diff options
Diffstat (limited to 'lib/tdb/common')
| -rw-r--r-- | lib/tdb/common/dump.c | 137 | ||||
| -rw-r--r-- | lib/tdb/common/error.c | 57 | ||||
| -rw-r--r-- | lib/tdb/common/freelist.c | 382 | ||||
| -rw-r--r-- | lib/tdb/common/freelistcheck.c | 107 | ||||
| -rw-r--r-- | lib/tdb/common/io.c | 473 | ||||
| -rw-r--r-- | lib/tdb/common/lock.c | 553 | ||||
| -rw-r--r-- | lib/tdb/common/open.c | 488 | ||||
| -rw-r--r-- | lib/tdb/common/tdb.c | 802 | ||||
| -rw-r--r-- | lib/tdb/common/tdb_private.h | 213 | ||||
| -rw-r--r-- | lib/tdb/common/transaction.c | 1119 | ||||
| -rw-r--r-- | lib/tdb/common/traverse.c | 348 |
11 files changed, 4679 insertions, 0 deletions
diff --git a/lib/tdb/common/dump.c b/lib/tdb/common/dump.c new file mode 100644 index 0000000000..d1c902ddfd --- /dev/null +++ b/lib/tdb/common/dump.c @@ -0,0 +1,137 @@ + /* + 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 list_struct 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=%d " + "key_len=%d data_len=%d full_hash=0x%x magic=0x%x\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) +{ + tdb_off_t rec_ptr, top; + + 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); + + if (rec_ptr) + printf("hash=%d\n", i); + + while (rec_ptr) { + rec_ptr = tdb_dump_record(tdb, i, rec_ptr); + } + + return tdb_unlock(tdb, i, F_WRLCK); +} + +void tdb_dump_all(struct tdb_context *tdb) +{ + int i; + for (i=0;i<tdb->header.hash_size;i++) { + tdb_dump_chain(tdb, i); + } + printf("freelist:\n"); + tdb_dump_chain(tdb, -1); +} + +int tdb_printfreelist(struct tdb_context *tdb) +{ + int ret; + long total_free = 0; + tdb_off_t offset, rec_ptr; + struct list_struct 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 (%d)] (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%08x (%d)]\n", (int)total_free, + (int)total_free); + + return tdb_unlock(tdb, -1, F_WRLCK); +} + diff --git a/lib/tdb/common/error.c b/lib/tdb/common/error.c new file mode 100644 index 0000000000..195ab23815 --- /dev/null +++ b/lib/tdb/common/error.c @@ -0,0 +1,57 @@ + /* + 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" + +enum TDB_ERROR tdb_error(struct tdb_context *tdb) +{ + return tdb->ecode; +} + +static struct tdb_errname { + enum TDB_ERROR ecode; const char *estring; +} emap[] = { {TDB_SUCCESS, "Success"}, + {TDB_ERR_CORRUPT, "Corrupt database"}, + {TDB_ERR_IO, "IO Error"}, + {TDB_ERR_LOCK, "Locking error"}, + {TDB_ERR_OOM, "Out of memory"}, + {TDB_ERR_EXISTS, "Record exists"}, + {TDB_ERR_NOLOCK, "Lock exists on other keys"}, + {TDB_ERR_EINVAL, "Invalid parameter"}, + {TDB_ERR_NOEXIST, "Record does not exist"}, + {TDB_ERR_RDONLY, "write not permitted"} }; + +/* Error string for the last tdb error */ +const char *tdb_errorstr(struct tdb_context *tdb) +{ + uint32_t i; + for (i = 0; i < sizeof(emap) / sizeof(struct tdb_errname); i++) + if (tdb->ecode == emap[i].ecode) + return emap[i].estring; + return "Invalid error code"; +} + diff --git a/lib/tdb/common/freelist.c b/lib/tdb/common/freelist.c new file mode 100644 index 0000000000..2f2a4c379b --- /dev/null +++ b/lib/tdb/common/freelist.c @@ -0,0 +1,382 @@ + /* + 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" + +/* 'right' merges can involve O(n^2) cost when combined with a + traverse, so they are disabled until we find a way to do them in + O(1) time +*/ +#define USE_RIGHT_MERGES 0 + +/* read a freelist record and check for simple errors */ +int tdb_rec_free_read(struct tdb_context *tdb, tdb_off_t off, struct list_struct *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=%d - fixing\n", + rec->magic, off)); + rec->magic = TDB_FREE_MAGIC; + if (tdb->methods->tdb_write(tdb, off, rec, sizeof(*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=%d\n", + rec->magic, off)); + return TDB_ERRCODE(TDB_ERR_CORRUPT, -1); + } + if (tdb->methods->tdb_oob(tdb, rec->next+sizeof(*rec), 0) != 0) + return -1; + return 0; +} + + +#if USE_RIGHT_MERGES +/* Remove an element from the freelist. Must have alloc lock. */ +static int remove_from_freelist(struct tdb_context *tdb, tdb_off_t off, tdb_off_t next) +{ + tdb_off_t last_ptr, i; + + /* read in the freelist top */ + last_ptr = FREELIST_TOP; + while (tdb_ofs_read(tdb, last_ptr, &i) != -1 && i != 0) { + if (i == off) { + /* We've found it! */ + return tdb_ofs_write(tdb, last_ptr, &next); + } + /* Follow chain (next offset is at start of record) */ + last_ptr = i; + } + TDB_LOG((tdb, TDB_DEBUG_FATAL,"remove_from_freelist: not on list at off=%d\n", off)); + return TDB_ERRCODE(TDB_ERR_CORRUPT, -1); +} +#endif + + +/* update a record tailer (must hold allocation lock) */ +static int update_tailer(struct tdb_context *tdb, tdb_off_t offset, + const struct list_struct *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); +} + +/* Add an element into the freelist. Merge adjacent records if + neccessary. */ +int tdb_free(struct tdb_context *tdb, tdb_off_t offset, struct list_struct *rec) +{ + /* 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; + } + +#if USE_RIGHT_MERGES + /* Look right first (I'm an Australian, dammit) */ + if (offset + sizeof(*rec) + rec->rec_len + sizeof(*rec) <= tdb->map_size) { + tdb_off_t right = offset + sizeof(*rec) + rec->rec_len; + struct list_struct r; + + if (tdb->methods->tdb_read(tdb, right, &r, sizeof(r), DOCONV()) == -1) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_free: right read failed at %u\n", right)); + goto left; + } + + /* If it's free, expand to include it. */ + if (r.magic == TDB_FREE_MAGIC) { + if (remove_from_freelist(tdb, right, r.next) == -1) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_free: right free failed at %u\n", right)); + goto left; + } + rec->rec_len += sizeof(r) + r.rec_len; + if (update_tailer(tdb, offset, rec) == -1) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_free: update_tailer failed at %u\n", offset)); + goto fail; + } + } + } +left: +#endif + + /* Look left */ + if (offset - sizeof(tdb_off_t) > TDB_DATA_START(tdb->header.hash_size)) { + tdb_off_t left = offset - sizeof(tdb_off_t); + struct list_struct l; + tdb_off_t leftsize; + + /* Read in tailer and jump back to header */ + if (tdb_ofs_read(tdb, left, &leftsize) == -1) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_free: left offset read failed at %u\n", left)); + goto update; + } + + /* it could be uninitialised data */ + if (leftsize == 0 || leftsize == TDB_PAD_U32) { + goto update; + } + + left = offset - leftsize; + + if (leftsize > offset || + left < TDB_DATA_START(tdb->header.hash_size)) { + goto update; + } + + /* Now read in the left record */ + if (tdb->methods->tdb_read(tdb, left, &l, sizeof(l), DOCONV()) == -1) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_free: left read failed at %u (%u)\n", left, leftsize)); + goto update; + } + + /* If it's free, expand to include it. */ + if (l.magic == TDB_FREE_MAGIC) { + /* we now merge the new record into the left record, rather than the other + way around. This makes the operation O(1) instead of O(n). This change + prevents traverse from being O(n^2) after a lot of deletes */ + l.rec_len += sizeof(*rec) + rec->rec_len; + if (tdb_rec_write(tdb, left, &l) == -1) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_free: update_left failed at %u\n", left)); + goto fail; + } + if (update_tailer(tdb, left, &l) == -1) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_free: update_tailer failed at %u\n", offset)); + goto fail; + } + tdb_unlock(tdb, -1, F_WRLCK); + return 0; + } + } + +update: + + /* Now, 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=%d\n", offset)); + goto fail; + } + + /* 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 list_struct *rec, tdb_off_t last_ptr) +{ +#define MIN_REC_SIZE (sizeof(struct list_struct) + 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 list_struct within the database with room for at + least length bytes of total data + + 0 is returned if the space could not be allocated + */ +tdb_off_t tdb_allocate(struct tdb_context *tdb, tdb_len_t length, struct list_struct *rec) +{ + tdb_off_t rec_ptr, last_ptr, newrec_ptr; + struct { + tdb_off_t rec_ptr, last_ptr; + tdb_len_t rec_len; + } bestfit; + float multiplier = 1.0; + + if (tdb_lock(tdb, -1, F_WRLCK) == -1) + return 0; + + /* Extra bytes required for tailer */ + length += sizeof(tdb_off_t); + length = TDB_ALIGN(length, TDB_ALIGNMENT); + + again: + last_ptr = FREELIST_TOP; + + /* read in the freelist top */ + if (tdb_ofs_read(tdb, FREELIST_TOP, &rec_ptr) == -1) + goto fail; + + 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) { + if (tdb_rec_free_read(tdb, rec_ptr, rec) == -1) { + goto fail; + } + + 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 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) { + goto fail; + } + + newrec_ptr = tdb_allocate_ofs(tdb, length, bestfit.rec_ptr, + rec, bestfit.last_ptr); + tdb_unlock(tdb, -1, F_WRLCK); + return newrec_ptr; + } + + /* 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; + fail: + tdb_unlock(tdb, -1, F_WRLCK); + return 0; +} + + + +/* + return the size of the freelist - used to decide if we should repack +*/ +int tdb_freelist_size(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; +} diff --git a/lib/tdb/common/freelistcheck.c b/lib/tdb/common/freelistcheck.c new file mode 100644 index 0000000000..efc050df9c --- /dev/null +++ b/lib/tdb/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, data; + + memset(&data, '\0', sizeof(data)); + key.dptr = (unsigned char *)&rec_ptr; + key.dsize = sizeof(rec_ptr); + return tdb_store(mem_tdb, key, data, TDB_INSERT); +} + +int tdb_validate_freelist(struct tdb_context *tdb, int *pnum_entries) +{ + struct tdb_context *mem_tdb = NULL; + struct list_struct rec; + tdb_off_t rec_ptr, last_ptr; + int ret = -1; + + *pnum_entries = 0; + + mem_tdb = tdb_open("flval", tdb->header.