/* Unix SMB/Netbios implementation. Version 3.0 Samba database functions Copyright (C) Andrew Tridgell 1999-2000 Copyright (C) Luke Kenneth Casson Leighton 2000 Copyright (C) Paul `Rusty' Russell 2000 Copyright (C) Jeremy Allison 2000 This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This program 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 General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */ #ifdef STANDALONE #if HAVE_CONFIG_H #include #endif #include #include #include #include #include #include #include #include #include #include "tdb.h" #include "spinlock.h" #else #include "includes.h" #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_ALIGNMENT 4 #define MIN_REC_SIZE (2*sizeof(struct list_struct) + TDB_ALIGNMENT) #define DEFAULT_HASH_SIZE 131 #define TDB_PAGE_SIZE 0x2000 #define FREELIST_TOP (sizeof(struct tdb_header)) #define TDB_ALIGN(x,a) (((x) + (a)-1) & ~((a)-1)) #define TDB_BYTEREV(x) (((x<<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)) /* lock offsets */ #define GLOBAL_LOCK 0 #define ACTIVE_LOCK 4 #ifndef MAP_FILE #define MAP_FILE 0 #endif #define BUCKET(hash) ((hash) % tdb->header.hash_size) TDB_DATA tdb_null; /* all contexts, to ensure no double-opens (fcntl locks don't nest!) */ static TDB_CONTEXT *tdbs = NULL; static void *tdb_munmap(void *ptr, tdb_len size) { #ifdef HAVE_MMAP munmap(ptr, size); #endif return NULL; } static void *tdb_mmap(tdb_len size, int readonly, int fd) { void *ret = NULL; #ifdef HAVE_MMAP ret = mmap(NULL, size, PROT_READ | (readonly ? 0 : PROT_WRITE), MAP_SHARED|MAP_FILE, fd, 0); #endif return ret; } /* Endian conversion: we only ever deal with 4 byte quantities */ static void *convert(void *buf, u32 size) { u32 i, *p = buf; for (i = 0; i < size / 4; i++) p[i] = TDB_BYTEREV(p[i]); return buf; } #define DOCONV() (tdb->flags & TDB_CONVERT) #define CONVERT(x) (DOCONV() ? 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 next; /* offset of the next record in the list */ tdb_len rec_len; /* total byte length of record */ tdb_len key_len; /* byte length of key */ tdb_len data_len; /* byte length of data */ u32 full_hash; /* the full 32 bit hash of the key */ u32 magic; /* try to catch errors */ /* the following union is implied: union { char record[rec_len]; struct { char key[key_len]; char data[data_len]; } u32 totalsize; (tailer) } */ }; /* a byte range locking function - return 0 on success this functions locks/unlocks 1 byte at the specified offset */ static int tdb_brlock(TDB_CONTEXT *tdb, tdb_off offset, int rw_type, int lck_type) { struct flock fl; if (tdb->flags & TDB_NOLOCK) return 0; if (tdb->read_only) return -1; fl.l_type = rw_type; fl.l_whence = SEEK_SET; fl.l_start = offset; fl.l_len = 1; fl.l_pid = 0; if (fcntl(tdb->fd,lck_type,&fl)) return TDB_ERRCODE(TDB_ERR_LOCK, -1); return 0; } /* lock a list in the database. list -1 is the alloc list */ static int tdb_lock(TDB_CONTEXT *tdb, int list, int ltype) { if (list < -1 || list >= (int)tdb->header.hash_size) return -1; if (tdb->flags & TDB_NOLOCK) return 0; /* Since fcntl locks don't nest, we do a lock for the first one, and simply bump the count for future ones */ if (tdb->locked[list+1].count == 0) { if (tdb->header.rwlocks) { if (tdb_spinlock(tdb, list, ltype)) return -1; } else if (tdb_brlock(tdb,FREELIST_TOP+4*list,ltype,F_SETLKW)) return -1; tdb->locked[list+1].ltype = ltype; } tdb->locked[list+1].count++; return 0; } /* unlock the database: returns void because it's too late for errors. */ static void