| -rw-r--r-- | common/freelistcheck.c | 107 | ||||
| -rw-r--r-- | common/hash.c | 345 | ||||
| -rw-r--r-- | common/io.c | 806 | ||||
| -rw-r--r-- | common/lock.c | 1033 | ||||
| -rw-r--r-- | common/mutex.c | 1078 | ||||
| -rw-r--r-- | common/open.c | 968 | ||||
| -rw-r--r-- | common/rescue.c | 351 | ||||
| -rw-r--r-- | common/summary.c | 219 | ||||
| -rw-r--r-- | common/tdb.c | 1348 | ||||
| -rw-r--r-- | common/tdb_private.h | 370 | ||||
| -rw-r--r-- | common/transaction.c | 1388 | ||||
| -rw-r--r-- | common/traverse.c | 510 |
16 files changed, 9982 insertions, 0 deletions
diff --git a/common/check.c b/common/check.c new file mode 100644 index 0000000..d7741f6 --- /dev/null +++ b/common/check.c @@ -0,0 +1,489 @@ + /* + Unix SMB/CIFS implementation. + + trivial database library + + Copyright (C) Rusty Russell 2009 + + ** NOTE! The following LGPL license applies to the tdb + ** library. This does NOT imply that all of Samba is released + ** under the LGPL + + This library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 3 of the License, or (at your option) any later version. + + This library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with this library; if not, see <http://www.gnu.org/licenses/>. +*/ +#include "tdb_private.h" + +/* Since we opened it, these shouldn't fail unless it's recent corruption. */ +static bool tdb_check_header(struct tdb_context *tdb, tdb_off_t *recovery) +{ + struct tdb_header hdr; + uint32_t h1, h2; + + if (tdb->methods->tdb_read(tdb, 0, &hdr, sizeof(hdr), 0) == -1) + return false; + if (strcmp(hdr.magic_food, TDB_MAGIC_FOOD) != 0) + goto corrupt; + + CONVERT(hdr); + if (hdr.version != TDB_VERSION) + goto corrupt; + + if (hdr.rwlocks != 0 && + hdr.rwlocks != TDB_FEATURE_FLAG_MAGIC && + hdr.rwlocks != TDB_HASH_RWLOCK_MAGIC) + goto corrupt; + + tdb_header_hash(tdb, &h1, &h2); + if (hdr.magic1_hash && hdr.magic2_hash && + (hdr.magic1_hash != h1 || hdr.magic2_hash != h2)) + goto corrupt; + + if (hdr.hash_size == 0) + goto corrupt; + + if (hdr.hash_size != tdb->hash_size) + goto corrupt; + + if (hdr.recovery_start != 0 && + hdr.recovery_start < TDB_DATA_START(tdb->hash_size)) + goto corrupt; + + *recovery = hdr.recovery_start; + return true; + +corrupt: + tdb->ecode = TDB_ERR_CORRUPT; + TDB_LOG((tdb, TDB_DEBUG_ERROR, "Header is corrupt\n")); + return false; +} + +/* Generic record header check. */ +static bool tdb_check_record(struct tdb_context *tdb, + tdb_off_t off, + const struct tdb_record *rec) +{ + tdb_off_t tailer; + + /* Check rec->next: 0 or points to record offset, aligned. */ + if (rec->next > 0 && rec->next < TDB_DATA_START(tdb->hash_size)){ + TDB_LOG((tdb, TDB_DEBUG_ERROR, + "Record offset %u too small next %u\n", + off, rec->next)); + goto corrupt; + } + if (rec->next + sizeof(*rec) < rec->next) { + TDB_LOG((tdb, TDB_DEBUG_ERROR, + "Record offset %u too large next %u\n", + off, rec->next)); + goto corrupt; + } + if ((rec->next % TDB_ALIGNMENT) != 0) { + TDB_LOG((tdb, TDB_DEBUG_ERROR, + "Record offset %u misaligned next %u\n", + off, rec->next)); + goto corrupt; + } + if (tdb_oob(tdb, rec->next, sizeof(*rec), 0)) + goto corrupt; + + /* Check rec_len: similar to rec->next, implies next record. */ + if ((rec->rec_len % TDB_ALIGNMENT) != 0) { + TDB_LOG((tdb, TDB_DEBUG_ERROR, + "Record offset %u misaligned length %u\n", + off, rec->rec_len)); + goto corrupt; + } + /* Must fit tailer. */ + if (rec->rec_len < sizeof(tailer)) { + TDB_LOG((tdb, TDB_DEBUG_ERROR, + "Record offset %u too short length %u\n", + off, rec->rec_len)); + goto corrupt; + } + /* OOB allows "right at the end" access, so this works for last rec. */ + if (tdb_oob(tdb, off, sizeof(*rec)+rec->rec_len, 0)) + goto corrupt; + + /* Check tailer. */ + if (tdb_ofs_read(tdb, off+sizeof(*rec)+rec->rec_len-sizeof(tailer), + &tailer) == -1) + goto corrupt; + if (tailer != sizeof(*rec) + rec->rec_len) { + TDB_LOG((tdb, TDB_DEBUG_ERROR, + "Record offset %u invalid tailer\n", off)); + goto corrupt; + } + + return true; + +corrupt: + tdb->ecode = TDB_ERR_CORRUPT; + return false; +} + +/* Grab some bytes: may copy if can't use mmap. + Caller has already done bounds check. */ +static TDB_DATA get_bytes(struct tdb_context *tdb, + tdb_off_t off, tdb_len_t len) +{ + TDB_DATA d; + + d.dsize = len; + + if (tdb->transaction == NULL && tdb->map_ptr != NULL) + d.dptr = (unsigned char *)tdb->map_ptr + off; + else + d.dptr = tdb_alloc_read(tdb, off, d.dsize); + return d; +} + +/* Frees data if we're not able to simply use mmap. */ +static void put_bytes(struct tdb_context *tdb, TDB_DATA d) +{ + if (tdb->transaction == NULL && tdb->map_ptr != NULL) + return; + free(d.dptr); +} + +/* We use the excellent Jenkins lookup3 hash; this is based on hash_word2. + * See: http://burtleburtle.net/bob/c/lookup3.c + */ +#define rot(x,k) (((x)<<(k)) | ((x)>>(32-(k)))) +static void hash(uint32_t key, uint32_t *pc, uint32_t *pb) +{ + uint32_t a,b,c; + + /* Set up the internal state */ + a = b = c = 0xdeadbeef + *pc; + c += *pb; + a += key; + c ^= b; c -= rot(b,14); + a ^= c; a -= rot(c,11); + b ^= a; b -= rot(a,25); + c ^= b; c -= rot(b,16); + a ^= c; a -= rot(c,4); + b ^= a; b -= rot(a,14); + c ^= b; c -= rot(b,24); + *pc=c; *pb=b; +} + +/* + We want to check that all free records are in the free list + (only once), and all free list entries are free records. Similarly + for each hash chain of used records. + + Doing that naively (without walking hash chains, since we want to be + linear) means keeping a list of records which have been seen in each + hash chain, and another of records pointed to (ie. next pointers + from records and the initial hash chain heads). These two lists + should be equal. This will take 8 bytes per record, and require + sorting at the end. + + So instead, we record each offset in a bitmap such a way that + recording it twice will cancel out. Since each offset should appear + exactly twice, the bitmap should be zero at the end. + + The approach was inspired by Bloom Filters (see Wikipedia). For + each value, we flip K bits in a bitmap of size N. The number of + distinct arrangements is: + + N! / (K! * (N-K)!) + + Of course, not all arrangements are actually distinct, but testing + shows this formula to be close enough. + + So, if K == 8 and N == 256, the probability of two things flipping the same + bits is 1 in 409,663,695,276,000. + + Given that ldb uses a hash size of 10000, using 32 bytes per hash chain + (320k) seems reasonable. +*/ +#define NUM_HASHES 8 +#define BITMAP_BITS 256 + +static void bit_flip(unsigned char bits[], unsigned int idx) +{ + bits[idx / CHAR_BIT] ^= (1 << (idx % CHAR_BIT)); +} + +/* We record offsets in a bitmap for the particular chain it should be in. */ +static void record_offset(unsigned char bits[], tdb_off_t off) +{ + uint32_t h1 = off, h2 = 0; + unsigned int i; + + /* We get two good hash values out of jhash2, so we use both. Then + * we keep going to produce further hash values. */ + for (i = 0; i < NUM_HASHES / 2; i++) { + hash(off, &h1, &h2); + bit_flip(bits, h1 % BITMAP_BITS); + bit_flip(bits, h2 % BITMAP_BITS); + h2++; + } +} + +/* Check that an in-use record is valid. */ +static bool tdb_check_used_record(struct tdb_context *tdb, + tdb_off_t off, + const struct tdb_record *rec, + unsigned char **hashes, + int (*check)(TDB_DATA, TDB_DATA, void *), + void *private_data) +{ + TDB_DATA key, data; + tdb_len_t len; + + if (!tdb_check_record(tdb, off, rec)) + return false; + + /* key + data + tailer must fit in record */ + len = rec->key_len; + len += rec->data_len; + if (len < rec->data_len) { + /* overflow */ + TDB_LOG((tdb, TDB_DEBUG_ERROR, "Record lengths overflow\n")); + return false; + } + len += sizeof(tdb_off_t); + if (len < sizeof(tdb_off_t)) { + /* overflow */ + TDB_LOG((tdb, TDB_DEBUG_ERROR, "Record lengths overflow\n")); + return false; + } + + if (len > rec->rec_len) { + TDB_LOG((tdb, TDB_DEBUG_ERROR, + "Record offset %u too short for contents\n", off)); + return false; + } + + key = get_bytes(tdb, off + sizeof(*rec), rec->key_len); + if (!key.dptr) + return false; + + if (tdb->hash_fn(&key) != rec->full_hash) { + TDB_LOG((tdb, TDB_DEBUG_ERROR, + "Record offset %u has incorrect hash\n", off)); + goto fail_put_key; + } + + /* Mark this offset as a known value for this hash bucket. */ + record_offset(hashes[BUCKET(rec->full_hash)+1], off); + /* And similarly if the next pointer is valid. */ + if (rec->next) + record_offset(hashes[BUCKET(rec->full_hash)+1], rec->next); + + /* If they supply a check function and this record isn't dead, + get data and feed it. */ + if (check && rec->magic != TDB_DEAD_MAGIC) { + data = get_bytes(tdb, off + sizeof(*rec) + rec->key_len, + rec->data_len); + if (!data.dptr) + goto fail_put_key; + + if (check(key, data, private_data) == -1) + goto fail_put_data; + put_bytes(tdb, data); + } + + put_bytes(tdb, key); + return true; + +fail_put_data: + put_bytes(tdb, data); +fail_put_key: + put_bytes(tdb, key); + return false; +} + +/* Check that an unused record is valid. */ +static bool tdb_check_free_record(struct tdb_context *tdb, + tdb_off_t off, + const struct tdb_record *rec, + unsigned char **hashes) +{ + if (!tdb_check_record(tdb, off, rec)) + return false; + + /* Mark this offset as a known value for the free list. */ + record_offset(hashes[0], off); + /* And similarly if the next pointer is valid. */ + if (rec->next) + record_offset(hashes[0], rec->next); + return true; +} + +/* Slow, but should be very rare. */ +size_t tdb_dead_space(struct tdb_context *tdb, tdb_off_t off) +{ + size_t len; + + for (len = 0; off + len < tdb->map_size; len++) { + char c; + if (tdb->methods->tdb_read(tdb, off, &c, 1, 0)) + return 0; + if (c != 0 && c != 0x42) + break; + } + return len; +} + +_PUBLIC_ int tdb_check(struct tdb_context *tdb, + int (*check)(TDB_DATA key, TDB_DATA data, void *private_data), + void *private_data) +{ + unsigned int h; + unsigned char **hashes; + tdb_off_t off, recovery_start; + struct tdb_record rec; + bool found_recovery = false; + tdb_len_t dead; + bool locked; + + /* Read-only databases use no locking at all: it's best-effort. + * We may have a write lock already, so skip that case too. */ + if (tdb->read_only || tdb->allrecord_lock.count != 0) { + locked = false; + } else { + if (tdb_lockall_read(tdb) == -1) + return -1; + locked = true; + } + + /* Make sure we know true size of the underlying file. */ + tdb_oob(tdb, tdb->map_size, 1, 1); + + /* Header must be OK: also gets us the recovery ptr, if any. */ + if (!tdb_check_header(tdb, &recovery_start)) + goto unlock; + + /* We should have the whole header, too. */ + if (tdb->map_size < TDB_DATA_START(tdb->hash_size)) { + tdb->ecode = TDB_ERR_CORRUPT; + TDB_LOG((tdb, TDB_DEBUG_ERROR, "File too short for hashes\n")); + goto unlock; + } + + /* One big malloc: pointers then bit arrays. */ + hashes = (unsigned char **)calloc( + 1, sizeof(hashes[0]) * (1+tdb->hash_size) + + BITMAP_BITS / CHAR_BIT * (1+tdb->hash_size)); + if (!hashes) { + tdb->ecode = TDB_ERR_OOM; + goto unlock; + } + + /* Initialize pointers */ + hashes[0] = (unsigned char *)(&hashes[1+tdb->hash_size]); + for (h = 1; h < 1+tdb->hash_size; h++) + hashes[h] = hashes[h-1] + BITMAP_BITS / CHAR_BIT; + + /* Freelist and hash headers are all in a row: read them. */ + for (h = 0; h < 1+tdb->hash_size; h++) { + if (tdb_ofs_read(tdb, FREELIST_TOP + h*sizeof(tdb_off_t), + &off) == -1) + goto free; + if (off) + record_offset(hashes[h], off); + } + + /* For each record, read it in and check it's ok. */ + for (off = TDB_DATA_START(tdb->hash_size); + off < tdb->map_size; + off += sizeof(rec) + rec.rec_len) { + if (tdb->methods->tdb_read(tdb, off, &rec, sizeof(rec), + DOCONV()) == -1) + goto free; + switch (rec.magic) { + case TDB_MAGIC: + case TDB_DEAD_MAGIC: + if (!tdb_check_used_record(tdb, off, &rec, hashes, + check, private_data)) + goto free; + break; + case TDB_FREE_MAGIC: + if (!tdb_check_free_record(tdb, off, &rec, hashes)) + goto free; + break; + /* If we crash after ftruncate, we can get zeroes or fill. */ + case TDB_RECOVERY_INVALID_MAGIC: + case 0x42424242: + if (recovery_start == off) { + found_recovery = true; + break; + } + dead = tdb_dead_space(tdb, off); + if (dead < sizeof(rec)) + goto corrupt; + + TDB_LOG((tdb, TDB_DEBUG_ERROR, + "Dead space at %u-%u (of %u)\n", + off, off + dead, tdb->map_size)); + rec.rec_len = dead - sizeof(rec); + break; + case TDB_RECOVERY_MAGIC: + if (recovery_start != off) { + TDB_LOG((tdb, TDB_DEBUG_ERROR, + "Unexpected recovery record at offset %u\n", + off)); + goto free; + } + found_recovery = true; + break; + default: ; + corrupt: + tdb->ecode = TDB_ERR_CORRUPT; + TDB_LOG((tdb, TDB_DEBUG_ERROR, + "Bad magic 0x%x at offset %u\n", + rec.magic, off)); + goto free; + } + } + + /* Now, hashes should all be empty: each record exists and is referred + * to by one other. */ + for (h = 0; h < 1+tdb->hash_size; h++) { + unsigned int i; + for (i = 0; i < BITMAP_BITS / CHAR_BIT; i++) { + if (hashes[h][i] != 0) { + tdb->ecode = TDB_ERR_CORRUPT; + TDB_LOG((tdb, TDB_DEBUG_ERROR, + "Hashes do not match records\n")); + goto free; + } + } + } + + /* We must have found recovery area if there was one. */ + if (recovery_start != 0 && !found_recovery) { + TDB_LOG((tdb, TDB_DEBUG_ERROR, + "Expected a recovery area at %u\n", + recovery_start)); + goto free; + } + + free(hashes); + if (locked) { + tdb_unlockall_read(tdb); + } + return 0; + +free: + free(hashes); +unlock: + if (locked) { + tdb_unlockall_read(tdb); + } + return -1; +} diff --git a/common/dump.c b/common/dump.c new file mode 100644 index 0000000..adcf591 --- /dev/null +++ b/common/dump.c @@ -0,0 +1,149 @@ + /* + Unix SMB/CIFS implementation. + + trivial database library + + Copyright (C) Andrew Tridgell 1999-2005 + Copyright (C) Paul `Rusty' Russell 2000 + Copyright (C) Jeremy Allison 2000-2003 + + ** NOTE! The following LGPL license applies to the tdb + ** library. This does NOT imply that all of Samba is released + ** under the LGPL + + This library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 3 of the License, or (at your option) any later version. + + This library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with this library; if not, see <http://www.gnu.org/licenses/>. +*/ + +#include "tdb_private.h" + +static tdb_off_t tdb_dump_record(struct tdb_context *tdb, int hash, + tdb_off_t offset) +{ + struct tdb_record rec; + tdb_off_t tailer_ofs, tailer; + + if (tdb->methods->tdb_read(tdb, offset, (char *)&rec, + sizeof(rec), DOCONV()) == -1) { + printf("ERROR: failed to read record at %u\n", offset); + return 0; + } + + printf(" rec: hash=%d offset=0x%08x next=0x%08x rec_len=%u " + "key_len=%u data_len=%u full_hash=0x%08x magic=0x%08x\n", + hash, offset, rec.next, rec.rec_len, rec.key_len, rec.data_len, + rec.full_hash, rec.magic); + + tailer_ofs = offset + sizeof(rec) + rec.rec_len - sizeof(tdb_off_t); + + if (tdb_ofs_read(tdb, tailer_ofs, &tailer) == -1) { + printf("ERROR: failed to read tailer at %u\n", tailer_ofs); + return rec.next; + } + + if (tailer != rec.rec_len + sizeof(rec)) { + printf("ERROR: tailer does not match record! tailer=%u totalsize=%u\n", + (unsigned int)tailer, (unsigned int)(rec.rec_len + sizeof(rec))); + } + return rec.next; +} + +static int tdb_dump_chain(struct tdb_context *tdb, int i) +{ + struct tdb_chainwalk_ctx chainwalk; + tdb_off_t rec_ptr, top; + + if (i == -1) { + top = FREELIST_TOP; + } else { + top = TDB_HASH_TOP(i); + } + + if (tdb_lock(tdb, i, F_WRLCK) != 0) + return -1; + + if (tdb_ofs_read(tdb, top, &rec_ptr) == -1) + return tdb_unlock(tdb, i, F_WRLCK); + + tdb_chainwalk_init(&chainwalk, rec_ptr); + + if (rec_ptr) + printf("hash=%d\n", i); + + while (rec_ptr) { + bool ok; + rec_ptr = tdb_dump_record(tdb, i, rec_ptr); + ok = tdb_chainwalk_check(tdb, &chainwalk, rec_ptr); + if (!ok) { + printf("circular hash chain %d\n", i); + break; + } + } + + return tdb_unlock(tdb, i, F_WRLCK); +} + +_PUBLIC_ void tdb_dump_all(struct tdb_context *tdb) +{ + uint32_t i; + for (i=0;i<tdb->hash_size;i++) { + tdb_dump_chain(tdb, i); + } + printf("freelist:\n"); + tdb_dump_chain(tdb, -1); +} + +_PUBLIC_ int tdb_printfreelist(struct tdb_context *tdb) +{ + int ret; + long total_free = 0; + tdb_off_t offset, rec_ptr; + struct tdb_record rec; + + if ((ret = tdb_lock(tdb, -1, F_WRLCK)) != 0) + return ret; + + offset = FREELIST_TOP; + + /* read in the freelist top */ + if (tdb_ofs_read(tdb, offset, &rec_ptr) == -1) { + tdb_unlock(tdb, -1, F_WRLCK); + return 0; + } + + printf("freelist top=[0x%08x]\n", rec_ptr ); + while (rec_ptr) { + if (tdb->methods->tdb_read(tdb, rec_ptr, (char *)&rec, + sizeof(rec), DOCONV()) == -1) { + tdb_unlock(tdb, -1, F_WRLCK); + return -1; + } + + if (rec.magic != TDB_FREE_MAGIC) { + printf("bad magic 0x%08x in free list\n", rec.magic); + tdb_unlock(tdb, -1, F_WRLCK); + return -1; + } + + printf("entry offset=[0x%08x], rec.rec_len = [0x%08x (%u)] (end = 0x%08x)\n", + rec_ptr, rec.rec_len, rec.rec_len, rec_ptr + rec.rec_len); + total_free += rec.rec_len; + + /* move to the next record */ + rec_ptr = rec.next; + } + printf("total rec_len = [0x%08lx (%lu)]\n", total_free, total_free); + + return tdb_unlock(tdb, -1, F_WRLCK); +} + diff --git a/common/error.c b/common/error.c new file mode 100644 index 0000000..c3ef8bd --- /dev/null +++ b/common/error.c @@ -0,0 +1,74 @@ + /* + Unix SMB/CIFS implementation. + + trivial database library + + Copyright (C) Andrew Tridgell 1999-2005 + Copyright (C) Paul `Rusty' Russell 2000 + Copyright (C) Jeremy Allison 2000-2003 + + ** NOTE! The following LGPL license applies to the tdb + ** library. This does NOT imply that all of Samba is released + ** under the LGPL + + This library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 3 of the License, or (at your option) any later version. + + This library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with this library; if not, see <http://www.gnu.org/licenses/>. +*/ + +#include "tdb_private.h" + +_PUBLIC_ enum TDB_ERROR tdb_error(struct tdb_context *tdb) +{ + return tdb->ecode; +} + +_PUBLIC_ const char *tdb_errorstr(struct tdb_context *tdb) +{ + switch (tdb->ecode) { + case TDB_SUCCESS: + return "Success"; + break; + case TDB_ERR_CORRUPT: + return "Corrupt database"; + break; + case TDB_ERR_IO: + return "IO Error"; + break; + case TDB_ERR_LOCK: + return "Locking error"; + break; + case TDB_ERR_OOM: + return "Out of memory"; + break; + case TDB_ERR_EXISTS: + return "Record exists"; + break; + case TDB_ERR_NOLOCK: + return "Lock exists on other keys"; + break; + case TDB_ERR_EINVAL: + return "Invalid parameter"; + break; + case TDB_ERR_NOEXIST: + return "Record does not exist"; + break; + case TDB_ERR_RDONLY: + return "write not permitted"; + break; + default: + break; + } + + return "Invalid error code"; +} + diff --git a/common/freelist.c b/common/freelist.c new file mode 100644 index 0000000..046c747 --- /dev/null +++ b/common/freelist.c @@ -0,0 +1,747 @@ + /* + Unix SMB/CIFS implementation. + + trivial database library + + Copyright (C) Andrew Tridgell 1999-2005 + Copyright (C) Paul `Rusty' Russell 2000 + Copyright (C) Jeremy Allison 2000-2003 + + ** NOTE! The following LGPL license applies to the tdb + ** library. This does NOT imply that all of Samba is released + ** under the LGPL + + This library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 3 of the License, or (at your option) any later version. + + This library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with this library; if not, see <http://www.gnu.org/licenses/>. +*/ + +#include "tdb_private.h" + +/* read a freelist record and check for simple errors */ +int tdb_rec_free_read(struct tdb_context *tdb, tdb_off_t off, struct tdb_record *rec) +{ + if (tdb->methods->tdb_read(tdb, off, rec, sizeof(*rec),DOCONV()) == -1) + return -1; + + if (rec->magic == TDB_MAGIC) { + /* this happens when a app is showdown while deleting a record - we should + not completely fail when this happens */ + TDB_LOG((tdb, TDB_DEBUG_WARNING, "tdb_rec_free_read non-free magic 0x%x at offset=%u - fixing\n", + rec->magic, off)); + rec->magic = TDB_FREE_MAGIC; + if (tdb_rec_write(tdb, off, rec) == -1) + return -1; + } + + if (rec->magic != TDB_FREE_MAGIC) { + /* Ensure ecode is set for log fn. */ + tdb->ecode = TDB_ERR_CORRUPT; + TDB_LOG((tdb, TDB_DEBUG_WARNING, "tdb_rec_free_read bad magic 0x%x at offset=%u\n", + rec->magic, off)); + return -1; + } + if (tdb_oob(tdb, rec->next, sizeof(*rec), 0) != 0) + return -1; + return 0; +} + +/* update a record tailer (must hold allocation lock) */ +static int update_tailer(struct tdb_context *tdb, tdb_off_t offset, + const struct tdb_record *rec) +{ + tdb_off_t totalsize; + + /* Offset of tailer from record header */ + totalsize = sizeof(*rec) + rec->rec_len; + return tdb_ofs_write(tdb, offset + totalsize - sizeof(tdb_off_t), + &totalsize); +} + +/** + * Read the record directly on the left. + * Fail if there is no record on the left. + */ +static int read_record_on_left(struct tdb_context *tdb, tdb_off_t rec_ptr, + tdb_off_t *left_p, + struct tdb_record *left_r) +{ + tdb_off_t left_ptr; + tdb_off_t left_size; + struct tdb_record left_rec; + int ret; + + left_ptr = rec_ptr - sizeof(tdb_off_t); + + if (left_ptr <= TDB_DATA_START(tdb->hash_size)) { + /* no record on the left */ + return -1; + } + + /* Read in tailer and jump back to header */ + ret = tdb_ofs_read(tdb, left_ptr, &left_size); + if (ret == -1) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, + "tdb_free: left offset read failed at %u\n", left_ptr)); + return -1; + } + + /* it could be uninitialised data */ + if (left_size == 0 || left_size == TDB_PAD_U32) { + return -1; + } + + if (left_size > rec_ptr) { + return -1; + } + + left_ptr = rec_ptr - left_size; + + if (left_ptr < TDB_DATA_START(tdb->hash_size)) { + return -1; + } + + /* Now read in the left record */ + ret = tdb->methods->tdb_read(tdb, left_ptr, &left_rec, + sizeof(left_rec), DOCONV()); + if (ret == -1) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, + "tdb_free: left read failed at %u (%u)\n", + left_ptr, left_size)); + return -1; + } + + *left_p = left_ptr; + *left_r = left_rec; + + return 0; +} + +/** + * Merge new freelist record with the direct left neighbour. + * This assumes that left_rec represents the record + * directly to the left of right_rec and that this is + * a freelist record. + */ +static int merge_with_left_record(struct tdb_context *tdb, + tdb_off_t left_ptr, + struct tdb_record *left_rec, + struct tdb_record *right_rec) +{ + int ret; + + left_rec->rec_len += sizeof(*right_rec) + right_rec->rec_len; + + ret = tdb_rec_write(tdb, left_ptr, left_rec); + if (ret == -1) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, + "merge_with_left_record: update_left failed at %u\n", + left_ptr)); + return -1; + } + + ret = update_tailer(tdb, left_ptr, left_rec); + if (ret == -1) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, + "merge_with_left_record: update_tailer failed at %u\n", + left_ptr)); + return -1; + } + + return 0; +} + +/** + * Check whether the record left of a given freelist record is + * also a freelist record, and if so, merge the two records. + * + * Return code: + * -1 upon error + * 0 if left was not a free record + * 1 if left was free and successfully merged. + * + * The current record is handed in with pointer and fully read record. + * + * The left record pointer and struct can be retrieved as result + * in lp and lr; + */ +static int check_merge_with_left_record(struct tdb_context *tdb, + tdb_off_t rec_ptr, + struct tdb_record *rec, + tdb_off_t *lp, + struct tdb_record *lr) +{ + tdb_off_t left_ptr; + struct tdb_record left_rec; + int ret; + + ret = read_record_on_left(tdb, rec_ptr, &left_ptr, &left_rec); + if (ret != 0) { + return 0; + } + + if (left_rec.magic != TDB_FREE_MAGIC) { + return 0; + } + + /* It's free - expand to include it. */ + ret = merge_with_left_record(tdb, left_ptr, &left_rec, rec); + if (ret != 0) { + return -1; + } + + if (lp != NULL) { + *lp = left_ptr; + } + + if (lr != NULL) { + *lr = left_rec; + } + + return 1; +} + +/** + * Check whether the record left of a given freelist record is + * also a freelist record, and if so, merge the two records. + * + * Return code: + * -1 upon error + * 0 if left was not a free record + * 1 if left was free and successfully merged. + * + * In this variant, the input record is specified just as the pointer + * and is read from the database if needed. + * + * next_ptr will contain the original record's next pointer after + * successful merging (which will be lost after merging), so that + * the caller can update the last pointer. + */ +static int check_merge_ptr_with_left_record(struct tdb_context *tdb, + tdb_off_t rec_ptr, + tdb_off_t *next_ptr) +{ + tdb_off_t left_ptr; + struct tdb_record rec, left_rec; + int ret; + + ret = read_record_on_left(tdb, rec_ptr, &left_ptr, &left_rec); + if (ret != 0) { + return 0; + } + + if (left_rec.magic != TDB_FREE_MAGIC) { + return 0; + } + + /* It's free - expand to include it. */ + + ret = tdb->methods->tdb_read(tdb, rec_ptr, &rec, + sizeof(rec), DOCONV()); + if (ret != 0) { + return -1; + } + + ret = merge_with_left_record(tdb, left_ptr, &left_rec, &rec); + if (ret != 0) { + return -1; + } + + if (next_ptr != NULL) { + *next_ptr = rec.next; + } + + return 1; +} + +/** + * Add an element into the freelist. + * + * We merge the new record into the left record if it is also a + * free record, but not with the right one. This makes the + * operation O(1) instead of O(n): merging with the right record + * requires a traverse of the freelist to find the previous + * record in the free list. + * + * This prevents db traverses from being O(n^2) after a lot of deletes. + */ +int tdb_free(struct tdb_context *tdb, tdb_off_t offset, struct tdb_record *rec) +{ + int ret; + + /* Allocation and tailer lock */ + if (tdb_lock(tdb, -1, F_WRLCK) != 0) + return -1; + + /* set an initial tailer, so if we fail we don't leave a bogus record */ + if (update_tailer(tdb, offset, rec) != 0) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_free: update_tailer failed!\n")); + goto fail; + } + + ret = check_merge_with_left_record(tdb, offset, rec, NULL, NULL); + if (ret == -1) { + goto fail; + } + if (ret == 1) { + /* merged */ + goto done; + } + + /* Nothing to merge, prepend to free list */ + + rec->magic = TDB_FREE_MAGIC; + + if (tdb_ofs_read(tdb, FREELIST_TOP, &rec->next) == -1 || + tdb_rec_write(tdb, offset, rec) == -1 || + tdb_ofs_write(tdb, FREELIST_TOP, &offset) == -1) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_free record write failed at offset=%u\n", offset)); + goto fail; + } + +done: + /* And we're done. */ + tdb_unlock(tdb, -1, F_WRLCK); + return 0; + + fail: + tdb_unlock(tdb, -1, F_WRLCK); + return -1; +} + + + +/* + the core of tdb_allocate - called when we have decided which + free list entry to use + + Note that we try to allocate by grabbing data from the end of an existing record, + not the beginning. This is so the left merge in a free is more likely to be + able to free up the record without fragmentation + */ +static tdb_off_t tdb_allocate_ofs(struct tdb_context *tdb, + tdb_len_t length, tdb_off_t rec_ptr, + struct tdb_record *rec, tdb_off_t last_ptr) +{ +#define MIN_REC_SIZE (sizeof(struct tdb_record) + sizeof(tdb_off_t) + 8) + + if (rec->rec_len < length + MIN_REC_SIZE) { + /* we have to grab the whole record */ + + /* unlink it from the previous record */ + if (tdb_ofs_write(tdb, last_ptr, &rec->next) == -1) { + return 0; + } + + /* mark it not free */ + rec->magic = TDB_MAGIC; + if (tdb_rec_write(tdb, rec_ptr, rec) == -1) { + return 0; + } + return rec_ptr; + } + + /* we're going to just shorten the existing record */ + rec->rec_len -= (length + sizeof(*rec)); + if (tdb_rec_write(tdb, rec_ptr, rec) == -1) { + return 0; + } + if (update_tailer(tdb, rec_ptr, rec) == -1) { + return 0; + } + + /* and setup the new record */ + rec_ptr += sizeof(*rec) + rec->rec_len; + + memset(rec, '\0', sizeof(*rec)); + rec->rec_len = length; + rec->magic = TDB_MAGIC; + + if (tdb_rec_write(tdb, rec_ptr, rec) == -1) { + return 0; + } + + if (update_tailer(tdb, rec_ptr, rec) == -1) { + return 0; + } + + return rec_ptr; +} + +/* allocate some space from the free list. The offset returned points + to a unconnected tdb_record within the database with room for at + least length bytes of total data + + 0 is returned if the space could not be allocated + */ +static tdb_off_t tdb_allocate_from_freelist( + struct tdb_context *tdb, tdb_len_t length, struct tdb_record *rec) +{ + tdb_off_t rec_ptr, last_ptr, newrec_ptr; + struct tdb_chainwalk_ctx chainwalk; + bool modified; + struct { + tdb_off_t rec_ptr, last_ptr; + tdb_len_t rec_len; + } bestfit; + float multiplier = 1.0; + bool merge_created_candidate; + + /* over-allocate to reduce fragmentation */ + length *= 1.25; + + /* Extra bytes required for tailer */ + length += sizeof(tdb_off_t); + length = TDB_ALIGN(length, TDB_ALIGNMENT); + + again: + merge_created_candidate = false; + last_ptr = FREELIST_TOP; + + /* read in the freelist top */ + if (tdb_ofs_read(tdb, FREELIST_TOP, &rec_ptr) == -1) + return 0; + + modified = false; + tdb_chainwalk_init(&chainwalk, rec_ptr); + + bestfit.rec_ptr = 0; + bestfit.last_ptr = 0; + bestfit.rec_len = 0; + + /* + this is a best fit allocation strategy. Originally we used + a first fit strategy, but it suffered from massive fragmentation + issues when faced with a slowly increasing record size. + */ + while (rec_ptr) { + int ret; + tdb_off_t left_ptr; + struct tdb_record left_rec; + + if (tdb_rec_free_read(tdb, rec_ptr, rec) == -1) { + return 0; + } + + ret = check_merge_with_left_record(tdb, rec_ptr, rec, + &left_ptr, &left_rec); + if (ret == -1) { + return 0; + } + if (ret == 1) { + /* merged */ + rec_ptr = rec->next; + ret = tdb_ofs_write(tdb, last_ptr, &rec->next); + if (ret == -1) { + return 0; + } + + /* + * We have merged the current record into the left + * neighbour. So our traverse of the freelist will + * skip it and consider the next record in the chain. + * + * But the enlarged left neighbour may be a candidate. + * If it is, we can not directly use it, though. + * The only thing we can do and have to do here is to + * update the current best fit size in the chain if the + * current best fit is the left record. (By that we may + * worsen the best fit we already had, bit this is not a + * problem.) + * + * If the current best fit is not the left record, + * all we can do is remember the fact that a merge + * created a new candidate so that we can trigger + * a second walk of the freelist if at the end of + * the first walk we have not found any fit. + * This way we can avoid expanding the database. + */ + + if (bestfit.rec_ptr == left_ptr) { + bestfit.rec_len = left_rec.rec_len; + } + + if (left_rec.rec_len > length) { + merge_created_candidate = true; + } + + modified = true; + + continue; + } + + if (rec->rec_len >= length) { + if (bestfit.rec_ptr == 0 || + rec->rec_len < bestfit.rec_len) { + bestfit.rec_len = rec->rec_len; + bestfit.rec_ptr = rec_ptr; + bestfit.last_ptr = last_ptr; + } + } + + /* move to the next record */ + last_ptr = rec_ptr; + rec_ptr = rec->next; + + if (!modified) { + bool ok; + ok = tdb_chainwalk_check(tdb, &chainwalk, rec_ptr); + if (!ok) { + return 0; + } + } + + /* if we've found a record that is big enough, then + stop searching if its also not too big. The + definition of 'too big' changes as we scan + through */ + if (bestfit.rec_len > 0 && + bestfit.rec_len < length * multiplier) { + break; + } + + /* this multiplier means we only extremely rarely + search more than 50 or so records. At 50 records we + accept records up to 11 times larger than what we + want */ + multiplier *= 1.05; + } + + if (bestfit.rec_ptr != 0) { + if (tdb_rec_free_read(tdb, bestfit.rec_ptr, rec) == -1) { + return 0; + } + + newrec_ptr = tdb_allocate_ofs(tdb, length, bestfit.rec_ptr, + rec, bestfit.last_ptr); + return newrec_ptr; + } + + if (merge_created_candidate) { + goto again; + } + + /* we didn't find enough space. See if we can expand the + database and if we can then try again */ + if (tdb_expand(tdb, length + sizeof(*rec)) == 0) + goto again; + + return 0; +} + +static bool tdb_alloc_dead( + struct tdb_context *tdb, int hash, tdb_len_t length, + tdb_off_t *rec_ptr, struct tdb_record *rec) +{ + tdb_off_t last_ptr; + + *rec_ptr = tdb_find_dead(tdb, hash, rec, length, &last_ptr); + if (*rec_ptr == 0) { + return false; + } + /* + * Unlink the record from the hash chain, it's about to be moved into + * another one. + */ + return (tdb_ofs_write(tdb, last_ptr, &rec->next) == 0); +} + +static void tdb_purge_dead(struct tdb_context *tdb, uint32_t hash) +{ + int max_dead_records = tdb->max_dead_records; + + tdb->max_dead_records = 0; + + tdb_trim_dead(tdb, hash); + + tdb->max_dead_records = max_dead_records; +} + +/* + * Chain "hash" is assumed to be locked + */ + +tdb_off_t tdb_allocate(struct tdb_context *tdb, int hash, tdb_len_t length, + struct tdb_record *rec) +{ + tdb_off_t ret; + uint32_t i; + + if (tdb->max_dead_records == 0) { + /* + * No dead records to expect anywhere. Do the blocking + * freelist lock without trying to steal from others + */ + goto blocking_freelist_allocate; + } + + /* + * The following loop tries to get the freelist lock nonblocking. If + * it gets the lock, allocate from there. If the freelist is busy, + * instead of waiting we try to steal dead records from other hash + * chains. + * + * Be aware that we do nonblocking locks on the other hash chains as + * well and fail gracefully. This way we avoid deadlocks (we block two + * hash chains, something which is pretty bad normally) + */ + + for (i=0; i<tdb->hash_size; i++) { + + int list; + + list = BUCKET(hash+i); + + if (tdb_lock_nonblock(tdb, list, F_WRLCK) == 0) { + bool got_dead; + + got_dead = tdb_alloc_dead(tdb, list, length, &ret, rec); + tdb_unlock(tdb, list, F_WRLCK); + + if (got_dead) { + return ret; + } + } + + if (tdb_lock_nonblock(tdb, -1, F_WRLCK) == 0) { + /* + * Under the freelist lock take the chance to give + * back our dead records. + */ + tdb_purge_dead(tdb, hash); + + ret = tdb_allocate_from_freelist(tdb, length, rec); + tdb_unlock(tdb, -1, F_WRLCK); + return ret; + } + } + +blocking_freelist_allocate: + + if (tdb_lock(tdb, -1, F_WRLCK) == -1) { + return 0; + } + /* + * Dead records can happen even if max_dead_records==0, they + * are older than the max_dead_records concept: They happen if + * tdb_delete happens concurrently with a traverse. + */ + tdb_purge_dead(tdb, hash); + ret = tdb_allocate_from_freelist(tdb, length, rec); + tdb_unlock(tdb, -1, F_WRLCK); + return ret; +} + +/** + * Merge adjacent records in the freelist. + */ +static int tdb_freelist_merge_adjacent(struct tdb_context *tdb, + int *count_records, int *count_merged) +{ + tdb_off_t cur, next; + int count = 0; + int merged = 0; + int ret; + + ret = tdb_lock(tdb, -1, F_RDLCK); + if (ret == -1) { + return -1; + } + + cur = FREELIST_TOP; + while (tdb_ofs_read(tdb, cur, &next) == 0 && next != 0) { + tdb_off_t next2; + + count++; + + ret = check_merge_ptr_with_left_record(tdb, next, &next2); + if (ret == -1) { + goto done; + } + if (ret == 1) { + /* + * merged: + * now let cur->next point to next2 instead of next + */ + + ret = tdb_ofs_write(tdb, cur, &next2); + if (ret != 0) { + goto done; + } + + next = next2; + merged++; + } + + cur = next; + } + + if (count_records != NULL) { + *count_records = count; + } + + if (count_merged != NULL) { + *count_merged = merged; + } + + ret = 0; + +done: + tdb_unlock(tdb, -1, F_RDLCK); + return ret; +} + +/** + * return the size of the freelist - no merging done + */ +static int tdb_freelist_size_no_merge(struct tdb_context *tdb) +{ + tdb_off_t ptr; + int count=0; + + if (tdb_lock(tdb, -1, F_RDLCK) == -1) { + return -1; + } + + ptr = FREELIST_TOP; + while (tdb_ofs_read(tdb, ptr, &ptr) == 0 && ptr != 0) { + count++; + } + + tdb_unlock(tdb, -1, F_RDLCK); + return count; +} + +/** + * return the size of the freelist - used to decide if we should repack + * + * As a side effect, adjacent records are merged unless the + * database is read-only, in order to reduce the fragmentation + * without repacking. + */ +_PUBLIC_ int tdb_freelist_size(struct tdb_context *tdb) +{ + + int count = 0; + + if (tdb->read_only) { + count = tdb_freelist_size_no_merge(tdb); + } else { + int ret; + ret = tdb_freelist_merge_adjacent(tdb, &count, NULL); + if (ret != 0) { + return -1; + } + } + + return count; +} diff --git a/common/freelistcheck.c b/common/freelistcheck.c new file mode 100644 index 0000000..2f1e6eb --- /dev/null +++ b/common/freelistcheck.c @@ -0,0 +1,107 @@ +/* + Unix SMB/CIFS implementation. + + trivial database library + + Copyright (C) Jeremy Allison 2006 + + ** NOTE! The following LGPL license applies to the tdb + ** library. This does NOT imply that all of Samba is released + ** under the LGPL + + This library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 3 of the License, or (at your option) any later version. + + This library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with this library; if not, see <http://www.gnu.org/licenses/>. +*/ + +#include "tdb_private.h" + +/* Check the freelist is good and contains no loops. + Very memory intensive - only do this as a consistency + checker. Heh heh - uses an in memory tdb as the storage + for the "seen" record list. For some reason this strikes + me as extremely clever as I don't have to write another tree + data structure implementation :-). + */ + +static int seen_insert(struct tdb_context *mem_tdb, tdb_off_t rec_ptr) +{ + TDB_DATA key; + + key.dptr = (unsigned char *)&rec_ptr; + key.dsize = sizeof(rec_ptr); + return tdb_store(mem_tdb, key, tdb_null, TDB_INSERT); +} + +_PUBLIC_ int tdb_validate_freelist(struct tdb_context *tdb, int *pnum_entries) +{ + struct tdb_context *mem_tdb = NULL; + struct tdb_record rec; + tdb_off_t rec_ptr, last_ptr; + int ret = -1; + + *pnum_entries = 0; + + mem_tdb = tdb_open("flval", tdb->hash_size, + TDB_INTERNAL, O_RDWR, 0600); + if (!mem_tdb) { + return -1; + } + + if (tdb_lock(tdb, -1, F_WRLCK) == -1) { + tdb_close(mem_tdb); + return 0; + } + + last_ptr = FREELIST_TOP; + + /* Store the FREELIST_TOP record. */ + if (seen_insert(mem_tdb, last_ptr) == -1) { + tdb->ecode = TDB_ERR_CORRUPT; + ret = -1; + goto fail; + } + + /* read in the freelist top */ + if (tdb_ofs_read(tdb, FREELIST_TOP, &rec_ptr) == -1) { + goto fail; + } + + while (rec_ptr) { + + /* If we can't store this record (we've seen it + before) then the free list has a loop and must + be corrupt. */ + + if (seen_insert(mem_tdb, rec_ptr)) { + tdb->ecode = TDB_ERR_CORRUPT; + ret = -1; + goto fail; + } + + if (tdb_rec_free_read(tdb, rec_ptr, &rec) == -1) { + goto fail; + } + + /* move to the next record */ + rec_ptr = rec.next; + *pnum_entries += 1; + } + + ret = 0; + + fail: + + tdb_close(mem_tdb); + tdb_unlock(tdb, -1, F_WRLCK); + return ret; +} diff --git a/common/hash.c b/common/hash.c new file mode 100644 index 0000000..ca4cac3 --- /dev/null +++ b/common/hash.c @@ -0,0 +1,345 @@ + /* + Unix SMB/CIFS implementation. + + trivial database library + + Copyright (C) Rusty Russell 2010 + + ** NOTE! The following LGPL license applies to the tdb + ** library. This does NOT imply that all of Samba is released + ** under the LGPL + + This library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 3 of the License, or (at your option) any later version. + + This library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with this library; if not, see <http://www.gnu.org/licenses/>. +*/ +#include "tdb_private.h" + +/* This is based on the hash algorithm from gdbm */ +unsigned int tdb_old_hash(TDB_DATA *key) +{ + uint32_t value; /* Used to compute the hash value. */ + uint32_t i; /* Used to cycle through random values. */ + + /* Set the initial value from the key size. */ + for (value = 0x238F13AF * key->dsize, i=0; i < key->dsize; i++) + value = (value + (key->dptr[i] << (i*5 % 24))); + + return (1103515243 * value + 12345); +} + +#ifndef WORDS_BIGENDIAN +# define HASH_LITTLE_ENDIAN 1 +# define HASH_BIG_ENDIAN 0 +#else +# define HASH_LITTLE_ENDIAN 0 +# define HASH_BIG_ENDIAN 1 +#endif + +/* +------------------------------------------------------------------------------- +lookup3.c, by Bob Jenkins, May 2006, Public Domain. + +These are functions for producing 32-bit hashes for hash table lookup. +hash_word(), hashlittle(), hashlittle2(), hashbig(), mix(), and final() +are externally useful functions. Routines to test the hash are included +if SELF_TEST is defined. You can use this free for any purpose. It's in +the public domain. It has no warranty. + +You probably want to use hashlittle(). hashlittle() and hashbig() +hash byte arrays. hashlittle() is faster than hashbig() on +little-endian machines. Intel and AMD are little-endian machines. +On second thought, you probably want hashlittle2(), which is identical to +hashlittle() except it returns two 32-bit hashes for the price of one. +You could implement hashbig2() if you wanted but I haven't bothered here. + +If you want to find a hash of, say, exactly 7 integers, do + a = i1; b = i2; c = i3; + mix(a,b,c); + a += i4; b += i5; c += i6; + mix(a,b,c); + a += i7; + final(a,b,c); +then use c as the hash value. If you have a variable length array of +4-byte integers to hash, use hash_word(). If you have a byte array (like +a character string), use hashlittle(). If you have several byte arrays, or +a mix of things, see the comments above hashlittle(). + +Why is this so big? I read 12 bytes at a time into 3 4-byte integers, +then mix those integers. This is fast (you can do a lot more thorough +mixing with 12*3 instructions on 3 integers than you can with 3 instructions +on 1 byte), but shoehorning those bytes into integers efficiently is messy. +*/ + +#define hashsize(n) ((uint32_t)1<<(n)) +#define hashmask(n) (hashsize(n)-1) +#define rot(x,k) (((x)<<(k)) | ((x)>>(32-(k)))) + +/* +------------------------------------------------------------------------------- +mix -- mix 3 32-bit values reversibly. + +This is reversible, so any information in (a,b,c) before mix() is +still in (a,b,c) after mix(). + +If four pairs of (a,b,c) inputs are run through mix(), or through +mix() in reverse, there are at least 32 bits of the output that +are sometimes the same for one pair and different for another pair. +This was tested for: +* pairs that differed by one bit, by two bits, in any combination + of top bits of (a,b,c), or in any combination of bottom bits of + (a,b,c). +* "differ" is defined as +, -, ^, or ~^. For + and -, I transformed + the output delta to a Gray code (a^(a>>1)) so a string of 1's (as + is commonly produced by subtraction) look like a single 1-bit + difference. +* the base values were pseudorandom, all zero but one bit set, or + all zero plus a counter that starts at zero. + +Some k values for my "a-=c; a^=rot(c,k); c+=b;" arrangement that +satisfy this are + 4 6 8 16 19 4 + 9 15 3 18 27 15 + 14 9 3 7 17 3 +Well, "9 15 3 18 27 15" didn't quite get 32 bits diffing +for "differ" defined as + with a one-bit base and a two-bit delta. I +used http://burtleburtle.net/bob/hash/avalanche.html to choose +the operations, constants, and arrangements of the variables. + +This does not achieve avalanche. There are input bits of (a,b,c) +that fail to affect some output bits of (a,b,c), especially of a. The +most thoroughly mixed value is c, but it doesn't really even achieve +avalanche in c. + +This allows some parallelism. Read-after-writes are good at doubling +the number of bits affected, so the goal of mixing pulls in the opposite +direction as the goal of parallelism. I did what I could. Rotates +seem to cost as much as shifts on every machine I could lay my hands +on, and rotates are much kinder to the top and bottom bits, so I used +rotates. +------------------------------------------------------------------------------- +*/ +#define mix(a,b,c) \ +{ \ + a -= c; a ^= rot(c, 4); c += b; \ + b -= a; b ^= rot(a, 6); a += c; \ + c -= b; c ^= rot(b, 8); b += a; \ + a -= c; a ^= rot(c,16); c += b; \ + b -= a; b ^= rot(a,19); a += c; \ + c -= b; c ^= rot(b, 4); b += a; \ +} + +/* +------------------------------------------------------------------------------- +final -- final mixing of 3 32-bit values (a,b,c) into c + +Pairs of (a,b,c) values differing in only a few bits will usually +produce values of c that look totally different. This was tested for +* pairs that differed by one bit, by two bits, in any combination + of top bits of (a,b,c), or in any combination of bottom bits of + (a,b,c). +* "differ" is defined as +, -, ^, or ~^. For + and -, I transformed + the output delta to a Gray code (a^(a>>1)) so a string of 1's (as + is commonly produced by subtraction) look like a single 1-bit + difference. +* the base values were pseudorandom, all zero but one bit set, or + all zero plus a counter that starts at zero. + +These constants passed: + 14 11 25 16 4 14 24 + 12 14 25 16 4 14 24 +and these came close: + 4 8 15 26 3 22 24 + 10 8 15 26 3 22 24 + 11 8 15 26 3 22 24 +------------------------------------------------------------------------------- +*/ +#define final(a,b,c) \ +{ \ + c ^= b; c -= rot(b,14); \ + a ^= c; a -= rot(c,11); \ + b ^= a; b -= rot(a,25); \ + c ^= b; c -= rot(b,16); \ + a ^= c; a -= rot(c,4); \ + b ^= a; b -= rot(a,14); \ + c ^= b; c -= rot(b,24); \ +} + + +/* +------------------------------------------------------------------------------- +hashlittle() -- hash a variable-length key into a 32-bit value + k : the key (the unaligned variable-length array of bytes) + length : the length of the key, counting by bytes + val2 : IN: can be any 4-byte value OUT: second 32 bit hash. +Returns a 32-bit value. Every bit of the key affects every bit of +the return value. Two keys differing by one or two bits will have +totally different hash values. Note that the return value is better +mixed than val2, so use that first. + +The best hash table sizes are powers of 2. There is no need to do +mod a prime (mod is sooo slow!). If you need less than 32 bits, +use a bitmask. For example, if you need only 10 bits, do + h = (h & hashmask(10)); +In which case, the hash table should have hashsize(10) elements. + +If you are hashing n strings (uint8_t **)k, do it like this: + for (i=0, h=0; i<n; ++i) h = hashlittle( k[i], len[i], h); + +By Bob Jenkins, 2006. bob_jenkins@burtleburtle.net. You may use this +code any way you wish, private, educational, or commercial. It's free. + +Use for hash table lookup, or anything where one collision in 2^^32 is +acceptable. Do NOT use for cryptographic purposes. +------------------------------------------------------------------------------- +*/ + +static uint32_t hashlittle( const void *key, size_t length ) +{ + uint32_t a,b,c; /* internal state */ + union { const void *ptr; size_t i; } u; /* needed for Mac Powerbook G4 */ + + /* Set up the internal state */ + a = b = c = 0xdeadbeef + ((uint32_t)length); + + u.ptr = key; + if (HASH_LITTLE_ENDIAN && ((u.i & 0x3) == 0)) { + const uint32_t *k = (const uint32_t *)key; /* read 32-bit chunks */ + const uint8_t *k8; + + /*------ all but last block: aligned reads and affect 32 bits of (a,b,c) */ + while (length > 12) + { + a += k[0]; + b += k[1]; + c += k[2]; + mix(a,b,c); + length -= 12; + k += 3; + } + + /*----------------------------- handle the last (probably partial) block */ + k8 = (const uint8_t *)k; + switch(length) + { + case 12: c+=k[2]; b+=k[1]; a+=k[0]; break; + case 11: c+=((uint32_t)k8[10])<<16; FALL_THROUGH; + case 10: c+=((uint32_t)k8[9])<<8; FALL_THROUGH; + case 9 : c+=k8[8]; FALL_THROUGH; + case 8 : b+=k[1]; a+=k[0]; break; + case 7 : b+=((uint32_t)k8[6])<<16; FALL_THROUGH; + case 6 : b+=((uint32_t)k8[5])<<8; FALL_THROUGH; + case 5 : b+=k8[4]; FALL_THROUGH; + case 4 : a+=k[0]; break; + case 3 : a+=((uint32_t)k8[2])<<16; FALL_THROUGH; + case 2 : a+=((uint32_t)k8[1])<<8; FALL_THROUGH; + case 1 : a+=k8[0]; break; + case 0 : return c; + } + } else if (HASH_LITTLE_ENDIAN && ((u.i & 0x1) == 0)) { + const uint16_t *k = (const uint16_t *)key; /* read 16-bit chunks */ + const uint8_t *k8; + + /*--------------- all but last block: aligned reads and different mixing */ + while (length > 12) + { + a += k[0] + (((uint32_t)k[1])<<16); + b += k[2] + (((uint32_t)k[3])<<16); + c += k[4] + (((uint32_t)k[5])<<16); + mix(a,b,c); + length -= 12; + k += 6; + } + + /*----------------------------- handle the last (probably partial) block */ + k8 = (const uint8_t *)k; + switch(length) + { + case 12: c+=k[4]+(((uint32_t)k[5])<<16); + b+=k[2]+(((uint32_t)k[3])<<16); + a+=k[0]+(((uint32_t)k[1])<<16); + break; + case 11: c+=((uint32_t)k8[10])<<16; FALL_THROUGH; + case 10: c+=k[4]; + b+=k[2]+(((uint32_t)k[3])<<16); + a+=k[0]+(((uint32_t)k[1])<<16); + break; + case 9 : c+=k8[8]; FALL_THROUGH; + case 8 : b+=k[2]+(((uint32_t)k[3])<<16); + a+=k[0]+(((uint32_t)k[1])<<16); + break; + case 7 : b+=((uint32_t)k8[6])<<16; FALL_THROUGH; + case 6 : b+=k[2]; + a+=k[0]+(((uint32_t)k[1])<<16); + break; + case 5 : b+=k8[4]; FALL_THROUGH; + case 4 : a+=k[0]+(((uint32_t)k[1])<<16); + break; + case 3 : a+=((uint32_t)k8[2])<<16; FALL_THROUGH; + case 2 : a+=k[0]; + break; + case 1 : a+=k8[0]; + break; + case 0 : return c; /* zero length requires no mixing */ + } + + } else { /* need to read the key one byte at a time */ + const uint8_t *k = (const uint8_t *)key; + + /*--------------- all but the last block: affect some 32 bits of (a,b,c) */ + while (length > 12) + { + a += k[0]; + a += ((uint32_t)k[1])<<8; + a += ((uint32_t)k[2])<<16; + a += ((uint32_t)k[3])<<24; + b += k[4]; + b += ((uint32_t)k[5])<<8; + b += ((uint32_t)k[6])<<16; + b += ((uint32_t)k[7])<<24; + c += k[8]; + c += ((uint32_t)k[9])<<8; + c += ((uint32_t)k[10])<<16; + c += ((uint32_t)k[11])<<24; + mix(a,b,c); + length -= 12; + k += 12; + } + + /*-------------------------------- last block: affect all 32 bits of (c) */ + switch(length) + { + case 12: c+=((uint32_t)k[11])<<24; FALL_THROUGH; + case 11: c+=((uint32_t)k[10])<<16; FALL_THROUGH; + case 10: c+=((uint32_t)k[9])<<8; FALL_THROUGH; + case 9 : c+=k[8]; FALL_THROUGH; + case 8 : b+=((uint32_t)k[7])<<24; FALL_THROUGH; + case 7 : b+=((uint32_t)k[6])<<16; FALL_THROUGH; + case 6 : b+=((uint32_t)k[5])<<8; FALL_THROUGH; + case 5 : b+=k[4]; FALL_THROUGH; + case 4 : a+=((uint32_t)k[3])<<24; FALL_THROUGH; + case 3 : a+=((uint32_t)k[2])<<16; FALL_THROUGH; + case 2 : a+=((uint32_t)k[1])<<8; FALL_THROUGH; + case 1 : a+=k[0]; + break; + case 0 : return c; + } + } + + final(a,b,c); + return c; +} + +_PUBLIC_ unsigned int tdb_jenkins_hash(TDB_DATA *key) +{ + return hashlittle(key->dptr, key->dsize); +} diff --git a/common/io.c b/common/io.c new file mode 100644 index 0000000..0de0dab --- /dev/null +++ b/common/io.c @@ -0,0 +1,806 @@ + /* + Unix SMB/CIFS implementation. + + trivial database library + + Copyright (C) Andrew Tridgell 1999-2005 + Copyright (C) Paul `Rusty' Russell 2000 + Copyright (C) Jeremy Allison 2000-2003 + + ** NOTE! The following LGPL license applies to the tdb + ** library. This does NOT imply that all of Samba is released + ** under the LGPL + + This library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 3 of the License, or (at your option) any later version. + + This library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with this library; if not, see <http://www.gnu.org/licenses/>. +*/ + + +#include "tdb_private.h" + +/* + * We prepend the mutex area, so fixup offsets. See mutex.c for details. + * tdb->hdr_ofs is 0 or header.mutex_size. + * + * Note: that we only have the 4GB limit of tdb_off_t for + * tdb->map_size. The file size on disk can be 4GB + tdb->hdr_ofs! + */ + +static bool tdb_adjust_offset(struct tdb_context *tdb, off_t *off) +{ + off_t tmp = tdb->hdr_ofs + *off; + + if ((tmp < tdb->hdr_ofs) || (tmp < *off)) { + errno = EIO; + return false; + } + + *off = tmp; + return true; +} + +static ssize_t tdb_pwrite(struct tdb_context *tdb, const void *buf, + size_t count, off_t offset) +{ + ssize_t ret; + + if (!tdb_adjust_offset(tdb, &offset)) { + return -1; + } + + do { + ret = pwrite(tdb->fd, buf, count, offset); + } while ((ret == -1) && (errno == EINTR)); + + return ret; +} + +static ssize_t tdb_pread(struct tdb_context *tdb, void *buf, + size_t count, off_t offset) +{ + ssize_t ret; + + if (!tdb_adjust_offset(tdb, &offset)) { + return -1; + } + + do { + ret = pread(tdb->fd, buf, count, offset); + } while ((ret == -1) && (errno == EINTR)); + + return ret; +} + +static int tdb_ftruncate(struct tdb_context *tdb, off_t length) +{ + ssize_t ret; + + if (!tdb_adjust_offset(tdb, &length)) { + return -1; + } + + do { + ret = ftruncate(tdb->fd, length); + } while ((ret == -1) && (errno == EINTR)); + + return ret; +} + +#ifdef HAVE_POSIX_FALLOCATE +static int tdb_posix_fallocate(struct tdb_context *tdb, off_t offset, + off_t len) +{ + ssize_t ret; + + if (!tdb_adjust_offset(tdb, &offset)) { + return -1; + } + + do { + ret = posix_fallocate(tdb->fd, offset, len); + } while ((ret == -1) && (errno == EINTR)); + + return ret; +} +#endif + +static int tdb_fstat(struct tdb_context *tdb, struct stat *buf) +{ + int ret; + + ret = fstat(tdb->fd, buf); + if (ret == -1) { + return -1; + } + + if (buf->st_size < tdb->hdr_ofs) { + errno = EIO; + return -1; + } + buf->st_size -= tdb->hdr_ofs; + + return ret; +} + +/* check for an out of bounds access - if it is out of bounds then + see if the database has been expanded by someone else and expand + if necessary +*/ +static int tdb_notrans_oob( + struct tdb_context *tdb, tdb_off_t off, tdb_len_t len, int probe) +{ + struct stat st; + if (len + off < len) { + if (!probe) { + /* Ensure ecode is set for log fn. */ + tdb->ecode = TDB_ERR_IO; + TDB_LOG((tdb, TDB_DEBUG_FATAL,"tdb_oob off %u len %u wrap\n", + off, len)); + } + return -1; + } + + /* + * This duplicates functionality from tdb_oob(). Don't remove: + * we still have direct callers of tdb->methods->tdb_oob() + * inside transaction.c. + */ + if (off + len <= tdb->map_size) + return 0; + if (tdb->flags & TDB_INTERNAL) { + if (!probe) { + /* Ensure ecode is set for log fn. */ + tdb->ecode = TDB_ERR_IO; + TDB_LOG((tdb, TDB_DEBUG_FATAL,"tdb_oob len %u beyond internal malloc size %u\n", + (int)(off + len), (int)tdb->map_size)); + } + return -1; + } + + if (tdb_fstat(tdb, &st) == -1) { + tdb->ecode = TDB_ERR_IO; + return -1; + } + + /* Beware >4G files! */ + if ((tdb_off_t)st.st_size != st.st_size) { + /* Ensure ecode is set for log fn. */ + tdb->ecode = TDB_ERR_IO; + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_oob len %llu too large!\n", + (long long)st.st_size)); + return -1; + } + + /* Unmap, update size, remap. We do this unconditionally, to handle + * the unusual case where the db is truncated. + * + * This can happen to a child using tdb_reopen_all(true) on a + * TDB_CLEAR_IF_FIRST tdb whose parent crashes: the next + * opener will truncate the database. */ + if (tdb_munmap(tdb) == -1) { + tdb->ecode = TDB_ERR_IO; + return -1; + } + tdb->map_size = st.st_size; + if (tdb_mmap(tdb) != 0) { + return -1; + } + + if (st.st_size < (size_t)off + len) { + if (!probe) { + /* Ensure ecode is set for log fn. */ + tdb->ecode = TDB_ERR_IO; + TDB_LOG((tdb, TDB_DEBUG_FATAL,"tdb_oob len %u beyond eof at %u\n", + (int)(off + len), (int)st.st_size)); + } + return -1; + } + return 0; +} + +/* write a lump of data at a specified offset */ +static int tdb_write(struct tdb_context *tdb, tdb_off_t off, + const void *buf, tdb_len_t len) +{ + if (len == 0) { + return 0; + } + + if (tdb->read_only || tdb->traverse_read) { + tdb->ecode = TDB_ERR_RDONLY; + return -1; + } + + if (tdb_oob(tdb, off, len, 0) != 0) + return -1; + + if (tdb->map_ptr) { + memcpy(off + (char *)tdb->map_ptr, buf, len); + } else { +#ifdef HAVE_INCOHERENT_MMAP + tdb->ecode = TDB_ERR_IO; + return -1; +#else + ssize_t written; + + written = tdb_pwrite(tdb, buf, len, off); + + if ((written != (ssize_t)len) && (written != -1)) { + /* try once more */ + tdb->ecode = TDB_ERR_IO; + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_write: wrote only " + "%zi of %u bytes at %u, trying once more\n", + written, len, off)); + written = tdb_pwrite(tdb, (const char *)buf+written, + len-written, off+written); + } + if (written == -1) { + /* Ensure ecode is set for log fn. */ + tdb->ecode = TDB_ERR_IO; + TDB_LOG((tdb, TDB_DEBUG_FATAL,"tdb_write failed at %u " + "len=%u (%s)\n", off, len, strerror(errno))); + return -1; + } else if (written != (ssize_t)len) { + tdb->ecode = TDB_ERR_IO; + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_write: failed to " + "write %u bytes at %u in two attempts\n", + len, off)); + return -1; + } +#endif + } + return 0; +} + +/* Endian conversion: we only ever deal with 4 byte quantities */ +void *tdb_convert(void *buf, uint32_t size) +{ + uint32_t i, *p = (uint32_t *)buf; + for (i = 0; i < size / 4; i++) + p[i] = TDB_BYTEREV(p[i]); + return buf; +} + + +/* read a lump of data at a specified offset, maybe convert */ +static int tdb_read(struct tdb_context *tdb, tdb_off_t off, void *buf, + tdb_len_t len, int cv) +{ + if (tdb_oob(tdb, off, len, 0) != 0) { + return -1; + } + + if (tdb->map_ptr) { + memcpy(buf, off + (char *)tdb->map_ptr, len); + } else { +#ifdef HAVE_INCOHERENT_MMAP + tdb->ecode = TDB_ERR_IO; + return -1; +#else + ssize_t ret; + + ret = tdb_pread(tdb, buf, len, off); + if (ret != (ssize_t)len) { + /* Ensure ecode is set for log fn. */ + tdb->ecode = TDB_ERR_IO; + TDB_LOG((tdb, TDB_DEBUG_FATAL,"tdb_read failed at %u " + "len=%u ret=%zi (%s) map_size=%u\n", + off, len, ret, strerror(errno), + tdb->map_size)); + return -1; + } +#endif + } + if (cv) { + tdb_convert(buf, len); + } + return 0; +} + + + +/* + do an unlocked scan of the hash table heads to find the next non-zero head. The value + will then be confirmed with the lock held +*/ +static void tdb_next_hash_chain(struct tdb_context *tdb, uint32_t *chain) +{ + uint32_t h = *chain; + if (tdb->map_ptr) { + for (;h < tdb->hash_size;h++) { + if (0 != *(uint32_t *)(TDB_HASH_TOP(h) + (unsigned char *)tdb->map_ptr)) { + break; + } + } + } else { + uint32_t off=0; + for (;h < tdb->hash_size;h++) { + if (tdb_ofs_read(tdb, TDB_HASH_TOP(h), &off) != 0 || off != 0) { + break; + } + } + } + (*chain) = h; +} + + +int tdb_munmap(struct tdb_context *tdb) +{ + if (tdb->flags & TDB_INTERNAL) + return 0; + +#ifdef HAVE_MMAP + if (tdb->map_ptr) { + int ret; + + ret = munmap(tdb->map_ptr, tdb->map_size); + if (ret != 0) + return ret; + } +#endif + tdb->map_ptr = NULL; + return 0; +} + +/* If mmap isn't coherent, *everyone* must always mmap. */ +static bool should_mmap(const struct tdb_context *tdb) +{ +#ifdef HAVE_INCOHERENT_MMAP + return true; +#else + return !(tdb->flags & TDB_NOMMAP); +#endif +} + +int tdb_mmap(struct tdb_context *tdb) +{ + if (tdb->flags & TDB_INTERNAL) + return 0; + +#ifdef HAVE_MMAP + if (should_mmap(tdb)) { + tdb->map_ptr = mmap(NULL, tdb->map_size, + PROT_READ|(tdb->read_only? 0:PROT_WRITE), + MAP_SHARED|MAP_FILE, tdb->fd, + tdb->hdr_ofs); + + /* + * NB. When mmap fails it returns MAP_FAILED *NOT* NULL !!!! + */ + + if (tdb->map_ptr == MAP_FAILED) { + tdb->map_ptr = NULL; + TDB_LOG((tdb, TDB_DEBUG_WARNING, "tdb_mmap failed for size %u (%s)\n", + tdb->map_size, strerror(errno))); +#ifdef HAVE_INCOHERENT_MMAP + tdb->ecode = TDB_ERR_IO; + return -1; +#endif + } + } else { + tdb->map_ptr = NULL; + } +#else + tdb->map_ptr = NULL; +#endif + return 0; +} + +/* expand a file. we prefer to use ftruncate, as that is what posix + says to use for mmap expansion */ +static int tdb_expand_file(struct tdb_context *tdb, tdb_off_t size, tdb_off_t addition) +{ + char buf[8192]; + tdb_off_t new_size; + int ret; + + if (tdb->read_only || tdb->traverse_read) { + tdb->ecode = TDB_ERR_RDONLY; + return -1; + } + + if (!tdb_add_off_t(size, addition, &new_size)) { + tdb->ecode = TDB_ERR_OOM; + TDB_LOG((tdb, TDB_DEBUG_FATAL, "expand_file write " + "overflow detected current size[%u] addition[%u]!\n", + (unsigned)size, (unsigned)addition)); + errno = ENOSPC; + return -1; + } + +#ifdef HAVE_POSIX_FALLOCATE + ret = tdb_posix_fallocate(tdb, size, addition); + if (ret == 0) { + return 0; + } + if (ret == ENOSPC) { + /* + * The Linux glibc (at least as of 2.24) fallback if + * the file system does not support fallocate does not + * reset the file size back to where it was. Also, to + * me it is unclear from the posix spec of + * posix_fallocate whether this is allowed or + * not. Better be safe than sorry and "goto fail" but + * "return -1" here, leaving the EOF pointer too + * large. + */ + goto fail; + } + + /* + * Retry the "old" way. Possibly unnecessary, but looking at + * our configure script there seem to be weird failure modes + * for posix_fallocate. See commit 3264a98ff16de, which + * probably refers to + * https://sourceware.org/bugzilla/show_bug.cgi?id=1083. + */ +#endif + + ret = tdb_ftruncate(tdb, new_size); + if (ret == -1) { + char b = 0; + ssize_t written = tdb_pwrite(tdb, &b, 1, new_size - 1); + if (written == 0) { + /* try once more, potentially revealing errno */ + written = tdb_pwrite(tdb, &b, 1, new_size - 1); + } + if (written == 0) { + /* again - give up, guessing errno */ + errno = ENOSPC; + } + if (written != 1) { + tdb->ecode = TDB_ERR_OOM; + TDB_LOG((tdb, TDB_DEBUG_FATAL, "expand_file to %u failed (%s)\n", + (unsigned)new_size, strerror(errno))); + return -1; + } + } + + /* now fill the file with something. This ensures that the + file isn't sparse, which would be very bad if we ran out of + disk. This must be done with write, not via mmap */ + memset(buf, TDB_PAD_BYTE, sizeof(buf)); + while (addition) { + size_t n = addition>sizeof(buf)?sizeof(buf):addition; + ssize_t written = tdb_pwrite(tdb, buf, n, size); + if (written == 0) { + /* prevent infinite loops: try _once_ more */ + written = tdb_pwrite(tdb, buf, n, size); + } + if (written == 0) { + /* give up, trying to provide a useful errno */ + tdb->ecode = TDB_ERR_OOM; + TDB_LOG((tdb, TDB_DEBUG_FATAL, "expand_file write " + "returned 0 twice: giving up!\n")); + errno = ENOSPC; + goto fail; + } + if (written == -1) { + tdb->ecode = TDB_ERR_OOM; + TDB_LOG((tdb, TDB_DEBUG_FATAL, "expand_file write of " + "%u bytes failed (%s)\n", (int)n, + strerror(errno))); + goto fail; + } + if (written != n) { + TDB_LOG((tdb, TDB_DEBUG_WARNING, "expand_file: wrote " + "only %zu of %zi bytes - retrying\n", written, + n)); + } + addition -= written; + size += written; + } + return 0; + +fail: + { + int err = errno; + + /* + * We're holding the freelist lock or are inside a + * transaction. Cutting the file is safe, the space we + * tried to allocate can't have been used anywhere in + * the meantime. + */ + + ret = tdb_ftruncate(tdb, size); + if (ret == -1) { + TDB_LOG((tdb, TDB_DEBUG_WARNING, "expand_file: " + "retruncate to %ju failed\n", + (uintmax_t)size)); + } + errno = err; + } + + return -1; +} + + +/* You need 'size', this tells you how much you should expand by. */ +tdb_off_t tdb_expand_adjust(tdb_off_t map_size, tdb_off_t size, int page_size) +{ + tdb_off_t new_size, top_size, increment; + tdb_off_t max_size = UINT32_MAX - map_size; + + if (size > max_size) { + /* + * We can't round up anymore, just give back + * what we're asked for. + * + * The caller has to take care of the ENOSPC handling. + */ + return size; + } + + /* limit size in order to avoid using up huge amounts of memory for + * in memory tdbs if an oddball huge record creeps in */ + if (size > 100 * 1024) { + increment = size * 2; + } else { + increment = size * 100; + } + if (increment < size) { + goto overflow; + } + + if (!tdb_add_off_t(map_size, increment, &top_size)) { + goto overflow; + } + + /* always make room for at least top_size more records, and at + least 25% more space. if the DB is smaller than 100MiB, + otherwise grow it by 10% only. */ + if (map_size > 100 * 1024 * 1024) { + new_size = map_size * 1.10; + } else { + new_size = map_size * 1.25; + } + if (new_size < map_size) { + goto overflow; + } + + /* Round the database up to a multiple of the page size */ + new_size = MAX(top_size, new_size); + + if (new_size + page_size < new_size) { + /* There's a "+" in TDB_ALIGN that might overflow... */ + goto overflow; + } + + return TDB_ALIGN(new_size, page_size) - map_size; + +overflow: + /* + * Somewhere in between we went over 4GB. Make one big jump to + * exactly 4GB database size. + */ + return max_size; +} + +/* expand the database at least size bytes by expanding the underlying + file and doing the mmap again if necessary */ +int tdb_expand(struct tdb_context *tdb, tdb_off_t size) +{ + struct tdb_record rec; + tdb_off_t offset; + tdb_off_t new_size; + + if (tdb_lock(tdb, -1, F_WRLCK) == -1) { + TDB_LOG((tdb, TDB_DEBUG_ERROR, "lock failed in tdb_expand\n")); + return -1; + } + + /* must know about any previous expansions by another process */ + tdb_oob(tdb, tdb->map_size, 1, 1); + + /* + * Note: that we don't care about tdb->hdr_ofs != 0 here + * + * The 4GB limitation is just related to tdb->map_size + * and the offset calculation in the records. + * + * The file on disk can be up to 4GB + tdb->hdr_ofs + */ + size = tdb_expand_adjust(tdb->map_size, size, tdb->page_size); + + if (!tdb_add_off_t(tdb->map_size, size, &new_size)) { + tdb->ecode = TDB_ERR_OOM; + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_expand " + "overflow detected current map_size[%u] size[%u]!