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) { + ret = TDB_ERRCODE(TDB_ERR_CORRUPT, -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)) { + ret = TDB_ERRCODE(TDB_ERR_CORRUPT, -1); + goto fail; + } + + if (tdb_rec_free_read(tdb, rec_ptr, &rec) == -1) { + goto fail; + } + + /* move to the next record */ + last_ptr = rec_ptr; + 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/lib/tdb/common/io.c b/lib/tdb/common/io.c new file mode 100644 index 0000000000..661f761489 --- /dev/null +++ b/lib/tdb/common/io.c @@ -0,0 +1,473 @@ + /* + 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" + +/* 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 + note that "len" is the minimum length needed for the db +*/ +static int tdb_oob(struct tdb_context *tdb, tdb_off_t len, int probe) +{ + struct stat st; + if (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 %d beyond internal malloc size %d\n", + (int)len, (int)tdb->map_size)); + } + return TDB_ERRCODE(TDB_ERR_IO, -1); + } + + if (fstat(tdb->fd, &st) == -1) { + return TDB_ERRCODE(TDB_ERR_IO, -1); + } + + if (st.st_size < (size_t)len) { + if (!probe) { + /* Ensure ecode is set for log fn. */ + tdb->ecode = TDB_ERR_IO; + TDB_LOG((tdb, TDB_DEBUG_FATAL,"tdb_oob len %d beyond eof at %d\n", + (int)len, (int)st.st_size)); + } + return TDB_ERRCODE(TDB_ERR_IO, -1); + } + + /* Unmap, update size, remap */ + if (tdb_munmap(tdb) == -1) + return TDB_ERRCODE(TDB_ERR_IO, -1); + tdb->map_size = st.st_size; + tdb_mmap(tdb); + 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->methods->tdb_oob(tdb, off + len, 0) != 0) + return -1; + + if (tdb->map_ptr) { + memcpy(off + (char *)tdb->map_ptr, buf, len); + } else { + ssize_t written = pwrite(tdb->fd, buf, len, off); + if ((written != (ssize_t)len) && (written != -1)) { + /* try once more */ + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_write: wrote only " + "%d of %d bytes at %d, trying once more\n", + (int)written, len, off)); + errno = ENOSPC; + written = pwrite(tdb->fd, (const void *)((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 %d " + "len=%d (%s)\n", off, len, strerror(errno))); + return TDB_ERRCODE(TDB_ERR_IO, -1); + } else if (written != (ssize_t)len) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_write: failed to " + "write %d bytes at %d in two attempts\n", + len, off)); + errno = ENOSPC; + return TDB_ERRCODE(TDB_ERR_IO, -1); + } + } + 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->methods->tdb_oob(tdb, off + len, 0) != 0) { + return -1; + } + + if (tdb->map_ptr) { + memcpy(buf, off + (char *)tdb->map_ptr, len); + } else { + ssize_t ret = pread(tdb->fd, 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 %d " + "len=%d ret=%d (%s) map_size=%d\n", + (int)off, (int)len, (int)ret, strerror(errno), + (int)tdb->map_size)); + return TDB_ERRCODE(TDB_ERR_IO, -1); + } + } + 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->header.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->header.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; +} + +void tdb_mmap(struct tdb_context *tdb) +{ + if (tdb->flags & TDB_INTERNAL) + return; + +#ifdef HAVE_MMAP + if (!(tdb->flags & TDB_NOMMAP)) { + tdb->map_ptr = mmap(NULL, tdb->map_size, + PROT_READ|(tdb->read_only? 0:PROT_WRITE), + MAP_SHARED|MAP_FILE, tdb->fd, 0); + + /* + * 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 %d (%s)\n", + tdb->map_size, strerror(errno))); + } + } else { + tdb->map_ptr = NULL; + } +#else + tdb->map_ptr = NULL; +#endif +} + +/* 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]; + + if (tdb->read_only || tdb->traverse_read) { + tdb->ecode = TDB_ERR_RDONLY; + return -1; + } + + if (ftruncate(tdb->fd, size+addition) == -1) { + char b = 0; + ssize_t written = pwrite(tdb->fd, &b, 1, (size+addition) - 1); + if (written == 0) { + /* try once more, potentially revealing errno */ + written = pwrite(tdb->fd, &b, 1, (size+addition) - 1); + } + if (written == 0) { + /* again - give up, guessing errno */ + errno = ENOSPC; + } + if (written != 1) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "expand_file to %d failed (%s)\n", + size+addition, 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 = pwrite(tdb->fd, buf, n, size); + if (written == 0) { + /* prevent infinite loops: try _once_ more */ + written = pwrite(tdb->fd, buf, n, size); + } + if (written == 0) { + /* give up, trying to provide a useful errno */ + TDB_LOG((tdb, TDB_DEBUG_FATAL, "expand_file write " + "returned 0 twice: giving up!\n")); + errno = ENOSPC; + return -1; + } else if (written == -1) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "expand_file write of " + "%d bytes failed (%s)\n", (int)n, + strerror(errno))); + return -1; + } else if (written != n) { + TDB_LOG((tdb, TDB_DEBUG_WARNING, "expand_file: wrote " + "only %d of %d bytes - retrying\n", (int)written, + (int)n)); + } + addition -= written; + size += written; + } + return 0; +} + + +/* 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 list_struct rec; + tdb_off_t offset, 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->methods->tdb_oob(tdb, tdb->map_size + 1, 1); + + /* always make room for at least 100 more records, and at + least 25% more space. Round the database up to a multiple + of the page size */ + new_size = MAX(tdb->map_size + size*100, tdb->map_size * 1.25); + size = TDB_ALIGN(new_size, tdb->page_size) - tdb->map_size; + + if (!(tdb->flags & TDB_INTERNAL)) + tdb_munmap(tdb); + + /* + * We must ensure the file is unmapped before doing this + * to ensure consistency with systems like OpenBSD where + * writes and mmaps are not consistent. + */ + + /* expand the file itself */ + if (!(tdb->flags & TDB_INTERNAL)) { + if (tdb->methods->tdb_expand_file(tdb, tdb->map_size, size) != 0) + goto fail; + } + + tdb->map_size += size; + + if (tdb->flags & TDB_INTERNAL) { + char *new_map_ptr = (char *)realloc(tdb->map_ptr, + tdb->map_size); + if (!new_map_ptr) { + tdb->map_size -= size; + goto fail; + } + tdb->map_ptr = new_map_ptr; + } else { + /* + * We must ensure the file is remapped before adding the space + * to ensure consistency with systems like OpenBSD where + * writes and mmaps are not consistent. + */ + + /* We're ok if the mmap fails as we'll fallback to read/write */ + tdb_mmap(tdb); + } + + /* form a new freelist record */ + memset(&rec,'\0',sizeof(rec)); + rec.rec_len = size - sizeof(rec); + + /* link it into the free list */ + offset = tdb->map_size - size; + 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; +} + +/* 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 (len == 0) { + len = 1; + } + + if (!