tdb_unlock(TDB_CONTEXT *tdb, int list, int ltype) { if (tdb->flags & TDB_NOLOCK) return; /* Sanity checks */ if (list < -1 || list >= (int)tdb->header.hash_size) return; if (tdb->locked[list+1].count==0) return; if (tdb->locked[list+1].count == 1) { /* Down to last nested lock: unlock underneath */ if (tdb->header.rwlocks) tdb_spinunlock(tdb, list, ltype); else tdb_brlock(tdb, FREELIST_TOP+4*list, F_UNLCK, F_SETLKW); } tdb->locked[list+1].count--; } /* This is based on the hash agorithm from gdbm */ static u32 tdb_hash(TDB_DATA *key) { u32 value; /* Used to compute the hash value. */ u32 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); } /* check for an out of bounds access - if it is out of bounds then see if the database has been expanded by someone else and expand if necessary */ static int tdb_oob(TDB_CONTEXT *tdb, tdb_off offset) { struct stat st; if (offset <= tdb->map_size) return 0; if (tdb->flags & TDB_INTERNAL) return 0; fstat(tdb->fd, &st); if (st.st_size <= (size_t)offset) return TDB_ERRCODE(TDB_ERR_IO, -1); /* Unmap, update size, remap */ if (tdb->map_ptr) tdb->map_ptr=tdb_munmap(tdb->map_ptr, tdb->map_size); tdb->map_size = st.st_size; if (!(tdb->flags & TDB_NOMMAP)) tdb->map_ptr = tdb_mmap(tdb->map_size, tdb->read_only,tdb->fd); return 0; } /* write a lump of data at a specified offset */ static int tdb_write(TDB_CONTEXT *tdb, tdb_off off, void *buf, tdb_len len) { if (tdb_oob(tdb, off + len) != 0) return -1; if (tdb->map_ptr) memcpy(off + (char *)tdb->map_ptr, buf, len); else if (lseek(tdb->fd, off, SEEK_SET) != off || write(tdb->fd, buf, len) != (ssize_t)len) return TDB_ERRCODE(TDB_ERR_IO, -1); return 0; } /* read a lump of data at a specified offset, maybe convert */ static int tdb_read(TDB_CONTEXT *tdb,tdb_off off,void *buf,tdb_len len,int cv) { if (tdb_oob(tdb, off + len) != 0) return -1; if (tdb->map_ptr) memcpy(buf, off + (char *)tdb->map_ptr, len); else if (lseek(tdb->fd, off, SEEK_SET) != off || read(tdb->fd, buf, len) != (ssize_t)len) return TDB_ERRCODE(TDB_ERR_IO, -1); if (cv) convert(buf, len); return 0; } /* read a lump of data, allocating the space for it */ static char *tdb_alloc_read(TDB_CONTEXT *tdb, tdb_off offset, tdb_len len) { char *buf; if (!(buf = malloc(len))) return TDB_ERRCODE(TDB_ERR_OOM, buf); if (tdb_read(tdb, offset, buf, len, 0) == -1) { free(buf); return NULL; } return buf; } /* read/write a tdb_off */ static int ofs_read(TDB_CONTEXT *tdb, tdb_off offset, tdb_off *d) { return tdb_read(tdb, offset, (char*)d, sizeof(*d), DOCONV()); } static int ofs_write(TDB_CONTEXT *tdb, tdb_off offset, tdb_off *d) { tdb_off off = *d; return tdb_write(tdb, offset, CONVERT(off), sizeof(*d)); } /* read/write a record */ static int rec_read(TDB_CONTEXT *tdb, tdb_off offset, struct list_struct *rec) { if (tdb_read(tdb, offset, rec, sizeof(*rec),DOCONV()) == -1) return -1; if (TDB_BAD_MAGIC(rec)) return TDB_ERRCODE(TDB_ERR_CORRUPT, -1); return tdb_oob(tdb, rec->next); } static int rec_write(TDB_CONTEXT *tdb, tdb_off offset, struct list_struct *rec) { struct list_struct r = *rec; return tdb_write(tdb, offset, CONVERT(r), sizeof(r)); } /* read a freelist record and check for simple errors */ static int rec_free_read(TDB_CONTEXT *tdb, tdb_off off, struct list_struct*rec) { if (tdb_read(tdb, off, rec, sizeof(*rec),DOCONV()) == -1) return -1; if (rec->magic != TDB_FREE_MAGIC) { #ifdef TDB_DEBUG printf("bad magic 0x%08x at offset %d\n", rec->magic, off); #endif return TDB_ERRCODE(TDB_ERR_CORRUPT, -1); } if (tdb_oob(tdb, rec->next) != 