\n", + (unsigned)tdb->map_size, (unsigned)size)); + goto fail; + } + + /* form a new freelist record */ + offset = tdb->map_size; + memset(&rec,'\0',sizeof(rec)); + rec.rec_len = size - sizeof(rec); + + if (tdb->flags & TDB_INTERNAL) { + char *new_map_ptr; + + new_map_ptr = (char *)realloc(tdb->map_ptr, new_size); + if (!new_map_ptr) { + tdb->ecode = TDB_ERR_OOM; + goto fail; + } + tdb->map_ptr = new_map_ptr; + tdb->map_size = new_size; + } else { + int ret; + + /* + * expand the file itself + */ + ret = tdb->methods->tdb_expand_file(tdb, tdb->map_size, size); + if (ret != 0) { + goto fail; + } + + /* Explicitly remap: if we're in a transaction, this won't + * happen automatically! */ + tdb_munmap(tdb); + tdb->map_size = new_size; + if (tdb_mmap(tdb) != 0) { + goto fail; + } + } + + /* link it into the free list */ + if (tdb_free(tdb, offset, &rec) == -1) + goto fail; + + tdb_unlock(tdb, -1, F_WRLCK); + return 0; + fail: + tdb_unlock(tdb, -1, F_WRLCK); + return -1; +} + +int _tdb_oob(struct tdb_context *tdb, tdb_off_t off, tdb_len_t len, int probe) +{ + int ret = tdb->methods->tdb_oob(tdb, off, len, probe); + return ret; +} + +/* read/write a tdb_off_t */ +int tdb_ofs_read(struct tdb_context *tdb, tdb_off_t offset, tdb_off_t *d) +{ + return tdb->methods->tdb_read(tdb, offset, (char*)d, sizeof(*d), DOCONV()); +} + +int tdb_ofs_write(struct tdb_context *tdb, tdb_off_t offset, tdb_off_t *d) +{ + tdb_off_t off = *d; + return tdb->methods->tdb_write(tdb, offset, CONVERT(off), sizeof(*d)); +} + + +/* read a lump of data, allocating the space for it */ +unsigned char *tdb_alloc_read(struct tdb_context *tdb, tdb_off_t offset, tdb_len_t len) +{ + unsigned char *buf; + + /* some systems don't like zero length malloc */ + + if (!(buf = (unsigned char *)malloc(len ? len : 1))) { + /* Ensure ecode is set for log fn. */ + tdb->ecode = TDB_ERR_OOM; + TDB_LOG((tdb, TDB_DEBUG_ERROR,"tdb_alloc_read malloc failed len=%u (%s)\n", + len, strerror(errno))); + return NULL; + } + if (tdb->methods->tdb_read(tdb, offset, buf, len, 0) == -1) { + SAFE_FREE(buf); + return NULL; + } + return buf; +} + +/* Give a piece of tdb data to a parser */ + +int tdb_parse_data(struct tdb_context *tdb, TDB_DATA key, + tdb_off_t offset, tdb_len_t len, + int (*parser)(TDB_DATA key, TDB_DATA data, + void *private_data), + void *private_data) +{ + TDB_DATA data; + int result; + + data.dsize = len; + + if ((tdb->transaction == NULL) && (tdb->map_ptr != NULL)) { + /* + * Optimize by avoiding the malloc/memcpy/free, point the + * parser directly at the mmap area. + */ + if (tdb_oob(tdb, offset, len, 0) != 0) { + return -1; + } + data.dptr = offset + (unsigned char *)tdb->map_ptr; + return parser(key, data, private_data); + } + + if (!(data.dptr = tdb_alloc_read(tdb, offset, len))) { + return -1; + } + + result = parser(key, data, private_data); + free(data.dptr); + return result; +} + +/* read/write a record */ +int tdb_rec_read(struct tdb_context *tdb, tdb_off_t offset, struct tdb_record *rec) +{ + int ret; + tdb_len_t overall_len; + + if (tdb->methods->tdb_read(tdb, offset, rec, sizeof(*rec),DOCONV()) == -1) + return -1; + if (TDB_BAD_MAGIC(rec)) { + /* Ensure ecode is set for log fn. */ + tdb->ecode = TDB_ERR_CORRUPT; + TDB_LOG((tdb, TDB_DEBUG_FATAL,"tdb_rec_read bad magic 0x%x at offset=%u\n", rec->magic, offset)); + return -1; + } + + overall_len = rec->key_len + rec->data_len; + if (overall_len < rec->data_len) { + /* overflow */ + return -1; + } + + if (overall_len > rec->rec_len) { + /* invalid record */ + return -1; + } + + ret = tdb_oob(tdb, offset, rec->key_len, 1); + if (ret == -1) { + return -1; + } + ret = tdb_oob(tdb, offset, rec->data_len, 1); + if (ret == -1) { + return -1; + } + ret = tdb_oob(tdb, offset, rec->rec_len, 1); + if (ret == -1) { + return -1; + } + + return tdb_oob(tdb, rec->next, sizeof(*rec), 0); +} + +int tdb_rec_write(struct tdb_context *tdb, tdb_off_t offset, struct tdb_record *rec) +{ + struct tdb_record r = *rec; + return tdb->methods->tdb_write(tdb, offset, CONVERT(r), sizeof(r)); +} + +static const struct tdb_methods io_methods = { + tdb_read, + tdb_write, + tdb_next_hash_chain, + tdb_notrans_oob, + tdb_expand_file, +}; + +/* + initialise the default methods table +*/ +void tdb_io_init(struct tdb_context *tdb) +{ + tdb->methods = &io_methods; +} diff --git a/common/lock.c b/common/lock.c new file mode 100644 index 0000000..045ded9 --- /dev/null +++ b/common/lock.c @@ -0,0 +1,1033 @@ + /* + Unix SMB/CIFS implementation. + + trivial database library + + Copyright (C) Andrew Tridgell 1999-2005 + Copyright (C) Paul `Rusty' Russell 2000 + Copyright (C) Jeremy Allison 2000-2003 + + ** NOTE! The following LGPL license applies to the tdb + ** library. This does NOT imply that all of Samba is released + ** under the LGPL + + This library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 3 of the License, or (at your option) any later version. + + This library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with this library; if not, see <http://www.gnu.org/licenses/>. +*/ + +#include "tdb_private.h" + +_PUBLIC_ void tdb_setalarm_sigptr(struct tdb_context *tdb, volatile sig_atomic_t *ptr) +{ + tdb->interrupt_sig_ptr = ptr; +} + +static int fcntl_lock(struct tdb_context *tdb, + int rw, off_t off, off_t len, bool waitflag) +{ + struct flock fl; + int cmd; + +#ifdef USE_TDB_MUTEX_LOCKING + { + int ret; + if (tdb_mutex_lock(tdb, rw, off, len, waitflag, &ret)) { + return ret; + } + } +#endif + + fl.l_type = rw; + fl.l_whence = SEEK_SET; + fl.l_start = off; + fl.l_len = len; + fl.l_pid = 0; + + cmd = waitflag ? F_SETLKW : F_SETLK; + + return fcntl(tdb->fd, cmd, &fl); +} + +static int fcntl_unlock(struct tdb_context *tdb, int rw, off_t off, off_t len) +{ + struct flock fl; +#if 0 /* Check they matched up locks and unlocks correctly. */ + char line[80]; + FILE *locks; + bool found = false; + + locks = fopen("/proc/locks", "r"); + + while (fgets(line, 80, locks)) { + char *p; + int type, start, l; + + /* eg. 1: FLOCK ADVISORY WRITE 2440 08:01:2180826 0 EOF */ + p = strchr(line, ':') + 1; + if (strncmp(p, " POSIX ADVISORY ", strlen(" POSIX ADVISORY "))) + continue; + p += strlen(" FLOCK ADVISORY "); + if (strncmp(p, "READ ", strlen("READ ")) == 0) + type = F_RDLCK; + else if (strncmp(p, "WRITE ", strlen("WRITE ")) == 0) + type = F_WRLCK; + else + abort(); + p += 6; + if (atoi(p) != getpid()) + continue; + p = strchr(strchr(p, ' ') + 1, ' ') + 1; + start = atoi(p); + p = strchr(p, ' ') + 1; + if (strncmp(p, "EOF", 3) == 0) + l = 0; + else + l = atoi(p) - start + 1; + + if (off == start) { + if (len != l) { + fprintf(stderr, "Len %u should be %u: %s", + (int)len, l, line); + abort(); + } + if (type != rw) { + fprintf(stderr, "Type %s wrong: %s", + rw == F_RDLCK ? "READ" : "WRITE", line); + abort(); + } + found = true; + break; + } + } + + if (!found) { + fprintf(stderr, "Unlock on %u@%u not found!\n", + (int)off, (int)len); + abort(); + } + + fclose(locks); +#endif + +#ifdef USE_TDB_MUTEX_LOCKING + { + int ret; + if (tdb_mutex_unlock(tdb, rw, off, len, &ret)) { + return ret; + } + } +#endif + + fl.l_type = F_UNLCK; + fl.l_whence = SEEK_SET; + fl.l_start = off; + fl.l_len = len; + fl.l_pid = 0; + + return fcntl(tdb->fd, F_SETLKW, &fl); +} + +/* + * Calculate the lock offset for a list + * + * list -1 is the freelist, otherwise a hash chain. + * + * Note that we consistently (but without real reason) lock hash chains at an + * offset that is 4 bytes below the real offset of the corresponding list head + * in the db. + * + * This is the memory layout of the hashchain array: + * + * FREELIST_TOP + 0 = freelist + * FREELIST_TOP + 4 = hashtable list 0 + * FREELIST_TOP + 8 = hashtable list 1 + * ... + * + * Otoh lock_offset computes: + * + * freelist = FREELIST_TOP - 4 + * list 0 = FREELIST_TOP + 0 + * list 1 = FREELIST_TOP + 4 + * ... + * + * Unfortunately we can't change this calculation in order to align the locking + * offset with the memory layout, as that would make the locking incompatible + * between different tdb versions. + */ +static tdb_off_t lock_offset(int list) +{ + return FREELIST_TOP + 4*list; +} + +/* a byte range locking function - return 0 on success + this functions locks/unlocks "len" byte at the specified offset. + + On error, errno is also set so that errors are passed back properly + through tdb_open(). + + note that a len of zero means lock to end of file +*/ +int tdb_brlock(struct tdb_context *tdb, + int rw_type, tdb_off_t offset, size_t len, + enum tdb_lock_flags flags) +{ + int ret; + + if (tdb->flags & TDB_NOLOCK) { + return 0; + } + + if (flags & TDB_LOCK_MARK_ONLY) { + return 0; + } + + if ((rw_type == F_WRLCK) && (tdb->read_only || tdb->traverse_read)) { + tdb->ecode = TDB_ERR_RDONLY; + return -1; + } + + do { + ret = fcntl_lock(tdb, rw_type, offset, len, + flags & TDB_LOCK_WAIT); + /* Check for a sigalarm break. */ + if (ret == -1 && errno == EINTR && + tdb->interrupt_sig_ptr && + *tdb->interrupt_sig_ptr) { + break; + } + } while (ret == -1 && errno == EINTR); + + if (ret == -1) { + tdb->ecode = TDB_ERR_LOCK; + /* Generic lock error. errno set by fcntl. + * EAGAIN is an expected return from non-blocking + * locks. */ + if (!(flags & TDB_LOCK_PROBE) && errno != EAGAIN) { + TDB_LOG((tdb, TDB_DEBUG_TRACE,"tdb_brlock failed (fd=%d) at offset %u rw_type=%d flags=%d len=%zu\n", + tdb->fd, offset, rw_type, flags, len)); + } + return -1; + } + return 0; +} + +int tdb_brunlock(struct tdb_context *tdb, + int rw_type, tdb_off_t offset, size_t len) +{ + int ret; + + if (tdb->flags & TDB_NOLOCK) { + return 0; + } + + do { + ret = fcntl_unlock(tdb, rw_type, offset, len); + } while (ret == -1 && errno == EINTR); + + if (ret == -1) { + TDB_LOG((tdb, TDB_DEBUG_TRACE,"tdb_brunlock failed (fd=%d) at offset %u rw_type=%u len=%zu\n", + tdb->fd, offset, rw_type, len)); + } + return ret; +} + +/* + * Do a tdb_brlock in a loop. Some OSes (such as solaris) have too + * conservative deadlock detection and claim a deadlock when progress can be + * made. For those OSes we may loop for a while. + */ + +static int tdb_brlock_retry(struct tdb_context *tdb, + int rw_type, tdb_off_t offset, size_t len, + enum tdb_lock_flags flags) +{ + int count = 1000; + + while (count--) { + struct timeval tv; + int ret; + + ret = tdb_brlock(tdb, rw_type, offset, len, flags); + if (ret == 0) { + return 0; + } + if (errno != EDEADLK) { + break; + } + /* sleep for as short a time as we can - more portable than usleep() */ + tv.tv_sec = 0; + tv.tv_usec = 1; + select(0, NULL, NULL, NULL, &tv); + } + return -1; +} + +/* + upgrade a read lock to a write lock. +*/ +int tdb_allrecord_upgrade(struct tdb_context *tdb) +{ + int ret; + + if (tdb->allrecord_lock.count != 1) { + TDB_LOG((tdb, TDB_DEBUG_ERROR, + "tdb_allrecord_upgrade failed: count %u too high\n", + tdb->allrecord_lock.count)); + tdb->ecode = TDB_ERR_LOCK; + return -1; + } + + if (tdb->allrecord_lock.off != 1) { + TDB_LOG((tdb, TDB_DEBUG_ERROR, + "tdb_allrecord_upgrade failed: already upgraded?\n")); + tdb->ecode = TDB_ERR_LOCK; + return -1; + } + + if (tdb_have_mutexes(tdb)) { + ret = tdb_mutex_allrecord_upgrade(tdb); + if (ret == -1) { + goto fail; + } + ret = tdb_brlock_retry(tdb, F_WRLCK, lock_offset(tdb->hash_size), + 0, TDB_LOCK_WAIT|TDB_LOCK_PROBE); + if (ret == -1) { + tdb_mutex_allrecord_downgrade(tdb); + } + } else { + ret = tdb_brlock_retry(tdb, F_WRLCK, FREELIST_TOP, 0, + TDB_LOCK_WAIT|TDB_LOCK_PROBE); + } + + if (ret == 0) { + tdb->allrecord_lock.ltype = F_WRLCK; + tdb->allrecord_lock.off = 0; + return 0; + } +fail: + TDB_LOG((tdb, TDB_DEBUG_TRACE,"tdb_allrecord_upgrade failed\n")); + return -1; +} + +static struct tdb_lock_type *find_nestlock(struct tdb_context *tdb, + tdb_off_t offset) +{ + int i; + + for (i=0; i<tdb->num_lockrecs; i++) { + if (tdb->lockrecs[i].off == offset) { + return &tdb->lockrecs[i]; + } + } + return NULL; +} + +/* lock an offset in the database. */ +int tdb_nest_lock(struct tdb_context *tdb, uint32_t offset, int ltype, + enum tdb_lock_flags flags) +{ + struct tdb_lock_type *new_lck; + + if (offset >= lock_offset(tdb->hash_size)) { + tdb->ecode = TDB_ERR_LOCK; + TDB_LOG((tdb, TDB_DEBUG_ERROR,"tdb_lock: invalid offset %u for ltype=%d\n", + offset, ltype)); + return -1; + } + if (tdb->flags & TDB_NOLOCK) + return 0; + + new_lck = find_nestlock(tdb, offset); + if (new_lck) { + if ((new_lck->ltype == F_RDLCK) && (ltype == F_WRLCK)) { + if (!tdb_have_mutexes(tdb)) { + int ret; + /* + * Upgrade the underlying fcntl + * lock. Mutexes don't do readlocks, + * so this only applies to fcntl + * locking. + */ + ret = tdb_brlock(tdb, ltype, offset, 1, flags); + if (ret != 0) { + return ret; + } + } + new_lck->ltype = F_WRLCK; + } + /* + * Just increment the in-memory struct, posix locks + * don't stack. + */ + new_lck->count++; + return 0; + } + + if (tdb->num_lockrecs == tdb->lockrecs_array_length) { + new_lck = (struct tdb_lock_type *)realloc( + tdb->lockrecs, + sizeof(*tdb->lockrecs) * (tdb->num_lockrecs+1)); + if (new_lck == NULL) { + errno = ENOMEM; + return -1; + } + tdb->lockrecs_array_length = tdb->num_lockrecs+1; + tdb->lockrecs = new_lck; + } + + /* Since fcntl locks don't nest, we do a lock for the first one, + and simply bump the count for future ones */ + if (tdb_brlock(tdb, ltype, offset, 1, flags)) { + return -1; + } + + new_lck = &tdb->lockrecs[tdb->num_lockrecs]; + + new_lck->off = offset; + new_lck->count = 1; + new_lck->ltype = ltype; + tdb->num_lockrecs++; + + return 0; +} + +static int tdb_lock_and_recover(struct tdb_context *tdb) +{ + int ret; + + /* We need to match locking order in transaction commit. */ + if (tdb_brlock(tdb, F_WRLCK, FREELIST_TOP, 0, TDB_LOCK_WAIT)) { + return -1; + } + + if (tdb_brlock(tdb, F_WRLCK, OPEN_LOCK, 1, TDB_LOCK_WAIT)) { + tdb_brunlock(tdb, F_WRLCK, FREELIST_TOP, 0); + return -1; + } + + ret = tdb_transaction_recover(tdb); + + tdb_brunlock(tdb, F_WRLCK, OPEN_LOCK, 1); + tdb_brunlock(tdb, F_WRLCK, FREELIST_TOP, 0); + + return ret; +} + +static bool have_data_locks(const struct tdb_context *tdb) +{ + int i; + + for (i = 0; i < tdb->num_lockrecs; i++) { + if (tdb->lockrecs[i].off >= lock_offset(-1)) + return true; + } + return false; +} + +/* + * A allrecord lock allows us to avoid per chain locks. Check if the allrecord + * lock is strong enough. + */ +static int tdb_lock_covered_by_allrecord_lock(struct tdb_context *tdb, + int ltype) +{ + if (ltype == F_RDLCK) { + /* + * The allrecord_lock is equal (F_RDLCK) or stronger + * (F_WRLCK). Pass. + */ + return 0; + } + + if (tdb->allrecord_lock.ltype == F_RDLCK) { + /* + * We ask for ltype==F_WRLCK, but the allrecord_lock + * is too weak. We can't upgrade here, so fail. + */ + tdb->ecode = TDB_ERR_LOCK; + return -1; + } + + /* + * Asking for F_WRLCK, allrecord is F_WRLCK as well. Pass. + */ + return 0; +} + +static int tdb_lock_list(struct tdb_context *tdb, int list, int ltype, + enum tdb_lock_flags waitflag) +{ + int ret; + bool check = false; + + if (tdb->allrecord_lock.count) { + return tdb_lock_covered_by_allrecord_lock(tdb, ltype); + } + + /* + * Check for recoveries: Someone might have kill -9'ed a process + * during a commit. + */ + check = !have_data_locks(tdb); + ret = tdb_nest_lock(tdb, lock_offset(list), ltype, waitflag); + + if (ret == 0 && check && tdb_needs_recovery(tdb)) { + tdb_nest_unlock(tdb, lock_offset(list), ltype, false); + + if (tdb_lock_and_recover(tdb) == -1) { + return -1; + } + return tdb_lock_list(tdb, list, ltype, waitflag); + } + return ret; +} + +/* lock a list in the database. list -1 is the alloc list */ +int tdb_lock(struct tdb_context *tdb, int list, int ltype) +{ + int ret; + + ret = tdb_lock_list(tdb, list, ltype, TDB_LOCK_WAIT); + if (ret) { + TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_lock failed on list %d " + "ltype=%d (%s)\n", list, ltype, strerror(errno))); + } + return ret; +} + +/* lock a list in the database. list -1 is the alloc list. non-blocking lock */ +_PUBLIC_ int tdb_lock_nonblock(struct tdb_context *tdb, int list, int ltype); +_PUBLIC_ int tdb_lock_nonblock(struct tdb_context *tdb, int list, int ltype) +{ + return tdb_lock_list(tdb, list, ltype, TDB_LOCK_NOWAIT); +} + + +int tdb_nest_unlock(struct tdb_context *tdb, uint32_t offset, int ltype, + bool mark_lock) +{ + int ret = -1; + struct tdb_lock_type *lck; + + if (tdb->flags & TDB_NOLOCK) + return 0; + + /* Sanity checks */ + if (offset >= lock_offset(tdb->hash_size)) { + TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_unlock: offset %u invalid (%d)\n", offset, tdb->hash_size)); + return ret; + } + + lck = find_nestlock(tdb, offset); + if ((lck == NULL) || (lck->count == 0)) { + TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_unlock: count is 0\n")); + return -1; + } + + if (lck->count > 1) { + lck->count--; + return 0; + } + + /* + * This lock has count==1 left, so we need to unlock it in the + * kernel. We don't bother with decrementing the in-memory array + * element, we're about to overwrite it with the last array element + * anyway. + */ + + if (mark_lock) { + ret = 0; + } else { + ret = tdb_brunlock(tdb, ltype, offset, 1); + } + + /* + * Shrink the array by overwriting the element just unlocked with the + * last array element. + */ + *lck = tdb->lockrecs[--tdb->num_lockrecs]; + + /* + * We don't bother with realloc when the array shrinks, but if we have + * a completely idle tdb we should get rid of the locked array. + */ + + if (ret) + TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_unlock: An error occurred unlocking!\n")); + return ret; +} + +_PUBLIC_ int tdb_unlock(struct tdb_context *tdb, int list, int ltype); +_PUBLIC_ int tdb_unlock(struct tdb_context *tdb, int list, int ltype) +{ + /* a global lock allows us to avoid per chain locks */ + if (tdb->allrecord_lock.count) { + return tdb_lock_covered_by_allrecord_lock(tdb, ltype); + } + + return tdb_nest_unlock(tdb, lock_offset(list), ltype, false); +} + +/* + get the transaction lock + */ +int tdb_transaction_lock(struct tdb_context *tdb, int ltype, + enum tdb_lock_flags lockflags) +{ + return tdb_nest_lock(tdb, TRANSACTION_LOCK, ltype, lockflags); +} + +/* + release the transaction lock + */ +int tdb_transaction_unlock(struct tdb_context *tdb, int ltype) +{ + return tdb_nest_unlock(tdb, TRANSACTION_LOCK, ltype, false); +} + +/* Returns 0 if all done, -1 if error, 1 if ok. */ +static int tdb_allrecord_check(struct tdb_context *tdb, int ltype, + enum tdb_lock_flags flags, bool upgradable) +{ + /* There are no locks on read-only dbs */ + if (tdb->read_only || tdb->traverse_read) { + tdb->ecode = TDB_ERR_LOCK; + return -1; + } + + if (tdb->allrecord_lock.count && + tdb->allrecord_lock.ltype == (uint32_t)ltype) { + tdb->allrecord_lock.count++; + return 0; + } + + if (tdb->allrecord_lock.count) { + /* a global lock of a different type exists */ + tdb->ecode = TDB_ERR_LOCK; + return -1; + } + + if (tdb_have_extra_locks(tdb)) { + /* can't combine global and chain locks */ + tdb->ecode = TDB_ERR_LOCK; + return -1; + } + + if (upgradable && ltype != F_RDLCK) { + /* tdb error: you can't upgrade a write lock! */ + tdb->ecode = TDB_ERR_LOCK; + return -1; + } + return 1; +} + +/* We only need to lock individual bytes, but Linux merges consecutive locks + * so we lock in contiguous ranges. */ +static int tdb_chainlock_gradual(struct tdb_context *tdb, + int ltype, enum tdb_lock_flags flags, + size_t off, size_t len) +{ + int ret; + enum tdb_lock_flags nb_flags = (flags & ~TDB_LOCK_WAIT); + + if (len <= 4) { + /* Single record. Just do blocking lock. */ + return tdb_brlock(tdb, ltype, off, len, flags); + } + + /* First we try non-blocking. */ + ret = tdb_brlock(tdb, ltype, off, len, nb_flags); + if (ret == 0) { + return 0; + } + + /* Try locking first half, then second. */ + ret = tdb_chainlock_gradual(tdb, ltype, flags, off, len / 2); + if (ret == -1) + return -1; + + ret = tdb_chainlock_gradual(tdb, ltype, flags, + off + len / 2, len - len / 2); + if (ret == -1) { + tdb_brunlock(tdb, ltype, off, len / 2); + return -1; + } + return 0; +} + +/* lock/unlock entire database. It can only be upgradable if you have some + * other way of guaranteeing exclusivity (ie. transaction write lock). + * We do the locking gradually to avoid being starved by smaller locks. */ +int tdb_allrecord_lock(struct tdb_context *tdb, int ltype, + enum tdb_lock_flags flags, bool upgradable) +{ + int ret; + + switch (tdb_allrecord_check(tdb, ltype, flags, upgradable)) { + case -1: + return -1; + case 0: + return 0; + } + + /* We cover two kinds of locks: + * 1) Normal chain locks. Taken for almost all operations. + * 2) Individual records locks. Taken after normal or free + * chain locks. + * + * It is (1) which cause the starvation problem, so we're only + * gradual for that. */ + + if (tdb_have_mutexes(tdb)) { + ret = tdb_mutex_allrecord_lock(tdb, ltype, flags); + } else { + ret = tdb_chainlock_gradual(tdb, ltype, flags, FREELIST_TOP, + tdb->hash_size * 4); + } + + if (ret == -1) { + return -1; + } + + /* Grab individual record locks. */ + if (tdb_brlock(tdb, ltype, lock_offset(tdb->hash_size), 0, + flags) == -1) { + if (tdb_have_mutexes(tdb)) { + tdb_mutex_allrecord_unlock(tdb); + } else { + tdb_brunlock(tdb, ltype, FREELIST_TOP, + tdb->hash_size * 4); + } + return -1; + } + + tdb->allrecord_lock.count = 1; + /* If it's upgradable, it's actually exclusive so we can treat + * it as a write lock. */ + tdb->allrecord_lock.ltype = upgradable ? F_WRLCK : ltype; + tdb->allrecord_lock.off = upgradable; + + if (tdb_needs_recovery(tdb)) { + bool mark = flags & TDB_LOCK_MARK_ONLY; + tdb_allrecord_unlock(tdb, ltype, mark); + if (mark) { + tdb->ecode = TDB_ERR_LOCK; + TDB_LOG((tdb, TDB_DEBUG_ERROR, + "tdb_lockall_mark cannot do recovery\n")); + return -1; + } + if (tdb_lock_and_recover(tdb) == -1) { + return -1; + } + return tdb_allrecord_lock(tdb, ltype, flags, upgradable); + } + + return 0; +} + + + +/* unlock entire db */ +int tdb_allrecord_unlock(struct tdb_context *tdb, int ltype, bool mark_lock) +{ + /* There are no locks on read-only dbs */ + if (tdb->read_only || tdb->traverse_read) { + tdb->ecode = TDB_ERR_LOCK; + return -1; + } + + if (tdb->allrecord_lock.count == 0) { + tdb->ecode = TDB_ERR_LOCK; + return -1; + } + + /* Upgradable locks are marked as write locks. */ + if (tdb->allrecord_lock.ltype != (uint32_t)ltype + && (!tdb->allrecord_lock.off || ltype != F_RDLCK)) { + tdb->ecode = TDB_ERR_LOCK; + return -1; + } + + if (tdb->allrecord_lock.count > 1) { + tdb->allrecord_lock.count--; + return 0; + } + + if (!mark_lock) { + int ret; + + if (tdb_have_mutexes(tdb)) { + ret = tdb_mutex_allrecord_unlock(tdb); + if (ret == 0) { + ret = tdb_brunlock(tdb, ltype, + lock_offset(tdb->hash_size), + 0); + } + } else { + ret = tdb_brunlock(tdb, ltype, FREELIST_TOP, 0); + } + + if (ret != 0) { + TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_unlockall failed " + "(%s)\n", strerror(errno))); + return -1; + } + } + + tdb->allrecord_lock.count = 0; + tdb->allrecord_lock.ltype = 0; + + return 0; +} + +/* lock entire database with write lock */ +_PUBLIC_ int tdb_lockall(struct tdb_context *tdb) +{ + tdb_trace(tdb, "tdb_lockall"); + return tdb_allrecord_lock(tdb, F_WRLCK, TDB_LOCK_WAIT, false); +} + +/* lock entire database with write lock - mark only */ +_PUBLIC_ int tdb_lockall_mark(struct tdb_context *tdb) +{ + tdb_trace(tdb, "tdb_lockall_mark"); + return tdb_allrecord_lock(tdb, F_WRLCK, TDB_LOCK_MARK_ONLY, false); +} + +/* unlock entire database with write lock - unmark only */ +_PUBLIC_ int tdb_lockall_unmark(struct tdb_context *tdb) +{ + tdb_trace(tdb, "tdb_lockall_unmark"); + return tdb_allrecord_unlock(tdb, F_WRLCK, true); +} + +/* lock entire database with write lock - nonblocking variant */ +_PUBLIC_ int tdb_lockall_nonblock(struct tdb_context *tdb) +{ + int ret = tdb_allrecord_lock(tdb, F_WRLCK, TDB_LOCK_NOWAIT, false); + tdb_trace_ret(tdb, "tdb_lockall_nonblock", ret); + return ret; +} + +/* unlock entire database with write lock */ +_PUBLIC_ int tdb_unlockall(struct tdb_context *tdb) +{ + tdb_trace(tdb, "tdb_unlockall"); + return tdb_allrecord_unlock(tdb, F_WRLCK, false); +} + +/* lock entire database with read lock */ +_PUBLIC_ int tdb_lockall_read(struct tdb_context *tdb) +{ + tdb_trace(tdb, "tdb_lockall_read"); + return tdb_allrecord_lock(tdb, F_RDLCK, TDB_LOCK_WAIT, false); +} + +/* lock entire database with read lock - nonblock variant */ +_PUBLIC_ int tdb_lockall_read_nonblock(struct tdb_context *tdb) +{ + int ret = tdb_allrecord_lock(tdb, F_RDLCK, TDB_LOCK_NOWAIT, false); + tdb_trace_ret(tdb, "tdb_lockall_read_nonblock", ret); + return ret; +} + +/* unlock entire database with read lock */ +_PUBLIC_ int tdb_unlockall_read(struct tdb_context *tdb) +{ + tdb_trace(tdb, "tdb_unlockall_read"); + return tdb_allrecord_unlock(tdb, F_RDLCK, false); +} + +/* lock/unlock one hash chain. This is meant to be used to reduce + contention - it cannot guarantee how many records will be locked */ +_PUBLIC_ int tdb_chainlock(struct tdb_context *tdb, TDB_DATA key) +{ + int ret = tdb_lock(tdb, BUCKET(tdb->hash_fn(&key)), F_WRLCK); + tdb_trace_1rec(tdb, "tdb_chainlock", key); + return ret; +} + +/* lock/unlock one hash chain, non-blocking. This is meant to be used + to reduce contention - it cannot guarantee how many records will be + locked */ +_PUBLIC_ int tdb_chainlock_nonblock(struct tdb_context *tdb, TDB_DATA key) +{ + int ret = tdb_lock_nonblock(tdb, BUCKET(tdb->hash_fn(&key)), F_WRLCK); + tdb_trace_1rec_ret(tdb, "tdb_chainlock_nonblock", key, ret); + return ret; +} + +/* mark a chain as locked without actually locking it. Warning! use with great caution! */ +_PUBLIC_ int tdb_chainlock_mark(struct tdb_context *tdb, TDB_DATA key) +{ + int ret = tdb_nest_lock(tdb, lock_offset(BUCKET(tdb->hash_fn(&key))), + F_WRLCK, TDB_LOCK_MARK_ONLY); + tdb_trace_1rec(tdb, "tdb_chainlock_mark", key); + return ret; +} + +/* unmark a chain as locked without actually locking it. Warning! use with great caution! */ +_PUBLIC_ int tdb_chainlock_unmark(struct tdb_context *tdb, TDB_DATA key) +{ + tdb_trace_1rec(tdb, "tdb_chainlock_unmark", key); + return tdb_nest_unlock(tdb, lock_offset(BUCKET(tdb->hash_fn(&key))), + F_WRLCK, true); +} + +_PUBLIC_ int tdb_chainunlock(struct tdb_context *tdb, TDB_DATA key) +{ + tdb_trace_1rec(tdb, "tdb_chainunlock", key); + return tdb_unlock(tdb, BUCKET(tdb->hash_fn(&key)), F_WRLCK); +} + +_PUBLIC_ int tdb_chainlock_read(struct tdb_context *tdb, TDB_DATA key) +{ + int ret; + ret = tdb_lock(tdb, BUCKET(tdb->hash_fn(&key)), F_RDLCK); + tdb_trace_1rec(tdb, "tdb_chainlock_read", key); + return ret; +} + +_PUBLIC_ int tdb_chainunlock_read(struct tdb_context *tdb, TDB_DATA key) +{ + tdb_trace_1rec(tdb, "tdb_chainunlock_read", key); + return tdb_unlock(tdb, BUCKET(tdb->hash_fn(&key)), F_RDLCK); +} + +_PUBLIC_ int tdb_chainlock_read_nonblock(struct tdb_context *tdb, TDB_DATA key) +{ + int ret = tdb_lock_nonblock(tdb, BUCKET(tdb->hash_fn(&key)), F_RDLCK); + tdb_trace_1rec_ret(tdb, "tdb_chainlock_read_nonblock", key, ret); + return ret; +} + +/* record lock stops delete underneath */ +int tdb_lock_record(struct tdb_context *tdb, tdb_off_t off) +{ + if (tdb->allrecord_lock.count) { + return 0; + } + return off ? tdb_brlock(tdb, F_RDLCK, off, 1, TDB_LOCK_WAIT) : 0; +} + +/* + Write locks override our own fcntl readlocks, so check it here. + Note this is meant to be F_SETLK, *not* F_SETLKW, as it's not + an error to fail to get the lock here. +*/ +int tdb_write_lock_record(struct tdb_context *tdb, tdb_off_t off) +{ + struct tdb_traverse_lock *i; + if (tdb == NULL) { + return -1; + } + for (i = &tdb->travlocks; i; i = i->next) + if (i->off == off) + return -1; + if (tdb->allrecord_lock.count) { + if (tdb->allrecord_lock.ltype == F_WRLCK) { + return 0; + } + return -1; + } + return tdb_brlock(tdb, F_WRLCK, off, 1, TDB_LOCK_NOWAIT|TDB_LOCK_PROBE); +} + +int tdb_write_unlock_record(struct tdb_context *tdb, tdb_off_t off) +{ + if (tdb->allrecord_lock.count) { + return 0; + } + return tdb_brunlock(tdb, F_WRLCK, off, 1); +} + +/* fcntl locks don't stack: avoid unlocking someone else's */ +int tdb_unlock_record(struct tdb_context *tdb, tdb_off_t off) +{ + struct tdb_traverse_lock *i; + uint32_t count = 0; + + if (tdb->allrecord_lock.count) { + return 0; + } + + if (off == 0) + return 0; + for (i = &tdb->travlocks; i; i = i->next) + if (i->off == off) + count++; + return (count == 1 ? tdb_brunlock(tdb, F_RDLCK, off, 1) : 0); +} + +bool tdb_have_extra_locks(struct tdb_context *tdb) +{ + unsigned int extra = tdb->num_lockrecs; + + /* A transaction holds the lock for all records. */ + if (!tdb->transaction && tdb->allrecord_lock.count) { + return true; + } + + /* We always hold the active lock if CLEAR_IF_FIRST. */ + if (find_nestlock(tdb, ACTIVE_LOCK)) { + extra--; + } + + /* In a transaction, we expect to hold the transaction lock */ + if (tdb->transaction && find_nestlock(tdb, TRANSACTION_LOCK)) { + extra--; + } + + return extra; +} + +/* The transaction code uses this to remove all locks. */ +void tdb_release_transaction_locks(struct tdb_context *tdb) +{ + int i; + unsigned int active = 0; + + if (tdb->allrecord_lock.count != 0) { + tdb_allrecord_unlock(tdb, tdb->allrecord_lock.ltype, false); + tdb->allrecord_lock.count = 0; + } + + for (i=0;i<tdb->num_lockrecs;i++) { + struct tdb_lock_type *lck = &tdb->lockrecs[i]; + + /* Don't release the active lock! Copy it to first entry. */ + if (lck->off == ACTIVE_LOCK) { + tdb->lockrecs[active++] = *lck; + } else { + tdb_brunlock(tdb, lck->ltype, lck->off, 1); + } + } + tdb->num_lockrecs = active; +} + +/* Following functions are added specifically to support CTDB. */ + +/* Don't do actual fcntl locking, just mark tdb locked */ +_PUBLIC_ int tdb_transaction_write_lock_mark(struct tdb_context *tdb); +_PUBLIC_ int tdb_transaction_write_lock_mark(struct tdb_context *tdb) +{ + return tdb_transaction_lock(tdb, F_WRLCK, TDB_LOCK_MARK_ONLY); +} + +/* Don't do actual fcntl unlocking, just mark tdb unlocked */ +_PUBLIC_ int tdb_transaction_write_lock_unmark(struct tdb_context *tdb); +_PUBLIC_ int tdb_transaction_write_lock_unmark(struct tdb_context *tdb) +{ + return tdb_nest_unlock(tdb, TRANSACTION_LOCK, F_WRLCK, true); +} diff --git a/common/mutex.c b/common/mutex.c new file mode 100644 index 0000000..a710616 --- /dev/null +++ b/common/mutex.c @@ -0,0 +1,1078 @@ +/* + Unix SMB/CIFS implementation. + + trivial database library + + Copyright (C) Volker Lendecke 2012,2013 + Copyright (C) Stefan Metzmacher 2013,2014 + Copyright (C) Michael Adam 2014 + + ** NOTE! The following LGPL license applies to the tdb + ** library. This does NOT imply that all of Samba is released + ** under the LGPL + + This library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 3 of the License, or (at your option) any later version. + + This library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with this library; if not, see <http://www.gnu.org/licenses/>. +*/ +#include "tdb_private.h" +#include "system/threads.h" + +#ifdef USE_TDB_MUTEX_LOCKING + +/* + * If we run with mutexes, we store the "struct tdb_mutexes" at the + * beginning of the file. We store an additional tdb_header right + * beyond the mutex area, page aligned. All the offsets within the tdb + * are relative to the area behind the mutex area. tdb->map_ptr points + * behind the mmap area as well, so the read and write path in the + * mutex case can remain unchanged. + * + * Early in the mutex development the mutexes were