(buf = (unsigned char *)malloc(len))) { + /* Ensure ecode is set for log fn. */ + tdb->ecode = TDB_ERR_OOM; + TDB_LOG((tdb, TDB_DEBUG_ERROR,"tdb_alloc_read malloc failed len=%d (%s)\n", + len, strerror(errno))); + return TDB_ERRCODE(TDB_ERR_OOM, buf); + } + 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->methods->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 list_struct *rec) +{ + 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=%d\n", rec->magic, offset)); + return TDB_ERRCODE(TDB_ERR_CORRUPT, -1); + } + return tdb->methods->tdb_oob(tdb, rec->next+sizeof(*rec), 0); +} + +int tdb_rec_write(struct tdb_context *tdb, tdb_off_t offset, struct list_struct *rec) +{ + struct list_struct 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_oob, + tdb_expand_file, + tdb_brlock +}; + +/* + initialise the default methods table +*/ +void tdb_io_init(struct tdb_context *tdb) +{ + tdb->methods = &io_methods; +} diff --git a/lib/tdb/common/lock.c b/lib/tdb/common/lock.c new file mode 100644 index 0000000000..f156c0fa7b --- /dev/null +++ b/lib/tdb/common/lock.c @@ -0,0 +1,553 @@ + /* + 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_MARK_LOCK 0x80000000 + +void tdb_setalarm_sigptr(struct tdb_context *tdb, volatile sig_atomic_t *ptr) +{ + tdb->interrupt_sig_ptr = ptr; +} + +/* a byte range locking function - return 0 on success + this functions locks/unlocks 1 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, tdb_off_t offset, + int rw_type, int lck_type, int probe, size_t len) +{ + struct flock fl; + int ret; + + if (tdb->flags & TDB_NOLOCK) { + return 0; + } + + if ((rw_type == F_WRLCK) && (tdb->read_only || tdb->traverse_read)) { + tdb->ecode = TDB_ERR_RDONLY; + return -1; + } + + fl.l_type = rw_type; + fl.l_whence = SEEK_SET; + fl.l_start = offset; + fl.l_len = len; + fl.l_pid = 0; + + do { + ret = fcntl(tdb->fd,lck_type,&fl); + + /* 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) { + /* Generic lock error. errno set by fcntl. + * EAGAIN is an expected return from non-blocking + * locks. */ + if (!probe && lck_type != F_SETLK) { + /* Ensure error code is set for log fun to examine. */ + tdb->ecode = TDB_ERR_LOCK; + TDB_LOG((tdb, TDB_DEBUG_TRACE,"tdb_brlock failed (fd=%d) at offset %d rw_type=%d lck_type=%d len=%d\n", + tdb->fd, offset, rw_type, lck_type, (int)len)); + } + return TDB_ERRCODE(TDB_ERR_LOCK, -1); + } + return 0; +} + + +/* + upgrade a read lock to a write lock. This needs to be handled in a + special way as 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. +*/ +int tdb_brlock_upgrade(struct tdb_context *tdb, tdb_off_t offset, size_t len) +{ + int count = 1000; + while (count--) { + struct timeval tv; + if (tdb_brlock(tdb, offset, F_WRLCK, F_SETLKW, 1, len) == 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); + } + TDB_LOG((tdb, TDB_DEBUG_TRACE,"tdb_brlock_upgrade failed at offset %d\n", offset)); + return -1; +} + + +/* lock a list in the database. list -1 is the alloc list */ +static int _tdb_lock(struct tdb_context *tdb, int list, int ltype, int op) +{ + struct tdb_lock_type *new_lck; + int i; + bool mark_lock = ((ltype & TDB_MARK_LOCK) == TDB_MARK_LOCK); + + ltype &= ~TDB_MARK_LOCK; + + /* a global lock allows us to avoid per chain locks */ + if (tdb->global_lock.count && + (ltype == tdb->global_lock.ltype || ltype == F_RDLCK)) { + return 0; + } + + if (tdb->global_lock.count) { + return TDB_ERRCODE(TDB_ERR_LOCK, -1); + } + + if (list < -1 || list >= (int)tdb->header.hash_size) { + TDB_LOG((tdb, TDB_DEBUG_ERROR,"tdb_lock: invalid list %d for ltype=%d\n", + list, ltype)); + return -1; + } + if (tdb->flags & TDB_NOLOCK) + return 0; + + for (i=0; i<tdb->num_lockrecs; i++) { + if (tdb->lockrecs[i].list == list) { + if (tdb->lockrecs[i].count == 0) { + /* + * Can't happen, see tdb_unlock(). It should + * be an assert. + */ + TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_lock: " + "lck->count == 0 for list %d", list)); + } + /* + * Just increment the in-memory struct, posix locks + * don't stack. + */ + tdb->lockrecs[i].count++; + return 0; + } + } + + 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 = 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 (!mark_lock && + tdb->methods->tdb_brlock(tdb,FREELIST_TOP+4*list, ltype, op, + 0, 1)) { + return -1; + } + + tdb->num_locks++; + + tdb->lockrecs[tdb->num_lockrecs].list = list; + tdb->lockrecs[tdb->num_lockrecs].count = 1; + tdb->lockrecs[tdb->num_lockrecs].ltype = ltype; + tdb->num_lockrecs += 1; + + return 0; +} + +/* 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(tdb, list, ltype, F_SETLKW); + 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 */ +int tdb_lock_nonblock(struct tdb_context *tdb, int list, int ltype) +{ + return _tdb_lock(tdb, list, ltype, F_SETLK); +} + + +/* unlock the database: returns void because it's too late for errors. */ + /* changed to return int it may be interesting to know there + has been an error --simo */ +int tdb_unlock(struct tdb_context *tdb, int list, int ltype) +{ + int ret = -1; + int i; + struct tdb_lock_type *lck = NULL; + bool mark_lock = ((ltype & TDB_MARK_LOCK) == TDB_MARK_LOCK); + + ltype &= ~TDB_MARK_LOCK; + + /* a global lock allows us to avoid per chain locks */ + if (tdb->global_lock.count && + (ltype == tdb->global_lock.ltype || ltype == F_RDLCK)) { + return 0; + } + + if (tdb->global_lock.count) { + return TDB_ERRCODE(TDB_ERR_LOCK, -1); + } + + if (tdb->flags & TDB_NOLOCK) + return 0; + + /* Sanity checks */ + if (list < -1 || list >= (int)tdb->header.hash_size) { + TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_unlock: list %d invalid (%d)\n", list, tdb->header.hash_size)); + return ret; + } + + for (i=0; i<tdb->num_lockrecs; i++) { + if (tdb->lockrecs[i].list == list) { + lck = &tdb->lockrecs[i]; + break; + } + } + + 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->methods->tdb_brlock(tdb, FREELIST_TOP+4*list, F_UNLCK, + F_SETLKW, 0, 1); + } + tdb->num_locks--; + + /* + * Shrink the array by overwriting the element just unlocked with the + * last array element. + */ + + if (tdb->num_lockrecs > 1) { + *lck = tdb->lockrecs[tdb->num_lockrecs-1]; + } + tdb->num_lockrecs -= 1; + + /* + * 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 (tdb->num_lockrecs == 0) { + SAFE_FREE(tdb->lockrecs); + } + + if (ret) + TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_unlock: An error occurred unlocking!\n")); + return ret; +} + +/* + get the transaction lock + */ +int tdb_transaction_lock(struct tdb_context *tdb, int ltype) +{ + if (tdb->have_transaction_lock || tdb->global_lock.count) { + return 0; + } + if (tdb->methods->tdb_brlock(tdb, TRANSACTION_LOCK, ltype, + F_SETLKW, 0, 1) == -1) { + TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_lock: failed to get transaction lock\n")); + tdb->ecode = TDB_ERR_LOCK; + return -1; + } + tdb->have_transaction_lock = 1; + return 0; +} + +/* + release the transaction lock + */ +int tdb_transaction_unlock(struct tdb_context *tdb) +{ + int ret; + if (!tdb->have_transaction_lock) { + return 0; + } + ret = tdb->methods->tdb_brlock(tdb, TRANSACTION_LOCK, F_UNLCK, F_SETLKW, 0, 1); + if (ret == 0) { + tdb->have_transaction_lock = 0; + } + return ret; +} + + + + +/* lock/unlock entire database */ +static int _tdb_lockall(struct tdb_context *tdb, int ltype, int op) +{ + bool mark_lock = ((ltype & TDB_MARK_LOCK) == TDB_MARK_LOCK); + + ltype &= ~TDB_MARK_LOCK; + + /* There are no locks on read-only dbs */ + if (tdb->read_only || tdb->traverse_read) + return TDB_ERRCODE(TDB_ERR_LOCK, -1); + + if (tdb->global_lock.count && tdb->global_lock.ltype == ltype) { + tdb->global_lock.count++; + return 0; + } + + if (tdb->global_lock.count) { + /* a global lock of a different type exists */ + return TDB_ERRCODE(TDB_ERR_LOCK, -1); + } + + if (tdb->num_locks != 0) { + /* can't combine global and chain locks */ + return TDB_ERRCODE(TDB_ERR_LOCK, -1); + } + + if (!mark_lock && + tdb->methods->tdb_brlock(tdb, FREELIST_TOP, ltype, op, + 0, 4*tdb->header.hash_size)) { + if (op == F_SETLKW) { + TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_lockall failed (%s)\n", strerror(errno))); + } + return -1; + } + + tdb->global_lock.count = 1; + tdb->global_lock.ltype = ltype; + + return 0; +} + + + +/* unlock entire db */ +static int _tdb_unlockall(struct tdb_context *tdb, int ltype) +{ + bool mark_lock = ((ltype & TDB_MARK_LOCK) == TDB_MARK_LOCK); + + ltype &= ~TDB_MARK_LOCK; + + /* There are no locks on read-only dbs */ + if (tdb->read_only || tdb->traverse_read) { + return TDB_ERRCODE(TDB_ERR_LOCK, -1); + } + + if (tdb->global_lock.ltype != ltype || tdb->global_lock.count == 0) { + return TDB_ERRCODE(TDB_ERR_LOCK, -1); + } + + if (tdb->global_lock.count > 1) { + tdb->global_lock.count--; + return 0; + } + + if (!mark_lock && + tdb->methods->tdb_brlock(tdb, FREELIST_TOP, F_UNLCK, F_SETLKW, + 0, 4*tdb->header.hash_size)) { + TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_unlockall failed (%s)\n", strerror(errno))); + return -1; + } + + tdb->global_lock.count = 0; + tdb->global_lock.ltype = 0; + + return 0; +} + +/* lock entire database with write lock */ +int tdb_lockall(struct tdb_context *tdb) +{ + return _tdb_lockall(tdb, F_WRLCK, F_SETLKW); +} + +/* lock entire database with write lock - mark only */ +int tdb_lockall_mark(struct tdb_context *tdb) +{ + return _tdb_lockall(tdb, F_WRLCK | TDB_MARK_LOCK, F_SETLKW); +} + +/* unlock entire database with write lock - unmark only */ +int tdb_lockall_unmark(struct tdb_context *tdb) +{ + return _tdb_unlockall(tdb, F_WRLCK | TDB_MARK_LOCK); +} + +/* lock entire database with write lock - nonblocking varient */ +int tdb_lockall_nonblock(struct tdb_context *tdb) +{ + return _tdb_lockall(tdb, F_WRLCK, F_SETLK); +} + +/* unlock entire database with write lock */ +int tdb_unlockall(struct tdb_context *tdb) +{ + return _tdb_unlockall(tdb, F_WRLCK); +} + +/* lock entire database with read lock */ +int tdb_lockall_read(struct tdb_context *tdb) +{ + return _tdb_lockall(tdb, F_RDLCK, F_SETLKW); +} + +/* lock entire database with read lock - nonblock varient */ +int tdb_lockall_read_nonblock(struct tdb_context *tdb) +{ + return _tdb_lockall(tdb, F_RDLCK, F_SETLK); +} + +/* unlock entire database with read lock */ +int tdb_unlockall_read(struct tdb_context *tdb) +{ + return _tdb_unlockall(tdb, F_RDLCK); +} + +/* lock/unlock one hash chain. This is meant to be used to reduce + contention - it cannot guarantee how many records will be locked */ +int tdb_chainlock(struct tdb_context *tdb, TDB_DATA key) +{ + return tdb_lock(tdb, BUCKET(tdb->hash_fn(&key)), F_WRLCK); +} + +/* 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 */ +int tdb_chainlock_nonblock(struct tdb_context *tdb, TDB_DATA key) +{ + return tdb_lock_nonblock(tdb, BUCKET(tdb->hash_fn(&key)), F_WRLCK); +} + +/* mark a chain as locked without actually locking it. Warning! use with great caution! */ +int tdb_chainlock_mark(struct tdb_context *tdb, TDB_DATA key) +{ + return tdb_lock(tdb, BUCKET(tdb->hash_fn(&key)), F_WRLCK | TDB_MARK_LOCK); +} + +/* unmark a chain as locked without actually locking it. Warning! use with great caution! */ +int tdb_chainlock_unmark(struct tdb_context *tdb, TDB_DATA key) +{ + return tdb_unlock(tdb, BUCKET(tdb->hash_fn(&key)), F_WRLCK | TDB_MARK_LOCK); +} + +int tdb_chainunlock(struct tdb_context *tdb, TDB_DATA key) +{ + return tdb_unlock(tdb, BUCKET(tdb->hash_fn(&key)), F_WRLCK); +} + +int tdb_chainlock_read(struct tdb_context *tdb, TDB_DATA key) +{ + return tdb_lock(tdb, BUCKET(tdb->hash_fn(&key)), F_RDLCK); +} + +int tdb_chainunlock_read(struct tdb_context *tdb, TDB_DATA key) +{ + return tdb_unlock(tdb, BUCKET(tdb->hash_fn(&key)), F_RDLCK); +} + + + +/* record lock stops delete underneath */ +int tdb_lock_record(struct tdb_context *tdb, tdb_off_t off) +{ + if (tdb->global_lock.count) { + return 0; + } + return off ? tdb->methods->tdb_brlock(tdb, off, F_RDLCK, F_SETLKW, 0, 1) : 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; + for (i = &tdb->travlocks; i; i = i->next) + if (i->off == off) + return -1; + return tdb->methods->tdb_brlock(tdb, off, F_WRLCK, F_SETLK, 1, 1); +} + +/* + 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_unlock_record(struct tdb_context *tdb, tdb_off_t off) +{ + return tdb->methods->tdb_brlock(tdb, off, F_UNLCK, F_SETLK, 0, 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->global_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->methods->tdb_brlock(tdb, off, F_UNLCK, F_SETLKW, 0, 1) : 0); +} diff --git a/lib/tdb/common/open.c b/lib/tdb/common/open.c new file mode 100644 index 0000000000..b19e4cea29 --- /dev/null +++ b/lib/tdb/common/open.c @@ -0,0 +1,488 @@ + /* + 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; + + +/* This is based on the hash algorithm from gdbm */ +static unsigned int default_tdb_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); +} + + +/* initialise a new database with a specified hash size */ +static int tdb_new_database(struct tdb_context *tdb, int hash_size) +{ + struct tdb_header *newdb; + size_t size; + int ret = -1; + ssize_t written; + + /* 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))) + return TDB_ERRCODE(TDB_ERR_OOM, -1); + + /* Fill in the header */ + newdb->version = TDB_VERSION; + newdb->hash_size = hash_size; + if (tdb->flags & TDB_INTERNAL) { + tdb->map_size = size; + tdb->map_ptr = (char *)newdb; + memcpy(&tdb->header, newdb, sizeof(tdb->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; + + /* This creates an endian-converted header, as if read from disk */ + CONVERT(*newdb); + memcpy(&tdb->header, newdb, sizeof(tdb->header)); + /* Don't endian-convert the magic food! */ + memcpy(newdb->magic_food, TDB_MAGIC_FOOD, strlen(TDB_MAGIC_FOOD)+1); + /* we still have "ret == -1" here */ + written = write(tdb->fd, newdb, size); + if (written == size) { + ret = 0; + } else if (written != -1) { + /* call write once again, this usually should return -1 and + * set errno appropriately */ + size -= written; + written = write(tdb->fd, newdb+written, size); + if (written == size) { + ret = 0; + } else if (written >= 0) { + /* a second incomplete write - we give up. + * guessing the errno... */ + errno = ENOSPC; + } + } + + 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. */ +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, ...) +{ +} + + +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) +{ + struct tdb_context *tdb; + struct stat st; + int rev = 0, locked = 0; + unsigned char *vp; + uint32_t vertest; + unsigned v; + + if (!(tdb = (struct tdb_context *)calloc(1, sizeof *tdb))) { + /* Can't log this */ + errno = ENOMEM; + goto fail; + } + tdb_io_init(tdb); + tdb->fd = -1; + 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; + } + tdb->hash_fn = hash_fn ? hash_fn : default_tdb_hash; + + /* 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; + } + + /* 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, hash_size) != 0) { + TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_open_ex: tdb_new_database failed!")); + goto fail; + } + 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->methods->tdb_brlock(tdb, GLOBAL_LOCK, F_WRLCK, F_SETLKW, 0, 1) == -1) { + TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_open_ex: failed to get global 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) && + (locked = (tdb->methods->tdb_brlock(tdb, ACTIVE_LOCK, F_WRLCK, F_SETLK, 0, 1) == 0))) { + open_flags |= O_CREAT; + if (ftruncate(tdb->fd, 0) == -1) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_open_ex: " + "failed to truncate %s: %s\n", + name, strerror(errno))); + goto fail; /* errno set by ftruncate */ + } + } + + errno = 0; + if (read(tdb->fd, &tdb->header, sizeof(tdb->header)) != sizeof(tdb->header) + || strcmp(tdb->header.magic_food, TDB_MAGIC_FOOD) != 0 + || (tdb->header.version != TDB_VERSION + && !(rev = (tdb->header.version==TDB_BYTEREV(TDB_VERSION))))) { + /* its not a valid database - possibly initialise it */ + if (!(open_flags & O_CREAT) || tdb_new_database(tdb, hash_size) == -1) { + if (errno == 0) { + errno = EIO; /* ie bad format or something */ + } + goto fail; + } + rev = (tdb->flags & TDB_CONVERT); + } + vp = (unsigned char *)&tdb->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(&tdb->header, sizeof(tdb->header)); + } + if (fstat(tdb->fd, &st) == -1) + goto fail; + + if (tdb->header.rwlocks != 0) { + TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_open_ex: spinlocks no longer supported\n")); + goto fail; + } + + /* Is it already in the open list? If so, fail. */ + if (tdb_already_open(st.st_dev, st.st_ino)) { + TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_open_ex: " + "%s (%d,%d) is already open in this process\n", + name, (int)st.st_dev, (int)st.st_ino)); + errno = EBUSY; + goto fail; + } + + if (!(tdb->name = (char *)strdup(name))) { + errno = ENOMEM; + goto fail; + } + + tdb->map_size = st.st_size; + tdb->device = st.st_dev; + tdb->inode = st.st_ino; + tdb_mmap(tdb); + if (locked) { + if (tdb->methods->tdb_brlock(tdb, ACTIVE_LOCK, F_UNLCK, F_SETLK, 0, 1) == -1) { + TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_open_ex: " + "failed to take ACTIVE_LOCK on %s: %s\n", + name, strerror(errno))); + goto fail; + } + + } + + /* 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. */ + + if (tdb_flags & TDB_CLEAR_IF_FIRST) { + /* leave this lock in place to indicate it's in use */ + if (tdb->methods->tdb_brlock(tdb, ACTIVE_LOCK, F_RDLCK, F_SETLKW, 0, 1) == -1) + goto fail; + } + + /* if needed, run recovery */ + if (tdb_transaction_recover(tdb) == -1) { + goto fail; + } + + internal: + /* Internal (memory-only) databases skip all the code above to + * do with disk files, and resume here by releasing their + * global lock and hooking into the active list. */ + if (tdb->methods->tdb_brlock(tdb, GLOBAL_LOCK, F_UNLCK, F_SETLKW, 0, 1) == -1) + goto fail; + tdb->next = tdbs; + tdbs = tdb; + return tdb; + + fail: + { int save_errno = errno; + + if (!tdb) + return NULL; + + if (tdb->map_ptr) { + if (tdb->flags & TDB_INTERNAL) + SAFE_FREE(tdb->map_ptr); + else + tdb_munmap(tdb); + } + SAFE_FREE(tdb->name); + 