0) return -1; return 0; } /* update a record tailer (must hold allocation lock) */ static int update_tailer(TDB_CONTEXT *tdb, tdb_off offset, const struct list_struct *rec) { tdb_off totalsize; /* Offset of tailer from record header */ totalsize = sizeof(*rec) + rec->rec_len; return ofs_write(tdb, offset + totalsize - sizeof(tdb_off), &totalsize); } #ifdef TDB_DEBUG void tdb_printfreelist(TDB_CONTEXT *tdb) { tdb_off offset, rec_ptr, last_ptr; struct list_struct rec, lastrec, newrec; tdb_lock(tdb, -1, F_WRLCK); last_ptr = 0; offset = FREELIST_TOP; /* read in the freelist top */ if (ofs_read(tdb, offset, &rec_ptr) == -1) { return; } printf("freelist top=[0x%08x]\n", rec_ptr ); while (rec_ptr) { if (tdb_read(tdb, rec_ptr, (char *)&rec, sizeof(rec), DOCONV()) == -1) { return; } if (rec.magic != TDB_FREE_MAGIC) { printf("bad magic 0x%08x in free list\n", rec.magic); return; } printf("entry offset=[0x%08x], rec.rec_len = [0x%08x]\n", rec.next, rec.rec_len ); /* move to the next record */ rec_ptr = rec.next; } tdb_unlock(tdb, -1, F_WRLCK); } #endif /* Remove an element from the freelist. Must have alloc lock. */ static int remove_from_freelist(TDB_CONTEXT *tdb, tdb_off off, tdb_off next) { tdb_off last_ptr, i; /* read in the freelist top */ last_ptr = FREELIST_TOP; while (ofs_read(tdb, last_ptr, &i) != -1 && i != 0) { if (i == off) { /* We've found it! */ return ofs_write(tdb, last_ptr, &next); } /* Follow chain (next offset is at start of record) */ last_ptr = i; } return TDB_ERRCODE(TDB_ERR_CORRUPT, -1); } /* Add an element into the freelist. Merge adjacent records if neccessary. */ static int tdb_free(TDB_CONTEXT *tdb, tdb_off offset, struct list_struct *rec) { tdb_off right, left; /* Allocation and tailer lock */ if (tdb_lock(tdb, -1, F_WRLCK) != 0) return -1; /* Look right first (I'm an Australian, dammit) */ right = offset + sizeof(*rec) + rec->rec_len; if (tdb_oob(tdb, right + sizeof(*rec)) == 0) { struct list_struct r; if (tdb_read(tdb, right, &r, sizeof(r), DOCONV()) == -1) goto fail; /* If it's free, expand to include it. */ if (r.magic == TDB_FREE_MAGIC) { if (remove_from_freelist(tdb, right, r.next) == -1) goto fail; rec->rec_len += sizeof(r) + r.rec_len; } } /* Look left */ left = offset - 4; if (left > TDB_HASH_TOP(tdb->header.hash_size-1)) { struct list_struct l; tdb_off leftsize; /* Read in tailer and jump back to header */ if (ofs_read(tdb, left, &leftsize) == -1) goto fail; left = offset - leftsize; /* Now read in record */ if (tdb_read(tdb, left, &l, sizeof(l), DOCONV()) == -1) goto fail; /* If it's free, expand to include it. */ if (l.magic == TDB_FREE_MAGIC) { if (remove_from_freelist(tdb, left, l.next) == -1) goto fail; offset = left; rec->rec_len += leftsize; } } if (update_tailer(tdb, offset, rec) == -1) goto fail; /* Now, prepend to free list */ rec->magic = TDB_FREE_MAGIC; if (ofs_read(tdb, FREELIST_TOP, &rec->next) == -1) goto fail; if (rec_write(tdb, offset, rec) == -1) goto fail; if (ofs_write(tdb, FREELIST_TOP, &offset) == -1) goto fail; /* And we're done. */ tdb_unlock(tdb, -1, F_WRLCK); return 0; fail: tdb_unlock(tdb, -1, F_WRLCK); return -1; } /* expand the database at least size bytes by expanding the underlying file and doing the mmap again if necessary */ static int tdb_expand(TDB_CONTEXT *tdb, tdb_off size) { struct list_struct rec; tdb_off offset; char b = 0; if (tdb_lock(tdb, -1, F_WRLCK) == -1) return 0; /* must know about any previous expansions by another process */ tdb_oob(tdb, tdb->map_size + 1); /* always make room for at least 10 more records, and round the database up to a multiple of TDB_PAGE_SIZE */ size = TDB_ALIGN(tdb->map_size + size*10, TDB_PAGE_SIZE) - tdb->map_size; /* expand the file itself */ if (!