placed between the hash + * chain pointers and the real tdb data. This had two drawbacks: First, it + * made pointer calculations more complex. Second, we had to mmap the mutex + * area twice. One was the normal map_ptr in the tdb. This frequently changed + * from within tdb_oob. At least the Linux glibc robust mutex code assumes + * constant pointers in memory, so a constantly changing mmap area destroys + * the mutex list. So we had to mmap the first bytes of the file with a second + * mmap call. With that scheme, very weird errors happened that could be + * easily fixed by doing the mutex mmap in a second file. It seemed that + * mapping the same memory area twice does not end up in accessing the same + * physical page, looking at the mutexes in gdb it seemed that old data showed + * up after some re-mapping. To avoid a separate mutex file, the code now puts + * the real content of the tdb file after the mutex area. This way we do not + * have overlapping mmap areas, the mutex area is mmapped once and not + * changed, the tdb data area's mmap is constantly changed but does not + * overlap. + */ + +struct tdb_mutexes { + struct tdb_header hdr; + + /* protect allrecord_lock */ + pthread_mutex_t allrecord_mutex; + + /* + * F_UNLCK: free, + * F_RDLCK: shared, + * F_WRLCK: exclusive + */ + short int allrecord_lock; + + /* + * Index 0 is the freelist mutex, followed by + * one mutex per hashchain. + */ + pthread_mutex_t hashchains[1]; +}; + +bool tdb_have_mutexes(struct tdb_context *tdb) +{ + return ((tdb->feature_flags & TDB_FEATURE_FLAG_MUTEX) != 0); +} + +size_t tdb_mutex_size(struct tdb_context *tdb) +{ + size_t mutex_size; + + if (!tdb_have_mutexes(tdb)) { + return 0; + } + + mutex_size = sizeof(struct tdb_mutexes); + mutex_size += tdb->hash_size * sizeof(pthread_mutex_t); + + return TDB_ALIGN(mutex_size, tdb->page_size); +} + +/* + * Get the index for a chain mutex + */ +static bool tdb_mutex_index(struct tdb_context *tdb, off_t off, off_t len, + unsigned *idx) +{ + /* + * Weird but true: We fcntl lock 1 byte at an offset 4 bytes before + * the 4 bytes of the freelist start and the hash chain that is about + * to be locked. See lock_offset() where the freelist is -1 vs the + * "+1" in TDB_HASH_TOP(). Because the mutex array is represented in + * the tdb file itself as data, we need to adjust the offset here. + */ + const off_t freelist_lock_ofs = FREELIST_TOP - sizeof(tdb_off_t); + + if (!tdb_have_mutexes(tdb)) { + return false; + } + if (len != 1) { + /* Possibly the allrecord lock */ + return false; + } + if (off < freelist_lock_ofs) { + /* One of the special locks */ + return false; + } + if (tdb->hash_size == 0) { + /* tdb not initialized yet, called from tdb_open_ex() */ + return false; + } + if (off >= TDB_DATA_START(tdb->hash_size)) { + /* Single record lock from traverses */ + return false; + } + + /* + * Now we know it's a freelist or hash chain lock. Those are always 4 + * byte aligned. Paranoia check. + */ + if ((off % sizeof(tdb_off_t)) != 0) { + abort(); + } + + /* + * Re-index the fcntl offset into an offset into the mutex array + */ + off -= freelist_lock_ofs; /* rebase to index 0 */ + off /= sizeof(tdb_off_t); /* 0 for freelist 1-n for hashchain */ + + *idx = off; + return true; +} + +static bool tdb_have_mutex_chainlocks(struct tdb_context *tdb) +{ + int i; + + for (i=0; i < tdb->num_lockrecs; i++) { + bool ret; + unsigned idx; + + ret = tdb_mutex_index(tdb, + tdb->lockrecs[i].off, + tdb->lockrecs[i].count, + &idx); + if (!ret) { + continue; + } + + if (idx == 0) { + /* this is the freelist mutex */ + continue; + } + + return true; + } + + return false; +} + +static int chain_mutex_lock(pthread_mutex_t *m, bool waitflag) +{ + int ret; + + if (waitflag) { + ret = pthread_mutex_lock(m); + } else { + ret = pthread_mutex_trylock(m); + } + if (ret != EOWNERDEAD) { + return ret; + } + + /* + * For chainlocks, we don't do any cleanup (yet?) + */ + return pthread_mutex_consistent(m); +} + +static int allrecord_mutex_lock(struct tdb_mutexes *m, bool waitflag) +{ + int ret; + + if (waitflag) { + ret = pthread_mutex_lock(&m->allrecord_mutex); + } else { + ret = pthread_mutex_trylock(&m->allrecord_mutex); + } + if (ret != EOWNERDEAD) { + return ret; + } + + /* + * The allrecord lock holder died. We need to reset the allrecord_lock + * to F_UNLCK. This should also be the indication for + * tdb_needs_recovery. + */ + m->allrecord_lock = F_UNLCK; + + return pthread_mutex_consistent(&m->allrecord_mutex); +} + +bool tdb_mutex_lock(struct tdb_context *tdb, int rw, off_t off, off_t len, + bool waitflag, int *pret) +{ + struct tdb_mutexes *m = tdb->mutexes; + pthread_mutex_t *chain; + int ret; + unsigned idx; + bool allrecord_ok; + + if (!tdb_mutex_index(tdb, off, len, &idx)) { + return false; + } + chain = &m->hashchains[idx]; + +again: + ret = chain_mutex_lock(chain, waitflag); + if (ret == EBUSY) { + ret = EAGAIN; + } + if (ret != 0) { + errno = ret; + goto fail; + } + + if (idx == 0) { + /* + * This is a freelist lock, which is independent to + * the allrecord lock. So we're done once we got the + * freelist mutex. + */ + *pret = 0; + return true; + } + + if (tdb_have_mutex_chainlocks(tdb)) { + /* + * We can only check the allrecord lock once. If we do it with + * one chain mutex locked, we will deadlock with the allrecord + * locker process in the following way: We lock the first hash + * chain, we check for the allrecord lock. We keep the hash + * chain locked. Then the allrecord locker locks the + * allrecord_mutex. It walks the list of chain mutexes, + * locking them all in sequence. Meanwhile, we have the chain + * mutex locked, so the allrecord locker blocks trying to lock + * our chain mutex. Then we come in and try to lock the second + * chain lock, which in most cases will be the freelist. We + * see that the allrecord lock is locked and put ourselves on + * the allrecord_mutex. This will never be signalled though + * because the allrecord locker waits for us to give up the + * chain lock. + */ + + *pret = 0; + return true; + } + + /* + * Check if someone is has the allrecord lock: queue if so. + */ + + allrecord_ok = false; + + if (m->allrecord_lock == F_UNLCK) { + /* + * allrecord lock not taken + */ + allrecord_ok = true; + } + + if ((m->allrecord_lock == F_RDLCK) && (rw == F_RDLCK)) { + /* + * allrecord shared lock taken, but we only want to read + */ + allrecord_ok = true; + } + + if (allrecord_ok) { + *pret = 0; + return true; + } + + ret = pthread_mutex_unlock(chain); + if (ret != 0) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "pthread_mutex_unlock" + "(chain_mutex) failed: %s\n", strerror(ret))); + errno = ret; + goto fail; + } + ret = allrecord_mutex_lock(m, waitflag); + if (ret == EBUSY) { + ret = EAGAIN; + } + if (ret != 0) { + if (waitflag || (ret != EAGAIN)) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "pthread_mutex_%slock" + "(allrecord_mutex) failed: %s\n", + waitflag ? "" : "try_", strerror(ret))); + } + errno = ret; + goto fail; + } + ret = pthread_mutex_unlock(&m->allrecord_mutex); + if (ret != 0) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "pthread_mutex_unlock" + "(allrecord_mutex) failed: %s\n", strerror(ret))); + errno = ret; + goto fail; + } + goto again; + +fail: + *pret = -1; + return true; +} + +bool tdb_mutex_unlock(struct tdb_context *tdb, int rw, off_t off, off_t len, + int *pret) +{ + struct tdb_mutexes *m = tdb->mutexes; + pthread_mutex_t *chain; + int ret; + unsigned idx; + + if (!tdb_mutex_index(tdb, off, len, &idx)) { + return false; + } + chain = &m->hashchains[idx]; + + ret = pthread_mutex_unlock(chain); + if (ret == 0) { + *pret = 0; + return true; + } + errno = ret; + *pret = -1; + return true; +} + +int tdb_mutex_allrecord_lock(struct tdb_context *tdb, int ltype, + enum tdb_lock_flags flags) +{ + struct tdb_mutexes *m = tdb->mutexes; + int ret; + uint32_t i; + bool waitflag = (flags & TDB_LOCK_WAIT); + int saved_errno; + + if (tdb->flags & TDB_NOLOCK) { + return 0; + } + + if (flags & TDB_LOCK_MARK_ONLY) { + return 0; + } + + ret = allrecord_mutex_lock(m, waitflag); + if (!waitflag && (ret == EBUSY)) { + errno = EAGAIN; + tdb->ecode = TDB_ERR_LOCK; + return -1; + } + if (ret != 0) { + if (!(flags & TDB_LOCK_PROBE)) { + TDB_LOG((tdb, TDB_DEBUG_TRACE, + "allrecord_mutex_lock() failed: %s\n", + strerror(ret))); + } + tdb->ecode = TDB_ERR_LOCK; + return -1; + } + + if (m->allrecord_lock != F_UNLCK) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "allrecord_lock == %d\n", + (int)m->allrecord_lock)); + goto fail_unlock_allrecord_mutex; + } + m->allrecord_lock = (ltype == F_RDLCK) ? F_RDLCK : F_WRLCK; + + for (i=0; i<tdb->hash_size; i++) { + + /* ignore hashchains[0], the freelist */ + pthread_mutex_t *chain = &m->hashchains[i+1]; + + ret = chain_mutex_lock(chain, waitflag); + if (!waitflag && (ret == EBUSY)) { + errno = EAGAIN; + goto fail_unroll_allrecord_lock; + } + if (ret != 0) { + if (!(flags & TDB_LOCK_PROBE)) { + TDB_LOG((tdb, TDB_DEBUG_TRACE, + "chain_mutex_lock() failed: %s\n", + strerror(ret))); + } + errno = ret; + goto fail_unroll_allrecord_lock; + } + + ret = pthread_mutex_unlock(chain); + if (ret != 0) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "pthread_mutex_unlock" + "(chainlock) failed: %s\n", strerror(ret))); + errno = ret; + goto fail_unroll_allrecord_lock; + } + } + /* + * We leave this routine with m->allrecord_mutex locked + */ + return 0; + +fail_unroll_allrecord_lock: + m->allrecord_lock = F_UNLCK; + +fail_unlock_allrecord_mutex: + saved_errno = errno; + ret = pthread_mutex_unlock(&m->allrecord_mutex); + if (ret != 0) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "pthread_mutex_unlock" + "(allrecord_mutex) failed: %s\n", strerror(ret))); + } + errno = saved_errno; + tdb->ecode = TDB_ERR_LOCK; + return -1; +} + +int tdb_mutex_allrecord_upgrade(struct tdb_context *tdb) +{ + struct tdb_mutexes *m = tdb->mutexes; + int ret; + uint32_t i; + + if (tdb->flags & TDB_NOLOCK) { + return 0; + } + + /* + * Our only caller tdb_allrecord_upgrade() + * guarantees that we already own the allrecord lock. + * + * Which means m->allrecord_mutex is still locked by us. + */ + + if (m->allrecord_lock != F_RDLCK) { + tdb->ecode = TDB_ERR_LOCK; + TDB_LOG((tdb, TDB_DEBUG_FATAL, "allrecord_lock == %d\n", + (int)m->allrecord_lock)); + return -1; + } + + m->allrecord_lock = F_WRLCK; + + for (i=0; i<tdb->hash_size; i++) { + + /* ignore hashchains[0], the freelist */ + pthread_mutex_t *chain = &m->hashchains[i+1]; + + ret = chain_mutex_lock(chain, true); + if (ret != 0) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "pthread_mutex_lock" + "(chainlock) failed: %s\n", strerror(ret))); + goto fail_unroll_allrecord_lock; + } + + ret = pthread_mutex_unlock(chain); + if (ret != 0) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "pthread_mutex_unlock" + "(chainlock) failed: %s\n", strerror(ret))); + goto fail_unroll_allrecord_lock; + } + } + + return 0; + +fail_unroll_allrecord_lock: + m->allrecord_lock = F_RDLCK; + tdb->ecode = TDB_ERR_LOCK; + return -1; +} + +void tdb_mutex_allrecord_downgrade(struct tdb_context *tdb) +{ + struct tdb_mutexes *m = tdb->mutexes; + + /* + * Our only caller tdb_allrecord_upgrade() (in the error case) + * guarantees that we already own the allrecord lock. + * + * Which means m->allrecord_mutex is still locked by us. + */ + + if (m->allrecord_lock != F_WRLCK) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "allrecord_lock == %d\n", + (int)m->allrecord_lock)); + return; + } + + m->allrecord_lock = F_RDLCK; + return; +} + + +int tdb_mutex_allrecord_unlock(struct tdb_context *tdb) +{ + struct tdb_mutexes *m = tdb->mutexes; + short old; + int ret; + + if (tdb->flags & TDB_NOLOCK) { + return 0; + } + + /* + * Our only callers tdb_allrecord_unlock() and + * tdb_allrecord_lock() (in the error path) + * guarantee that we already own the allrecord lock. + * + * Which means m->allrecord_mutex is still locked by us. + */ + + if ((m->allrecord_lock != F_RDLCK) && (m->allrecord_lock != F_WRLCK)) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "allrecord_lock == %d\n", + (int)m->allrecord_lock)); + return -1; + } + + old = m->allrecord_lock; + m->allrecord_lock = F_UNLCK; + + ret = pthread_mutex_unlock(&m->allrecord_mutex); + if (ret != 0) { + m->allrecord_lock = old; + TDB_LOG((tdb, TDB_DEBUG_FATAL, "pthread_mutex_unlock" + "(allrecord_mutex) failed: %s\n", strerror(ret))); + return -1; + } + return 0; +} + +int tdb_mutex_init(struct tdb_context *tdb) +{ + struct tdb_mutexes *m; + pthread_mutexattr_t ma; + uint32_t i; + int ret; + + ret = tdb_mutex_mmap(tdb); + if (ret == -1) { + return -1; + } + m = tdb->mutexes; + + ret = pthread_mutexattr_init(&ma); + if (ret != 0) { + goto fail_munmap; + } + ret = pthread_mutexattr_settype(&ma, PTHREAD_MUTEX_ERRORCHECK); + if (ret != 0) { + goto fail; + } + ret = pthread_mutexattr_setpshared(&ma, PTHREAD_PROCESS_SHARED); + if (ret != 0) { + goto fail; + } + ret = pthread_mutexattr_setrobust(&ma, PTHREAD_MUTEX_ROBUST); + if (ret != 0) { + goto fail; + } + + for (i=0; i<tdb->hash_size+1; i++) { + pthread_mutex_t *chain = &m->hashchains[i]; + + ret = pthread_mutex_init(chain, &ma); + if (ret != 0) { + goto fail; + } + } + + m->allrecord_lock = F_UNLCK; + + ret = pthread_mutex_init(&m->allrecord_mutex, &ma); + if (ret != 0) { + goto fail; + } + ret = 0; +fail: + pthread_mutexattr_destroy(&ma); +fail_munmap: + + if (ret == 0) { + return 0; + } + + tdb_mutex_munmap(tdb); + + errno = ret; + return -1; +} + +int tdb_mutex_mmap(struct tdb_context *tdb) +{ + size_t len; + void *ptr; + + len = tdb_mutex_size(tdb); + if (len == 0) { + return 0; + } + + if (tdb->mutexes != NULL) { + return 0; + } + + ptr = mmap(NULL, len, PROT_READ|PROT_WRITE, MAP_SHARED|MAP_FILE, + tdb->fd, 0); + if (ptr == MAP_FAILED) { + return -1; + } + tdb->mutexes = (struct tdb_mutexes *)ptr; + + return 0; +} + +int tdb_mutex_munmap(struct tdb_context *tdb) +{ + size_t len; + int ret; + + len = tdb_mutex_size(tdb); + if (len == 0) { + return 0; + } + + ret = munmap(tdb->mutexes, len); + if (ret == -1) { + return -1; + } + tdb->mutexes = NULL; + + return 0; +} + +static bool tdb_mutex_locking_cached; + +static bool tdb_mutex_locking_supported(void) +{ + pthread_mutexattr_t ma; + pthread_mutex_t m; + int ret; + static bool initialized; + + if (initialized) { + return tdb_mutex_locking_cached; + } + + initialized = true; + + ret = pthread_mutexattr_init(&ma); + if (ret != 0) { + return false; + } + ret = pthread_mutexattr_settype(&ma, PTHREAD_MUTEX_ERRORCHECK); + if (ret != 0) { + goto cleanup_ma; + } + ret = pthread_mutexattr_setpshared(&ma, PTHREAD_PROCESS_SHARED); + if (ret != 0) { + goto cleanup_ma; + } + ret = pthread_mutexattr_setrobust(&ma, PTHREAD_MUTEX_ROBUST); + if (ret != 0) { + goto cleanup_ma; + } + ret = pthread_mutex_init(&m, &ma); + if (ret != 0) { + goto cleanup_ma; + } + ret = pthread_mutex_lock(&m); + if (ret != 0) { + goto cleanup_m; + } + /* + * This makes sure we have real mutexes + * from a threading library instead of just + * stubs from libc. + */ + ret = pthread_mutex_lock(&m); + if (ret != EDEADLK) { + goto cleanup_lock; + } + ret = pthread_mutex_unlock(&m); + if (ret != 0) { + goto cleanup_m; + } + + tdb_mutex_locking_cached = true; + goto cleanup_m; + +cleanup_lock: + pthread_mutex_unlock(&m); +cleanup_m: + pthread_mutex_destroy(&m); +cleanup_ma: + pthread_mutexattr_destroy(&ma); + return tdb_mutex_locking_cached; +} + +static void (*tdb_robust_mutext_old_handler)(int) = SIG_ERR; +static pid_t tdb_robust_mutex_pid = -1; + +static bool tdb_robust_mutex_setup_sigchild(void (*handler)(int), + void (**p_old_handler)(int)) +{ +#ifdef HAVE_SIGACTION + struct sigaction act; + struct sigaction oldact; + + memset(&act, '\0', sizeof(act)); + + act.sa_handler = handler; +#ifdef SA_RESTART + act.sa_flags = SA_RESTART; +#endif + sigemptyset(&act.sa_mask); + sigaddset(&act.sa_mask, SIGCHLD); + sigaction(SIGCHLD, &act, &oldact); + if (p_old_handler) { + *p_old_handler = oldact.sa_handler; + } + return true; +#else /* !HAVE_SIGACTION */ + return false; +#endif +} + +static void tdb_robust_mutex_handler(int sig) +{ + pid_t child_pid = tdb_robust_mutex_pid; + + if (child_pid != -1) { + pid_t pid; + + pid = waitpid(child_pid, NULL, WNOHANG); + if (pid == -1) { + switch (errno) { + case ECHILD: + tdb_robust_mutex_pid = -1; + return; + + default: + return; + } + } + if (pid == child_pid) { + tdb_robust_mutex_pid = -1; + return; + } + } + + if (tdb_robust_mutext_old_handler == SIG_DFL) { + return; + } + if (tdb_robust_mutext_old_handler == SIG_IGN) { + return; + } + if (tdb_robust_mutext_old_handler == SIG_ERR) { + return; + } + + tdb_robust_mutext_old_handler(sig); +} + +static void tdb_robust_mutex_wait_for_child(pid_t *child_pid) +{ + int options = WNOHANG; + + if (*child_pid == -1) { + return; + } + + while (tdb_robust_mutex_pid > 0) { + pid_t pid; + + /* + * First we try with WNOHANG, as the process might not exist + * anymore. Once we've sent SIGKILL we block waiting for the + * exit. + */ + pid = waitpid(*child_pid, NULL, options); + if (pid == -1) { + if (errno == EINTR) { + continue; + } else if (errno == ECHILD) { + break; + } else { + abort(); + } + } + if (pid == *child_pid) { + break; + } + + kill(*child_pid, SIGKILL); + options = 0; + } + + tdb_robust_mutex_pid = -1; + *child_pid = -1; +} + +_PUBLIC_ bool tdb_runtime_check_for_robust_mutexes(void) +{ + void *ptr = NULL; + pthread_mutex_t *m = NULL; + pthread_mutexattr_t ma; + int ret = 1; + int pipe_down[2] = { -1, -1 }; + int pipe_up[2] = { -1, -1 }; + ssize_t nread; + char c = 0; + bool ok; + static bool initialized; + pid_t saved_child_pid = -1; + bool cleanup_ma = false; + + if (initialized) { + return tdb_mutex_locking_cached; + } + + initialized = true; + + ok = tdb_mutex_locking_supported(); + if (!ok) { + return false; + } + + tdb_mutex_locking_cached = false; + + ptr = mmap(NULL, sizeof(pthread_mutex_t), PROT_READ|PROT_WRITE, + MAP_SHARED|MAP_ANON, -1 /* fd */, 0); + if (ptr == MAP_FAILED) { + return false; + } + + ret = pipe(pipe_down); + if (ret != 0) { + goto cleanup; + } + ret = pipe(pipe_up); + if (ret != 0) { + goto cleanup; + } + + ret = pthread_mutexattr_init(&ma); + if (ret != 0) { + goto cleanup; + } + cleanup_ma = true; + ret = pthread_mutexattr_settype(&ma, PTHREAD_MUTEX_ERRORCHECK); + if (ret != 0) { + goto cleanup; + } + ret = pthread_mutexattr_setpshared(&ma, PTHREAD_PROCESS_SHARED); + if (ret != 0) { + goto cleanup; + } + ret = pthread_mutexattr_setrobust(&ma, PTHREAD_MUTEX_ROBUST); + if (ret != 0) { + goto cleanup; + } + ret = pthread_mutex_init(ptr, &ma); + if (ret != 0) { + goto cleanup; + } + m = (pthread_mutex_t *)ptr; + + if (tdb_robust_mutex_setup_sigchild(tdb_robust_mutex_handler, + &tdb_robust_mutext_old_handler) == false) { + goto cleanup; + } + + tdb_robust_mutex_pid = fork(); + saved_child_pid = tdb_robust_mutex_pid; + if (tdb_robust_mutex_pid == 0) { + size_t nwritten; + close(pipe_down[1]); + close(pipe_up[0]); + ret = pthread_mutex_lock(m); + nwritten = write(pipe_up[1], &ret, sizeof(ret)); + if (nwritten != sizeof(ret)) { + _exit(1); + } + if (ret != 0) { + _exit(1); + } + nread = read(pipe_down[0], &c, 1); + if (nread != 1) { + _exit(1); + } + /* leave locked */ + _exit(0); + } + if (tdb_robust_mutex_pid == -1) { + goto cleanup; + } + close(pipe_down[0]); + pipe_down[0] = -1; + close(pipe_up[1]); + pipe_up[1] = -1; + + nread = read(pipe_up[0], &ret, sizeof(ret)); + if (nread != sizeof(ret)) { + goto cleanup; + } + + ret = pthread_mutex_trylock(m); + if (ret != EBUSY) { + if (ret == 0) { + pthread_mutex_unlock(m); + } + goto cleanup; + } + + if (write(pipe_down[1], &c, 1) != 1) { + goto cleanup; + } + + nread = read(pipe_up[0], &c, 1); + if (nread != 0) { + goto cleanup; + } + + tdb_robust_mutex_wait_for_child(&saved_child_pid); + + ret = pthread_mutex_trylock(m); + if (ret != EOWNERDEAD) { + if (ret == 0) { + pthread_mutex_unlock(m); + } + goto cleanup; + } + + ret = pthread_mutex_consistent(m); + if (ret != 0) { + goto cleanup; + } + + ret = pthread_mutex_trylock(m); + if (ret != EDEADLK && ret != EBUSY) { + pthread_mutex_unlock(m); + goto cleanup; + } + + ret = pthread_mutex_unlock(m); + if (ret != 0) { + goto cleanup; + } + + tdb_mutex_locking_cached = true; + +cleanup: + /* + * Note that we don't reset the signal handler we just reset + * tdb_robust_mutex_pid to -1. This is ok as this code path is only + * called once per process. + * + * Leaving our signal handler avoids races with other threads potentially + * setting up their SIGCHLD handlers. + * + * The worst thing that can happen is that the other newer signal + * handler will get the SIGCHLD signal for our child and/or reap the + * child with a wait() function. tdb_robust_mutex_wait_for_child() + * handles the case where waitpid returns ECHILD. + */ + tdb_robust_mutex_wait_for_child(&saved_child_pid); + + if (m != NULL) { + pthread_mutex_destroy(m); + } + if (cleanup_ma) { + pthread_mutexattr_destroy(&ma); + } + if (pipe_down[0] != -1) { + close(pipe_down[0]); + } + if (pipe_down[1] != -1) { + close(pipe_down[1]); + } + if (pipe_up[0] != -1) { + close(pipe_up[0]); + } + if (pipe_up[1] != -1) { + close(pipe_up[1]); + } + if (ptr != NULL) { + munmap(ptr, sizeof(pthread_mutex_t)); + } + + return tdb_mutex_locking_cached; +} + +#else + +size_t tdb_mutex_size(struct tdb_context *tdb) +{ + return 0; +} + +bool tdb_have_mutexes(struct tdb_context *tdb) +{ + return false; +} + +int tdb_mutex_allrecord_lock(struct tdb_context *tdb, int ltype, + enum tdb_lock_flags flags) +{ + tdb->ecode = TDB_ERR_LOCK; + return -1; +} + +int tdb_mutex_allrecord_unlock(struct tdb_context *tdb) +{ + return -1; +} + +int tdb_mutex_allrecord_upgrade(struct tdb_context *tdb) +{ + tdb->ecode = TDB_ERR_LOCK; + return -1; +} + +void tdb_mutex_allrecord_downgrade(struct tdb_context *tdb) +{ + return; +} + +int tdb_mutex_mmap(struct tdb_context *tdb) +{ + errno = ENOSYS; + return -1; +} + +int tdb_mutex_munmap(struct tdb_context *tdb) +{ + errno = ENOSYS; + return -1; +} + +int tdb_mutex_init(struct tdb_context *tdb) +{ + errno = ENOSYS; + return -1; +} + +_PUBLIC_ bool tdb_runtime_check_for_robust_mutexes(void) +{ + return false; +} + +#endif diff --git a/common/open.c b/common/open.c new file mode 100644 index 0000000..3fa7ce1 --- /dev/null +++ b/common/open.c @@ -0,0 +1,968 @@ + /* + Unix SMB/CIFS implementation. + + trivial database library + + Copyright (C) Andrew Tridgell 1999-2005 + Copyright (C) Paul `Rusty' Russell 2000 + Copyright (C) Jeremy Allison 2000-2003 + + ** NOTE! The following LGPL license applies to the tdb + ** library. This does NOT imply that all of Samba is released + ** under the LGPL + + This library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 3 of the License, or (at your option) any later version. + + This library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with this library; if not, see <http://www.gnu.org/licenses/>. +*/ + +#include "tdb_private.h" + +/* all contexts, to ensure no double-opens (fcntl locks don't nest!) */ +static struct tdb_context *tdbs = NULL; + +/* We use two hashes to double-check they're using the right hash function. */ +void tdb_header_hash(struct tdb_context *tdb, + uint32_t *magic1_hash, uint32_t *magic2_hash) +{ + TDB_DATA hash_key; + uint32_t tdb_magic = TDB_MAGIC; + + hash_key.dptr = discard_const_p(unsigned char, TDB_MAGIC_FOOD); + hash_key.dsize = sizeof(TDB_MAGIC_FOOD); + *magic1_hash = tdb->hash_fn(&hash_key); + + hash_key.dptr = (unsigned char *)CONVERT(tdb_magic); + hash_key.dsize = sizeof(tdb_magic); + *magic2_hash = tdb->hash_fn(&hash_key); + + /* Make sure at least one hash is non-zero! */ + if (*magic1_hash == 0 && *magic2_hash == 0) + *magic1_hash = 1; +} + +/* initialise a new database with a specified hash size */ +static int tdb_new_database(struct tdb_context *tdb, struct tdb_header *header, + int hash_size) +{ + struct tdb_header *newdb; + size_t size; + int ret = -1; + + /* We make it up in memory, then write it out if not internal */ + size = sizeof(struct tdb_header) + (hash_size+1)*sizeof(tdb_off_t); + if (!(newdb = (struct tdb_header *)calloc(size, 1))) { + tdb->ecode = TDB_ERR_OOM; + return -1; + } + + /* Fill in the header */ + newdb->version = TDB_VERSION; + newdb->hash_size = hash_size; + + tdb_header_hash(tdb, &newdb->magic1_hash, &newdb->magic2_hash); + + /* Make sure older tdbs (which don't check the magic hash fields) + * will refuse to open this TDB. */ + if (tdb->flags & TDB_INCOMPATIBLE_HASH) + newdb->rwlocks = TDB_HASH_RWLOCK_MAGIC; + + /* + * We create a tdb with TDB_FEATURE_FLAG_MUTEX support, + * the flag combination and runtime feature checks + * are done by the caller already. + */ + if (tdb->flags & TDB_MUTEX_LOCKING) { + newdb->feature_flags |= TDB_FEATURE_FLAG_MUTEX; + } + + /* + * If we have any features we add the FEATURE_FLAG_MAGIC, overwriting the + * TDB_HASH_RWLOCK_MAGIC above. + */ + if (newdb->feature_flags != 0) { + newdb->rwlocks = TDB_FEATURE_FLAG_MAGIC; + } + + /* + * It's required for some following code paths + * to have the fields on 'tdb' up-to-date. + * + * E.g. tdb_mutex_size() requires it + */ + tdb->feature_flags = newdb->feature_flags; + tdb->hash_size = newdb->hash_size; + + if (tdb->flags & TDB_INTERNAL) { + tdb->map_size = size; + tdb->map_ptr = (char *)newdb; + memcpy(header, newdb, sizeof(*header)); + /* Convert the `ondisk' version if asked. */ + CONVERT(*newdb); + return 0; + } + if (lseek(tdb->fd, 0, SEEK_SET) == -1) + goto fail; + + if (ftruncate(tdb->fd, 0) == -1) + goto fail; + + if (newdb->feature_flags & TDB_FEATURE_FLAG_MUTEX) { + newdb->mutex_size = tdb_mutex_size(tdb); + tdb->hdr_ofs = newdb->mutex_size; + } + + /* This creates an endian-converted header, as if read from disk */ + CONVERT(*newdb); + memcpy(header, newdb, sizeof(*header)); + /* Don't endian-convert the magic food! */ + memcpy(newdb->magic_food, TDB_MAGIC_FOOD, strlen(TDB_MAGIC_FOOD)+1); + + if (!tdb_write_all(tdb->fd, newdb, size)) + goto fail; + + if (newdb->feature_flags & TDB_FEATURE_FLAG_MUTEX) { + + /* + * Now we init the mutex area + * followed by a second header. + */ + + ret = ftruncate( + tdb->fd, + newdb->mutex_size + sizeof(struct tdb_header)); + if (ret == -1) { + goto fail; + } + ret = tdb_mutex_init(tdb); + if (ret == -1) { + goto fail; + } + + /* + * Write a second header behind the mutexes. That's the area + * that will be mmapp'ed. + */ + ret = lseek(tdb->fd, newdb->mutex_size, SEEK_SET); + if (ret == -1) { + goto fail; + } + if (!tdb_write_all(tdb->fd, newdb, size)) { + goto fail; + } + } + + ret = 0; + fail: + SAFE_FREE(newdb); + return ret; +} + + + +static int tdb_already_open(dev_t device, + ino_t ino) +{ + struct tdb_context *i; + + for (i = tdbs; i; i = i->next) { + if (i->device == device && i->inode == ino) { + return 1; + } + } + + return 0; +} + +/* open the database, creating it if necessary + + The open_flags and mode are passed straight to the open call on the + database file. A flags value of O_WRONLY is invalid. The hash size + is advisory, use zero for a default value. + + Return is NULL on error, in which case errno is also set. Don't + try to call tdb_error or tdb_errname, just do strerror(errno). + + @param name may be NULL for internal databases. */ +_PUBLIC_ struct tdb_context *tdb_open(const char *name, int hash_size, int tdb_flags, + int open_flags, mode_t mode) +{ + return tdb_open_ex(name, hash_size, tdb_flags, open_flags, mode, NULL, NULL); +} + +/* a default logging function */ +static void null_log_fn(struct tdb_context *tdb, enum tdb_debug_level level, const char *fmt, ...) PRINTF_ATTRIBUTE(3, 4); +static void null_log_fn(struct tdb_context *tdb, enum tdb_debug_level level, const char *fmt, ...) +{ +} + +static bool check_header_hash(struct tdb_context *tdb, + struct tdb_header *header, + bool default_hash, uint32_t *m1, uint32_t *m2) +{ + tdb_header_hash(tdb, m1, m2); + if (header->magic1_hash == *m1 && + header->magic2_hash == *m2) { + return true; + } + + /* If they explicitly set a hash, always respect it. */ + if (!default_hash) + return false; + + /* Otherwise, try the other inbuilt hash. */ + if (tdb->hash_fn == tdb_old_hash) + tdb->hash_fn = tdb_jenkins_hash; + else + tdb->hash_fn = tdb_old_hash; + return check_header_hash(tdb, header, false, m1, m2); +} + +static bool tdb_mutex_open_ok(struct tdb_context *tdb, + const struct tdb_header *header) +{ + if (tdb->flags & TDB_NOLOCK) { + /* + * We don't look at locks, so it does not matter to have a + * compatible mutex implementation. Allow the open. + */ + return true; + } + + if (!(tdb->flags & TDB_MUTEX_LOCKING)) { + TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_mutex_open_ok[%s]: " + "Can use mutexes only with " + "MUTEX_LOCKING or NOLOCK\n", + tdb->name)); + return false; + } + + if (tdb_mutex_size(tdb) != header->mutex_size) { + TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_mutex_open_ok[%s]: " + "Mutex size changed from %"PRIu32" to %zu\n.", + tdb->name, + header->mutex_size, + tdb_mutex_size(tdb))); + return false; + } + + return true; +} + +_PUBLIC_ struct tdb_context *tdb_open_ex(const char *name, int hash_size, int tdb_flags, + int open_flags, mode_t mode, + const struct tdb_logging_context *log_ctx, + tdb_hash_func hash_fn) +{ + int orig_errno = errno; + struct tdb_header header = { + .version = 0, + }; + struct tdb_context *tdb; + struct stat st; + int rev = 0; + bool locked = false; + unsigned char *vp; + uint32_t vertest; + unsigned v; + const char *hash_alg; + uint32_t magic1, magic2; + int ret; + + if (!(tdb = (struct tdb_context *)calloc(1, sizeof *tdb))) { + /* Can't log this */ + errno = ENOMEM; + goto fail; + } + tdb_io_init(tdb); + + if (tdb_flags & TDB_INTERNAL) { + tdb_flags |= TDB_INCOMPATIBLE_HASH; + } + if (tdb_flags & TDB_MUTEX_LOCKING) { + tdb_flags |= TDB_INCOMPATIBLE_HASH; + } + + tdb->fd = -1; +#ifdef TDB_TRACE + tdb->tracefd = -1; +#endif + tdb->name = NULL; + tdb->map_ptr = NULL; + tdb->flags = tdb_flags; + tdb->open_flags = open_flags; + if (log_ctx) { + tdb->log = *log_ctx; + } else { + tdb->log.log_fn = null_log_fn; + tdb->log.log_private = NULL; + } + + if (name == NULL && (tdb_flags & TDB_INTERNAL)) { + name = "__TDB_INTERNAL__"; + } + + if (name == NULL) { + tdb->name = discard_const_p(char, "__NULL__"); + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_open_ex: called with name == NULL\n")); + tdb->name = NULL; + errno = EINVAL; + goto fail; + } + + /* now make a copy of the name, as the caller memory might go away */ + if (!(tdb->name = (char *)strdup(name))) { + /* + * set the name as the given string, so that tdb_name() will + * work in case of an error. + */ + tdb->name = discard_const_p(char, name); + TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_open_ex: can't strdup(%s)\n", + name)); + tdb->name = NULL; + errno = ENOMEM; + goto fail; + } + + if (hash_fn) { + tdb->hash_fn = hash_fn; + hash_alg = "the user defined"; + } else { + /* This controls what we use when creating a tdb. */ + if (tdb->flags & TDB_INCOMPATIBLE_HASH) { + tdb->hash_fn = tdb_jenkins_hash; + } else { + tdb->hash_fn = tdb_old_hash; + } + hash_alg = "either default"; + } + + /* cache the page size */ + tdb->page_size = getpagesize(); + if (tdb->page_size <= 0) { + tdb->page_size = 0x2000; + } + + tdb->max_dead_records = (tdb_flags & TDB_VOLATILE) ? 