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); + errno = save_errno; + return NULL; + } +} + +/* + * Set the maximum number of dead records per hash chain + */ + +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. + **/ +int tdb_close(struct tdb_context *tdb) +{ + struct tdb_context **i; + int ret = 0; + + if (tdb->transaction) { + tdb_transaction_cancel(tdb); + } + + if (tdb->map_ptr) { + if (tdb->flags & TDB_INTERNAL) + SAFE_FREE(tdb->map_ptr); + else + tdb_munmap(tdb); + } + SAFE_FREE(tdb->name); + if (tdb->fd != -1) + ret = close(tdb->fd); + SAFE_FREE(tdb->lockrecs); + + /* Remove from contexts list */ + for (i = &tdbs; *i; i = &(*i)->next) { + if (*i == tdb) { + *i = tdb->next; + break; + } + } + + memset(tdb, 0, sizeof(*tdb)); + SAFE_FREE(tdb); + + return ret; +} + +/* register a loging function */ +void tdb_set_logging_function(struct tdb_context *tdb, + const struct tdb_logging_context *log_ctx) +{ + tdb->log = *log_ctx; +} + +void *tdb_get_logging_private(struct tdb_context *tdb) +{ + return tdb->log.log_private; +} + +/* 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 */ +int tdb_reopen(struct tdb_context *tdb) +{ + struct stat st; + + if (tdb->flags & TDB_INTERNAL) { + return 0; /* Nothing to do. */ + } + + if (tdb->num_locks != 0 || tdb->global_lock.count) { + 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 (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; + } + if ((tdb->flags & TDB_CLEAR_IF_FIRST) && + (tdb->methods->tdb_brlock(tdb, ACTIVE_LOCK, F_RDLCK, F_SETLKW, 0, 1) == -1)) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_reopen: failed to obtain active lock\n")); + goto fail; + } + 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; + } + tdb_mmap(tdb); + + return 0; + +fail: + tdb_close(tdb); + return -1; +} + +/* reopen all tdb's */ +int tdb_reopen_all(int parent_longlived) +{ + struct tdb_context *tdb; + + for (tdb=tdbs; tdb; tdb = tdb->next) { + /* + * 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. */ + tdb->flags &= ~TDB_CLEAR_IF_FIRST; + } + + if (tdb_reopen(tdb) != 0) + return -1; + } + + return 0; +} diff --git a/lib/tdb/common/tdb.c b/lib/tdb/common/tdb.c new file mode 100644 index 0000000000..c7cec297f6 --- /dev/null +++ b/lib/tdb/common/tdb.c @@ -0,0 +1,802 @@ + /* + 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" + +TDB_DATA tdb_null; + +/* + non-blocking increment of the tdb sequence number if the tdb has been opened using + the TDB_SEQNUM flag +*/ +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_brlock(tdb, TDB_SEQNUM_OFS, F_WRLCK, F_SETLKW, 1, 1) != 0) { + return; + } + + tdb_increment_seqnum_nonblock(tdb); + + tdb_brlock(tdb, TDB_SEQNUM_OFS, F_UNLCK, F_SETLKW, 1, 1); +} + +static int tdb_key_compare(TDB_DATA key, TDB_DATA data, void *private_data) +{ + return memcmp(data.dptr, key.dptr, data.dsize); +} + +/* 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 list_struct *r) +{ + tdb_off_t rec_ptr; + + /* read in the hash top */ + if (tdb_ofs_read(tdb, TDB_HASH_TOP(hash), &rec_ptr) == -1) + return 0; + + /* keep looking until we find the right record */ + while (rec_ptr) { + 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; + } + return TDB_ERRCODE(TDB_ERR_NOEXIST, 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 list_struct *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; +} + + +/* 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, TDB_DATA dbuf) +{ + struct list_struct rec; + tdb_off_t rec_ptr; + + /* find entry */ + if (!(rec_ptr = tdb_find(tdb, key, hash, &rec))) + return -1; + + /* must be long enough key, data and tailer */ + if (rec.rec_len < key.dsize + dbuf.dsize + sizeof(tdb_off_t)) { + tdb->ecode = TDB_SUCCESS; /* Not really an error */ + return -1; + } + + if (tdb->methods->tdb_write(tdb, rec_ptr + sizeof(rec) + rec.key_len, + dbuf.dptr, dbuf.dsize) == -1) + return -1; + + if (dbuf.dsize != rec.data_len) { + /* update size */ + rec.data_len = dbuf.dsize; + 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 + */ +TDB_DATA tdb_fetch(struct tdb_context *tdb, TDB_DATA key) +{ + tdb_off_t rec_ptr; + struct list_struct 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; +} + +/* + * 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. + * + * DONT 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. + */ + +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 list_struct 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))) { + return TDB_ERRCODE(TDB_ERR_NOEXIST, 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 list_struct 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; +} + +int tdb_exists(struct tdb_context *tdb, TDB_DATA key) +{ + uint32_t hash = tdb->hash_fn(&key); + return tdb_exists_hash(tdb, key, hash); +} + +/* actually delete an entry in the database given the offset */ +int tdb_do_delete(struct tdb_context *tdb, tdb_off_t rec_ptr, struct list_struct *rec) +{ + tdb_off_t last_ptr, i; + struct list_struct lastrec; + + if (tdb->read_only || tdb->traverse_read) return -1; + + if (((tdb->traverse_write != 0) && (!TDB_DEAD(rec))) || + tdb_write_lock_record(tdb, rec_ptr) == -1) { + /* Someone traversing here: mark it as dead */ + rec->magic = TDB_DEAD_MAGIC; + return tdb_rec_write(tdb, rec_ptr, rec); + } + if (tdb_write_unlock_record(tdb, rec_ptr) != 0) + return -1; + + /* find previous record in hash chain */ + if (tdb_ofs_read(tdb, TDB_HASH_TOP(rec->full_hash), &i) == -1) + return -1; + for (last_ptr = 0; i != rec_ptr; last_ptr = i, i = lastrec.next) + if (tdb_rec_read(tdb, i, &lastrec) == -1) + return -1; + + /* unlink it: next ptr is at start of record. */ + if (last_ptr == 0) + last_ptr = TDB_HASH_TOP(rec->full_hash); + if (tdb_ofs_write(tdb, last_ptr, &rec->next) == -1) + return -1; + + /* recover the space */ + if (tdb_free(tdb, rec_ptr, rec) == -1) + return -1; + return 0; +} + +static int tdb_count_dead(struct tdb_context *tdb, uint32_t hash) +{ + int res = 0; + tdb_off_t rec_ptr; + struct list_struct rec; + + /* read in the hash top */ + if (tdb_ofs_read(tdb, TDB_HASH_TOP(hash), &rec_ptr) == -1) + return 0; + + while (rec_ptr) { + if (tdb_rec_read(tdb, rec_ptr, &rec) == -1) + return 0; + + if (rec.magic == TDB_DEAD_MAGIC) { + res += 1; + } + rec_ptr = rec.next; + } + return res; +} + +/* + * Purge all DEAD records from a hash chain + */ +static int tdb_purge_dead(struct tdb_context *tdb, uint32_t hash) +{ + int res = -1; + struct list_struct rec; + tdb_off_t rec_ptr; + + if (tdb_lock(tdb, -1, F_WRLCK) == -1) { + return -1; + } + + /* read in the hash top */ + if (tdb_ofs_read(tdb, TDB_HASH_TOP(hash), &rec_ptr) == -1) + goto fail; + + while (rec_ptr) { + tdb_off_t next; + + if (tdb_rec_read(tdb, rec_ptr, &rec) == -1) { + goto fail; + } + + next = rec.next; + + if (rec.magic == TDB_DEAD_MAGIC + && tdb_do_delete(tdb, rec_ptr, &rec) == -1) { + goto fail; + } + rec_ptr = next; + } + res = 0; + fail: + tdb_unlock(tdb, -1, F_WRLCK); + return res; +} + +/* 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 list_struct rec; + int ret; + + if (tdb->max_dead_records != 0) { + + /* + * Allow for some dead records per hash chain, mainly for + * tdb's with a very high create/delete rate like locking.tdb. + */ + + if (tdb_lock(tdb, BUCKET(hash), F_WRLCK) == -1) + return -1; + + if (tdb_count_dead(tdb, hash) >= tdb->max_dead_records) { + /* + * Don't let the per-chain freelist grow too large, + * delete all existing dead records + */ + tdb_purge_dead(tdb, hash); + } + + if (!(rec_ptr = tdb_find(tdb, key, hash, &rec))) { + tdb_unlock(tdb, BUCKET(hash), F_WRLCK); + return -1; + } + + /* + * Just mark the record as dead. + */ + rec.magic = TDB_DEAD_MAGIC; + ret = tdb_rec_write(tdb, rec_ptr, &rec); + } + else { + if (!(rec_ptr = tdb_find_lock_hash(tdb, key, hash, F_WRLCK, + &rec))) + return -1; + + ret = tdb_do_delete(tdb, rec_ptr, &rec); + } + + if (ret == 0) { + tdb_increment_seqnum(tdb); + } + + if (tdb_unlock(tdb, BUCKET(rec.full_hash), F_WRLCK) != 0) + TDB_LOG((tdb, TDB_DEBUG_WARNING, "tdb_delete: WARNING tdb_unlock failed!