(tdb->flags & TDB_INTERNAL)) { lseek(tdb->fd, tdb->map_size + size - 1, SEEK_SET); if (write(tdb->fd, &b, 1) != 1) goto fail; } if (!(tdb->flags & TDB_INTERNAL) && tdb->map_ptr) tdb->map_ptr = tdb_munmap(tdb->map_ptr, tdb->map_size); tdb->map_size += size; if (tdb->flags & TDB_INTERNAL) tdb->map_ptr = realloc(tdb->map_ptr, tdb->map_size); /* 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; if (!(tdb->flags & TDB_NOMMAP)) tdb->map_ptr = tdb_mmap(tdb->map_size, 0, tdb->fd); tdb_unlock(tdb, -1, F_WRLCK); return 0; fail: tdb_unlock(tdb, -1, F_WRLCK); return -1; } /* 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 */ static tdb_off tdb_allocate(TDB_CONTEXT *tdb, tdb_len length, struct list_struct *rec) { tdb_off rec_ptr, last_ptr, newrec_ptr; struct list_struct newrec; if (tdb_lock(tdb, -1, F_WRLCK) == -1) return 0; /* Extra bytes required for tailer */ length += sizeof(tdb_off); again: last_ptr = FREELIST_TOP; /* read in the freelist top */ if (ofs_read(tdb, FREELIST_TOP, &rec_ptr) == -1) goto fail; /* keep looking until we find a freelist record big enough */ while (rec_ptr) { if (rec_free_read(tdb, rec_ptr, rec) == -1) goto fail; if (rec->rec_len >= length) { /* found it - now possibly split it up */ if (rec->rec_len > length + MIN_REC_SIZE) { /* Length of left piece */ length = TDB_ALIGN(length, TDB_ALIGNMENT); /* Right piece to go on free list */ newrec.rec_len = rec->rec_len - (sizeof(*rec) + length); newrec_ptr = rec_ptr + sizeof(*rec) + length; /* And left record is shortened */ rec->rec_len = length; } else newrec_ptr = 0; /* Remove allocated record from the free list */ if (ofs_write(tdb, last_ptr, &rec->next) == -1) goto fail; /* Update header: do this before we drop alloc lock, otherwise tdb_free() might try to merge with us, thinking we're free. (Thanks Jeremy Allison). */ rec->magic = TDB_MAGIC; if (rec_write(tdb, rec_ptr, rec) == -1) goto fail; /* Did we create new block? */ if (newrec_ptr) { /* Update allocated record tailer (we shortened it). */ if (update_tailer(tdb, rec_ptr, rec) == -1) goto fail; /* Free new record */ if (tdb_free(tdb, newrec_ptr, &newrec) == -1) goto fail; } /* all done - return the new record offset */ tdb_unlock(tdb, -1, F_WRLCK); return rec_ptr; } /* move to the next record */ last_ptr = rec_ptr; rec_ptr = rec->next; } /* 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; } /* initialise a new database with a specified hash size */ static int tdb_new_database(TDB_CONTEXT *tdb, int hash_size) { struct tdb_header *newdb; int size, ret; /* We make it up in memory, then write it out if not internal */ size = sizeof(struct tdb_header) + (hash_size+1)*sizeof(tdb_off); if (!(newdb = calloc(size, 1))) return TDB_ERRCODE(TDB_ERR_OOM, -1); /* Fill in the header */ newdb->version = TDB_VERSION; newdb->hash_size = hash_size; #ifdef USE_SPINLOCKS newdb->rwlocks = size; #endif 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; } lseek(tdb->fd, 0, SEEK_SET); ftruncate(tdb->fd, 0); /* 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); if (write(tdb->fd, newdb, size) != size) ret = -1; else ret = tdb_create_rwlocks(tdb->fd, hash_size); free(newdb); return ret; } /* Returns 0 on fail. On success, return offset of record, and fills in rec */ static tdb_off tdb_find(TDB_CONTEXT *tdb, TDB_DATA key, u32 