5 : 0; + + if ((open_flags & O_ACCMODE) == O_WRONLY) { + TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_open_ex: can't open tdb %s write-only\n", + name)); + errno = EINVAL; + goto fail; + } + + if (hash_size == 0) + hash_size = DEFAULT_HASH_SIZE; + if ((open_flags & O_ACCMODE) == O_RDONLY) { + tdb->read_only = 1; + /* read only databases don't do locking or clear if first */ + tdb->flags |= TDB_NOLOCK; + tdb->flags &= ~(TDB_CLEAR_IF_FIRST|TDB_MUTEX_LOCKING); + } + + if ((tdb->flags & TDB_ALLOW_NESTING) && + (tdb->flags & TDB_DISALLOW_NESTING)) { + tdb->ecode = TDB_ERR_NESTING; + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_open_ex: " + "allow_nesting and disallow_nesting are not allowed together!")); + errno = EINVAL; + goto fail; + } + + if (tdb->flags & TDB_MUTEX_LOCKING) { + /* + * Here we catch bugs in the callers, + * the runtime check for existing tdb's comes later. + */ + + if (tdb->flags & TDB_INTERNAL) { + TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_open_ex: " + "invalid flags for %s - TDB_MUTEX_LOCKING and " + "TDB_INTERNAL are not allowed together\n", name)); + errno = EINVAL; + goto fail; + } + + if (tdb->flags & TDB_NOMMAP) { + TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_open_ex: " + "invalid flags for %s - TDB_MUTEX_LOCKING and " + "TDB_NOMMAP are not allowed together\n", name)); + errno = EINVAL; + goto fail; + } + + if (tdb->read_only) { + TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_open_ex: " + "invalid flags for %s - TDB_MUTEX_LOCKING " + "not allowed read only\n", name)); + errno = EINVAL; + goto fail; + } + + /* + * The callers should have called + * tdb_runtime_check_for_robust_mutexes() + * before using TDB_MUTEX_LOCKING! + * + * This makes sure the caller understands + * that the locking may behave a bit differently + * than with pure fcntl locking. E.g. multiple + * read locks are not supported. + */ + if (!tdb_runtime_check_for_robust_mutexes()) { + TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_open_ex: " + "invalid flags for %s - TDB_MUTEX_LOCKING " + "requires support for robust_mutexes\n", + name)); + errno = ENOSYS; + goto fail; + } + } + + if (getenv("TDB_NO_FSYNC")) { + tdb->flags |= TDB_NOSYNC; + } + + /* + * TDB_ALLOW_NESTING is the default behavior. + * Note: this may change in future versions! + */ + if (!(tdb->flags & TDB_DISALLOW_NESTING)) { + tdb->flags |= TDB_ALLOW_NESTING; + } + + /* internal databases don't mmap or lock, and start off cleared */ + if (tdb->flags & TDB_INTERNAL) { + tdb->flags |= (TDB_NOLOCK | TDB_NOMMAP); + tdb->flags &= ~TDB_CLEAR_IF_FIRST; + if (tdb_new_database(tdb, &header, hash_size) != 0) { + TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_open_ex: tdb_new_database failed!")); + goto fail; + } + tdb->hash_size = hash_size; + goto internal; + } + + if ((tdb->fd = open(name, open_flags, mode)) == -1) { + TDB_LOG((tdb, TDB_DEBUG_WARNING, "tdb_open_ex: could not open file %s: %s\n", + name, strerror(errno))); + goto fail; /* errno set by open(2) */ + } + + /* on exec, don't inherit the fd */ + v = fcntl(tdb->fd, F_GETFD, 0); + fcntl(tdb->fd, F_SETFD, v | FD_CLOEXEC); + + /* ensure there is only one process initialising at once */ + if (tdb_nest_lock(tdb, OPEN_LOCK, F_WRLCK, TDB_LOCK_WAIT) == -1) { + TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_open_ex: failed to get open lock on %s: %s\n", + name, strerror(errno))); + goto fail; /* errno set by tdb_brlock */ + } + + /* we need to zero database if we are the only one with it open */ + if ((tdb_flags & TDB_CLEAR_IF_FIRST) && + (!tdb->read_only)) { + ret = tdb_nest_lock(tdb, ACTIVE_LOCK, F_WRLCK, + TDB_LOCK_NOWAIT|TDB_LOCK_PROBE); + locked = (ret == 0); + + if (locked) { + ret = tdb_brlock(tdb, F_WRLCK, FREELIST_TOP, 0, + TDB_LOCK_WAIT); + if (ret == -1) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_open_ex: " + "tdb_brlock failed for %s: %s\n", + name, strerror(errno))); + goto fail; + } + ret = tdb_new_database(tdb, &header, hash_size); + if (ret == -1) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_open_ex: " + "tdb_new_database failed for " + "%s: %s\n", name, strerror(errno))); + tdb_unlockall(tdb); + goto fail; + } + ret = tdb_brunlock(tdb, F_WRLCK, FREELIST_TOP, 0); + if (ret == -1) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_open_ex: " + "tdb_unlockall failed for %s: %s\n", + name, strerror(errno))); + goto fail; + } + ret = lseek(tdb->fd, 0, SEEK_SET); + if (ret == -1) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_open_ex: " + "lseek failed for %s: %s\n", + name, strerror(errno))); + goto fail; + } + } + } + + errno = 0; + if (read(tdb->fd, &header, sizeof(header)) != sizeof(header) + /* + * Call strncmp() rather than strcmp() in case header.magic_food is + * not zero‐terminated. We’re still checking the full string for + * equality, as tdb_header::magic_food is larger than + * TDB_MAGIC_FOOD. + */ + || strncmp(header.magic_food, TDB_MAGIC_FOOD, sizeof(header.magic_food)) != 0) { + if (!(open_flags & O_CREAT) || + tdb_new_database(tdb, &header, hash_size) == -1) { + if (errno == 0) { + errno = EIO; /* ie bad format or something */ + } + goto fail; + } + rev = (tdb->flags & TDB_CONVERT); + } else if (header.version != TDB_VERSION + && !(rev = (header.version==TDB_BYTEREV(TDB_VERSION)))) { + /* wrong version */ + errno = EIO; + goto fail; + } + vp = (unsigned char *)&header.version; + vertest = (((uint32_t)vp[0]) << 24) | (((uint32_t)vp[1]) << 16) | + (((uint32_t)vp[2]) << 8) | (uint32_t)vp[3]; + tdb->flags |= (vertest==TDB_VERSION) ? TDB_BIGENDIAN : 0; + if (!rev) + tdb->flags &= ~TDB_CONVERT; + else { + tdb->flags |= TDB_CONVERT; + tdb_convert(&header, sizeof(header)); + } + + /* + * We only use st.st_dev and st.st_ino from the raw fstat() + * call, everything else needs to use tdb_fstat() in order + * to skip tdb->hdr_ofs! + */ + if (fstat(tdb->fd, &st) == -1) { + goto fail; + } + tdb->device = st.st_dev; + tdb->inode = st.st_ino; + ZERO_STRUCT(st); + + if (header.rwlocks != 0 && + header.rwlocks != TDB_FEATURE_FLAG_MAGIC && + header.rwlocks != TDB_HASH_RWLOCK_MAGIC) { + TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_open_ex: spinlocks no longer supported\n")); + errno = ENOSYS; + goto fail; + } + + if (header.hash_size == 0) { + TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_open_ex: invalid database: 0 hash_size\n")); + errno = ENOSYS; + goto fail; + } + + tdb->hash_size = header.hash_size; + + if (header.rwlocks == TDB_FEATURE_FLAG_MAGIC) { + tdb->feature_flags = header.feature_flags; + } + + if (tdb->feature_flags & ~TDB_SUPPORTED_FEATURE_FLAGS) { + TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_open_ex: unsupported " + "features in tdb %s: 0x%08x (supported: 0x%08x)\n", + name, (unsigned)tdb->feature_flags, + (unsigned)TDB_SUPPORTED_FEATURE_FLAGS)); + errno = ENOSYS; + goto fail; + } + + if (tdb->feature_flags & TDB_FEATURE_FLAG_MUTEX) { + if (!tdb_mutex_open_ok(tdb, &header)) { + errno = EINVAL; + goto fail; + } + + /* + * We need to remember the hdr_ofs + * also for the TDB_NOLOCK case + * if the current library doesn't support + * mutex locking. + */ + tdb->hdr_ofs = header.mutex_size; + + if ((!(tdb_flags & TDB_CLEAR_IF_FIRST)) && (!tdb->read_only)) { + /* + * Open an existing mutexed tdb, but without + * CLEAR_IF_FIRST. We need to initialize the + * mutex array and keep the CLEAR_IF_FIRST + * lock locked. + */ + ret = tdb_nest_lock(tdb, ACTIVE_LOCK, F_WRLCK, + TDB_LOCK_NOWAIT|TDB_LOCK_PROBE); + locked = (ret == 0); + + if (locked) { + ret = tdb_mutex_init(tdb); + if (ret == -1) { + TDB_LOG((tdb, + TDB_DEBUG_FATAL, + "tdb_open_ex: tdb_mutex_init " + "failed for ""%s: %s\n", + name, strerror(errno))); + goto fail; + } + } + } + } + + if ((header.magic1_hash == 0) && (header.magic2_hash == 0)) { + /* older TDB without magic hash references */ + tdb->hash_fn = tdb_old_hash; + } else if (!check_header_hash(tdb, &header, !hash_fn, + &magic1, &magic2)) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_open_ex: " + "%s was not created with %s hash function we are using\n" + "magic1_hash[0x%08X %s 0x%08X] " + "magic2_hash[0x%08X %s 0x%08X]\n", + name, hash_alg, + header.magic1_hash, + (header.magic1_hash == magic1) ? "==" : "!=", + magic1, + header.magic2_hash, + (header.magic2_hash == magic2) ? "==" : "!=", + magic2)); + errno = EINVAL; + goto fail; + } + + /* Is it already in the open list? If so, fail. */ + if (tdb_already_open(tdb->device, tdb->inode)) { + TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_open_ex: " + "%s (%d,%d) is already open in this process\n", + name, (int)tdb->device, (int)tdb->inode)); + errno = EBUSY; + goto fail; + } + + /* + * We had tdb_mmap(tdb) here before, + * but we need to use tdb_fstat(), + * which is triggered from tdb_oob() before calling tdb_mmap(). + * As this skips tdb->hdr_ofs. + */ + tdb->map_size = 0; + ret = tdb_oob(tdb, 0, 1, 0); + if (ret == -1) { + errno = EIO; + goto fail; + } + + if (tdb->feature_flags & TDB_FEATURE_FLAG_MUTEX) { + if (!(tdb->flags & TDB_NOLOCK)) { + ret = tdb_mutex_mmap(tdb); + if (ret != 0) { + goto fail; + } + } + } + + if (tdb->hash_size > UINT32_MAX/4) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_open_ex: " + "hash size %"PRIu32" too large\n", tdb->hash_size)); + errno = EINVAL; + goto fail; + } + + ret = tdb_oob(tdb, FREELIST_TOP, 4*tdb->hash_size, 1); + if (ret == -1) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_open_ex: " + "hash size %"PRIu32" does not fit\n", tdb->hash_size)); + errno = EINVAL; + goto fail; + } + + if (locked) { + if (tdb_nest_unlock(tdb, ACTIVE_LOCK, F_WRLCK, false) == -1) { + TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_open_ex: " + "failed to release ACTIVE_LOCK on %s: %s\n", + name, strerror(errno))); + goto fail; + } + + + } + + if (locked || (tdb_flags & TDB_CLEAR_IF_FIRST)) { + /* + * We always need to do this if the CLEAR_IF_FIRST + * flag is set, even if we didn't get the initial + * exclusive lock as we need to let all other users + * know we're using it. + */ + + ret = tdb_nest_lock(tdb, ACTIVE_LOCK, F_RDLCK, TDB_LOCK_WAIT); + if (ret == -1) { + goto fail; + } + } + + /* if needed, run recovery */ + if (tdb_transaction_recover(tdb) == -1) { + goto fail; + } + +#ifdef TDB_TRACE + { + char tracefile[strlen(name) + 32]; + + snprintf(tracefile, sizeof(tracefile), + "%s.trace.%li", name, (long)getpid()); + tdb->tracefd = open(tracefile, O_WRONLY|O_CREAT|O_EXCL, 0600); + if (tdb->tracefd >= 0) { + tdb_enable_seqnum(tdb); + tdb_trace_open(tdb, "tdb_open", hash_size, tdb_flags, + open_flags); + } else + TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_open_ex: failed to open trace file %s!\n", tracefile)); + } +#endif + + internal: + /* Internal (memory-only) databases skip all the code above to + * do with disk files, and resume here by releasing their + * open lock and hooking into the active list. */ + if (tdb_nest_unlock(tdb, OPEN_LOCK, F_WRLCK, false) == -1) { + goto fail; + } + tdb->next = tdbs; + tdbs = tdb; + errno = orig_errno; + return tdb; + + fail: + { int save_errno = errno; + + if (!tdb) + return NULL; + +#ifdef TDB_TRACE + close(tdb->tracefd); +#endif + if (tdb->map_ptr) { + if (tdb->flags & TDB_INTERNAL) + SAFE_FREE(tdb->map_ptr); + else + tdb_munmap(tdb); + } + if (tdb->fd != -1) + if (close(tdb->fd) != 0) + TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_open_ex: failed to close tdb->fd on error!\n")); + SAFE_FREE(tdb->lockrecs); + SAFE_FREE(tdb->name); + SAFE_FREE(tdb); + errno = save_errno; + return NULL; + } +} + +/* + * Set the maximum number of dead records per hash chain + */ + +_PUBLIC_ void tdb_set_max_dead(struct tdb_context *tdb, int max_dead) +{ + tdb->max_dead_records = max_dead; +} + +/** + * Close a database. + * + * @returns -1 for error; 0 for success. + **/ +_PUBLIC_ int tdb_close(struct tdb_context *tdb) +{ + struct tdb_context **i; + int ret = 0; + + if (tdb->transaction) { + tdb_transaction_cancel(tdb); + } + tdb_trace(tdb, "tdb_close"); + + if (tdb->map_ptr) { + if (tdb->flags & TDB_INTERNAL) + SAFE_FREE(tdb->map_ptr); + else + tdb_munmap(tdb); + } + + tdb_mutex_munmap(tdb); + + SAFE_FREE(tdb->name); + if (tdb->fd != -1) { + ret = close(tdb->fd); + tdb->fd = -1; + } + SAFE_FREE(tdb->lockrecs); + + /* Remove from contexts list */ + for (i = &tdbs; *i; i = &(*i)->next) { + if (*i == tdb) { + *i = tdb->next; + break; + } + } + +#ifdef TDB_TRACE + close(tdb->tracefd); +#endif + memset(tdb, 0, sizeof(*tdb)); + SAFE_FREE(tdb); + + return ret; +} + +/* register a logging function */ +_PUBLIC_ void tdb_set_logging_function(struct tdb_context *tdb, + const struct tdb_logging_context *log_ctx) +{ + tdb->log = *log_ctx; +} + +_PUBLIC_ void *tdb_get_logging_private(struct tdb_context *tdb) +{ + return tdb->log.log_private; +} + +static int tdb_reopen_internal(struct tdb_context *tdb, bool active_lock) +{ +#if !defined(LIBREPLACE_PREAD_NOT_REPLACED) || \ + !defined(LIBREPLACE_PWRITE_NOT_REPLACED) + struct stat st; +#endif + + if (tdb->flags & TDB_INTERNAL) { + return 0; /* Nothing to do. */ + } + + if (tdb_have_extra_locks(tdb)) { + TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_reopen: reopen not allowed with locks held\n")); + goto fail; + } + + if (tdb->transaction != 0) { + TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_reopen: reopen not allowed inside a transaction\n")); + goto fail; + } + +/* If we have real pread & pwrite, we can skip reopen. */ +#if !defined(LIBREPLACE_PREAD_NOT_REPLACED) || \ + !defined(LIBREPLACE_PWRITE_NOT_REPLACED) + if (tdb_munmap(tdb) != 0) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_reopen: munmap failed (%s)\n", strerror(errno))); + goto fail; + } + if (close(tdb->fd) != 0) + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_reopen: WARNING closing tdb->fd failed!\n")); + tdb->fd = open(tdb->name, tdb->open_flags & ~(O_CREAT|O_TRUNC), 0); + if (tdb->fd == -1) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_reopen: open failed (%s)\n", strerror(errno))); + goto fail; + } + /* + * We only use st.st_dev and st.st_ino from the raw fstat() + * call, everything else needs to use tdb_fstat() in order + * to skip tdb->hdr_ofs! + */ + if (fstat(tdb->fd, &st) != 0) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_reopen: fstat failed (%s)\n", strerror(errno))); + goto fail; + } + if (st.st_ino != tdb->inode || st.st_dev != tdb->device) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_reopen: file dev/inode has changed!\n")); + goto fail; + } + ZERO_STRUCT(st); + + /* + * We had tdb_mmap(tdb) here before, + * but we need to use tdb_fstat(), + * which is triggered from tdb_oob() before calling tdb_mmap(). + * As this skips tdb->hdr_ofs. + */ + tdb->map_size = 0; + if (tdb_oob(tdb, 0, 1, 0) != 0) { + goto fail; + } +#endif /* fake pread or pwrite */ + + /* We may still think we hold the active lock. */ + tdb->num_lockrecs = 0; + SAFE_FREE(tdb->lockrecs); + tdb->lockrecs_array_length = 0; + + if (active_lock && tdb_nest_lock(tdb, ACTIVE_LOCK, F_RDLCK, TDB_LOCK_WAIT) == -1) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_reopen: failed to obtain active lock\n")); + goto fail; + } + + return 0; + +fail: + tdb_close(tdb); + return -1; +} + +/* reopen a tdb - this can be used after a fork to ensure that we have an independent + seek pointer from our parent and to re-establish locks */ +_PUBLIC_ int tdb_reopen(struct tdb_context *tdb) +{ + bool active_lock; + active_lock = (tdb->flags & (TDB_CLEAR_IF_FIRST|TDB_MUTEX_LOCKING)); + + return tdb_reopen_internal(tdb, active_lock); +} + +/* reopen all tdb's */ +_PUBLIC_ int tdb_reopen_all(int parent_longlived) +{ + struct tdb_context *tdb; + + for (tdb=tdbs; tdb; tdb = tdb->next) { + bool active_lock; + + active_lock = + (tdb->flags & (TDB_CLEAR_IF_FIRST|TDB_MUTEX_LOCKING)); + + /* + * If the parent is longlived (ie. a + * parent daemon architecture), we know + * it will keep it's active lock on a + * tdb opened with CLEAR_IF_FIRST. Thus + * for child processes we don't have to + * add an active lock. This is essential + * to improve performance on systems that + * keep POSIX locks as a non-scalable data + * structure in the kernel. + */ + if (parent_longlived) { + /* Ensure no clear-if-first. */ + active_lock = false; + } + + if (tdb_reopen_internal(tdb, active_lock) != 0) + return -1; + } + + return 0; +} diff --git a/common/rescue.c b/common/rescue.c new file mode 100644 index 0000000..7a85ebc --- /dev/null +++ b/common/rescue.c @@ -0,0 +1,351 @@ + /* + Unix SMB/CIFS implementation. + + trivial database library, rescue attempt code. + + Copyright (C) Rusty Russell 2012 + + ** NOTE! The following LGPL license applies to the tdb + ** library. This does NOT imply that all of Samba is released + ** under the LGPL + + This library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 3 of the License, or (at your option) any later version. + + This library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with this library; if not, see <http://www.gnu.org/licenses/>. +*/ +#include "tdb_private.h" +#include <assert.h> + + +struct found { + tdb_off_t head; /* 0 -> invalid. */ + struct tdb_record rec; + TDB_DATA key; + bool in_hash; + bool in_free; +}; + +struct found_table { + /* As an ordered array (by head offset). */ + struct found *arr; + unsigned int num, max; +}; + +static bool looks_like_valid_record(struct tdb_context *tdb, + tdb_off_t off, + const struct tdb_record *rec, + TDB_DATA *key) +{ + unsigned int hval; + + if (rec->magic != TDB_MAGIC) + return false; + + if (rec->key_len + rec->data_len > rec->rec_len) + return false; + + if (rec->rec_len % TDB_ALIGNMENT) + return false; + + /* Next pointer must make some sense. */ + if (rec->next > 0 && rec->next < TDB_DATA_START(tdb->hash_size)) + return false; + + if (tdb_oob(tdb, rec->next, sizeof(*rec), 1)) + return false; + + key->dsize = rec->key_len; + key->dptr = tdb_alloc_read(tdb, off + sizeof(*rec), key->dsize); + if (!key->dptr) + return false; + + hval = tdb->hash_fn(key); + if (hval != rec->full_hash) { + free(key->dptr); + return false; + } + + /* Caller frees up key->dptr */ + return true; +} + +static bool add_to_table(struct found_table *found, + tdb_off_t off, + struct tdb_record *rec, + TDB_DATA key) +{ + if (found->num + 1 > found->max) { + struct found *new; + found->max = (found->max ? found->max * 2 : 128); + new = realloc(found->arr, found->max * sizeof(found->arr[0])); + if (!new) + return false; + found->arr = new; + } + + found->arr[found->num].head = off; + found->arr[found->num].rec = *rec; + found->arr[found->num].key = key; + found->arr[found->num].in_hash = false; + found->arr[found->num].in_free = false; + + found->num++; + return true; +} + +static bool walk_record(struct tdb_context *tdb, + const struct found *f, + void (*walk)(TDB_DATA, TDB_DATA, void *private_data), + void *private_data) +{ + TDB_DATA data; + + data.dsize = f->rec.data_len; + data.dptr = tdb_alloc_read(tdb, + f->head + sizeof(f->rec) + f->rec.key_len, + data.dsize); + if (!data.dptr) { + if (tdb->ecode == TDB_ERR_OOM) + return false; + /* I/O errors are expected. */ + return true; + } + + walk(f->key, data, private_data); + free(data.dptr); + return true; +} + +/* First entry which has offset >= this one. */ +static unsigned int find_entry(struct found_table *found, tdb_off_t off) +{ + unsigned int start = 0, end = found->num; + + while (start < end) { + /* We can't overflow here. */ + unsigned int mid = (start + end) / 2; + + if (off < found->arr[mid].head) { + end = mid; + } else if (off > found->arr[mid].head) { + start = mid + 1; + } else { + return mid; + } + } + + assert(start == end); + return end; +} + +static void found_in_hashchain(struct found_table *found, tdb_off_t head) +{ + unsigned int match; + + match = find_entry(found, head); + if (match < found->num && found->arr[match].head == head) { + found->arr[match].in_hash = true; + } +} + +static void mark_free_area(struct found_table *found, tdb_off_t head, + tdb_len_t len) +{ + unsigned int match; + + match = find_entry(found, head); + /* Mark everything within this free entry. */ + while (match < found->num) { + if (found->arr[match].head >= head + len) { + break; + } + found->arr[match].in_free = true; + match++; + } +} + +static int cmp_key(const void *a, const void *b) +{ + const struct found *fa = a, *fb = b; + + if (fa->key.dsize < fb->key.dsize) { + return -1; + } else if (fa->key.dsize > fb->key.dsize) { + return 1; + } + return memcmp(fa->key.dptr, fb->key.dptr, fa->key.dsize); +} + +static bool key_eq(TDB_DATA a, TDB_DATA b) +{ + return a.dsize == b.dsize + && memcmp(a.dptr, b.dptr, a.dsize) == 0; +} + +static void free_table(struct found_table *found) +{ + unsigned int i; + + for (i = 0; i < found->num; i++) { + free(found->arr[i].key.dptr); + } + free(found->arr); +} + +static void logging_suppressed(struct tdb_context *tdb, + enum tdb_debug_level level, const char *fmt, ...) +{ +} + +_PUBLIC_ int tdb_rescue(struct tdb_context *tdb, + void (*walk)(TDB_DATA, TDB_DATA, void *private_data), + void *private_data) +{ + struct found_table found = { NULL, 0, 0 }; + tdb_off_t h, off, i; + tdb_log_func oldlog = tdb->log.log_fn; + struct tdb_record rec; + TDB_DATA key; + bool locked; + + /* Read-only databases use no locking at all: it's best-effort. + * We may have a write lock already, so skip that case too. */ + if (tdb->read_only || tdb->allrecord_lock.count != 0) { + locked = false; + } else { + if (tdb_lockall_read(tdb) == -1) + return -1; + locked = true; + } + + /* Make sure we know true size of the underlying file. */ + tdb_oob(tdb, tdb->map_size, 1, 1); + + /* Suppress logging, since we anticipate errors. */ + tdb->log.log_fn = logging_suppressed; + + /* Now walk entire db looking for records. */ + for (off = TDB_DATA_START(tdb->hash_size); + off < tdb->map_size; + off += TDB_ALIGNMENT) { + if (tdb->methods->tdb_read(tdb, off, &rec, sizeof(rec), + DOCONV()) == -1) + continue; + + if (looks_like_valid_record(tdb, off, &rec, &key)) { + if (!add_to_table(&found, off, &rec, key)) { + goto oom; + } + } + } + + /* Walk hash chains to positive vet. */ + for (h = 0; h < 1+tdb->hash_size; h++) { + bool slow_chase = false; + tdb_off_t slow_off = FREELIST_TOP + h*sizeof(tdb_off_t); + + if (tdb_ofs_read(tdb, FREELIST_TOP + h*sizeof(tdb_off_t), + &off) == -1) + continue; + + while (off && off != slow_off) { + if (tdb->methods->tdb_read(tdb, off, &rec, sizeof(rec), + DOCONV()) != 0) { + break; + } + + /* 0 is the free list, rest are hash chains. */ + if (h == 0) { + /* Don't mark garbage as free. */ + if (rec.magic != TDB_FREE_MAGIC) { + break; + } + mark_free_area(&found, off, + sizeof(rec) + rec.rec_len); + } else { + found_in_hashchain(&found, off); + } + + off = rec.next; + + /* Loop detection using second pointer at half-speed */ + if (slow_chase) { + /* First entry happens to be next ptr */ + tdb_ofs_read(tdb, slow_off, &slow_off); + } + slow_chase = !slow_chase; + } + } + + /* Recovery area: must be marked as free, since it often has old + * records in there! */ + if (tdb_ofs_read(tdb, TDB_RECOVERY_HEAD, &off) == 0 && off != 0) { + if (tdb->methods->tdb_read(tdb, off, &rec, sizeof(rec), + DOCONV()) == 0) { + mark_free_area(&found, off, sizeof(rec) + rec.rec_len); + } + } + + /* Now sort by key! */ + if (found.arr != NULL) { + qsort(found.arr, found.num, sizeof(found.arr[0]), cmp_key); + } + + for (i = 0; (found.arr != NULL) && i < found.num; ) { + unsigned int num, num_in_hash = 0; + + /* How many are identical? */ + for (num = 0; num < found.num - i; num++) { + if (!key_eq(found.arr[i].key, found.arr[i+num].key)) { + break; + } + if (found.arr[i+num].in_hash) { + if (!walk_record(tdb, &found.arr[i+num], + walk, private_data)) + goto oom; + num_in_hash++; + } + } + assert(num); + + /* If none were in the hash, we print any not in free list. */ + if (num_in_hash == 0) { + unsigned int j; + + for (j = i; j < i + num; j++) { + if (!found.arr[j].in_free) { + if (!walk_record(tdb, &found.arr[j], + walk, private_data)) + goto oom; + } + } + } + + i += num; + } + + tdb->log.log_fn = oldlog; + if (locked) { + tdb_unlockall_read(tdb); + } + return 0; + +oom: + tdb->log.log_fn = oldlog; + tdb->ecode = TDB_ERR_OOM; + TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_rescue: failed allocating\n")); + free_table(&found); + if (locked) { + tdb_unlockall_read(tdb); + } + return -1; +} diff --git a/common/summary.c b/common/summary.c new file mode 100644 index 0000000..a93eb93 --- /dev/null +++ b/common/summary.c @@ -0,0 +1,219 @@ + /* + Trivial Database: human-readable summary code + Copyright (C) Rusty Russell 2010 + + This library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 3 of the License, or (at your option) any later version. + + This library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with this library; if not, see <http://www.gnu.org/licenses/>. +*/ +#include "tdb_private.h" + +#define SUMMARY_FORMAT \ + "Size of file/data: %llu/%zu\n" \ + "Header offset/logical size: %zu/%zu\n" \ + "Number of records: %zu\n" \ + "Incompatible hash: %s\n" \ + "Active/supported feature flags: 0x%08x/0x%08x\n" \ + "Robust mutexes locking: %s\n" \ + "Smallest/average/largest keys: %zu/%zu/%zu\n" \ + "Smallest/average/largest data: %zu/%zu/%zu\n" \ + "Smallest/average/largest padding: %zu/%zu/%zu\n" \ + "Number of dead records: %zu\n" \ + "Smallest/average/largest dead records: %zu/%zu/%zu\n" \ + "Number of free records: %zu\n" \ + "Smallest/average/largest free records: %zu/%zu/%zu\n" \ + "Number of hash chains: %zu\n" \ + "Smallest/average/largest hash chains: %zu/%zu/%zu\n" \ + "Number of uncoalesced records: %zu\n" \ + "Smallest/average/largest uncoalesced runs: %zu/%zu/%zu\n" \ + "Percentage keys/data/padding/free/dead/rechdrs&tailers/hashes: %.0f/%.0f/%.0f/%.0f/%.0f/%.0f/%.0f\n" + +/* We don't use tally module, to keep upstream happy. */ +struct tally { + size_t min, max, total; + size_t num; +}; + +static void tally_init(struct tally *tally) +{ + tally->total = 0; + tally->num = 0; + tally->min = tally->max = 0; +} + +static void tally_add(struct tally *tally, size_t len) +{ + if (tally->num == 0) + tally->max = tally->min = len; + else if (len > tally->max) + tally->max = len; + else if (len < tally->min) + tally->min = len; + tally->num++; + tally->total += len; +} + +static size_t tally_mean(const struct tally *tally) +{ + if (!tally->num) + return 0; + return tally->total / tally->num; +} + +static size_t get_hash_length(struct tdb_context *tdb, unsigned int i) +{ + tdb_off_t rec_ptr; + struct tdb_chainwalk_ctx chainwalk; + size_t count = 0; + + if (tdb_ofs_read(tdb, TDB_HASH_TOP(i), &rec_ptr) == -1) + return 0; + + tdb_chainwalk_init(&chainwalk, rec_ptr); + + /* keep looking until we find the right record */ + while (rec_ptr) { + struct tdb_record r; + bool ok; + ++count; + if (tdb_rec_read(tdb, rec_ptr, &r) == -1) + return 0; + rec_ptr = r.next; + ok = tdb_chainwalk_check(tdb, &chainwalk, rec_ptr); + if (!ok) { + return SIZE_MAX; + } + } + return count; +} + +_PUBLIC_ char *tdb_summary(struct tdb_context *tdb) +{ + off_t file_size; + tdb_off_t off, rec_off; + struct tally freet, keys, data, dead, extra, hashval, uncoal; + struct tdb_record rec; + char *ret = NULL; + bool locked; + size_t unc = 0; + int len; + struct tdb_record recovery; + + /* Read-only databases use no locking at all: it's best-effort. + * We may have a write lock already, so skip that case too. */ + if (tdb->read_only || tdb->allrecord_lock.count != 0) { + locked = false; + } else { + if (tdb_lockall_read(tdb) == -1) + return NULL; + locked = true; + } + + if (tdb_recovery_area(tdb, tdb->methods, &rec_off, &recovery) != 0) { + goto unlock; + } + + tally_init(&freet); + tally_init(&keys); + tally_init(&data); + tally_init(&dead); + tally_init(&extra); + tally_init(&hashval); + tally_init(&uncoal); + + for (off = TDB_DATA_START(tdb->hash_size); + off < tdb->map_size - 1; + off += sizeof(rec) + rec.rec_len) { + if (tdb->methods->tdb_read(tdb, off, &rec, sizeof(rec), + DOCONV()) == -1) + goto unlock; + switch (rec.magic) { + case TDB_MAGIC: + tally_add(&keys, rec.key_len); + tally_add(&data, rec.data_len); + tally_add(&extra, rec.rec_len - (rec.key_len + + rec.data_len)); + if (unc > 1) + tally_add(&uncoal, unc - 1); + unc = 0; + break; + case TDB_FREE_MAGIC: + tally_add(&freet, rec.rec_len); + unc++; + break; + /* If we crash after ftruncate, we can get zeroes or fill. */ + case TDB_RECOVERY_INVALID_MAGIC: + case 0x42424242: + unc++; + /* If it's a valid recovery, we can trust rec_len. */ + if (off != rec_off) { + rec.rec_len = tdb_dead_space(tdb, off) + - sizeof(rec); + } + + FALL_THROUGH; + case TDB_DEAD_MAGIC: + tally_add(&dead, rec.rec_len); + break; + default: + TDB_LOG((tdb, TDB_DEBUG_ERROR, + "Unexpected record magic 0x%x at offset %u\n", + rec.magic, off)); + goto unlock; + } + } + if (unc > 1) + tally_add(&uncoal, unc - 1); + + for (off = 0; off < tdb->hash_size; off++) + tally_add(&hashval, get_hash_length(tdb, off)); + + file_size = tdb->hdr_ofs + tdb->map_size; + + len = asprintf(&ret, SUMMARY_FORMAT, + (unsigned long long)file_size, keys.total+data.total, + (size_t)tdb->hdr_ofs, (size_t)tdb->map_size, + keys.num, + (tdb->hash_fn == tdb_jenkins_hash)?"yes":"no", + (unsigned)tdb->feature_flags, TDB_SUPPORTED_FEATURE_FLAGS, + (tdb->feature_flags & TDB_FEATURE_FLAG_MUTEX)?"yes":"no", + keys.min, tally_mean(&keys), keys.max, + data.min, tally_mean(&data), data.max, + extra.min, tally_mean(&extra), extra.max, + dead.num, + dead.min, tally_mean(&dead), dead.max, + freet.num, + freet.min, tally_mean(&freet), freet.max, + hashval.num, + hashval.min, tally_mean(&hashval), hashval.max, + uncoal.total, + uncoal.min, tally_mean(&uncoal), uncoal.max, + keys.total * 100.0 / file_size, + data.total * 100.0 / file_size, + extra.total * 100.0 / file_size, + freet.total * 100.0 / file_size, + dead.total * 100.0 / file_size, + (keys.num + freet.num + dead.num) + * (sizeof(struct tdb_record) + sizeof(uint32_t)) + * 100.0 / file_size, + tdb->hash_size * sizeof(tdb_off_t) + * 100.0 / file_size); + if (len == -1) { + goto unlock; + } + +unlock: + if (locked) { + tdb_unlockall_read(tdb); + } + return ret; +} diff --git a/common/tdb.c b/common/tdb.c new file mode 100644 index 0000000..de829bb --- /dev/null +++ b/common/tdb.c @@ -0,0 +1,1348 @@ + /* + Unix SMB/CIFS implementation. + + trivial database library + + Copyright (C) Andrew Tridgell 1999-2005 + Copyright (C) Paul `Rusty' Russell 2000 + Copyright (C) Jeremy Allison 2000-2003 + + ** NOTE! The following LGPL license applies to the tdb + ** library. This does NOT imply that all of Samba is released + ** under the LGPL + + This library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 3 of the License, or (at your option) any later version. + + This library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with this library; if not, see <http://www.gnu.org/licenses/>. +*/ + +#include "tdb_private.h" + +_PUBLIC_ TDB_DATA tdb_null; + +/* + non-blocking increment of the tdb sequence number if the tdb has been opened using + the TDB_SEQNUM flag +*/ +_PUBLIC_ void tdb_increment_seqnum_nonblock(struct tdb_context *tdb) +{ + tdb_off_t seqnum=0; + + if (!(tdb->flags & TDB_SEQNUM)) { + return; + } + + /* we ignore errors from this, as we have no sane way of + dealing with them. + */ + tdb_ofs_read(tdb, TDB_SEQNUM_OFS, &seqnum); + seqnum++; + tdb_ofs_write(tdb, TDB_SEQNUM_OFS, &seqnum); +} + +/* + increment the tdb sequence number if the tdb has been opened using + the TDB_SEQNUM flag +*/ +static void tdb_increment_seqnum(struct tdb_context *tdb) +{ + if (!(tdb->flags & TDB_SEQNUM)) { + return; + } + + if (tdb->transaction != NULL) { + tdb_increment_seqnum_nonblock(tdb); + return; + } + +#if defined(HAVE___ATOMIC_ADD_FETCH) && defined(HAVE___ATOMIC_ADD_LOAD) + if (tdb->map_ptr != NULL) { + uint32_t *pseqnum = (uint32_t *)( + TDB_SEQNUM_OFS + (char *)tdb->map_ptr); + __atomic_add_fetch(pseqnum, 1, __ATOMIC_SEQ_CST); + return; + } +#endif + + if (tdb_nest_lock(tdb, TDB_SEQNUM_OFS, F_WRLCK, + TDB_LOCK_WAIT|TDB_LOCK_PROBE) != 0) { + return; + } + + tdb_increment_seqnum_nonblock(tdb); + + tdb_nest_unlock(tdb, TDB_SEQNUM_OFS, F_WRLCK, false); +} + +static int tdb_key_compare(TDB_DATA key, TDB_DATA data, void *private_data) +{ + return memcmp(data.dptr, key.dptr, data.dsize); +} + +void tdb_chainwalk_init(struct tdb_chainwalk_ctx *ctx, tdb_off_t ptr) +{ + *ctx = (struct tdb_chainwalk_ctx) { .slow_ptr = ptr }; +} + +bool tdb_chainwalk_check(struct tdb_context *tdb, + struct tdb_chainwalk_ctx *ctx, + tdb_off_t next_ptr) +{ + int ret; + + if (ctx->slow_chase) { + ret = tdb_ofs_read(tdb, ctx->slow_ptr, &ctx->slow_ptr); + if (ret == -1) { + return false; + } + } + ctx->slow_chase = !ctx->slow_chase; + + if (next_ptr == ctx->slow_ptr) { + tdb->ecode = TDB_ERR_CORRUPT; + TDB_LOG((tdb, TDB_DEBUG_ERROR, + "tdb_chainwalk_check: circular chain\n")); + return false; + } + + return true; +} + +/* Returns 0 on fail. On success, return offset of record, and fills + in rec */ +static tdb_off_t tdb_find(struct tdb_context *tdb, TDB_DATA key, uint32_t hash, + struct tdb_record *r) +{ + tdb_off_t rec_ptr; + struct tdb_chainwalk_ctx chainwalk; + + /* read in the hash top */ + if (tdb_ofs_read(tdb, TDB_HASH_TOP(hash), &rec_ptr) == -1) + return 0; + + tdb_chainwalk_init(&chainwalk, rec_ptr); + + /* keep looking until we find the right record */ + while (rec_ptr) { + bool ok; + + if (tdb_rec_read(tdb, rec_ptr, r) == -1) + return 0; + + if (!TDB_DEAD(r) && hash==r->full_hash + && key.dsize==r->key_len + && tdb_parse_data(tdb, key, rec_ptr + sizeof(*r), + r->key_len, tdb_key_compare, + NULL) == 0) { + return rec_ptr; + } + rec_ptr = r->next; + + ok = tdb_chainwalk_check(tdb, &chainwalk, rec_ptr); + if (!ok) { + return 0; + } + } + tdb->ecode = TDB_ERR_NOEXIST; + return 0; +} + +/* As tdb_find, but if you succeed, keep the lock */ +tdb_off_t tdb_find_lock_hash(struct tdb_context *tdb, TDB_DATA key, uint32_t hash, int locktype, + struct tdb_record *rec) +{ + uint32_t rec_ptr; + + if (tdb_lock(tdb, BUCKET(hash), locktype) == -1) + return 0; + if (!