\n")); + return ret; +} + +int tdb_delete(struct tdb_context *tdb, TDB_DATA key) +{ + uint32_t hash = tdb->hash_fn(&key); + return tdb_delete_hash(tdb, key, hash); +} + +/* + * See if we have a dead record around with enough space + */ +static tdb_off_t tdb_find_dead(struct tdb_context *tdb, uint32_t hash, + struct list_struct *r, tdb_len_t length) +{ + tdb_off_t rec_ptr; + + /* read in the hash top */ + if (tdb_ofs_read(tdb, TDB_HASH_TOP(hash), &rec_ptr) == -1) + return 0; + + /* keep looking until we find the right record */ + while (rec_ptr) { + if (tdb_rec_read(tdb, rec_ptr, r) == -1) + return 0; + + if (TDB_DEAD(r) && r->rec_len >= length) { + /* + * First fit for simple coding, TODO: change to best + * fit + */ + return rec_ptr; + } + rec_ptr = r->next; + } + return 0; +} + +/* store an element in the database, replacing any existing element + with the same key + + return 0 on success, -1 on failure +*/ +int tdb_store(struct tdb_context *tdb, TDB_DATA key, TDB_DATA dbuf, int flag) +{ + struct list_struct rec; + uint32_t hash; + tdb_off_t rec_ptr; + char *p = NULL; + int ret = -1; + + if (tdb->read_only || tdb->traverse_read) { + tdb->ecode = TDB_ERR_RDONLY; + 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; + + /* 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, dbuf) == 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() */ + 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); + + /* Copy key+value *before* allocating free space in case malloc + fails and we are left with a dead spot in the tdb. */ + + if (!(p = (char *)malloc(key.dsize + dbuf.dsize))) { + tdb->ecode = TDB_ERR_OOM; + goto fail; + } + + memcpy(p, key.dptr, key.dsize); + if (dbuf.dsize) + memcpy(p+key.dsize, dbuf.dptr, dbuf.dsize); + + if (tdb->max_dead_records != 0) { + /* + * Allow for some dead records per hash chain, look if we can + * find one that can hold the new record. We need enough space + * for key, data and tailer. If we find one, we don't have to + * consult the central freelist. + */ + rec_ptr = tdb_find_dead( + tdb, hash, &rec, + key.dsize + dbuf.dsize + sizeof(tdb_off_t)); + + if (rec_ptr != 0) { + rec.key_len = key.dsize; + rec.data_len = dbuf.dsize; + rec.full_hash = hash; + rec.magic = TDB_MAGIC; + if (tdb_rec_write(tdb, rec_ptr, &rec) == -1 + || tdb->methods->tdb_write( + tdb, rec_ptr + sizeof(rec), + p, key.dsize + dbuf.dsize) == -1) { + goto fail; + } + goto done; + } + } + + /* + * We have to allocate some space from the freelist, so this means we + * have to lock it. Use the chance to purge all the DEAD records from + * the hash chain under the freelist lock. + */ + + if (tdb_lock(tdb, -1, F_WRLCK) == -1) { + goto fail; + } + + if ((tdb->max_dead_records != 0) + && (tdb_purge_dead(tdb, hash) == -1)) { + tdb_unlock(tdb, -1, F_WRLCK); + goto fail; + } + + /* we have to allocate some space */ + rec_ptr = tdb_allocate(tdb, key.dsize + dbuf.dsize, &rec); + + tdb_unlock(tdb, -1, F_WRLCK); + + 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 = dbuf.dsize; + rec.full_hash = hash; + rec.magic = TDB_MAGIC; + + /* write out and point the top of the hash chain at it */ + if (tdb_rec_write(tdb, rec_ptr, &rec) == -1 + || tdb->methods->tdb_write(tdb, rec_ptr+sizeof(rec), p, key.dsize+dbuf.dsize)==-1 + || tdb_ofs_write(tdb, TDB_HASH_TOP(hash), &rec_ptr) == -1) { + /* Need to tdb_unallocate() here */ + goto fail; + } + + done: + ret = 0; + fail: + if (ret == 0) { + tdb_increment_seqnum(tdb); + } + + SAFE_FREE(p); + tdb_unlock(tdb, BUCKET(hash), F_WRLCK); + return ret; +} + + +/* Append to an entry. Create if not exist. */ +int tdb_append(struct tdb_context *tdb, TDB_DATA key, TDB_DATA new_dbuf) +{ + uint32_t hash; + TDB_DATA dbuf; + 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; + + dbuf = tdb_fetch(tdb, key); + + if (dbuf.dptr == NULL) { + dbuf.dptr = (unsigned char *)malloc(new_dbuf.dsize); + } else { + unsigned char *new_dptr = (unsigned char *)realloc(dbuf.dptr, + dbuf.dsize + new_dbuf.dsize); + if (new_dptr == NULL) { + free(dbuf.dptr); + } + dbuf.dptr = new_dptr; + } + + if (dbuf.dptr == NULL) { + tdb->ecode = TDB_ERR_OOM; + goto failed; + } + + memcpy(dbuf.dptr + dbuf.dsize, new_dbuf.dptr, new_dbuf.dsize); + dbuf.dsize += new_dbuf.dsize; + + ret = tdb_store(tdb, key, dbuf, 0); + +failed: + tdb_unlock(tdb, BUCKET(hash), F_WRLCK); + SAFE_FREE(dbuf.dptr); + return ret; +} + + +/* + return the name of the current tdb file + useful for external logging functions +*/ +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 +*/ +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 +*/ +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. +*/ +int tdb_get_seqnum(struct tdb_context *tdb) +{ + tdb_off_t seqnum=0; + + tdb_ofs_read(tdb, TDB_SEQNUM_OFS, &seqnum); + return seqnum; +} + +int tdb_hash_size(struct tdb_context *tdb) +{ + return tdb->header.hash_size; +} + +size_t tdb_map_size(struct tdb_context *tdb) +{ + return tdb->map_size; +} + +int tdb_get_flags(struct tdb_context *tdb) +{ + return tdb->flags; +} + +void tdb_add_flags(struct tdb_context *tdb, unsigned flags) +{ + tdb->flags |= flags; +} + +void tdb_remove_flags(struct tdb_context *tdb, unsigned flags) +{ + tdb->flags &= ~flags; +} + + +/* + enable sequence number handling on an open tdb +*/ +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 list_struct 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 global 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 + */ +int tdb_wipe_all(struct tdb_context *tdb) +{ + int 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; + } + + /* 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 list_struct 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->header.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->header.hash_size)); + if (tdb_free_region(tdb, TDB_DATA_START(tdb->header.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->header.hash_size)); + if (tdb_free_region(tdb, TDB_DATA_START(tdb->header.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; + } + } + + 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; +} diff --git a/lib/tdb/common/tdb_private.h b/lib/tdb/common/tdb_private.h new file mode 100644 index 0000000000..ffac89ff0e --- /dev/null +++ b/lib/tdb/common/tdb_private.h @@ -0,0 +1,213 @@ + /* + 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" + +#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_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->header.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 + +/* 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 + +/* lock offsets */ +#define GLOBAL_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 + +#define BUCKET(hash) ((hash) % tdb->header.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 list_struct for the free space + plus a separate data list for each hash value */ +struct list_struct { + 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 */ + tdb_off_t reserved[29]; +}; + +struct tdb_lock_type { + int list; + uint32_t count; + uint32_t ltype; +}; + +struct tdb_traverse_lock { + struct tdb_traverse_lock *next; + uint32_t off; + uint32_t hash; + int lock_rw; +}; + + +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 , int ); + int (*tdb_expand_file)(struct tdb_context *, tdb_off_t , tdb_off_t ); + int (*tdb_brlock)(struct tdb_context *, tdb_off_t , int, int, int, size_t); +}; + +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 global_lock; + int num_lockrecs; + struct tdb_lock_type *lockrecs; /* only real locks, all with count>0 */ + enum TDB_ERROR ecode; /* error code for last tdb error */ + struct tdb_header header; /* a cached copy of the header */ + 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 */ + unsigned int num_locks; /* number of chain locks held */ + const struct tdb_methods *methods; + struct tdb_transaction *transaction; + int page_size; + int max_dead_records; + bool have_transaction_lock; + volatile sig_atomic_t *interrupt_sig_ptr; +}; + + +/* + internal prototypes +*/ +int tdb_munmap(struct tdb_context *tdb); +void 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_unlock(struct tdb_context *tdb, int list, int ltype); +int tdb_brlock(struct tdb_context *tdb, tdb_off_t offset, int rw_type, int lck_type, int probe, size_t len); +int tdb_transaction_lock(struct tdb_context *tdb, int ltype); +int tdb_transaction_unlock(struct tdb_context *tdb); +int tdb_brlock_upgrade(struct tdb_context *tdb, tdb_off_t offset, size_t len); +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 list_struct *rec); +tdb_off_t tdb_allocate(struct tdb_context *tdb, tdb_len_t length, struct list_struct *rec); +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); +int tdb_rec_read(struct tdb_context *tdb, tdb_off_t offset, struct list_struct *rec); +int tdb_rec_write(struct tdb_context *tdb, tdb_off_t offset, struct list_struct *rec); +int tdb_do_delete(struct tdb_context *tdb, tdb_off_t rec_ptr, struct list_struct *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 list_struct *rec); +void tdb_io_init(struct tdb_context *tdb); +int tdb_expand(struct tdb_context *tdb, tdb_off_t size); +int tdb_rec_free_read(struct tdb_context *tdb, tdb_off_t off, + struct list_struct *rec); + + diff --git a/lib/tdb/common/transaction.c b/lib/tdb/common/transaction.c new file mode 