hash, struct list_struct *r) { tdb_off rec_ptr; /* read in the hash top */ if (ofs_read(tdb, TDB_HASH_TOP(hash), &rec_ptr) == -1) return 0; /* keep looking until we find the right record */ while (rec_ptr) { if (rec_read(tdb, rec_ptr, r) == -1) return 0; if (!TDB_DEAD(r) && hash==r->full_hash && key.dsize==r->key_len) { char *k; /* a very likely hit - read the key */ k = tdb_alloc_read(tdb, rec_ptr + sizeof(*r), r->key_len); if (!k) return 0; if (memcmp(key.dptr, k, key.dsize) == 0) { free(k); return rec_ptr; } free(k); } rec_ptr = r->next; } return TDB_ERRCODE(TDB_ERR_NOEXIST, 0); } /* If they do lockkeys, check that this hash is one they locked */ static int tdb_keylocked(TDB_CONTEXT *tdb, u32 hash) { u32 i; if (!tdb->lockedkeys) return 1; for (i = 0; i < tdb->lockedkeys[0]; i++) if (tdb->lockedkeys[i+1] == hash) return 1; return TDB_ERRCODE(TDB_ERR_NOLOCK, 0); } /* As tdb_find, but if you succeed, keep the lock */ static tdb_off tdb_find_lock(TDB_CONTEXT *tdb, TDB_DATA key, int locktype, struct list_struct *rec) { u32 hash, rec_ptr; hash = tdb_hash(&key); if (!tdb_keylocked(tdb, hash)) return 0; 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; } enum TDB_ERROR tdb_error(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_NOEXIST, "Record does not exist"} }; /* Error string for the last tdb error */ const char *tdb_errorstr(TDB_CONTEXT *tdb) { u32 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"; } /* 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(TDB_CONTEXT *tdb, TDB_DATA key, TDB_DATA dbuf) { struct list_struct rec; tdb_off rec_ptr; int ret = -1; /* find entry */ if (!(rec_ptr = tdb_find_lock(tdb, key, F_WRLCK, &rec))) return -1; /* must be long enough key, data and tailer */ if (rec.rec_len < key.dsize + dbuf.dsize + sizeof(tdb_off)) goto out; if (tdb_write(tdb, rec_ptr + sizeof(rec) + rec.key_len, dbuf.dptr, dbuf.dsize) == -1) goto out; if (dbuf.dsize != rec.data_len) { /* update size */ rec.data_len = dbuf.dsize; ret = rec_write(tdb, rec_ptr, &rec); } else ret = 0; out: tdb_unlock(tdb, BUCKET(rec.full_hash), F_WRLCK); return ret; } /* find an entry in the database given a key */ TDB_DATA tdb_fetch(TDB_CONTEXT *tdb, TDB_DATA key) { tdb_off rec_ptr; struct list_struct rec; TDB_DATA ret; /* find which hash bucket it is in */ if (!(rec_ptr = tdb_find_lock(tdb,key,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; } /* 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 */ int tdb_exists(TDB_CONTEXT *tdb, TDB_DATA key) { struct list_struct rec; if (tdb_find_lock(tdb, key, F_RDLCK, &rec) == 0) return 0; tdb_unlock(tdb, BUCKET(rec.full_hash), F_RDLCK); return 1; } /* record lock stops delete underneath */ static int lock_record(TDB_CONTEXT *tdb, tdb_off off) { return off ? tdb_brlock(tdb, off, F_RDLCK, F_SETLKW) : 0; } /* write locks override our own fcntl readlocks, so check it here */ static int write_lock_record(TDB_CONTEXT *tdb, tdb_off off) { struct tdb_traverse_lock *i; for (i = &tdb->travlocks; i; i = i->next) if (i->off == off) return -1; return tdb_brlock(tdb, off, F_WRLCK, F_SETLK); } static int write_unlock_record(TDB_CONTEXT *tdb, tdb_off off) { return tdb_brlock(tdb, off, F_UNLCK, F_SETLK); } /* fcntl locks don't stack: avoid unlocking someone else's */ static int unlock_record(TDB_CONTEXT *tdb, tdb_off off) { struct tdb_traverse_lock *i; u32 count = 0; if (off == 0) return 0; for (i = &tdb->travlocks; i; i = i->next) if (i->off == off) count++; return (count == 1 ? tdb_brlock(tdb, off, F_UNLCK, F_SETLKW) : 