(rec_ptr = tdb_find(tdb, key, hash, rec))) + tdb_unlock(tdb, BUCKET(hash), locktype); + return rec_ptr; +} + +static TDB_DATA _tdb_fetch(struct tdb_context *tdb, TDB_DATA key); + +struct tdb_update_hash_state { + const TDB_DATA *dbufs; + int num_dbufs; + tdb_len_t dbufs_len; +}; + +static int tdb_update_hash_cmp(TDB_DATA key, TDB_DATA data, void *private_data) +{ + struct tdb_update_hash_state *state = private_data; + unsigned char *dptr = data.dptr; + int i; + + if (state->dbufs_len != data.dsize) { + return -1; + } + + for (i=0; i<state->num_dbufs; i++) { + TDB_DATA dbuf = state->dbufs[i]; + if( dbuf.dsize > 0) { + int ret; + ret = memcmp(dptr, dbuf.dptr, dbuf.dsize); + if (ret != 0) { + return -1; + } + dptr += dbuf.dsize; + } + } + + return 0; +} + +/* update an entry in place - this only works if the new data size + is <= the old data size and the key exists. + on failure return -1. +*/ +static int tdb_update_hash(struct tdb_context *tdb, TDB_DATA key, + uint32_t hash, + const TDB_DATA *dbufs, int num_dbufs, + tdb_len_t dbufs_len) +{ + struct tdb_record rec; + tdb_off_t rec_ptr, ofs; + int i; + + /* find entry */ + if (!(rec_ptr = tdb_find(tdb, key, hash, &rec))) + return -1; + + /* it could be an exact duplicate of what is there - this is + * surprisingly common (eg. with a ldb re-index). */ + if (rec.data_len == dbufs_len) { + struct tdb_update_hash_state state = { + .dbufs = dbufs, .num_dbufs = num_dbufs, + .dbufs_len = dbufs_len + }; + int ret; + + ret = tdb_parse_record(tdb, key, tdb_update_hash_cmp, &state); + if (ret == 0) { + return 0; + } + } + + /* must be long enough key, data and tailer */ + if (rec.rec_len < key.dsize + dbufs_len + sizeof(tdb_off_t)) { + tdb->ecode = TDB_SUCCESS; /* Not really an error */ + return -1; + } + + ofs = rec_ptr + sizeof(rec) + rec.key_len; + + for (i=0; i<num_dbufs; i++) { + TDB_DATA dbuf = dbufs[i]; + int ret; + + ret = tdb->methods->tdb_write(tdb, ofs, dbuf.dptr, dbuf.dsize); + if (ret == -1) { + return -1; + } + ofs += dbuf.dsize; + } + + if (dbufs_len != rec.data_len) { + /* update size */ + rec.data_len = dbufs_len; + return tdb_rec_write(tdb, rec_ptr, &rec); + } + + return 0; +} + +/* find an entry in the database given a key */ +/* If an entry doesn't exist tdb_err will be set to + * TDB_ERR_NOEXIST. If a key has no data attached + * then the TDB_DATA will have zero length but + * a non-zero pointer + */ +static TDB_DATA _tdb_fetch(struct tdb_context *tdb, TDB_DATA key) +{ + tdb_off_t rec_ptr; + struct tdb_record rec; + TDB_DATA ret; + uint32_t hash; + + /* find which hash bucket it is in */ + hash = tdb->hash_fn(&key); + if (!(rec_ptr = tdb_find_lock_hash(tdb,key,hash,F_RDLCK,&rec))) + return tdb_null; + + ret.dptr = tdb_alloc_read(tdb, rec_ptr + sizeof(rec) + rec.key_len, + rec.data_len); + ret.dsize = rec.data_len; + tdb_unlock(tdb, BUCKET(rec.full_hash), F_RDLCK); + return ret; +} + +_PUBLIC_ TDB_DATA tdb_fetch(struct tdb_context *tdb, TDB_DATA key) +{ + TDB_DATA ret = _tdb_fetch(tdb, key); + + tdb_trace_1rec_retrec(tdb, "tdb_fetch", key, ret); + return ret; +} + +/* + * Find an entry in the database and hand the record's data to a parsing + * function. The parsing function is executed under the chain read lock, so it + * should be fast and should not block on other syscalls. + * + * DON'T CALL OTHER TDB CALLS FROM THE PARSER, THIS MIGHT LEAD TO SEGFAULTS. + * + * For mmapped tdb's that do not have a transaction open it points the parsing + * function directly at the mmap area, it avoids the malloc/memcpy in this + * case. If a transaction is open or no mmap is available, it has to do + * malloc/read/parse/free. + * + * This is interesting for all readers of potentially large data structures in + * the tdb records, ldb indexes being one example. + * + * Return -1 if the record was not found. + */ + +_PUBLIC_ int tdb_parse_record(struct tdb_context *tdb, TDB_DATA key, + int (*parser)(TDB_DATA key, TDB_DATA data, + void *private_data), + void *private_data) +{ + tdb_off_t rec_ptr; + struct tdb_record rec; + int ret; + uint32_t hash; + + /* find which hash bucket it is in */ + hash = tdb->hash_fn(&key); + + if (!(rec_ptr = tdb_find_lock_hash(tdb,key,hash,F_RDLCK,&rec))) { + /* record not found */ + tdb_trace_1rec_ret(tdb, "tdb_parse_record", key, -1); + tdb->ecode = TDB_ERR_NOEXIST; + return -1; + } + tdb_trace_1rec_ret(tdb, "tdb_parse_record", key, 0); + + ret = tdb_parse_data(tdb, key, rec_ptr + sizeof(rec) + rec.key_len, + rec.data_len, parser, private_data); + + tdb_unlock(tdb, BUCKET(rec.full_hash), F_RDLCK); + + return ret; +} + +/* check if an entry in the database exists + + note that 1 is returned if the key is found and 0 is returned if not found + this doesn't match the conventions in the rest of this module, but is + compatible with gdbm +*/ +static int tdb_exists_hash(struct tdb_context *tdb, TDB_DATA key, uint32_t hash) +{ + struct tdb_record rec; + + if (tdb_find_lock_hash(tdb, key, hash, F_RDLCK, &rec) == 0) + return 0; + tdb_unlock(tdb, BUCKET(rec.full_hash), F_RDLCK); + return 1; +} + +_PUBLIC_ int tdb_exists(struct tdb_context *tdb, TDB_DATA key) +{ + uint32_t hash = tdb->hash_fn(&key); + int ret; + + ret = tdb_exists_hash(tdb, key, hash); + tdb_trace_1rec_ret(tdb, "tdb_exists", key, ret); + return ret; +} + +/* + * Move a dead record to the freelist. The hash chain and freelist + * must be locked. + */ +static int tdb_del_dead(struct tdb_context *tdb, + uint32_t last_ptr, + uint32_t rec_ptr, + struct tdb_record *rec, + bool *deleted) +{ + int ret; + + ret = tdb_write_lock_record(tdb, rec_ptr); + if (ret == -1) { + /* Someone traversing here: Just leave it dead */ + return 0; + } + ret = tdb_write_unlock_record(tdb, rec_ptr); + if (ret == -1) { + return -1; + } + ret = tdb_ofs_write(tdb, last_ptr, &rec->next); + if (ret == -1) { + return -1; + } + + *deleted = true; + + ret = tdb_free(tdb, rec_ptr, rec); + return ret; +} + +/* + * Walk the hash chain and leave tdb->max_dead_records around. Move + * the rest of dead records to the freelist. + */ +int tdb_trim_dead(struct tdb_context *tdb, uint32_t hash) +{ + struct tdb_chainwalk_ctx chainwalk; + struct tdb_record rec; + tdb_off_t last_ptr, rec_ptr; + bool locked_freelist = false; + int num_dead = 0; + int ret; + + last_ptr = TDB_HASH_TOP(hash); + + /* + * Init chainwalk with the pointer to the hash top. It might + * be that the very first record in the chain is a dead one + * that we have to delete. + */ + tdb_chainwalk_init(&chainwalk, last_ptr); + + ret = tdb_ofs_read(tdb, last_ptr, &rec_ptr); + if (ret == -1) { + return -1; + } + + while (rec_ptr != 0) { + bool deleted = false; + uint32_t next; + + ret = tdb_rec_read(tdb, rec_ptr, &rec); + if (ret == -1) { + goto fail; + } + + /* + * Make a copy of rec.next: Further down we might + * delete and put the record on the freelist. Make + * sure that modifications in that code path can't + * break the chainwalk here. + */ + next = rec.next; + + if (rec.magic == TDB_DEAD_MAGIC) { + num_dead += 1; + + if (num_dead > tdb->max_dead_records) { + + if (!locked_freelist) { + /* + * Lock the freelist only if + * it's really required. + */ + ret = tdb_lock(tdb, -1, F_WRLCK); + if (ret == -1) { + goto fail; + }; + locked_freelist = true; + } + + ret = tdb_del_dead( + tdb, + last_ptr, + rec_ptr, + &rec, + &deleted); + + if (ret == -1) { + goto fail; + } + } + } + + /* + * Don't do the chainwalk check if "rec_ptr" was + * deleted. We reduced the chain, and the chainwalk + * check might catch up early. Imagine a valid chain + * with just dead records: We never can bump the + * "slow" pointer in chainwalk_check, as there isn't + * anything left to jump to and compare. + */ + if (!deleted) { + bool ok; + + last_ptr = rec_ptr; + + ok = tdb_chainwalk_check(tdb, &chainwalk, next); + if (!ok) { + ret = -1; + goto fail; + } + } + rec_ptr = next; + } + ret = 0; +fail: + if (locked_freelist) { + tdb_unlock(tdb, -1, F_WRLCK); + } + return ret; +} + +/* delete an entry in the database given a key */ +static int tdb_delete_hash(struct tdb_context *tdb, TDB_DATA key, uint32_t hash) +{ + tdb_off_t rec_ptr; + struct tdb_record rec; + int ret; + + if (tdb->read_only || tdb->traverse_read) { + tdb->ecode = TDB_ERR_RDONLY; + return -1; + } + + rec_ptr = tdb_find_lock_hash(tdb, key, hash, F_WRLCK, &rec); + if (rec_ptr == 0) { + return -1; + } + + /* + * Mark the record dead + */ + rec.magic = TDB_DEAD_MAGIC; + ret = tdb_rec_write(tdb, rec_ptr, &rec); + if (ret == -1) { + goto done; + } + + tdb_increment_seqnum(tdb); + + ret = tdb_trim_dead(tdb, hash); +done: + if (tdb_unlock(tdb, BUCKET(hash), F_WRLCK) != 0) + TDB_LOG((tdb, TDB_DEBUG_WARNING, "tdb_delete: WARNING tdb_unlock failed!\n")); + return ret; +} + +_PUBLIC_ int tdb_delete(struct tdb_context *tdb, TDB_DATA key) +{ + uint32_t hash = tdb->hash_fn(&key); + int ret; + + ret = tdb_delete_hash(tdb, key, hash); + tdb_trace_1rec_ret(tdb, "tdb_delete", key, ret); + return ret; +} + +/* + * See if we have a dead record around with enough space + */ +tdb_off_t tdb_find_dead(struct tdb_context *tdb, uint32_t hash, + struct tdb_record *r, tdb_len_t length, + tdb_off_t *p_last_ptr) +{ + tdb_off_t rec_ptr, last_ptr; + struct tdb_chainwalk_ctx chainwalk; + tdb_off_t best_rec_ptr = 0; + tdb_off_t best_last_ptr = 0; + struct tdb_record best = { .rec_len = UINT32_MAX }; + + length += sizeof(tdb_off_t); /* tailer */ + + last_ptr = TDB_HASH_TOP(hash); + + /* read in the hash top */ + if (tdb_ofs_read(tdb, last_ptr, &rec_ptr) == -1) + return 0; + + tdb_chainwalk_init(&chainwalk, rec_ptr); + + /* keep looking until we find the right record */ + while (rec_ptr) { + bool ok; + + if (tdb_rec_read(tdb, rec_ptr, r) == -1) + return 0; + + if (TDB_DEAD(r) && (r->rec_len >= length) && + (r->rec_len < best.rec_len)) { + best_rec_ptr = rec_ptr; + best_last_ptr = last_ptr; + best = *r; + } + last_ptr = rec_ptr; + rec_ptr = r->next; + + ok = tdb_chainwalk_check(tdb, &chainwalk, rec_ptr); + if (!ok) { + return 0; + } + } + + if (best.rec_len == UINT32_MAX) { + return 0; + } + + *r = best; + *p_last_ptr = best_last_ptr; + return best_rec_ptr; +} + +static int _tdb_storev(struct tdb_context *tdb, TDB_DATA key, + const TDB_DATA *dbufs, int num_dbufs, + int flag, uint32_t hash) +{ + struct tdb_record rec; + tdb_off_t rec_ptr, ofs; + tdb_len_t rec_len, dbufs_len; + int i; + int ret = -1; + + dbufs_len = 0; + + for (i=0; i<num_dbufs; i++) { + size_t dsize = dbufs[i].dsize; + + if ((dsize != 0) && (dbufs[i].dptr == NULL)) { + tdb->ecode = TDB_ERR_EINVAL; + goto fail; + } + + dbufs_len += dsize; + if (dbufs_len < dsize) { + tdb->ecode = TDB_ERR_OOM; + goto fail; + } + } + + rec_len = key.dsize + dbufs_len; + if ((rec_len < key.dsize) || (rec_len < dbufs_len)) { + tdb->ecode = TDB_ERR_OOM; + goto fail; + } + + /* check for it existing, on insert. */ + if (flag == TDB_INSERT) { + if (tdb_exists_hash(tdb, key, hash)) { + tdb->ecode = TDB_ERR_EXISTS; + goto fail; + } + } else { + /* first try in-place update, on modify or replace. */ + if (tdb_update_hash(tdb, key, hash, dbufs, num_dbufs, + dbufs_len) == 0) { + goto done; + } + if (tdb->ecode == TDB_ERR_NOEXIST && + flag == TDB_MODIFY) { + /* if the record doesn't exist and we are in TDB_MODIFY mode then + we should fail the store */ + goto fail; + } + } + /* reset the error code potentially set by the tdb_update_hash() */ + tdb->ecode = TDB_SUCCESS; + + /* delete any existing record - if it doesn't exist we don't + care. Doing this first reduces fragmentation, and avoids + coalescing with `allocated' block before it's updated. */ + if (flag != TDB_INSERT) + tdb_delete_hash(tdb, key, hash); + + /* we have to allocate some space */ + rec_ptr = tdb_allocate(tdb, hash, rec_len, &rec); + + if (rec_ptr == 0) { + goto fail; + } + + /* Read hash top into next ptr */ + if (tdb_ofs_read(tdb, TDB_HASH_TOP(hash), &rec.next) == -1) + goto fail; + + rec.key_len = key.dsize; + rec.data_len = dbufs_len; + rec.full_hash = hash; + rec.magic = TDB_MAGIC; + + ofs = rec_ptr; + + /* write out and point the top of the hash chain at it */ + ret = tdb_rec_write(tdb, ofs, &rec); + if (ret == -1) { + goto fail; + } + ofs += sizeof(rec); + + ret = tdb->methods->tdb_write(tdb, ofs, key.dptr, key.dsize); + if (ret == -1) { + goto fail; + } + ofs += key.dsize; + + for (i=0; i<num_dbufs; i++) { + if (dbufs[i].dsize == 0) { + continue; + } + + ret = tdb->methods->tdb_write(tdb, ofs, dbufs[i].dptr, + dbufs[i].dsize); + if (ret == -1) { + goto fail; + } + ofs += dbufs[i].dsize; + } + + ret = tdb_ofs_write(tdb, TDB_HASH_TOP(hash), &rec_ptr); + if (ret == -1) { + /* Need to tdb_unallocate() here */ + goto fail; + } + + done: + ret = 0; + fail: + if (ret == 0) { + tdb_increment_seqnum(tdb); + } + return ret; +} + +static int _tdb_store(struct tdb_context *tdb, TDB_DATA key, + TDB_DATA dbuf, int flag, uint32_t hash) +{ + return _tdb_storev(tdb, key, &dbuf, 1, flag, hash); +} + +/* store an element in the database, replacing any existing element + with the same key + + return 0 on success, -1 on failure +*/ +_PUBLIC_ int tdb_store(struct tdb_context *tdb, TDB_DATA key, TDB_DATA dbuf, int flag) +{ + uint32_t hash; + int ret; + + if (tdb->read_only || tdb->traverse_read) { + tdb->ecode = TDB_ERR_RDONLY; + tdb_trace_2rec_flag_ret(tdb, "tdb_store", key, dbuf, flag, -1); + return -1; + } + + /* find which hash bucket it is in */ + hash = tdb->hash_fn(&key); + if (tdb_lock(tdb, BUCKET(hash), F_WRLCK) == -1) + return -1; + + ret = _tdb_store(tdb, key, dbuf, flag, hash); + tdb_trace_2rec_flag_ret(tdb, "tdb_store", key, dbuf, flag, ret); + tdb_unlock(tdb, BUCKET(hash), F_WRLCK); + return ret; +} + +_PUBLIC_ int tdb_storev(struct tdb_context *tdb, TDB_DATA key, + const TDB_DATA *dbufs, int num_dbufs, int flag) +{ + uint32_t hash; + int ret; + + if (tdb->read_only || tdb->traverse_read) { + tdb->ecode = TDB_ERR_RDONLY; + tdb_trace_1plusn_rec_flag_ret(tdb, "tdb_storev", key, + dbufs, num_dbufs, flag, -1); + return -1; + } + + /* find which hash bucket it is in */ + hash = tdb->hash_fn(&key); + if (tdb_lock(tdb, BUCKET(hash), F_WRLCK) == -1) + return -1; + + ret = _tdb_storev(tdb, key, dbufs, num_dbufs, flag, hash); + tdb_trace_1plusn_rec_flag_ret(tdb, "tdb_storev", key, + dbufs, num_dbufs, flag, -1); + tdb_unlock(tdb, BUCKET(hash), F_WRLCK); + return ret; +} + +/* Append to an entry. Create if not exist. */ +_PUBLIC_ int tdb_append(struct tdb_context *tdb, TDB_DATA key, TDB_DATA new_dbuf) +{ + uint32_t hash; + TDB_DATA dbufs[2]; + int ret = -1; + + /* find which hash bucket it is in */ + hash = tdb->hash_fn(&key); + if (tdb_lock(tdb, BUCKET(hash), F_WRLCK) == -1) + return -1; + + dbufs[0] = _tdb_fetch(tdb, key); + dbufs[1] = new_dbuf; + + ret = _tdb_storev(tdb, key, dbufs, 2, 0, hash); + tdb_trace_2rec_retrec(tdb, "tdb_append", key, dbufs[0], dbufs[1]); + + tdb_unlock(tdb, BUCKET(hash), F_WRLCK); + SAFE_FREE(dbufs[0].dptr); + return ret; +} + + +/* + return the name of the current tdb file + useful for external logging functions +*/ +_PUBLIC_ const char *tdb_name(struct tdb_context *tdb) +{ + return tdb->name; +} + +/* + return the underlying file descriptor being used by tdb, or -1 + useful for external routines that want to check the device/inode + of the fd +*/ +_PUBLIC_ int tdb_fd(struct tdb_context *tdb) +{ + return tdb->fd; +} + +/* + return the current logging function + useful for external tdb routines that wish to log tdb errors +*/ +_PUBLIC_ tdb_log_func tdb_log_fn(struct tdb_context *tdb) +{ + return tdb->log.log_fn; +} + + +/* + get the tdb sequence number. Only makes sense if the writers opened + with TDB_SEQNUM set. Note that this sequence number will wrap quite + quickly, so it should only be used for a 'has something changed' + test, not for code that relies on the count of the number of changes + made. If you want a counter then use a tdb record. + + The aim of this sequence number is to allow for a very lightweight + test of a possible tdb change. +*/ +_PUBLIC_ int tdb_get_seqnum(struct tdb_context *tdb) +{ + tdb_off_t seqnum=0; + + if (tdb->transaction != NULL) { + tdb_ofs_read(tdb, TDB_SEQNUM_OFS, &seqnum); + return seqnum; + } + +#if defined(HAVE___ATOMIC_ADD_FETCH) && defined(HAVE___ATOMIC_ADD_LOAD) + if (tdb->map_ptr != NULL) { + uint32_t *pseqnum = (uint32_t *)( + TDB_SEQNUM_OFS + (char *)tdb->map_ptr); + uint32_t ret; + __atomic_load(pseqnum, &ret,__ATOMIC_SEQ_CST); + return ret; + } +#endif + + tdb_ofs_read(tdb, TDB_SEQNUM_OFS, &seqnum); + return seqnum; +} + +_PUBLIC_ int tdb_hash_size(struct tdb_context *tdb) +{ + return tdb->hash_size; +} + +_PUBLIC_ size_t tdb_map_size(struct tdb_context *tdb) +{ + return tdb->map_size; +} + +_PUBLIC_ int tdb_get_flags(struct tdb_context *tdb) +{ + return tdb->flags; +} + +_PUBLIC_ void tdb_add_flags(struct tdb_context *tdb, unsigned flags) +{ + if ((flags & TDB_ALLOW_NESTING) && + (flags & TDB_DISALLOW_NESTING)) { + tdb->ecode = TDB_ERR_NESTING; + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_add_flags: " + "allow_nesting and disallow_nesting are not allowed together!")); + return; + } + + if (flags & TDB_ALLOW_NESTING) { + tdb->flags &= ~TDB_DISALLOW_NESTING; + } + if (flags & TDB_DISALLOW_NESTING) { + tdb->flags &= ~TDB_ALLOW_NESTING; + } + + tdb->flags |= flags; +} + +_PUBLIC_ void tdb_remove_flags(struct tdb_context *tdb, unsigned flags) +{ + if ((flags & TDB_ALLOW_NESTING) && + (flags & TDB_DISALLOW_NESTING)) { + tdb->ecode = TDB_ERR_NESTING; + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_remove_flags: " + "allow_nesting and disallow_nesting are not allowed together!")); + return; + } + + if ((flags & TDB_NOLOCK) && + (tdb->feature_flags & TDB_FEATURE_FLAG_MUTEX) && + (tdb->mutexes == NULL)) { + tdb->ecode = TDB_ERR_LOCK; + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_remove_flags: " + "Can not remove NOLOCK flag on mutexed databases")); + return; + } + + if (flags & TDB_ALLOW_NESTING) { + tdb->flags |= TDB_DISALLOW_NESTING; + } + if (flags & TDB_DISALLOW_NESTING) { + tdb->flags |= TDB_ALLOW_NESTING; + } + + tdb->flags &= ~flags; +} + + +/* + enable sequence number handling on an open tdb +*/ +_PUBLIC_ void tdb_enable_seqnum(struct tdb_context *tdb) +{ + tdb->flags |= TDB_SEQNUM; +} + + +/* + add a region of the file to the freelist. Length is the size of the region in bytes, + which includes the free list header that needs to be added + */ +static int tdb_free_region(struct tdb_context *tdb, tdb_off_t offset, ssize_t length) +{ + struct tdb_record rec; + if (length <= sizeof(rec)) { + /* the region is not worth adding */ + return 0; + } + if (length + offset > tdb->map_size) { + TDB_LOG((tdb, TDB_DEBUG_FATAL,"tdb_free_region: adding region beyond end of file\n")); + return -1; + } + memset(&rec,'\0',sizeof(rec)); + rec.rec_len = length - sizeof(rec); + if (tdb_free(tdb, offset, &rec) == -1) { + TDB_LOG((tdb, TDB_DEBUG_FATAL,"tdb_free_region: failed to add free record\n")); + return -1; + } + return 0; +} + +/* + wipe the entire database, deleting all records. This can be done + very fast by using a allrecord lock. The entire data portion of the + file becomes a single entry in the freelist. + + This code carefully steps around the recovery area, leaving it alone + */ +_PUBLIC_ int tdb_wipe_all(struct tdb_context *tdb) +{ + uint32_t i; + tdb_off_t offset = 0; + ssize_t data_len; + tdb_off_t recovery_head; + tdb_len_t recovery_size = 0; + + if (tdb_lockall(tdb) != 0) { + return -1; + } + + tdb_trace(tdb, "tdb_wipe_all"); + + /* see if the tdb has a recovery area, and remember its size + if so. We don't want to lose this as otherwise each + tdb_wipe_all() in a transaction will increase the size of + the tdb by the size of the recovery area */ + if (tdb_ofs_read(tdb, TDB_RECOVERY_HEAD, &recovery_head) == -1) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_wipe_all: failed to read recovery head\n")); + goto failed; + } + + if (recovery_head != 0) { + struct tdb_record rec; + if (tdb->methods->tdb_read(tdb, recovery_head, &rec, sizeof(rec), DOCONV()) == -1) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_wipe_all: failed to read recovery record\n")); + return -1; + } + recovery_size = rec.rec_len + sizeof(rec); + } + + /* wipe the hashes */ + for (i=0;i<tdb->hash_size;i++) { + if (tdb_ofs_write(tdb, TDB_HASH_TOP(i), &offset) == -1) { + TDB_LOG((tdb, TDB_DEBUG_FATAL,"tdb_wipe_all: failed to write hash %d\n", i)); + goto failed; + } + } + + /* wipe the freelist */ + if (tdb_ofs_write(tdb, FREELIST_TOP, &offset) == -1) { + TDB_LOG((tdb, TDB_DEBUG_FATAL,"tdb_wipe_all: failed to write freelist\n")); + goto failed; + } + + /* add all the rest of the file to the freelist, possibly leaving a gap + for the recovery area */ + if (recovery_size == 0) { + /* the simple case - the whole file can be used as a freelist */ + data_len = (tdb->map_size - TDB_DATA_START(tdb->hash_size)); + if (tdb_free_region(tdb, TDB_DATA_START(tdb->hash_size), data_len) != 0) { + goto failed; + } + } else { + /* we need to add two freelist entries - one on either + side of the recovery area + + Note that we cannot shift the recovery area during + this operation. Only the transaction.c code may + move the recovery area or we risk subtle data + corruption + */ + data_len = (recovery_head - TDB_DATA_START(tdb->hash_size)); + if (tdb_free_region(tdb, TDB_DATA_START(tdb->hash_size), data_len) != 0) { + goto failed; + } + /* and the 2nd free list entry after the recovery area - if any */ + data_len = tdb->map_size - (recovery_head+recovery_size); + if (tdb_free_region(tdb, recovery_head+recovery_size, data_len) != 0) { + goto failed; + } + } + + tdb_increment_seqnum_nonblock(tdb); + + if (tdb_unlockall(tdb) != 0) { + TDB_LOG((tdb, TDB_DEBUG_FATAL,"tdb_wipe_all: failed to unlock\n")); + goto failed; + } + + return 0; + +failed: + tdb_unlockall(tdb); + return -1; +} + +struct traverse_state { + bool error; + struct tdb_context *dest_db; +}; + +/* + traverse function for repacking + */ +static int repack_traverse(struct tdb_context *tdb, TDB_DATA key, TDB_DATA data, void *private_data) +{ + struct traverse_state *state = (struct traverse_state *)private_data; + if (tdb_store(state->dest_db, key, data, TDB_INSERT) != 0) { + state->error = true; + return -1; + } + return 0; +} + +/* + repack a tdb + */ +_PUBLIC_ int tdb_repack(struct tdb_context *tdb) +{ + struct tdb_context *tmp_db; + struct traverse_state state; + + tdb_trace(tdb, "tdb_repack"); + + if (tdb_transaction_start(tdb) != 0) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, __location__ " Failed to start transaction\n")); + return -1; + } + + tmp_db = tdb_open("tmpdb", tdb_hash_size(tdb), TDB_INTERNAL, O_RDWR|O_CREAT, 0); + if (tmp_db == NULL) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, __location__ " Failed to create tmp_db\n")); + tdb_transaction_cancel(tdb); + return -1; + } + + state.error = false; + state.dest_db = tmp_db; + + if (tdb_traverse_read(tdb, repack_traverse, &state) == -1) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, __location__ " Failed to traverse copying out\n")); + tdb_transaction_cancel(tdb); + tdb_close(tmp_db); + return -1; + } + + if (state.error) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, __location__ " Error during traversal\n")); + tdb_transaction_cancel(tdb); + tdb_close(tmp_db); + return -1; + } + + if (tdb_wipe_all(tdb) != 0) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, __location__ " Failed to wipe database\n")); + tdb_transaction_cancel(tdb); + tdb_close(tmp_db); + return -1; + } + + state.error = false; + state.dest_db = tdb; + + if (tdb_traverse_read(tmp_db, repack_traverse, &state) == -1) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, __location__ " Failed to traverse copying back\n")); + tdb_transaction_cancel(tdb); + tdb_close(tmp_db); + return -1; + } + + if (state.error) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, __location__ " Error during second traversal\n")); + tdb_transaction_cancel(tdb); + tdb_close(tmp_db); + return -1; + } + + tdb_close(tmp_db); + + if (tdb_transaction_commit(tdb) != 0) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, __location__ " Failed to commit\n")); + return -1; + } + + return 0; +} + +/* Even on files, we can get partial writes due to signals. */ +bool tdb_write_all(int fd, const void *buf, size_t count) +{ + while (count) { + ssize_t ret; + ret = write(fd, buf, count); + if (ret < 0) + return false; + buf = (const char *)buf + ret; + count -= ret; + } + return true; +} + +bool tdb_add_off_t(tdb_off_t a, tdb_off_t b, tdb_off_t *pret) +{ + tdb_off_t ret = a + b; + + if ((ret < a) || (ret < b)) { + return false; + } + *pret = ret; + return true; +} + +#ifdef TDB_TRACE +static void tdb_trace_write(struct tdb_context *tdb, const char *str) +{ + if (!tdb_write_all(tdb->tracefd, str, strlen(str))) { + close(tdb->tracefd); + tdb->tracefd = -1; + } +} + +static void tdb_trace_start(struct tdb_context *tdb) +{ + tdb_off_t seqnum=0; + char msg[sizeof(tdb_off_t) * 4 + 1]; + + tdb_ofs_read(tdb, TDB_SEQNUM_OFS, &seqnum); + snprintf(msg, sizeof(msg), "%u ", seqnum); + tdb_trace_write(tdb, msg); +} + +static void tdb_trace_end(struct tdb_context *tdb) +{ + tdb_trace_write(tdb, "\n"); +} + +static void tdb_trace_end_ret(struct tdb_context *tdb, int ret) +{ + char msg[sizeof(ret) * 4 + 4]; + snprintf(msg, sizeof(msg), " = %i\n", ret); + tdb_trace_write(tdb, msg); +} + +static void tdb_trace_record(struct tdb_context *tdb, TDB_DATA rec) +{ + char msg[20 + rec.dsize*2], *p; + unsigned int i; + + /* We differentiate zero-length records from non-existent ones. */ + if (rec.dptr == NULL) { + tdb_trace_write(tdb, " NULL"); + return; + } + + /* snprintf here is purely cargo-cult programming. */ + p = msg; + p += snprintf(p, sizeof(msg), " %zu:", rec.dsize); + for (i = 0; i < rec.dsize; i++) + p += snprintf(p, 2, "%02x", rec.dptr[i]); + + tdb_trace_write(tdb, msg); +} + +void tdb_trace(struct tdb_context *tdb, const char *op) +{ + tdb_trace_start(tdb); + tdb_trace_write(tdb, op); + tdb_trace_end(tdb); +} + +void tdb_trace_seqnum(struct tdb_context *tdb, uint32_t seqnum, const char *op) +{ + char msg[sizeof(tdb_off_t) * 4 + 1]; + + snprintf(msg, sizeof(msg), "%u ", seqnum); + tdb_trace_write(tdb, msg); + tdb_trace_write(tdb, op); + tdb_trace_end(tdb); +} + +void tdb_trace_open(struct tdb_context *tdb, const char *op, + unsigned hash_size, unsigned tdb_flags, unsigned open_flags) +{ + char msg[128]; + + snprintf(msg, sizeof(msg), + "%s %u 0x%x 0x%x", op, hash_size, tdb_flags, open_flags); + tdb_trace_start(tdb); + tdb_trace_write(tdb, msg); + tdb_trace_end(tdb); +} + +void tdb_trace_ret(struct tdb_context *tdb, const char *op, int ret) +{ + tdb_trace_start(tdb); + tdb_trace_write(tdb, op); + tdb_trace_end_ret(tdb, ret); +} + +void tdb_trace_retrec(struct tdb_context *tdb, const char *op, TDB_DATA ret) +{ + tdb_trace_start(tdb); + tdb_trace_write(tdb, op); + tdb_trace_write(tdb, " ="); + tdb_trace_record(tdb, ret); + tdb_trace_end(tdb); +} + +void tdb_trace_1rec(struct tdb_context *tdb, const char *op, + TDB_DATA rec) +{ + tdb_trace_start(tdb); + tdb_trace_write(tdb, op); + tdb_trace_record(tdb, rec); + tdb_trace_end(tdb); +} + +void tdb_trace_1rec_ret(struct tdb_context *tdb, const char *op, + TDB_DATA rec, int ret) +{ + tdb_trace_start(tdb); + tdb_trace_write(tdb, op); + tdb_trace_record(tdb, rec); + tdb_trace_end_ret(tdb, ret); +} + +void tdb_trace_1rec_retrec(struct tdb_context *tdb, const char *op, + TDB_DATA rec, TDB_DATA ret) +{ + tdb_trace_start(tdb); + tdb_trace_write(tdb, op); + tdb_trace_record(tdb, rec); + tdb_trace_write(tdb, " ="); + tdb_trace_record(tdb, ret); + tdb_trace_end(tdb); +} + +void tdb_trace_2rec_flag_ret(struct tdb_context *tdb, const char *op, + TDB_DATA rec1, TDB_DATA rec2, unsigned flag, + int ret) +{ + char msg[1 + sizeof(ret) * 4]; + + snprintf(msg, sizeof(msg), " %#x", flag); + tdb_trace_start(tdb); + tdb_trace_write(tdb, op); + tdb_trace_record(tdb, rec1); + tdb_trace_record(tdb, rec2); + tdb_trace_write(tdb, msg); + tdb_trace_end_ret(tdb, ret); +} + +void tdb_trace_1plusn_rec_flag_ret(struct tdb_context *tdb, const char *op, + TDB_DATA rec, + const TDB_DATA *recs, int num_recs, + unsigned flag, int ret) +{ + char msg[1 + sizeof(ret) * 4]; + int i; + + snprintf(msg, sizeof(msg), " %#x", flag); + tdb_trace_start(tdb); + tdb_trace_write(tdb, op); + tdb_trace_record(tdb, rec); + for (i=0; i<num_recs; i++) { + tdb_trace_record(tdb, recs[i]); + } + tdb_trace_write(tdb, msg); + tdb_trace_end_ret(tdb, ret); +} + +void tdb_trace_2rec_retrec(struct tdb_context *tdb, const char *op, + TDB_DATA rec1, TDB_DATA rec2, TDB_DATA ret) +{ + tdb_trace_start(tdb); + tdb_trace_write(tdb, op); + tdb_trace_record(tdb, rec1); + tdb_trace_record(tdb, rec2); + tdb_trace_write(tdb, " ="); + tdb_trace_record(tdb, ret); + tdb_trace_end(tdb); +} +#endif diff --git a/common/tdb_private.h b/common/tdb_private.h new file mode 100644 index 0000000..2979043 --- /dev/null +++ b/common/tdb_private.h @@ -0,0 +1,370 @@ +#ifndef TDB_PRIVATE_H +#define TDB_PRIVATE_H + /* + Unix SMB/CIFS implementation. + + trivial database library - private includes + + Copyright (C) Andrew Tridgell 2005 + + ** NOTE! The following LGPL license applies to the tdb + ** library. This does NOT imply that all of Samba is released + ** under the LGPL + + This library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 3 of the License, or (at your option) any later version. + + This library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with this library; if not, see <http://www.gnu.org/licenses/>. +*/ + +#include "replace.h" +#include "system/filesys.h" +#include "system/time.h" +#include "system/shmem.h" +#include "system/select.h" +#include "system/wait.h" +#include "tdb.h" + +/* #define TDB_TRACE 1 */ +#ifndef HAVE_GETPAGESIZE +#define getpagesize() 0x2000 +#endif + +typedef uint32_t tdb_len_t; +typedef uint32_t tdb_off_t; + +#ifndef offsetof +#define offsetof(t,f) ((unsigned int)&((t *)0)->f) +#endif + +#define TDB_MAGIC_FOOD "TDB file\n" +#define TDB_VERSION (0x26011967 + 6) +#define TDB_MAGIC (0x26011999U) +#define TDB_FREE_MAGIC (~TDB_MAGIC) +#define TDB_DEAD_MAGIC (0xFEE1DEAD) +#define TDB_RECOVERY_MAGIC (0xf53bc0e7U) +#define TDB_RECOVERY_INVALID_MAGIC (0x0) +#define TDB_HASH_RWLOCK_MAGIC (0xbad1a51U) +#define TDB_FEATURE_FLAG_MAGIC (0xbad1a52U) +#define TDB_ALIGNMENT 4 +#define DEFAULT_HASH_SIZE 131 +#define FREELIST_TOP (sizeof(struct tdb_header)) +#define TDB_ALIGN(x,a) (((x) + (a)-1) & ~((a)-1)) +#define TDB_BYTEREV(x) (((((x)&0xff)<<24)|((x)&0xFF00)<<8)|(((x)>>8)&0xFF00)|((x)>>24)) +#define TDB_DEAD(r) ((r)->magic == TDB_DEAD_MAGIC) +#define TDB_BAD_MAGIC(r) ((r)->magic != TDB_MAGIC && !TDB_DEAD(r)) +#define TDB_HASH_TOP(hash) (FREELIST_TOP + (BUCKET(hash)+1)*sizeof(tdb_off_t)) +#define TDB_HASHTABLE_SIZE(tdb) ((tdb->hash_size+1)*sizeof(tdb_off_t)) +#define TDB_DATA_START(hash_size) (TDB_HASH_TOP(hash_size-1) + sizeof(tdb_off_t)) +#define TDB_RECOVERY_HEAD offsetof(struct tdb_header, recovery_start) +#define TDB_SEQNUM_OFS offsetof(struct tdb_header, sequence_number) +#define TDB_PAD_BYTE 0x42 +#define TDB_PAD_U32 0x42424242 + +#define TDB_FEATURE_FLAG_MUTEX 0x00000001 + +#define TDB_SUPPORTED_FEATURE_FLAGS ( \ + TDB_FEATURE_FLAG_MUTEX | \ + 0) + +/* NB assumes there is a local variable called "tdb" that is the + * current context, also takes doubly-parenthesized print-style + * argument. */ +#define TDB_LOG(x) tdb->log.log_fn x + +#ifdef TDB_TRACE +void tdb_trace(struct tdb_context *tdb, const