100644 index 0000000000..7acda640c8 --- /dev/null +++ b/lib/tdb/common/transaction.c @@ -0,0 +1,1119 @@ + /* + 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 writes all 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 stategy 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 + global 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 transaction recovery area is used and no + fsync/msync calls are made. + +*/ + + +/* + 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; + + /* old file size before transaction */ + tdb_len_t old_map_size; +}; + + +/* + 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=%d len=%d\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 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; + if (buf != NULL) { + 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 */ + if (tdb->transaction->blocks == NULL) { + new_blocks = (uint8_t **)malloc( + (blk+1)*sizeof(uint8_t *)); + } else { + 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 */ + if (buf == NULL) { + memset(tdb->transaction->blocks[blk] + off, 0, len); + } else { + 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=%d len=%d\n", + (blk*tdb->transaction->block_size) + off, len)); + tdb->transaction->transaction_error = 1; + return -1; +} + + +/* + write while in a transaction - this varient 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) { + 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->header.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 len, int probe) +{ + if (len <= tdb->map_size) { + return 0; + } + return TDB_ERRCODE(TDB_ERR_IO, -1); +} + +/* + transaction version of tdb_expand(). +*/ +static int transaction_expand_file(struct tdb_context *tdb, tdb_off_t size, + tdb_off_t addition) +{ + /* add a write to the transaction elements, so subsequent + reads see the zero data */ + if (transaction_write(tdb, size, NULL, addition) != 0) { + return -1; + } + + return 0; +} + +/* + brlock during a transaction - ignore them +*/ +static int transaction_brlock(struct tdb_context *tdb, tdb_off_t offset, + int rw_type, int lck_type, int probe, size_t len) +{ + return 0; +} + +static const struct tdb_methods transaction_methods = { + transaction_read, + transaction_write, + transaction_next_hash_chain, + transaction_oob, + transaction_expand_file, + transaction_brlock +}; + + +/* + start a tdb transaction. No token is returned, as only a single + transaction is allowed to be pending per tdb_context +*/ +int tdb_transaction_start(struct tdb_context *tdb) +{ + /* 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) { + tdb->transaction->nesting++; + TDB_LOG((tdb, TDB_DEBUG_TRACE, "tdb_transaction_start: nesting %d\n", + tdb->transaction->nesting)); + return 0; + } + + if (tdb->num_locks != 0 || tdb->global_lock.count) { + /* 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) == -1) { + SAFE_FREE(tdb->transaction->blocks); + SAFE_FREE(tdb->transaction); + 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_brlock(tdb, FREELIST_TOP, F_RDLCK, F_SETLKW, 0, 0) == -1) { + TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: failed to get hash locks\n")); + tdb->ecode = TDB_ERR_LOCK; + goto fail; + } + + /* 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->header.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->methods->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; + + return 0; + +fail: + tdb_brlock(tdb, FREELIST_TOP, F_UNLCK, F_SETLKW, 0, 0); + tdb_transaction_unlock(tdb); + SAFE_FREE(tdb->transaction->blocks); + SAFE_FREE(tdb->transaction->hash_heads); + SAFE_FREE(tdb->transaction); + return -1; +} + + +/* + cancel the current transaction +*/ +int tdb_transaction_cancel(struct tdb_context *tdb) +{ + int i; + + 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[i] != NULL) { + free(tdb->transaction->blocks[i]); + } + } + SAFE_FREE(tdb->transaction->blocks); + + /* remove any global lock created during the transaction */ + if (tdb->global_lock.count != 0) { + tdb_brlock(tdb, FREELIST_TOP, F_UNLCK, F_SETLKW, 0, 4*tdb->header.hash_size); + tdb->global_lock.count = 0; + } + + /* remove any locks created during the transaction */ + if (tdb->num_locks != 0) { + for (i=0;i<tdb->num_lockrecs;i++) { + tdb_brlock(tdb,FREELIST_TOP+4*tdb->lockrecs[i].list, + F_UNLCK,F_SETLKW, 0, 1); + } + tdb->num_locks = 0; + tdb->num_lockrecs = 0; + SAFE_FREE(tdb->lockrecs); + } + + /* restore the normal io methods */ + tdb->methods = tdb->transaction->io_methods; + + tdb_brlock(tdb, FREELIST_TOP, F_UNLCK, F_SETLKW, 0, 0); + tdb_transaction_unlock(tdb); + SAFE_FREE(tdb->transaction->hash_heads); + SAFE_FREE(tdb->transaction); + + return 0; +} + +/* + sync to disk +*/ +static int transaction_sync(struct tdb_context *tdb, tdb_off_t offset, tdb_len_t length) +{ + if (fsync(tdb->fd) != 0) { + 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; +} + + +/* + work out how much space the linearised recovery data will consume +*/ +static tdb_len_t tdb_recovery_size(struct tdb_context *tdb) +{ + tdb_len_t recovery_size = 0; + int i; + + recovery_size = sizeof(uint32_t); + for (i=0;i<tdb->transaction->num_blocks;i++) { + if (i * tdb->transaction->block_size >= tdb->transaction->old_map_size) { + break; + } + if (tdb->transaction->blocks[i] == NULL) { + continue; + } + recovery_size += 2*sizeof(tdb_off_t); + if (i == tdb->transaction->num_blocks-1) { + recovery_size += tdb->transaction->last_block_size; + } else { + recovery_size += tdb->transaction->block_size; + } + } + + return recovery_size; +} + +/* + 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 list_struct rec; + const struct tdb_methods *methods = tdb->transaction->io_methods; + tdb_off_t recovery_head; + + if (tdb_ofs_read(tdb, TDB_RECOVERY_HEAD, &recovery_head) == -1) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to read recovery head\n")); + return -1; + } + + rec.rec_len = 0; + + if (recovery_head != 0 && + methods->tdb_read(tdb, recovery_head, &rec, sizeof(rec), DOCONV()) == -1) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to read recovery record\n")); + return -1; + } + + *recovery_size = tdb_recovery_size(tdb); + + 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; + } + + /* 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 != 0) { + 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 */ + *recovery_size = tdb_recovery_size(tdb); + + /* round up to a multiple of page size */ + *recovery_max_size = TDB_ALIGN(sizeof(rec) + *recovery_size, tdb->page_size) - sizeof(rec); + *recovery_offset = tdb->map_size; + recovery_head = *recovery_offset; + + if (methods->tdb_expand_file(tdb, tdb->transaction->old_map_size, + (tdb->map_size - tdb->transaction->old_map_size) + + sizeof(rec) + *recovery_max_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 list_struct *rec; + tdb_off_t recovery_offset, recovery_max_size; + tdb_off_t old_map_size = tdb->transaction->old_map_size; + uint32_t magic, tailer; + int i; + + /* + check that the recovery area has enough space + */ + if (tdb_recovery_allocate(tdb, &recovery_size, + &recovery_offset, &recovery_max_size) == -1) { + return -1; + } + + data = (unsigned char *)malloc(recovery_size + sizeof(*rec)); + if (data == NULL) { + tdb->ecode = TDB_ERR_OOM; + return -1; + } + + rec = (struct list_struct *)data; + memset(rec, 0, sizeof(*rec)); + + rec->magic = 0; + rec->data_len = recovery_size; + rec->rec_len = recovery_max_size; + rec->key_len = old_map_size; + CONVERT(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); + CONVERT(p); + + /* 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 list_struct, 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; +} + +/* + commit the current transaction +*/ +int tdb_transaction_commit(struct tdb_context *tdb) +{ + const struct tdb_methods *methods; + tdb_off_t magic_offset = 0; + uint32_t zero = 0; + int i; + + if (tdb->transaction == NULL) { + TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_commit: no transaction\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_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; + } + + 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->num_locks || tdb->global_lock.count) { + tdb->ecode = TDB_ERR_LOCK; + TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_commit: locks pending on commit\n")); + tdb_transaction_cancel(tdb); + return -1; + } + + /* upgrade the main transaction lock region to a write lock */ + if (tdb_brlock_upgrade(tdb, FREELIST_TOP, 0) == -1) { + TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: failed to upgrade hash locks\n")); + tdb->ecode = TDB_ERR_LOCK; + tdb_transaction_cancel(tdb); + return -1; + } + + /* get the global lock - this prevents new users attaching to the database + during the commit */ + if (tdb_brlock(tdb, GLOBAL_LOCK, F_WRLCK, F_SETLKW, 0, 1) == -1) { + TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_commit: failed to get global lock\n")); + tdb->ecode = TDB_ERR_LOCK; + tdb_transaction_cancel(tdb); + return -1; + } + + if (!