0); } /* actually delete an entry in the database given the offset */ static int do_delete(TDB_CONTEXT *tdb, tdb_off rec_ptr, struct list_struct*rec) { tdb_off last_ptr, i; struct list_struct lastrec; if (tdb->read_only) return -1; if (write_lock_record(tdb, rec_ptr) == -1) { /* Someone traversing here: mark it as dead */ rec->magic = TDB_DEAD_MAGIC; return rec_write(tdb, rec_ptr, rec); } write_unlock_record(tdb, rec_ptr); /* find previous record in hash chain */ if (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 (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 (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; } /* Uses traverse lock: 0 = finish, -1 = error, other = record offset */ static int tdb_next_lock(TDB_CONTEXT *tdb, struct tdb_traverse_lock *tlock, struct list_struct *rec) { int want_next = (tlock->off != 0); /* No traversal allows if you've called tdb_lockkeys() */ if (tdb->lockedkeys) return TDB_ERRCODE(TDB_ERR_NOLOCK, -1); /* Lock each chain from the start one. */ for (; tlock->hash < tdb->header.hash_size; tlock->hash++) { if (tdb_lock(tdb, tlock->hash, F_WRLCK) == -1) return -1; /* No previous record? Start at top of chain. */ if (!tlock->off) { if (ofs_read(tdb, TDB_HASH_TOP(tlock->hash), &tlock->off) == -1) goto fail; } else { /* Otherwise unlock the previous record. */ unlock_record(tdb, tlock->off); } if (want_next) { /* We have offset of old record: grab next */ if (rec_read(tdb, tlock->off, rec) == -1) goto fail; tlock->off = rec->next; } /* Iterate through chain */ while( tlock->off) { tdb_off current; if (rec_read(tdb, tlock->off, rec) == -1) goto fail; if (!TDB_DEAD(rec)) { /* Woohoo: we found one! */ lock_record(tdb, tlock->off); return tlock->off; } /* Try to clean dead ones from old traverses */ current = tlock->off; tlock->off = rec->next; do_delete(tdb, current, rec); } tdb_unlock(tdb, tlock->hash, F_WRLCK); want_next = 0; } /* We finished iteration without finding anything */ return TDB_ERRCODE(TDB_SUCCESS, 0); fail: tlock->off = 0; tdb_unlock(tdb, tlock->hash, F_WRLCK); 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 */ int tdb_traverse(TDB_CONTEXT *tdb, tdb_traverse_func fn, void *state) { TDB_DATA key, dbuf; struct list_struct rec; struct tdb_traverse_lock tl = { tdb->travlocks.next, 0, 0 }; int ret, count = 0; /* 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) { tdb_unlock(tdb, tl.hash, F_WRLCK); unlock_record(tdb, tl.off); tdb->travlocks.next = tl.next; return -1; } key.dsize = rec.key_len; dbuf.dptr = key.dptr + rec.key_len; dbuf.dsize = rec.data_len; /* Drop chain lock, call out */ tdb_unlock(tdb, tl.hash, F_WRLCK); if (fn && fn(tdb, key, dbuf, state)) { /* They want us to terminate traversal */ unlock_record(tdb, tl.off); tdb->travlocks.next = tl.next; free(key.dptr); return count; } free(key.dptr); } tdb->travlocks.next = tl.next; if (ret < 0) return -1; else return count; } /* find the first entry in the database and return its key */ TDB_DATA tdb_firstkey(TDB_CONTEXT *tdb) { TDB_DATA key; struct list_struct rec; /* release any old lock */ unlock_record(tdb, tdb->travlocks.off); tdb->travlocks.off = tdb->travlocks.hash = 0; 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); tdb_unlock(tdb, BUCKET(tdb->travlocks.hash), F_WRLCK); return key; } /* find the next entry in the database, returning its key */ TDB_DATA tdb_nextkey(TDB_CONTEXT *tdb, TDB_DATA oldkey) { u32 oldhash; TDB_DATA key = tdb_null; struct list_struct rec; 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,F_WRLCK)) return