char *op); +void tdb_trace_seqnum(struct tdb_context *tdb, uint32_t seqnum, const char *op); +void tdb_trace_open(struct tdb_context *tdb, const char *op, + unsigned hash_size, unsigned tdb_flags, unsigned open_flags); +void tdb_trace_ret(struct tdb_context *tdb, const char *op, int ret); +void tdb_trace_retrec(struct tdb_context *tdb, const char *op, TDB_DATA ret); +void tdb_trace_1rec(struct tdb_context *tdb, const char *op, + TDB_DATA rec); +void tdb_trace_1rec_ret(struct tdb_context *tdb, const char *op, + TDB_DATA rec, int ret); +void tdb_trace_1rec_retrec(struct tdb_context *tdb, const char *op, + TDB_DATA rec, TDB_DATA ret); +void tdb_trace_2rec_flag_ret(struct tdb_context *tdb, const char *op, + TDB_DATA rec1, TDB_DATA rec2, unsigned flag, + int ret); +void tdb_trace_1plusn_rec_flag_ret(struct tdb_context *tdb, const char *op, + TDB_DATA rec, + const TDB_DATA *recs, int num_recs, + unsigned flag, int ret); +void tdb_trace_2rec_retrec(struct tdb_context *tdb, const char *op, + TDB_DATA rec1, TDB_DATA rec2, TDB_DATA ret); +#else +#define tdb_trace(tdb, op) +#define tdb_trace_seqnum(tdb, seqnum, op) +#define tdb_trace_open(tdb, op, hash_size, tdb_flags, open_flags) +#define tdb_trace_ret(tdb, op, ret) +#define tdb_trace_retrec(tdb, op, ret) +#define tdb_trace_1rec(tdb, op, rec) +#define tdb_trace_1rec_ret(tdb, op, rec, ret) +#define tdb_trace_1rec_retrec(tdb, op, rec, ret) +#define tdb_trace_2rec_flag_ret(tdb, op, rec1, rec2, flag, ret) +#define tdb_trace_1plusn_rec_flag_ret(tdb, op, rec, recs, num_recs, flag, ret); +#define tdb_trace_2rec_retrec(tdb, op, rec1, rec2, ret) +#endif /* !TDB_TRACE */ + +/* lock offsets */ +#define OPEN_LOCK 0 +#define ACTIVE_LOCK 4 +#define TRANSACTION_LOCK 8 + +/* free memory if the pointer is valid and zero the pointer */ +#ifndef SAFE_FREE +#define SAFE_FREE(x) do { if ((x) != NULL) {free(x); (x)=NULL;} } while(0) +#endif + +/* + * Note: the BUCKET macro is broken as it returns an unexpected result when + * called as BUCKET(-1) for the freelist: + * + * -1 is sign converted to an unsigned int 4294967295 and then the modulo + * tdb->hashtable_size is computed. So with a hashtable_size of 10 the result + * is + * + * 4294967295 % hashtable_size = 5. + * + * where it should be -1 (C uses symmetric modulo). + * + * As all callers will lock the same wrong list consistently locking is still + * consistent. We can not change this without an incompatible on-disk format + * change, otherwise different tdb versions would use incompatible locking. + */ +#define BUCKET(hash) ((hash) % tdb->hash_size) + +#define DOCONV() (tdb->flags & TDB_CONVERT) +#define CONVERT(x) (DOCONV() ? tdb_convert(&x, sizeof(x)) : &x) + + +/* the body of the database is made of one tdb_record for the free space + plus a separate data list for each hash value */ +struct tdb_record { + tdb_off_t next; /* offset of the next record in the list */ + tdb_len_t rec_len; /* total byte length of record */ + tdb_len_t key_len; /* byte length of key */ + tdb_len_t data_len; /* byte length of data */ + uint32_t full_hash; /* the full 32 bit hash of the key */ + uint32_t magic; /* try to catch errors */ + /* the following union is implied: + union { + char record[rec_len]; + struct { + char key[key_len]; + char data[data_len]; + } + uint32_t totalsize; (tailer) + } + */ +}; + + +/* this is stored at the front of every database */ +struct tdb_header { + char magic_food[32]; /* for /etc/magic */ + uint32_t version; /* version of the code */ + uint32_t hash_size; /* number of hash entries */ + tdb_off_t rwlocks; /* obsolete - kept to detect old formats */ + tdb_off_t recovery_start; /* offset of transaction recovery region */ + tdb_off_t sequence_number; /* used when TDB_SEQNUM is set */ + uint32_t magic1_hash; /* hash of TDB_MAGIC_FOOD. */ + uint32_t magic2_hash; /* hash of TDB_MAGIC. */ + uint32_t feature_flags; + tdb_len_t mutex_size; /* set if TDB_FEATURE_FLAG_MUTEX is set */ + tdb_off_t reserved[25]; +}; + +struct tdb_lock_type { + uint32_t off; + uint32_t count; + uint32_t ltype; +}; + +struct tdb_chainwalk_ctx { + tdb_off_t slow_ptr; + bool slow_chase; +}; + +struct tdb_traverse_lock { + struct tdb_traverse_lock *next; + uint32_t off; + uint32_t list; + int lock_rw; +}; + +void tdb_chainwalk_init(struct tdb_chainwalk_ctx *ctx, tdb_off_t ptr); +bool tdb_chainwalk_check(struct tdb_context *tdb, + struct tdb_chainwalk_ctx *ctx, + tdb_off_t next_ptr); + +enum tdb_lock_flags { + /* WAIT == F_SETLKW, NOWAIT == F_SETLK */ + TDB_LOCK_NOWAIT = 0, + TDB_LOCK_WAIT = 1, + /* If set, don't log an error on failure. */ + TDB_LOCK_PROBE = 2, + /* If set, don't actually lock at all. */ + TDB_LOCK_MARK_ONLY = 4, +}; + +struct tdb_methods { + int (*tdb_read)(struct tdb_context *, tdb_off_t , void *, tdb_len_t , int ); + int (*tdb_write)(struct tdb_context *, tdb_off_t, const void *, tdb_len_t); + void (*next_hash_chain)(struct tdb_context *, uint32_t *); + int (*tdb_oob)(struct tdb_context *, tdb_off_t , tdb_len_t, int ); + int (*tdb_expand_file)(struct tdb_context *, tdb_off_t , tdb_off_t ); +}; + +struct tdb_mutexes; + +struct tdb_context { + char *name; /* the name of the database */ + void *map_ptr; /* where it is currently mapped */ + int fd; /* open file descriptor for the database */ + tdb_len_t map_size; /* how much space has been mapped */ + int read_only; /* opened read-only */ + int traverse_read; /* read-only traversal */ + int traverse_write; /* read-write traversal */ + struct tdb_lock_type allrecord_lock; /* .offset == upgradable */ + int num_lockrecs; + struct tdb_lock_type *lockrecs; /* only real locks, all with count>0 */ + int lockrecs_array_length; + + tdb_off_t hdr_ofs; /* this is 0 or header.mutex_size */ + struct tdb_mutexes *mutexes; /* mmap of the mutex area */ + + enum TDB_ERROR ecode; /* error code for last tdb error */ + uint32_t hash_size; + uint32_t feature_flags; + uint32_t flags; /* the flags passed to tdb_open */ + struct tdb_traverse_lock travlocks; /* current traversal locks */ + struct tdb_context *next; /* all tdbs to avoid multiple opens */ + dev_t device; /* uniquely identifies this tdb */ + ino_t inode; /* uniquely identifies this tdb */ + struct tdb_logging_context log; + unsigned int (*hash_fn)(TDB_DATA *key); + int open_flags; /* flags used in the open - needed by reopen */ + const struct tdb_methods *methods; + struct tdb_transaction *transaction; + int page_size; + int max_dead_records; +#ifdef TDB_TRACE + int tracefd; +#endif + volatile sig_atomic_t *interrupt_sig_ptr; +}; + + +/* + internal prototypes +*/ +int tdb_munmap(struct tdb_context *tdb); +int tdb_mmap(struct tdb_context *tdb); +int tdb_lock(struct tdb_context *tdb, int list, int ltype); +int tdb_lock_nonblock(struct tdb_context *tdb, int list, int ltype); +int tdb_nest_lock(struct tdb_context *tdb, uint32_t offset, int ltype, + enum tdb_lock_flags flags); +int tdb_nest_unlock(struct tdb_context *tdb, uint32_t offset, int ltype, + bool mark_lock); +int tdb_unlock(struct tdb_context *tdb, int list, int ltype); +int tdb_brlock(struct tdb_context *tdb, + int rw_type, tdb_off_t offset, size_t len, + enum tdb_lock_flags flags); +int tdb_brunlock(struct tdb_context *tdb, + int rw_type, tdb_off_t offset, size_t len); +bool tdb_have_extra_locks(struct tdb_context *tdb); +void tdb_release_transaction_locks(struct tdb_context *tdb); +int tdb_transaction_lock(struct tdb_context *tdb, int ltype, + enum tdb_lock_flags lockflags); +int tdb_transaction_unlock(struct tdb_context *tdb, int ltype); +int tdb_recovery_area(struct tdb_context *tdb, + const struct tdb_methods *methods, + tdb_off_t *recovery_offset, + struct tdb_record *rec); +int tdb_allrecord_lock(struct tdb_context *tdb, int ltype, + enum tdb_lock_flags flags, bool upgradable); +int tdb_allrecord_unlock(struct tdb_context *tdb, int ltype, bool mark_lock); +int tdb_allrecord_upgrade(struct tdb_context *tdb); +int tdb_write_lock_record(struct tdb_context *tdb, tdb_off_t off); +int tdb_write_unlock_record(struct tdb_context *tdb, tdb_off_t off); +int tdb_ofs_read(struct tdb_context *tdb, tdb_off_t offset, tdb_off_t *d); +int tdb_ofs_write(struct tdb_context *tdb, tdb_off_t offset, tdb_off_t *d); +void *tdb_convert(void *buf, uint32_t size); +int tdb_free(struct tdb_context *tdb, tdb_off_t offset, struct tdb_record *rec); +tdb_off_t tdb_allocate(struct tdb_context *tdb, int hash, tdb_len_t length, + struct tdb_record *rec); + +int _tdb_oob(struct tdb_context *tdb, tdb_off_t off, tdb_len_t len, int probe); + +static inline int tdb_oob( + struct tdb_context *tdb, tdb_off_t off, tdb_len_t len, int probe) +{ + if (likely((off + len >= off) && (off + len <= tdb->map_size))) { + return 0; + } + return _tdb_oob(tdb, off, len, probe); +} + + +int tdb_ofs_read(struct tdb_context *tdb, tdb_off_t offset, tdb_off_t *d); +int tdb_ofs_write(struct tdb_context *tdb, tdb_off_t offset, tdb_off_t *d); +int tdb_lock_record(struct tdb_context *tdb, tdb_off_t off); +int tdb_unlock_record(struct tdb_context *tdb, tdb_off_t off); +bool tdb_needs_recovery(struct tdb_context *tdb); +int tdb_rec_read(struct tdb_context *tdb, tdb_off_t offset, struct tdb_record *rec); +int tdb_rec_write(struct tdb_context *tdb, tdb_off_t offset, struct tdb_record *rec); +unsigned char *tdb_alloc_read(struct tdb_context *tdb, tdb_off_t offset, tdb_len_t len); +int tdb_parse_data(struct tdb_context *tdb, TDB_DATA key, + tdb_off_t offset, tdb_len_t len, + int (*parser)(TDB_DATA key, TDB_DATA data, + void *private_data), + void *private_data); +tdb_off_t tdb_find_lock_hash(struct tdb_context *tdb, TDB_DATA key, uint32_t hash, int locktype, + struct tdb_record *rec); +tdb_off_t tdb_find_dead(struct tdb_context *tdb, uint32_t hash, + struct tdb_record *r, tdb_len_t length, + tdb_off_t *p_last_ptr); +int tdb_trim_dead(struct tdb_context *tdb, uint32_t hash); +void tdb_io_init(struct tdb_context *tdb); +int tdb_expand(struct tdb_context *tdb, tdb_off_t size); +tdb_off_t tdb_expand_adjust(tdb_off_t map_size, tdb_off_t size, int page_size); +int tdb_rec_free_read(struct tdb_context *tdb, tdb_off_t off, + struct tdb_record *rec); +bool tdb_write_all(int fd, const void *buf, size_t count); +int tdb_transaction_recover(struct tdb_context *tdb); +void tdb_header_hash(struct tdb_context *tdb, + uint32_t *magic1_hash, uint32_t *magic2_hash); +unsigned int tdb_old_hash(TDB_DATA *key); +size_t tdb_dead_space(struct tdb_context *tdb, tdb_off_t off); +bool tdb_add_off_t(tdb_off_t a, tdb_off_t b, tdb_off_t *pret); + +/* tdb_off_t and tdb_len_t right now are both uint32_t */ +#define tdb_add_len_t tdb_add_off_t + +size_t tdb_mutex_size(struct tdb_context *tdb); +bool tdb_have_mutexes(struct tdb_context *tdb); +int tdb_mutex_init(struct tdb_context *tdb); +int tdb_mutex_mmap(struct tdb_context *tdb); +int tdb_mutex_munmap(struct tdb_context *tdb); +bool tdb_mutex_lock(struct tdb_context *tdb, int rw, off_t off, off_t len, + bool waitflag, int *pret); +bool tdb_mutex_unlock(struct tdb_context *tdb, int rw, off_t off, off_t len, + int *pret); +int tdb_mutex_allrecord_lock(struct tdb_context *tdb, int ltype, + enum tdb_lock_flags flags); +int tdb_mutex_allrecord_unlock(struct tdb_context *tdb); +int tdb_mutex_allrecord_upgrade(struct tdb_context *tdb); +void tdb_mutex_allrecord_downgrade(struct tdb_context *tdb); + +#endif /* TDB_PRIVATE_H */ diff --git a/common/transaction.c b/common/transaction.c new file mode 100644 index 0000000..78bbd7a --- /dev/null +++ b/common/transaction.c @@ -0,0 +1,1388 @@ + /* + Unix SMB/CIFS implementation. + + trivial database library + + Copyright (C) Andrew Tridgell 2005 + + ** NOTE! The following LGPL license applies to the tdb + ** library. This does NOT imply that all of Samba is released + ** under the LGPL + + This library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 3 of the License, or (at your option) any later version. + + This library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with this library; if not, see <http://www.gnu.org/licenses/>. +*/ + +#include "tdb_private.h" + +/* + transaction design: + + - only allow a single transaction at a time per database. This makes + using the transaction API simpler, as otherwise the caller would + have to cope with temporary failures in transactions that conflict + with other current transactions + + - keep the transaction recovery information in the same file as the + database, using a special 'transaction recovery' record pointed at + by the header. This removes the need for extra journal files as + used by some other databases + + - dynamically allocated the transaction recover record, re-using it + for subsequent transactions. If a larger record is needed then + tdb_free() the old record to place it on the normal tdb freelist + before allocating the new record + + - during transactions, keep a linked list of all writes that have + been performed by intercepting all tdb_write() calls. The hooked + transaction versions of tdb_read() and tdb_write() check this + linked list and try to use the elements of the list in preference + to the real database. + + - don't allow any locks to be held when a transaction starts, + otherwise we can end up with deadlock (plus lack of lock nesting + in posix locks would mean the lock is lost) + + - if the caller gains a lock during the transaction but doesn't + release it then fail the commit + + - allow for nested calls to tdb_transaction_start(), re-using the + existing transaction record. If the inner transaction is cancelled + then a subsequent commit will fail + + - keep a mirrored copy of the tdb hash chain heads to allow for the + fast hash heads scan on traverse, updating the mirrored copy in + the transaction version of tdb_write + + - allow callers to mix transaction and non-transaction use of tdb, + although once a transaction is started then an exclusive lock is + gained until the transaction is committed or cancelled + + - the commit strategy involves first saving away all modified data + into a linearised buffer in the transaction recovery area, then + marking the transaction recovery area with a magic value to + indicate a valid recovery record. In total 4 fsync/msync calls are + needed per commit to prevent race conditions. It might be possible + to reduce this to 3 or even 2 with some more work. + + - check for a valid recovery record on open of the tdb, while the + open lock is held. Automatically recover from the transaction + recovery area if needed, then continue with the open as + usual. This allows for smooth crash recovery with no administrator + intervention. + + - if TDB_NOSYNC is passed to flags in tdb_open then transactions are + still available, but no fsync/msync calls are made. This means we + are still proof against a process dying during transaction commit, + but not against machine reboot. + + - if TDB_ALLOW_NESTING is passed to flags in tdb open, or added using + tdb_add_flags() transaction nesting is enabled. + It resets the TDB_DISALLOW_NESTING flag, as both cannot be used together. + The default is that transaction nesting is allowed. + Note: this default may change in future versions of tdb. + + Beware. when transactions are nested a transaction successfully + completed with tdb_transaction_commit() can be silently unrolled later. + + - if TDB_DISALLOW_NESTING is passed to flags in tdb open, or added using + tdb_add_flags() transaction nesting is disabled. + It resets the TDB_ALLOW_NESTING flag, as both cannot be used together. + An attempt create a nested transaction will fail with TDB_ERR_NESTING. + The default is that transaction nesting is allowed. + Note: this default may change in future versions of tdb. +*/ + + +/* + hold the context of any current transaction +*/ +struct tdb_transaction { + /* we keep a mirrored copy of the tdb hash heads here so + tdb_next_hash_chain() can operate efficiently */ + uint32_t *hash_heads; + + /* the original io methods - used to do IOs to the real db */ + const struct tdb_methods *io_methods; + + /* the list of transaction blocks. When a block is first + written to, it gets created in this list */ + uint8_t **blocks; + uint32_t num_blocks; + uint32_t block_size; /* bytes in each block */ + uint32_t last_block_size; /* number of valid bytes in the last block */ + + /* non-zero when an internal transaction error has + occurred. All write operations will then fail until the + transaction is ended */ + int transaction_error; + + /* when inside a transaction we need to keep track of any + nested tdb_transaction_start() calls, as these are allowed, + but don't create a new transaction */ + int nesting; + + /* set when a prepare has already occurred */ + bool prepared; + tdb_off_t magic_offset; + + /* old file size before transaction */ + tdb_len_t old_map_size; + + /* did we expand in this transaction */ + bool expanded; +}; + + +/* + read while in a transaction. We need to check first if the data is in our list + of transaction elements, then if not do a real read +*/ +static int transaction_read(struct tdb_context *tdb, tdb_off_t off, void *buf, + tdb_len_t len, int cv) +{ + uint32_t blk; + + /* break it down into block sized ops */ + while (len + (off % tdb->transaction->block_size) > tdb->transaction->block_size) { + tdb_len_t len2 = tdb->transaction->block_size - (off % tdb->transaction->block_size); + if (transaction_read(tdb, off, buf, len2, cv) != 0) { + return -1; + } + len -= len2; + off += len2; + buf = (void *)(len2 + (char *)buf); + } + + if (len == 0) { + return 0; + } + + blk = off / tdb->transaction->block_size; + + /* see if we have it in the block list */ + if (tdb->transaction->num_blocks <= blk || + tdb->transaction->blocks[blk] == NULL) { + /* nope, do a real read */ + if (tdb->transaction->io_methods->tdb_read(tdb, off, buf, len, cv) != 0) { + goto fail; + } + return 0; + } + + /* it is in the block list. Now check for the last block */ + if (blk == tdb->transaction->num_blocks-1) { + if (len > tdb->transaction->last_block_size) { + goto fail; + } + } + + /* now copy it out of this block */ + memcpy(buf, tdb->transaction->blocks[blk] + (off % tdb->transaction->block_size), len); + if (cv) { + tdb_convert(buf, len); + } + return 0; + +fail: + TDB_LOG((tdb, TDB_DEBUG_FATAL, "transaction_read: failed at off=%u len=%u\n", off, len)); + tdb->ecode = TDB_ERR_IO; + tdb->transaction->transaction_error = 1; + return -1; +} + + +/* + write while in a transaction +*/ +static int transaction_write(struct tdb_context *tdb, tdb_off_t off, + const void *buf, tdb_len_t len) +{ + uint32_t blk; + + if (buf == NULL) { + return -1; + } + + /* Only a commit is allowed on a prepared transaction */ + if (tdb->transaction->prepared) { + tdb->ecode = TDB_ERR_EINVAL; + TDB_LOG((tdb, TDB_DEBUG_FATAL, "transaction_write: transaction already prepared, write not allowed\n")); + tdb->transaction->transaction_error = 1; + return -1; + } + + /* if the write is to a hash head, then update the transaction + hash heads */ + if (len == sizeof(tdb_off_t) && off >= FREELIST_TOP && + off < FREELIST_TOP+TDB_HASHTABLE_SIZE(tdb)) { + uint32_t chain = (off-FREELIST_TOP) / sizeof(tdb_off_t); + memcpy(&tdb->transaction->hash_heads[chain], buf, len); + } + + /* break it up into block sized chunks */ + while (len + (off % tdb->transaction->block_size) > tdb->transaction->block_size) { + tdb_len_t len2 = tdb->transaction->block_size - (off % tdb->transaction->block_size); + if (transaction_write(tdb, off, buf, len2) != 0) { + return -1; + } + len -= len2; + off += len2; + buf = (const void *)(len2 + (const char *)buf); + } + + if (len == 0) { + return 0; + } + + blk = off / tdb->transaction->block_size; + off = off % tdb->transaction->block_size; + + if (tdb->transaction->num_blocks <= blk) { + uint8_t **new_blocks; + /* expand the blocks array */ + new_blocks = (uint8_t **)realloc(tdb->transaction->blocks, + (blk+1)*sizeof(uint8_t *)); + if (new_blocks == NULL) { + tdb->ecode = TDB_ERR_OOM; + goto fail; + } + memset(&new_blocks[tdb->transaction->num_blocks], 0, + (1+(blk - tdb->transaction->num_blocks))*sizeof(uint8_t *)); + tdb->transaction->blocks = new_blocks; + tdb->transaction->num_blocks = blk+1; + tdb->transaction->last_block_size = 0; + } + + /* allocate and fill a block? */ + if (tdb->transaction->blocks[blk] == NULL) { + tdb->transaction->blocks[blk] = (uint8_t *)calloc(tdb->transaction->block_size, 1); + if (tdb->transaction->blocks[blk] == NULL) { + tdb->ecode = TDB_ERR_OOM; + tdb->transaction->transaction_error = 1; + return -1; + } + if (tdb->transaction->old_map_size > blk * tdb->transaction->block_size) { + tdb_len_t len2 = tdb->transaction->block_size; + if (len2 + (blk * tdb->transaction->block_size) > tdb->transaction->old_map_size) { + len2 = tdb->transaction->old_map_size - (blk * tdb->transaction->block_size); + } + if (tdb->transaction->io_methods->tdb_read(tdb, blk * tdb->transaction->block_size, + tdb->transaction->blocks[blk], + len2, 0) != 0) { + SAFE_FREE(tdb->transaction->blocks[blk]); + tdb->ecode = TDB_ERR_IO; + goto fail; + } + if (blk == tdb->transaction->num_blocks-1) { + tdb->transaction->last_block_size = len2; + } + } + } + + /* overwrite part of an existing block */ + memcpy(tdb->transaction->blocks[blk] + off, buf, len); + if (blk == tdb->transaction->num_blocks-1) { + if (len + off > tdb->transaction->last_block_size) { + tdb->transaction->last_block_size = len + off; + } + } + + return 0; + +fail: + TDB_LOG((tdb, TDB_DEBUG_FATAL, "transaction_write: failed at off=%u len=%u\n", + (blk*tdb->transaction->block_size) + off, len)); + tdb->transaction->transaction_error = 1; + return -1; +} + + +/* + write while in a transaction - this variant never expands the transaction blocks, it only + updates existing blocks. This means it cannot change the recovery size +*/ +static int transaction_write_existing(struct tdb_context *tdb, tdb_off_t off, + const void *buf, tdb_len_t len) +{ + uint32_t blk; + + /* break it up into block sized chunks */ + while (len + (off % tdb->transaction->block_size) > tdb->transaction->block_size) { + tdb_len_t len2 = tdb->transaction->block_size - (off % tdb->transaction->block_size); + if (transaction_write_existing(tdb, off, buf, len2) != 0) { + return -1; + } + len -= len2; + off += len2; + if (buf != NULL) { + buf = (const void *)(len2 + (const char *)buf); + } + } + + if (len == 0 || buf == NULL) { + return 0; + } + + blk = off / tdb->transaction->block_size; + off = off % tdb->transaction->block_size; + + if (tdb->transaction->num_blocks <= blk || + tdb->transaction->blocks[blk] == NULL) { + return 0; + } + + if (blk == tdb->transaction->num_blocks-1 && + off + len > tdb->transaction->last_block_size) { + if (off >= tdb->transaction->last_block_size) { + return 0; + } + len = tdb->transaction->last_block_size - off; + } + + /* overwrite part of an existing block */ + memcpy(tdb->transaction->blocks[blk] + off, buf, len); + + return 0; +} + + +/* + accelerated hash chain head search, using the cached hash heads +*/ +static void transaction_next_hash_chain(struct tdb_context *tdb, uint32_t *chain) +{ + uint32_t h = *chain; + for (;h < tdb->hash_size;h++) { + /* the +1 takes account of the freelist */ + if (0 != tdb->transaction->hash_heads[h+1]) { + break; + } + } + (*chain) = h; +} + +/* + out of bounds check during a transaction +*/ +static int transaction_oob(struct tdb_context *tdb, tdb_off_t off, + tdb_len_t len, int probe) +{ + /* + * This duplicates functionality from tdb_oob(). Don't remove: + * we still have direct callers of tdb->methods->tdb_oob() + * inside transaction.c. + */ + if (off + len >= off && off + len <= tdb->map_size) { + return 0; + } + tdb->ecode = TDB_ERR_IO; + return -1; +} + +/* + transaction version of tdb_expand(). +*/ +static int transaction_expand_file(struct tdb_context *tdb, tdb_off_t size, + tdb_off_t addition) +{ + const char buf_zero[8192] = {0}; + size_t buf_len = sizeof(buf_zero); + + while (addition > 0) { + size_t n = MIN(addition, buf_len); + int ret; + + ret = transaction_write(tdb, size, buf_zero, n); + if (ret != 0) { + return ret; + } + + addition -= n; + size += n; + } + + tdb->transaction->expanded = true; + + return 0; +} + +static const struct tdb_methods transaction_methods = { + transaction_read, + transaction_write, + transaction_next_hash_chain, + transaction_oob, + transaction_expand_file, +}; + +/* + * Is a transaction currently active on this context? + * + */ +_PUBLIC_ bool tdb_transaction_active(struct tdb_context *tdb) +{ + return (tdb->transaction != NULL); +} + +/* + start a tdb transaction. No token is returned, as only a single + transaction is allowed to be pending per tdb_context +*/ +static int _tdb_transaction_start(struct tdb_context *tdb, + enum tdb_lock_flags lockflags) +{ + /* some sanity checks */ + if (tdb->read_only || (tdb->flags & TDB_INTERNAL) + || tdb->traverse_read) { + TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: cannot start a transaction on a read-only or internal db\n")); + tdb->ecode = TDB_ERR_EINVAL; + return -1; + } + + /* cope with nested tdb_transaction_start() calls */ + if (tdb->transaction != NULL) { + if (!(tdb->flags & TDB_ALLOW_NESTING)) { + tdb->ecode = TDB_ERR_NESTING; + return -1; + } + tdb->transaction->nesting++; + TDB_LOG((tdb, TDB_DEBUG_TRACE, "tdb_transaction_start: nesting %d\n", + tdb->transaction->nesting)); + return 0; + } + + if (tdb_have_extra_locks(tdb)) { + /* the caller must not have any locks when starting a + transaction as otherwise we'll be screwed by lack + of nested locks in posix */ + TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: cannot start a transaction with locks held\n")); + tdb->ecode = TDB_ERR_LOCK; + return -1; + } + + if (tdb->travlocks.next != NULL) { + /* you cannot use transactions inside a traverse (although you can use + traverse inside a transaction) as otherwise you can end up with + deadlock */ + TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: cannot start a transaction within a traverse\n")); + tdb->ecode = TDB_ERR_LOCK; + return -1; + } + + tdb->transaction = (struct tdb_transaction *) + calloc(sizeof(struct tdb_transaction), 1); + if (tdb->transaction == NULL) { + tdb->ecode = TDB_ERR_OOM; + return -1; + } + + /* a page at a time seems like a reasonable compromise between compactness and efficiency */ + tdb->transaction->block_size = tdb->page_size; + + /* get the transaction write lock. This is a blocking lock. As + discussed with Volker, there are a number of ways we could + make this async, which we will probably do in the future */ + if (tdb_transaction_lock(tdb, F_WRLCK, lockflags) == -1) { + SAFE_FREE(tdb->transaction->blocks); + SAFE_FREE(tdb->transaction); + if ((lockflags & TDB_LOCK_WAIT) == 0) { + tdb->ecode = TDB_ERR_NOLOCK; + } else { + TDB_LOG((tdb, TDB_DEBUG_ERROR, + "tdb_transaction_start: " + "failed to get transaction lock\n")); + } + return -1; + } + + /* get a read lock from the freelist to the end of file. This + is upgraded to a write lock during the commit */ + if (tdb_allrecord_lock(tdb, F_RDLCK, TDB_LOCK_WAIT, true) == -1) { + TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: failed to get hash locks\n")); + goto fail_allrecord_lock; + } + + /* setup a copy of the hash table heads so the hash scan in + traverse can be fast */ + tdb->transaction->hash_heads = (uint32_t *) + calloc(tdb->hash_size+1, sizeof(uint32_t)); + if (tdb->transaction->hash_heads == NULL) { + tdb->ecode = TDB_ERR_OOM; + goto fail; + } + if (tdb->methods->tdb_read(tdb, FREELIST_TOP, tdb->transaction->hash_heads, + TDB_HASHTABLE_SIZE(tdb), 0) != 0) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_start: failed to read hash heads\n")); + tdb->ecode = TDB_ERR_IO; + goto fail; + } + + /* make sure we know about any file expansions already done by + anyone else */ + tdb_oob(tdb, tdb->map_size, 1, 1); + tdb->transaction->old_map_size = tdb->map_size; + + /* finally hook the io methods, replacing them with + transaction specific methods */ + tdb->transaction->io_methods = tdb->methods; + tdb->methods = &transaction_methods; + + /* Trace at the end, so we get sequence number correct. */ + tdb_trace(tdb, "tdb_transaction_start"); + return 0; + +fail: + tdb_allrecord_unlock(tdb, F_RDLCK, false); +fail_allrecord_lock: + tdb_transaction_unlock(tdb, F_WRLCK); + SAFE_FREE(tdb->transaction->blocks); + SAFE_FREE(tdb->transaction->hash_heads); + SAFE_FREE(tdb->transaction); + return -1; +} + +_PUBLIC_ int tdb_transaction_start(struct tdb_context *tdb) +{ + return _tdb_transaction_start(tdb, TDB_LOCK_WAIT); +} + +_PUBLIC_ int tdb_transaction_start_nonblock(struct tdb_context *tdb) +{ + return _tdb_transaction_start(tdb, TDB_LOCK_NOWAIT|TDB_LOCK_PROBE); +} + +/* + sync to disk +*/ +static int transaction_sync(struct tdb_context *tdb, tdb_off_t offset, tdb_len_t length) +{ + if (tdb->flags & TDB_NOSYNC) { + return 0; + } + +#ifdef HAVE_FDATASYNC + if (fdatasync(tdb->fd) != 0) { +#else + if (fsync(tdb->fd) != 0) { +#endif + tdb->ecode = TDB_ERR_IO; + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction: fsync failed\n")); + return -1; + } +#ifdef HAVE_MMAP + if (tdb->map_ptr) { + tdb_off_t moffset = offset & ~(tdb->page_size-1); + if (msync(moffset + (char *)tdb->map_ptr, + length + (offset - moffset), MS_SYNC) != 0) { + tdb->ecode = TDB_ERR_IO; + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction: msync failed - %s\n", + strerror(errno))); + return -1; + } + } +#endif + return 0; +} + + +static int _tdb_transaction_cancel(struct tdb_context *tdb) +{ + uint32_t i; + int ret = 0; + + if (tdb->transaction == NULL) { + TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_cancel: no transaction\n")); + return -1; + } + + if (tdb->transaction->nesting != 0) { + tdb->transaction->transaction_error = 1; + tdb->transaction->nesting--; + return 0; + } + + tdb->map_size = tdb->transaction->old_map_size; + + /* free all the transaction blocks */ + for (i=0;i<tdb->transaction->num_blocks;i++) { + if ((tdb->transaction->blocks != NULL) && + tdb->transaction->blocks[i] != NULL) { + free(tdb->transaction->blocks[i]); + } + } + SAFE_FREE(tdb->transaction->blocks); + + if (tdb->transaction->magic_offset) { + const struct tdb_methods *methods = tdb->transaction->io_methods; + const uint32_t invalid = TDB_RECOVERY_INVALID_MAGIC; + + /* remove the recovery marker */ + if (methods->tdb_write(tdb, tdb->transaction->magic_offset, &invalid, 4) == -1 || + transaction_sync(tdb, tdb->transaction->magic_offset, 4) == -1) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_cancel: failed to remove recovery magic\n")); + ret = -1; + } + } + + /* This also removes the OPEN_LOCK, if we have it. */ + tdb_release_transaction_locks(tdb); + + /* restore the normal io methods */ + tdb->methods = tdb->transaction->io_methods; + + SAFE_FREE(tdb->transaction->hash_heads); + SAFE_FREE(tdb->transaction); + + return ret; +} + +/* + cancel the current transaction +*/ +_PUBLIC_ int tdb_transaction_cancel(struct tdb_context *tdb) +{ + tdb_trace(tdb, "tdb_transaction_cancel"); + return _tdb_transaction_cancel(tdb); +} + +/* + work out how much space the linearised recovery data will consume +*/ +static bool tdb_recovery_size(struct tdb_context *tdb, tdb_len_t *result) +{ + tdb_len_t recovery_size = 0; + uint32_t i; + + recovery_size = sizeof(uint32_t); + for (i=0;i<tdb->transaction->num_blocks;i++) { + tdb_len_t block_size; + if (i * tdb->transaction->block_size >= tdb->transaction->old_map_size) { + break; + } + if (tdb->transaction->blocks[i] == NULL) { + continue; + } + if (!tdb_add_len_t(recovery_size, 2*sizeof(tdb_off_t), + &recovery_size)) { + return false; + } + if (i == tdb->transaction->num_blocks-1) { + block_size = tdb->transaction->last_block_size; + } else { + block_size = tdb->transaction->block_size; + } + if (!tdb_add_len_t(recovery_size, block_size, + &recovery_size)) { + return false; + } + } + + *result = recovery_size; + return true; +} + +int tdb_recovery_area(struct tdb_context *tdb, + const struct tdb_methods *methods, + tdb_off_t *recovery_offset, + struct tdb_record *rec) +{ + int ret; + + if (tdb_ofs_read(tdb, TDB_RECOVERY_HEAD, recovery_offset) == -1) { + return -1; + } + + if (*recovery_offset == 0) { + rec->rec_len = 0; + return 0; + } + + if (methods->tdb_read(tdb, *recovery_offset, rec, sizeof(*rec), + DOCONV()) == -1) { + return -1; + } + + /* ignore