(tdb->flags & TDB_NOSYNC)) { + /* write the recovery data to the end of the file */ + if (transaction_setup_recovery(tdb, &magic_offset) == -1) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_commit: failed to setup recovery data\n")); + tdb_brlock(tdb, GLOBAL_LOCK, F_UNLCK, F_SETLKW, 0, 1); + tdb_transaction_cancel(tdb); + return -1; + } + } + + /* 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_commit: expansion failed\n")); + tdb_brlock(tdb, GLOBAL_LOCK, F_UNLCK, F_SETLKW, 0, 1); + tdb_transaction_cancel(tdb); + return -1; + } + tdb->map_size = tdb->transaction->old_map_size; + methods->tdb_oob(tdb, tdb->map_size + 1, 1); + } + + /* 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_brlock(tdb, GLOBAL_LOCK, F_UNLCK, F_SETLKW, 0, 1); + + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_commit: write failed\n")); + return -1; + } + SAFE_FREE(tdb->transaction->blocks[i]); + } + + SAFE_FREE(tdb->transaction->blocks); + tdb->transaction->num_blocks = 0; + + if (!(tdb->flags & TDB_NOSYNC)) { + /* ensure the new data is on disk */ + if (transaction_sync(tdb, 0, tdb->map_size) == -1) { + return -1; + } + + /* remove the recovery marker */ + if (methods->tdb_write(tdb, magic_offset, &zero, 4) == -1) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_commit: failed to remove recovery magic\n")); + return -1; + } + + /* ensure the recovery marker has been removed on disk */ + if (transaction_sync(tdb, magic_offset, 4) == -1) { + return -1; + } + } + + tdb_brlock(tdb, GLOBAL_LOCK, F_UNLCK, F_SETLKW, 0, 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); + + return 0; +} + + +/* + recover from an aborted transaction. Must be called with exclusive + database write access already established (including the global + 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 list_struct 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; + 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 %d bytes at offset %d\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 list_struct, 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; + } + + /* reduce the file size to the old size */ + tdb_munmap(tdb); + if (ftruncate(tdb->fd, recovery_eof) != 0) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to reduce to recovery size\n")); + tdb->ecode = TDB_ERR_IO; + return -1; + } + tdb->map_size = recovery_eof; + tdb_mmap(tdb); + + 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 %d byte database\n", + recovery_eof)); + + /* all done */ + return 0; +} diff --git a/lib/tdb/common/traverse.c b/lib/tdb/common/traverse.c new file mode 100644 index 0000000000..69c81e6e98 --- /dev/null +++ b/lib/tdb/common/traverse.c @@ -0,0 +1,348 @@ + /* + 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" + +/* Uses traverse lock: 0 = finish, -1 = error, other = record offset */ +static int tdb_next_lock(struct tdb_context *tdb, struct tdb_traverse_lock *tlock, + struct list_struct *rec) +{ + int want_next = (tlock->off != 0); + + /* Lock each chain from the start one. */ + for (; tlock->hash < tdb->header.hash_size; tlock->hash++) { + if (!tlock->off && tlock->hash != 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 thats 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->hash); + if (tlock->hash == tdb->header.hash_size) { + continue; + } + } + + if (tdb_lock(tdb, tlock->hash, tlock->lock_rw) == -1) + return -1; + + /* No previous record? Start at top of chain. */ + if (!tlock->off) { + if (tdb_ofs_read(tdb, TDB_HASH_TOP(tlock->hash), + &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) { + tdb_off_t current; + 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_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; + } + + /* Try to clean dead ones from old traverses */ + current = tlock->off; + tlock->off = rec->next; + if (!(tdb->read_only || tdb->traverse_read) && + tdb_do_delete(tdb, current, rec) != 0) + goto fail; + } + tdb_unlock(tdb, tlock->hash, tlock->lock_rw); + want_next = 0; + } + /* We finished iteration without finding anything */ + return TDB_ERRCODE(TDB_SUCCESS, 0); + + fail: + tlock->off = 0; + if (tdb_unlock(tdb, tlock->hash, tlock->lock_rw) != 0) + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_next_lock: On error unlock failed!\n")); + return -1; +} + +/* 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 list_struct rec; + int ret, count = 0; + + /* This was in the initializaton, 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 ((ret = tdb_next_lock(tdb, tl, &rec)) > 0) { + count++; + /* now read the full record */ + key.dptr = tdb_alloc_read(tdb, tl->off + sizeof(rec), + rec.key_len + rec.data_len); + if (!key.dptr) { + ret = -1; + if (tdb_unlock(tdb, tl->hash, 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; + + /* Drop chain lock, call out */ + if (tdb_unlock(tdb, tl->hash, tl->lock_rw) != 0) { + ret = -1; + SAFE_FREE(key.dptr); + goto out; + } + if (fn && fn(tdb, key, dbuf, private_data)) { + /* They want us to terminate traversal */ + ret = count; + if (tdb_unlock_record(tdb, tl->off) != 0) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_traverse: unlock_record failed!\n"));; + ret = -1; + } + SAFE_FREE(key.dptr); + goto out; + } + SAFE_FREE(key.dptr); + } +out: + tdb->travlocks.next = tl->next; + if (ret < 0) + return -1; + else + return count; +} + + +/* + a write style traverse - temporarily marks the db read only +*/ +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; + bool in_transaction = (tdb->transaction != NULL); + + /* we need to get a read lock on the transaction lock here to + cope with the lock ordering semantics of solaris10 */ + if (!in_transaction) { + if (tdb_transaction_lock(tdb, F_RDLCK)) { + return -1; + } + } + + tdb->traverse_read++; + ret = tdb_traverse_internal(tdb, fn, private_data, &tl); + tdb->traverse_read--; + + if (!in_transaction) { + tdb_transaction_unlock(tdb); + } + + 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 restrictions malloc gives you. +*/ +int tdb_traverse(struct tdb_context *tdb, + tdb_traverse_func fn, void *private_data) +{ + struct tdb_traverse_lock tl = { NULL, 0, 0, F_WRLCK }; + int ret; + bool in_transaction = (tdb->transaction != NULL); + + if (tdb->read_only || tdb->traverse_read) { + return tdb_traverse_read(tdb, fn, private_data); + } + + if (!in_transaction) { + if (tdb_transaction_lock(tdb, F_WRLCK)) { + return -1; + } + } + + tdb->traverse_write++; + ret = tdb_traverse_internal(tdb, fn, private_data, &tl); + tdb->traverse_write--; + + if (!in_transaction) { + tdb_transaction_unlock(tdb); + } + + return ret; +} + + +/* find the first entry in the database and return its key */ +TDB_DATA tdb_firstkey(struct tdb_context *tdb) +{ + TDB_DATA key; + struct list_struct rec; + + /* release any old lock */ + if (tdb_unlock_record(tdb, tdb->travlocks.off) != 0) + return tdb_null; + tdb->travlocks.off = tdb->travlocks.hash = 0; + tdb->travlocks.lock_rw = F_RDLCK; + + /* Grab first record: locks chain and returned record. */ + if (tdb_next_lock(tdb, &tdb->travlocks, &rec) <= 0) + 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); + + /* Unlock the hash chain of the record we just read. */ + if (tdb_unlock(tdb, tdb->travlocks.hash, 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 */ +TDB_DATA tdb_nextkey(struct tdb_context *tdb, TDB_DATA oldkey) +{ + uint32_t oldhash; + TDB_DATA key = tdb_null; + struct list_struct rec; + unsigned char *k = NULL; + + /* Is locked key the old key? If so, traverse will be reliable. */ + if (tdb->travlocks.off) { + if (tdb_lock(tdb,tdb->travlocks.hash,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) { + SAFE_FREE(k); + return tdb_null; + } + if (tdb_unlock(tdb, tdb->travlocks.hash, 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) + return tdb_null; + tdb->travlocks.hash = 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; + } + } + oldhash = tdb->travlocks.hash; + + /* Grab next record: locks chain and returned record, + unlocks old record */ + if (tdb_next_lock(tdb, &tdb->travlocks, &rec) > 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.hash, 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, BUCKET(oldhash), tdb->travlocks.lock_rw) != 0) + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_nextkey: WARNING tdb_unlock failed!\n")); + return key; +} + |