tdb_null; if (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 */ free(k); unlock_record(tdb, tdb->travlocks.off); tdb_unlock(tdb, tdb->travlocks.hash, F_WRLCK); tdb->travlocks.off = 0; } } if (!tdb->travlocks.off) { /* No previous element: do normal find, and lock record */ tdb->travlocks.off = tdb_find_lock(tdb, oldkey, F_WRLCK, &rec); if (!tdb->travlocks.off) return tdb_null; tdb->travlocks.hash = BUCKET(rec.full_hash); lock_record(tdb, tdb->travlocks.off); } 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 */ tdb_unlock(tdb, tdb->travlocks.hash, F_WRLCK); } /* Unlock the chain of old record */ tdb_unlock(tdb, BUCKET(oldhash), F_WRLCK); return key; } /* delete an entry in the database given a key */ int tdb_delete(TDB_CONTEXT *tdb, TDB_DATA key) { tdb_off rec_ptr; struct list_struct rec; int ret; if (!(rec_ptr = tdb_find_lock(tdb, key, F_WRLCK, &rec))) return -1; ret = do_delete(tdb, rec_ptr, &rec); tdb_unlock(tdb, BUCKET(rec.full_hash), F_WRLCK); return ret; } /* store an element in the database, replacing any existing element with the same key return 0 on success, -1 on failure */ int tdb_store(TDB_CONTEXT *tdb, TDB_DATA key, TDB_DATA dbuf, int flag) { struct list_struct rec; u32 hash; tdb_off rec_ptr; char *p = NULL; int ret = 0; /* find which hash bucket it is in */ hash = tdb_hash(&key); if (!tdb_keylocked(tdb, hash)) return -1; if (tdb_lock(tdb, BUCKET(hash), F_WRLCK) == -1) return -1; /* check for it existing, on insert. */ if (flag == TDB_INSERT) { if (tdb_exists(tdb, key)) { tdb->ecode = TDB_ERR_EXISTS; goto fail; } } else { /* first try in-place update, on modify or replace. */ if (tdb_update(tdb, key, dbuf) == 0) goto out; if (flag == TDB_MODIFY && tdb->ecode == TDB_ERR_NOEXIST) 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(tdb, key); /* now we're into insert / modify / replace of a record which * we know could not be optimised by an in-place store (for * various reasons). */ if (!(rec_ptr = tdb_allocate(tdb, key.dsize + dbuf.dsize, &rec))) goto fail; /* Read hash top into next ptr */ if (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; if (!(p = (char *)malloc(key.dsize + dbuf.dsize))) { tdb->ecode = TDB_ERR_OOM; goto fail; } memcpy(p, key.dptr, key.dsize); memcpy(p+key.dsize, dbuf.dptr, dbuf.dsize); /* write out and point the top of the hash chain at it */ if (rec_write(tdb, rec_ptr, &rec) == -1 || tdb_write(tdb, rec_ptr+sizeof(rec), p, key.dsize+dbuf.dsize)==-1 || ofs_write(tdb, TDB_HASH_TOP(hash), &rec_ptr) == -1) { fail: ret = -1; } out: free(p); tdb_unlock(tdb, BUCKET(hash), F_WRLCK); return ret; } /* 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 */ TDB_CONTEXT *tdb_open(char *name, int hash_size, int tdb_flags, int open_flags, mode_t mode) { TDB_CONTEXT tdb, *ret, *i; struct stat st; int rev = 0, locked; memset(&tdb, 0, sizeof(tdb)); tdb.fd = -1; tdb.name = NULL; tdb.map_ptr = NULL; tdb.lockedkeys = NULL; tdb.flags = tdb_flags; if ((open_flags & O_ACCMODE) == O_WRONLY) 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 */ tdb.flags |= TDB_NOLOCK; } /* 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; tdb_new_database(&tdb, hash_size); goto internal; } if ((tdb.fd = open(name, open_flags, mode)) == -1) goto fail; /* ensure there is only one process initialising at once */ tdb_brlock(&tdb, GLOBAL_LOCK, F_WRLCK, F_SETLKW); /* we need to zero database if we are the only one with it open */ if ((locked = (tdb_brlock(&tdb, ACTIVE_LOCK, F_WRLCK, F_SETLK) == 0)) && (tdb_flags & TDB_CLEAR_IF_FIRST)) { open_flags |= O_CREAT; ftruncate(tdb.fd, 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) goto fail; rev = (tdb.flags & TDB_CONVERT); } if (!rev) tdb.flags &= ~TDB_CONVERT; else { tdb.flags |= TDB_CONVERT; convert(&tdb.header, sizeof(tdb.header)); } fstat(tdb.fd, &st); /* Is it already in the open list? If so, fail. */ for (i = tdbs; i; i = i->next) { if (i->device == st.st_dev && i->inode == st.st_ino) { errno = EBUSY; close(tdb.fd); return NULL; } } /* map the database and fill in the return structure */ tdb.name = (char *)strdup(name); tdb.map_size = st.st_size; tdb.device = st.st_dev; tdb.inode = st.st_ino; tdb.locked = calloc(tdb.header.hash_size+1, sizeof(tdb.locked[0])); if (!tdb.locked) goto fail; if (!(tdb.flags & TDB_NOMMAP)) tdb.map_ptr = tdb_mmap(st.st_size, tdb.read_only, tdb.fd); if (locked) { tdb_clear_spinlocks(&tdb); tdb_brlock(&tdb, ACTIVE_LOCK, F_UNLCK, F_SETLK); } /* leave this lock in place to indicate it's in use */ tdb_brlock(&tdb, ACTIVE_LOCK, F_RDLCK, F_SETLKW); internal: if (!(ret = malloc(sizeof(tdb)))) goto fail; *ret = tdb; tdb_brlock(&tdb, GLOBAL_LOCK, F_UNLCK, F_SETLKW); ret->next = tdbs; tdbs = ret; return ret; fail: if (tdb.name) free(tdb.name); if (tdb.fd != -1) close(tdb.fd); if (tdb.map_ptr) tdb_munmap(tdb.map_ptr, tdb.map_size); return NULL; } /* close a database */ int tdb_close(TDB_CONTEXT *tdb) { TDB_CONTEXT **i; int ret = 0; if (tdb->map_ptr) { if (tdb->flags & TDB_INTERNAL) free(tdb->map_ptr); else tdb_munmap(tdb->map_ptr, tdb->map_size); } if (tdb->name) free(tdb->name); if (tdb->fd != -1) { ret = close(tdb->fd); } if (tdb->locked) free(tdb->locked); if (tdb->lockedkeys) free(tdb->lockedkeys); /* Remove from contexts list */ for (i = &tdbs; *i; i = &(*i)->next) { if (*i == tdb) { *i = tdb->next; break; } } memset(tdb, 0, sizeof(*tdb)); free(tdb); return ret; } /* lock/unlock entire database */ int tdb_lockall(TDB_CONTEXT *tdb) { u32 i; /* There are no locks on read-only dbs */ if (tdb->read_only) return TDB_ERRCODE(TDB_ERR_LOCK, -1); if (tdb->lockedkeys) return TDB_ERRCODE(TDB_ERR_NOLOCK, -1); for (i = 0; i < tdb->header.hash_size; i++) tdb_lock(tdb, i, F_WRLCK); return 0; } void tdb_unlockall(TDB_CONTEXT *tdb) { u32 i; for (i=0; i < tdb->header.hash_size; i++) tdb_unlock(tdb, i, F_WRLCK); } int tdb_lockkeys(TDB_CONTEXT *tdb, u32 number, TDB_DATA keys[]) { u32 i, j, hash; /* Can't lock more keys if already locked */ if (tdb->lockedkeys) return TDB_ERRCODE(TDB_ERR_NOLOCK, -1); if (!(tdb->lockedkeys = malloc(sizeof(u32) * (number+1)))) return TDB_ERRCODE(TDB_ERR_OOM, -1); /* First number in array is # keys */ tdb->lockedkeys[0] = number; /* Insertion sort by bucket */ for (i = 0; i < number; i++) { hash = tdb_hash(&keys[i]); for (j = 0; j < i && BUCKET(tdb->lockedkeys[j+1]) < BUCKET(hash); j++); memmove(&tdb->lockedkeys[j+2], &tdb->lockedkeys[j+1], sizeof(u32) * (i-j)); tdb->lockedkeys[j+1] = hash; } /* Finally, lock in order */ for (i = 0; i < number; i++) tdb_lock(tdb, i, F_WRLCK); return 0; } /* Unlock the keys previously locked by tdb_lockkeys() */ void tdb_unlockkeys(TDB_CONTEXT *tdb) { u32 i; for (i = 0; i < tdb->lockedkeys[0]; i++) tdb_unlock(tdb, tdb->lockedkeys[i+1], F_WRLCK); free(tdb->lockedkeys); tdb->lockedkeys = NULL; } /* 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(TDB_CONTEXT *tdb, TDB_DATA key) { return tdb_lock(tdb, BUCKET(tdb_hash(&key)), F_WRLCK); } void tdb_chainunlock(TDB_CONTEXT *tdb, TDB_DATA key) { tdb_unlock(tdb, BUCKET(tdb_hash(&key)), F_WRLCK); }