invalid recovery regions: can happen in crash */ + if (rec->magic != TDB_RECOVERY_MAGIC && + rec->magic != TDB_RECOVERY_INVALID_MAGIC) { + *recovery_offset = 0; + rec->rec_len = 0; + } + + ret = methods->tdb_oob(tdb, *recovery_offset, rec->rec_len, 1); + if (ret == -1) { + *recovery_offset = 0; + rec->rec_len = 0; + } + + return 0; +} + +/* + allocate the recovery area, or use an existing recovery area if it is + large enough +*/ +static int tdb_recovery_allocate(struct tdb_context *tdb, + tdb_len_t *recovery_size, + tdb_off_t *recovery_offset, + tdb_len_t *recovery_max_size) +{ + struct tdb_record rec; + const struct tdb_methods *methods = tdb->transaction->io_methods; + tdb_off_t recovery_head, new_end; + + if (tdb_recovery_area(tdb, methods, &recovery_head, &rec) == -1) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to read recovery head\n")); + return -1; + } + + if (!tdb_recovery_size(tdb, recovery_size)) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: " + "overflow recovery size\n")); + return -1; + } + + /* Existing recovery area? */ + if (recovery_head != 0 && *recovery_size <= rec.rec_len) { + /* it fits in the existing area */ + *recovery_max_size = rec.rec_len; + *recovery_offset = recovery_head; + return 0; + } + + /* If recovery area in middle of file, we need a new one. */ + if (recovery_head == 0 + || recovery_head + sizeof(rec) + rec.rec_len != tdb->map_size) { + /* we need to free up the old recovery area, then allocate a + new one at the end of the file. Note that we cannot use + tdb_allocate() to allocate the new one as that might return + us an area that is being currently used (as of the start of + the transaction) */ + if (recovery_head) { + if (tdb_free(tdb, recovery_head, &rec) == -1) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, + "tdb_recovery_allocate: failed to" + " free previous recovery area\n")); + return -1; + } + + /* the tdb_free() call might have increased + * the recovery size */ + if (!tdb_recovery_size(tdb, recovery_size)) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, + "tdb_recovery_allocate: " + "overflow recovery size\n")); + return -1; + } + } + + /* New head will be at end of file. */ + recovery_head = tdb->map_size; + } + + /* Now we know where it will be. */ + *recovery_offset = recovery_head; + + /* Expand by more than we need, so we don't do it often. */ + *recovery_max_size = tdb_expand_adjust(tdb->map_size, + *recovery_size, + tdb->page_size) + - sizeof(rec); + + if (!tdb_add_off_t(recovery_head, sizeof(rec), &new_end) || + !tdb_add_off_t(new_end, *recovery_max_size, &new_end)) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: " + "overflow recovery area\n")); + return -1; + } + + if (methods->tdb_expand_file(tdb, tdb->transaction->old_map_size, + new_end - tdb->transaction->old_map_size) + == -1) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to create recovery area\n")); + return -1; + } + + /* remap the file (if using mmap) */ + methods->tdb_oob(tdb, tdb->map_size, 1, 1); + + /* we have to reset the old map size so that we don't try to expand the file + again in the transaction commit, which would destroy the recovery area */ + tdb->transaction->old_map_size = tdb->map_size; + + /* write the recovery header offset and sync - we can sync without a race here + as the magic ptr in the recovery record has not been set */ + CONVERT(recovery_head); + if (methods->tdb_write(tdb, TDB_RECOVERY_HEAD, + &recovery_head, sizeof(tdb_off_t)) == -1) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to write recovery head\n")); + return -1; + } + if (transaction_write_existing(tdb, TDB_RECOVERY_HEAD, &recovery_head, sizeof(tdb_off_t)) == -1) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to write recovery head\n")); + return -1; + } + + return 0; +} + + +/* + setup the recovery data that will be used on a crash during commit +*/ +static int transaction_setup_recovery(struct tdb_context *tdb, + tdb_off_t *magic_offset) +{ + tdb_len_t recovery_size; + unsigned char *data, *p; + const struct tdb_methods *methods = tdb->transaction->io_methods; + struct tdb_record *rec; + tdb_off_t recovery_offset, recovery_max_size; + tdb_off_t old_map_size = tdb->transaction->old_map_size; + uint32_t magic, tailer; + uint32_t i; + + /* + check that the recovery area has enough space + */ + if (tdb_recovery_allocate(tdb, &recovery_size, + &recovery_offset, &recovery_max_size) == -1) { + return -1; + } + + rec = malloc(recovery_size + sizeof(*rec)); + if (rec == NULL) { + tdb->ecode = TDB_ERR_OOM; + return -1; + } + + memset(rec, 0, sizeof(*rec)); + + rec->magic = TDB_RECOVERY_INVALID_MAGIC; + rec->data_len = recovery_size; + rec->rec_len = recovery_max_size; + rec->key_len = old_map_size; + CONVERT(*rec); + + data = (unsigned char *)rec; + + /* build the recovery data into a single blob to allow us to do a single + large write, which should be more efficient */ + p = data + sizeof(*rec); + for (i=0;i<tdb->transaction->num_blocks;i++) { + tdb_off_t offset; + tdb_len_t length; + + if (tdb->transaction->blocks[i] == NULL) { + continue; + } + + offset = i * tdb->transaction->block_size; + length = tdb->transaction->block_size; + if (i == tdb->transaction->num_blocks-1) { + length = tdb->transaction->last_block_size; + } + + if (offset >= old_map_size) { + continue; + } + if (offset + length > tdb->transaction->old_map_size) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: transaction data over new region boundary\n")); + free(data); + tdb->ecode = TDB_ERR_CORRUPT; + return -1; + } + memcpy(p, &offset, 4); + memcpy(p+4, &length, 4); + if (DOCONV()) { + tdb_convert(p, 8); + } + /* the recovery area contains the old data, not the + new data, so we have to call the original tdb_read + method to get it */ + if (methods->tdb_read(tdb, offset, p + 8, length, 0) != 0) { + free(data); + tdb->ecode = TDB_ERR_IO; + return -1; + } + p += 8 + length; + } + + /* and the tailer */ + tailer = sizeof(*rec) + recovery_max_size; + memcpy(p, &tailer, 4); + if (DOCONV()) { + tdb_convert(p, 4); + } + + /* write the recovery data to the recovery area */ + if (methods->tdb_write(tdb, recovery_offset, data, sizeof(*rec) + recovery_size) == -1) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write recovery data\n")); + free(data); + tdb->ecode = TDB_ERR_IO; + return -1; + } + if (transaction_write_existing(tdb, recovery_offset, data, sizeof(*rec) + recovery_size) == -1) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write secondary recovery data\n")); + free(data); + tdb->ecode = TDB_ERR_IO; + return -1; + } + + /* as we don't have ordered writes, we have to sync the recovery + data before we update the magic to indicate that the recovery + data is present */ + if (transaction_sync(tdb, recovery_offset, sizeof(*rec) + recovery_size) == -1) { + free(data); + return -1; + } + + free(data); + + magic = TDB_RECOVERY_MAGIC; + CONVERT(magic); + + *magic_offset = recovery_offset + offsetof(struct tdb_record, magic); + + if (methods->tdb_write(tdb, *magic_offset, &magic, sizeof(magic)) == -1) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write recovery magic\n")); + tdb->ecode = TDB_ERR_IO; + return -1; + } + if (transaction_write_existing(tdb, *magic_offset, &magic, sizeof(magic)) == -1) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write secondary recovery magic\n")); + tdb->ecode = TDB_ERR_IO; + return -1; + } + + /* ensure the recovery magic marker is on disk */ + if (transaction_sync(tdb, *magic_offset, sizeof(magic)) == -1) { + return -1; + } + + return 0; +} + +static int _tdb_transaction_prepare_commit(struct tdb_context *tdb) +{ + const struct tdb_methods *methods; + + if (tdb->transaction == NULL) { + TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: no transaction\n")); + return -1; + } + + if (tdb->transaction->prepared) { + tdb->ecode = TDB_ERR_EINVAL; + _tdb_transaction_cancel(tdb); + TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: transaction already prepared\n")); + return -1; + } + + if (tdb->transaction->transaction_error) { + tdb->ecode = TDB_ERR_IO; + _tdb_transaction_cancel(tdb); + TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: transaction error pending\n")); + return -1; + } + + + if (tdb->transaction->nesting != 0) { + return 0; + } + + /* check for a null transaction */ + if (tdb->transaction->blocks == NULL) { + return 0; + } + + methods = tdb->transaction->io_methods; + + /* if there are any locks pending then the caller has not + nested their locks properly, so fail the transaction */ + if (tdb_have_extra_locks(tdb)) { + tdb->ecode = TDB_ERR_LOCK; + TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: locks pending on commit\n")); + _tdb_transaction_cancel(tdb); + return -1; + } + + /* upgrade the main transaction lock region to a write lock */ + if (tdb_allrecord_upgrade(tdb) == -1) { + if (tdb->ecode == TDB_ERR_RDONLY && tdb->read_only) { + TDB_LOG((tdb, TDB_DEBUG_ERROR, + "tdb_transaction_prepare_commit: " + "failed to upgrade hash locks: " + "database is read only\n")); + } else if (tdb->ecode == TDB_ERR_RDONLY + && tdb->traverse_read) { + TDB_LOG((tdb, TDB_DEBUG_ERROR, + "tdb_transaction_prepare_commit: " + "failed to upgrade hash locks: " + "a database traverse is in progress\n")); + } else { + TDB_LOG((tdb, TDB_DEBUG_ERROR, + "tdb_transaction_prepare_commit: " + "failed to upgrade hash locks: %s\n", + tdb_errorstr(tdb))); + } + _tdb_transaction_cancel(tdb); + return -1; + } + + /* get the open lock - this prevents new users attaching to the database + during the commit */ + if (tdb_nest_lock(tdb, OPEN_LOCK, F_WRLCK, TDB_LOCK_WAIT) == -1) { + TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: failed to get open lock\n")); + _tdb_transaction_cancel(tdb); + return -1; + } + + /* write the recovery data to the end of the file */ + if (transaction_setup_recovery(tdb, &tdb->transaction->magic_offset) == -1) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_prepare_commit: failed to setup recovery data\n")); + _tdb_transaction_cancel(tdb); + return -1; + } + + tdb->transaction->prepared = true; + + /* expand the file to the new size if needed */ + if (tdb->map_size != tdb->transaction->old_map_size) { + if (methods->tdb_expand_file(tdb, tdb->transaction->old_map_size, + tdb->map_size - + tdb->transaction->old_map_size) == -1) { + tdb->ecode = TDB_ERR_IO; + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_prepare_commit: expansion failed\n")); + _tdb_transaction_cancel(tdb); + return -1; + } + tdb->map_size = tdb->transaction->old_map_size; + methods->tdb_oob(tdb, tdb->map_size, 1, 1); + } + + /* Keep the open lock until the actual commit */ + + return 0; +} + +/* + prepare to commit the current transaction +*/ +_PUBLIC_ int tdb_transaction_prepare_commit(struct tdb_context *tdb) +{ + tdb_trace(tdb, "tdb_transaction_prepare_commit"); + return _tdb_transaction_prepare_commit(tdb); +} + +/* A repack is worthwhile if the largest is less than half total free. */ +static bool repack_worthwhile(struct tdb_context *tdb) +{ + tdb_off_t ptr; + struct tdb_record rec; + tdb_len_t total = 0, largest = 0; + + if (tdb_ofs_read(tdb, FREELIST_TOP, &ptr) == -1) { + return false; + } + + while (ptr != 0 && tdb_rec_free_read(tdb, ptr, &rec) == 0) { + total += rec.rec_len; + if (rec.rec_len > largest) { + largest = rec.rec_len; + } + ptr = rec.next; + } + + return total > largest * 2; +} + +/* + commit the current transaction +*/ +_PUBLIC_ int tdb_transaction_commit(struct tdb_context *tdb) +{ + const struct tdb_methods *methods; + uint32_t i; + bool need_repack = false; + + if (tdb->transaction == NULL) { + TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_commit: no transaction\n")); + return -1; + } + + tdb_trace(tdb, "tdb_transaction_commit"); + + if (tdb->transaction->transaction_error) { + tdb->ecode = TDB_ERR_IO; + _tdb_transaction_cancel(tdb); + TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_commit: transaction error pending\n")); + return -1; + } + + + if (tdb->transaction->nesting != 0) { + tdb->transaction->nesting--; + return 0; + } + + /* check for a null transaction */ + if (tdb->transaction->blocks == NULL) { + _tdb_transaction_cancel(tdb); + return 0; + } + + if (!tdb->transaction->prepared) { + int ret = _tdb_transaction_prepare_commit(tdb); + if (ret) + return ret; + } + + methods = tdb->transaction->io_methods; + + /* perform all the writes */ + for (i=0;i<tdb->transaction->num_blocks;i++) { + tdb_off_t offset; + tdb_len_t length; + + if (tdb->transaction->blocks[i] == NULL) { + continue; + } + + offset = i * tdb->transaction->block_size; + length = tdb->transaction->block_size; + if (i == tdb->transaction->num_blocks-1) { + length = tdb->transaction->last_block_size; + } + + if (methods->tdb_write(tdb, offset, tdb->transaction->blocks[i], length) == -1) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_commit: write failed during commit\n")); + + /* we've overwritten part of the data and + possibly expanded the file, so we need to + run the crash recovery code */ + tdb->methods = methods; + tdb_transaction_recover(tdb); + + _tdb_transaction_cancel(tdb); + + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_commit: write failed\n")); + return -1; + } + SAFE_FREE(tdb->transaction->blocks[i]); + } + + /* Do this before we drop lock or blocks. */ + if (tdb->transaction->expanded) { + need_repack = repack_worthwhile(tdb); + } + + SAFE_FREE(tdb->transaction->blocks); + tdb->transaction->num_blocks = 0; + + /* ensure the new data is on disk */ + if (transaction_sync(tdb, 0, tdb->map_size) == -1) { + return -1; + } + + /* + TODO: maybe write to some dummy hdr field, or write to magic + offset without mmap, before the last sync, instead of the + utime() call + */ + + /* on some systems (like Linux 2.6.x) changes via mmap/msync + don't change the mtime of the file, this means the file may + not be backed up (as tdb rounding to block sizes means that + file size changes are quite rare too). The following forces + mtime changes when a transaction completes */ +#ifdef HAVE_UTIME + utime(tdb->name, NULL); +#endif + + /* use a transaction cancel to free memory and remove the + transaction locks */ + _tdb_transaction_cancel(tdb); + + if (need_repack) { + int ret = tdb_repack(tdb); + if (ret != 0) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, + __location__ " Failed to repack database (not fatal)\n")); + } + /* + * Ignore the error. + * + * Why? + * + * We just committed to the DB above, so anything + * written during the transaction is committed, the + * caller needs to know that the long-term state was + * successfully modified. + * + * tdb_repack is an optimization that can fail for + * reasons like lock ordering and we cannot recover + * the transaction lock at this point, having released + * it above. + * + * If we return a failure the caller thinks the + * transaction was rolled back. + */ + } + + return 0; +} + + +/* + recover from an aborted transaction. Must be called with exclusive + database write access already established (including the open + lock to prevent new processes attaching) +*/ +int tdb_transaction_recover(struct tdb_context *tdb) +{ + tdb_off_t recovery_head, recovery_eof; + unsigned char *data, *p; + uint32_t zero = 0; + struct tdb_record rec; + + /* find the recovery area */ + if (tdb_ofs_read(tdb, TDB_RECOVERY_HEAD, &recovery_head) == -1) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to read recovery head\n")); + tdb->ecode = TDB_ERR_IO; + return -1; + } + + if (recovery_head == 0) { + /* we have never allocated a recovery record */ + return 0; + } + + /* read the recovery record */ + if (tdb->methods->tdb_read(tdb, recovery_head, &rec, + sizeof(rec), DOCONV()) == -1) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to read recovery record\n")); + tdb->ecode = TDB_ERR_IO; + return -1; + } + + if (rec.magic != TDB_RECOVERY_MAGIC) { + /* there is no valid recovery data */ + return 0; + } + + if (tdb->read_only) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: attempt to recover read only database\n")); + tdb->ecode = TDB_ERR_CORRUPT; + return -1; + } + + recovery_eof = rec.key_len; + + data = (unsigned char *)malloc(rec.data_len); + if (data == NULL) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to allocate recovery data\n")); + tdb->ecode = TDB_ERR_OOM; + return -1; + } + + /* read the full recovery data */ + if (tdb->methods->tdb_read(tdb, recovery_head + sizeof(rec), data, + rec.data_len, 0) == -1) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to read recovery data\n")); + tdb->ecode = TDB_ERR_IO; + free(data); + return -1; + } + + /* recover the file data */ + p = data; + while (p+8 < data + rec.data_len) { + uint32_t ofs, len; + if (DOCONV()) { + tdb_convert(p, 8); + } + memcpy(&ofs, p, 4); + memcpy(&len, p+4, 4); + + if (tdb->methods->tdb_write(tdb, ofs, p+8, len) == -1) { + free(data); + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to recover %u bytes at offset %u\n", len, ofs)); + tdb->ecode = TDB_ERR_IO; + return -1; + } + p += 8 + len; + } + + free(data); + + if (transaction_sync(tdb, 0, tdb->map_size) == -1) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to sync recovery\n")); + tdb->ecode = TDB_ERR_IO; + return -1; + } + + /* if the recovery area is after the recovered eof then remove it */ + if (recovery_eof <= recovery_head) { + if (tdb_ofs_write(tdb, TDB_RECOVERY_HEAD, &zero) == -1) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to remove recovery head\n")); + tdb->ecode = TDB_ERR_IO; + return -1; + } + } + + /* remove the recovery magic */ + if (tdb_ofs_write(tdb, recovery_head + offsetof(struct tdb_record, magic), + &zero) == -1) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to remove recovery magic\n")); + tdb->ecode = TDB_ERR_IO; + return -1; + } + + if (transaction_sync(tdb, 0, recovery_eof) == -1) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to sync2 recovery\n")); + tdb->ecode = TDB_ERR_IO; + return -1; + } + + TDB_LOG((tdb, TDB_DEBUG_TRACE, "tdb_transaction_recover: recovered %u byte database\n", + recovery_eof)); + + /* all done */ + return 0; +} + +/* Any I/O failures we say "needs recovery". */ +bool tdb_needs_recovery(struct tdb_context *tdb) +{ + tdb_off_t recovery_head; + struct tdb_record rec; + + /* find the recovery area */ + if (tdb_ofs_read(tdb, TDB_RECOVERY_HEAD, &recovery_head) == -1) { + return true; + } + + if (recovery_head == 0) { + /* we have never allocated a recovery record */ + return false; + } + + /* read the recovery record */ + if (tdb->methods->tdb_read(tdb, recovery_head, &rec, + sizeof(rec), DOCONV()) == -1) { + return true; + } + + return (rec.magic == TDB_RECOVERY_MAGIC); +} diff --git a/common/traverse.c b/common/traverse.c new file mode 100644 index 0000000..fcd2e00 --- /dev/null +++ b/common/traverse.c @@ -0,0 +1,510 @@ + /* + Unix SMB/CIFS implementation. + + trivial database library + + Copyright (C) Andrew Tridgell 1999-2005 + Copyright (C) Paul `Rusty' Russell 2000 + Copyright (C) Jeremy Allison 2000-2003 + + ** NOTE! The following LGPL license applies to the tdb + ** library. This does NOT imply that all of Samba is released + ** under the LGPL + + This library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 3 of the License, or (at your option) any later version. + + This library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with this library; if not, see <http://www.gnu.org/licenses/>. +*/ + +#include "tdb_private.h" + +#define TDB_NEXT_LOCK_ERR ((tdb_off_t)-1) + +/* Uses traverse lock: 0 = finish, TDB_NEXT_LOCK_ERR = error, + other = record offset */ +static tdb_off_t tdb_next_lock(struct tdb_context *tdb, struct tdb_traverse_lock *tlock, + struct tdb_record *rec) +{ + int want_next = (tlock->off != 0); + + /* Lock each chain from the start one. */ + for (; tlock->list < tdb->hash_size; tlock->list++) { + if (!tlock->off && tlock->list != 0) { + /* this is an optimisation for the common case where + the hash chain is empty, which is particularly + common for the use of tdb with ldb, where large + hashes are used. In that case we spend most of our + time in tdb_brlock(), locking empty hash chains. + + To avoid this, we do an unlocked pre-check to see + if the hash chain is empty before starting to look + inside it. If it is empty then we can avoid that + hash chain. If it isn't empty then we can't believe + the value we get back, as we read it without a + lock, so instead we get the lock and re-fetch the + value below. + + Notice that not doing this optimisation on the + first hash chain is critical. We must guarantee + that we have done at least one fcntl lock at the + start of a search to guarantee that memory is + coherent on SMP systems. If records are added by + others during the search then that's OK, and we + could possibly miss those with this trick, but we + could miss them anyway without this trick, so the + semantics don't change. + + With a non-indexed ldb search this trick gains us a + factor of around 80 in speed on a linux 2.6.x + system (testing using ldbtest). + */ + tdb->methods->next_hash_chain(tdb, &tlock->list); + if (tlock->list == tdb->hash_size) { + continue; + } + } + + if (tdb_lock(tdb, tlock->list, tlock->lock_rw) == -1) + return TDB_NEXT_LOCK_ERR; + + /* No previous record? Start at top of chain. */ + if (!tlock->off) { + if (tdb_ofs_read(tdb, TDB_HASH_TOP(tlock->list), + &tlock->off) == -1) + goto fail; + } else { + /* Otherwise unlock the previous record. */ + if (tdb_unlock_record(tdb, tlock->off) != 0) + goto fail; + } + + if (want_next) { + /* We have offset of old record: grab next */ + if (tdb_rec_read(tdb, tlock->off, rec) == -1) + goto fail; + tlock->off = rec->next; + } + + /* Iterate through chain */ + while( tlock->off) { + if (tdb_rec_read(tdb, tlock->off, rec) == -1) + goto fail; + + /* Detect infinite loops. From "Shlomi Yaakobovich" <Shlomi@exanet.com>. */ + if (tlock->off == rec->next) { + tdb->ecode = TDB_ERR_CORRUPT; + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_next_lock: loop detected.\n")); + goto fail; + } + + if (!TDB_DEAD(rec)) { + /* Woohoo: we found one! */ + if (tdb_lock_record(tdb, tlock->off) != 0) + goto fail; + return tlock->off; + } + + tlock->off = rec->next; + } + tdb_unlock(tdb, tlock->list, tlock->lock_rw); + want_next = 0; + } + /* We finished iteration without finding anything */ + tdb->ecode = TDB_SUCCESS; + return 0; + + fail: + tlock->off = 0; + if (tdb_unlock(tdb, tlock->list, tlock->lock_rw) != 0) + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_next_lock: On error unlock failed!\n")); + return TDB_NEXT_LOCK_ERR; +} + +/* traverse the entire database - calling fn(tdb, key, data) on each element. + return -1 on error or the record count traversed + if fn is NULL then it is not called + a non-zero return value from fn() indicates that the traversal should stop + */ +static int tdb_traverse_internal(struct tdb_context *tdb, + tdb_traverse_func fn, void *private_data, + struct tdb_traverse_lock *tl) +{ + TDB_DATA key, dbuf; + struct tdb_record rec; + int ret = 0, count = 0; + tdb_off_t off; + size_t recbuf_len; + + recbuf_len = 4096; + key.dptr = malloc(recbuf_len); + if (key.dptr == NULL) { + return -1; + } + + /* This was in the initialization, above, but the IRIX compiler + * did not like it. crh + */ + tl->next = tdb->travlocks.next; + + /* fcntl locks don't stack: beware traverse inside traverse */ + tdb->travlocks.next = tl; + + /* tdb_next_lock places locks on the record returned, and its chain */ + while ((off = tdb_next_lock(tdb, tl, &rec)) != 0) { + tdb_len_t full_len; + int nread; + + if (off == TDB_NEXT_LOCK_ERR) { + ret = -1; + goto out; + } + + full_len = rec.key_len + rec.data_len; + + if (full_len > recbuf_len) { + recbuf_len = full_len; + + /* + * No realloc, we don't need the old data and thus can + * do without the memcpy + */ + free(key.dptr); + key.dptr = malloc(recbuf_len); + + if (key.dptr == NULL) { + ret = -1; + if (tdb_unlock(tdb, tl->list, tl->lock_rw) + != 0) { + goto out; + } + if (tdb_unlock_record(tdb, tl->off) != 0) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, + "tdb_traverse: malloc " + "failed and unlock_record " + "failed!\n")); + } + goto out; + } + } + + count++; + /* now read the full record */ + nread = tdb->methods->tdb_read(tdb, tl->off + sizeof(rec), + key.dptr, full_len, 0); + if (nread == -1) { + ret = -1; + if (tdb_unlock(tdb, tl->list, tl->lock_rw) != 0) + goto out; + if (tdb_unlock_record(tdb, tl->off) != 0) + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_traverse: key.dptr == NULL and unlock_record failed!\n")); + goto out; + } + key.dsize = rec.key_len; + dbuf.dptr = key.dptr + rec.key_len; + dbuf.dsize = rec.data_len; + + tdb_trace_1rec_retrec(tdb, "traverse", key, dbuf); + + /* Drop chain lock, call out */ + if (tdb_unlock(tdb, tl->list, tl->lock_rw) != 0) { + ret = -1; + goto out; + } + if (fn && fn(tdb, key, dbuf, private_data)) { + /* They want us to terminate traversal */ + tdb_trace_ret(tdb, "tdb_traverse_end", count); + if (tdb_unlock_record(tdb, tl->off) != 0) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_traverse: unlock_record failed!\n"));; + ret = -1; + } + goto out; + } + } + tdb_trace(tdb, "tdb_traverse_end"); +out: + SAFE_FREE(key.dptr); + tdb->travlocks.next = tl->next; + if (ret < 0) + return -1; + else + return count; +} + + +/* + a read style traverse - temporarily marks each record read only +*/ +_PUBLIC_ int tdb_traverse_read(struct tdb_context *tdb, + tdb_traverse_func fn, void *private_data) +{ + struct tdb_traverse_lock tl = { NULL, 0, 0, F_RDLCK }; + int ret; + + tdb->traverse_read++; + tdb_trace(tdb, "tdb_traverse_read_start"); + ret = tdb_traverse_internal(tdb, fn, private_data, &tl); + tdb->traverse_read--; + + return ret; +} + +/* + a write style traverse - needs to get the transaction lock to + prevent deadlocks + + WARNING: The data buffer given to the callback fn does NOT meet the + alignment guarantees malloc gives you. +*/ +_PUBLIC_ int tdb_traverse(struct tdb_context *tdb, + tdb_traverse_func fn, void *private_data) +{ + struct tdb_traverse_lock tl = { NULL, 0, 0, F_WRLCK }; + enum tdb_lock_flags lock_flags; + int ret; + + if (tdb->read_only || tdb->traverse_read) { + return tdb_traverse_read(tdb, fn, private_data); + } + + lock_flags = TDB_LOCK_WAIT; + + if (tdb->allrecord_lock.count != 0) { + /* + * This avoids a deadlock between tdb_lockall() and + * tdb_traverse(). See + * https://bugzilla.samba.org/show_bug.cgi?id=11381 + */ + lock_flags = TDB_LOCK_NOWAIT; + } + + if (tdb_transaction_lock(tdb, F_WRLCK, lock_flags)) { + return -1; + } + + tdb->traverse_write++; + tdb_trace(tdb, "tdb_traverse_start"); + ret = tdb_traverse_internal(tdb, fn, private_data, &tl); + tdb->traverse_write--; + + tdb_transaction_unlock(tdb, F_WRLCK); + + return ret; +} + + +/* find the first entry in the database and return its key */ +_PUBLIC_ TDB_DATA tdb_firstkey(struct tdb_context *tdb) +{ + TDB_DATA key; + struct tdb_record rec; + tdb_off_t off; + + /* release any old lock */ + if (tdb_unlock_record(tdb, tdb->travlocks.off) != 0) + return tdb_null; + tdb->travlocks.off = tdb->travlocks.list = 0; + tdb->travlocks.lock_rw = F_RDLCK; + + /* Grab first record: locks chain and returned record. */ + off = tdb_next_lock(tdb, &tdb->travlocks, &rec); + if (off == 0 || off == TDB_NEXT_LOCK_ERR) { + tdb_trace_retrec(tdb, "tdb_firstkey", tdb_null); + return tdb_null; + } + /* now read the key */ + key.dsize = rec.key_len; + key.dptr =tdb_alloc_read(tdb,tdb->travlocks.off+sizeof(rec),key.dsize); + + tdb_trace_retrec(tdb, "tdb_firstkey", key); + + /* Unlock the hash chain of the record we just read. */ + if (tdb_unlock(tdb, tdb->travlocks.list, tdb->travlocks.lock_rw) != 0) + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_firstkey: error occurred while tdb_unlocking!\n")); + return key; +} + +/* find the next entry in the database, returning its key */ +_PUBLIC_ TDB_DATA tdb_nextkey(struct tdb_context *tdb, TDB_DATA oldkey) +{ + uint32_t oldlist; + TDB_DATA key = tdb_null; + struct tdb_record rec; + unsigned char *k = NULL; + tdb_off_t off; + + /* Is locked key the old key? If so, traverse will be reliable. */ + if (tdb->travlocks.off) { + if (tdb_lock(tdb,tdb->travlocks.list,tdb->travlocks.lock_rw)) + return tdb_null; + if (tdb_rec_read(tdb, tdb->travlocks.off, &rec) == -1 + || !(k = tdb_alloc_read(tdb,tdb->travlocks.off+sizeof(rec), + rec.key_len)) + || memcmp(k, oldkey.dptr, oldkey.dsize) != 0) { + /* No, it wasn't: unlock it and start from scratch */ + if (tdb_unlock_record(tdb, tdb->travlocks.off) != 0) { + tdb_trace_1rec_retrec(tdb, "tdb_nextkey", + oldkey, tdb_null); + SAFE_FREE(k); + return tdb_null; + } + if (tdb_unlock(tdb, tdb->travlocks.list, tdb->travlocks.lock_rw) != 0) { + SAFE_FREE(k); + return tdb_null; + } + tdb->travlocks.off = 0; + } + + SAFE_FREE(k); + } + + if (!tdb->travlocks.off) { + /* No previous element: do normal find, and lock record */ + tdb->travlocks.off = tdb_find_lock_hash(tdb, oldkey, tdb->hash_fn(&oldkey), tdb->travlocks.lock_rw, &rec); + if (!tdb->travlocks.off) { + tdb_trace_1rec_retrec(tdb, "tdb_nextkey", oldkey, tdb_null); + return tdb_null; + } + tdb->travlocks.list = BUCKET(rec.full_hash); + if (tdb_lock_record(tdb, tdb->travlocks.off) != 0) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_nextkey: lock_record failed (%s)!\n", strerror(errno))); + return tdb_null; + } + } + oldlist = tdb->travlocks.list; + + /* Grab next record: locks chain and returned record, + unlocks old record */ + off = tdb_next_lock(tdb, &tdb->travlocks, &rec); + if (off != TDB_NEXT_LOCK_ERR && off != 0) { + key.dsize = rec.key_len; + key.dptr = tdb_alloc_read(tdb, tdb->travlocks.off+sizeof(rec), + key.dsize); + /* Unlock the chain of this new record */ + if (tdb_unlock(tdb, tdb->travlocks.list, tdb->travlocks.lock_rw) != 0) + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_nextkey: WARNING tdb_unlock failed!\n")); + } + /* Unlock the chain of old record */ + if (tdb_unlock(tdb, oldlist, tdb->travlocks.lock_rw) != 0) + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_nextkey: WARNING tdb_unlock failed!\n")); + tdb_trace_1rec_retrec(tdb, "tdb_nextkey", oldkey, key); + return key; +} + +_PUBLIC_ int tdb_traverse_chain(struct tdb_context *tdb, + unsigned chain, + tdb_traverse_func fn, + void *private_data) +{ + tdb_off_t rec_ptr; + struct tdb_chainwalk_ctx chainwalk; + int count = 0; + int ret; + + if (chain >= tdb->hash_size) { + tdb->ecode = TDB_ERR_EINVAL; + return -1; + } + + if (tdb->traverse_read != 0) { + tdb->ecode = TDB_ERR_LOCK; + return -1; + } + + ret = tdb_lock(tdb, chain, F_RDLCK); + if (ret == -1) { + return -1; + } + + tdb->traverse_read += 1; + + ret = tdb_ofs_read(tdb, TDB_HASH_TOP(chain), &rec_ptr); + if (ret == -1) { + goto fail; + } + + tdb_chainwalk_init(&chainwalk, rec_ptr); + + while (rec_ptr != 0) { + struct tdb_record rec; + bool ok; + + ret = tdb_rec_read(tdb, rec_ptr, &rec); + if (ret == -1) { + goto fail; + } + + if (!TDB_DEAD(&rec)) { + /* no overflow checks, tdb_rec_read checked it */ + tdb_off_t key_ofs = rec_ptr + sizeof(rec); + size_t full_len = rec.key_len + rec.data_len; + uint8_t *buf = NULL; + + TDB_DATA key = { .dsize = rec.key_len }; + TDB_DATA data = { .dsize = rec.data_len }; + + if ((tdb->transaction == NULL) && + (tdb->map_ptr != NULL)) { + ret = tdb_oob(tdb, key_ofs, full_len, 0); + if (ret == -1) { + goto fail; + } + key.dptr = (uint8_t *)tdb->map_ptr + key_ofs; + } else { + buf = tdb_alloc_read(tdb, key_ofs, full_len); + if (buf == NULL) { + goto fail; + } + key.dptr = buf; + } + data.dptr = key.dptr + key.dsize; + + ret = fn(tdb, key, data, private_data); + free(buf); + + count += 1; + + if (ret != 0) { + break; + } + } + + rec_ptr = rec.next; + + ok = tdb_chainwalk_check(tdb, &chainwalk, rec_ptr); + if (!ok) { + goto fail; + } + } + tdb->traverse_read -= 1; + tdb_unlock(tdb, chain, F_RDLCK); + return count; + +fail: + tdb->traverse_read -= 1; + tdb_unlock(tdb, chain, F_RDLCK); + return -1; +} + +_PUBLIC_ int tdb_traverse_key_chain(struct tdb_context *tdb, + TDB_DATA key, + tdb_traverse_func fn, + void *private_data) +{ + uint32_t hash, chain; + int ret; + + hash = tdb->hash_fn(&key); + chain = BUCKET(hash); + ret = tdb_traverse_chain(tdb, chain, fn, private_data); + + return ret; +} |