/* Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You under the Apache License, Version 2.0 * (the "License"); you may not use this file except in compliance with * the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ /* * sdbm - ndbm work-alike hashed database library * based on Per-Aake Larson's Dynamic Hashing algorithms. BIT 18 (1978). * author: oz@nexus.yorku.ca * ex-public domain, ported to APR for Apache 2 * core routines */ #include "apr.h" #include "apr_file_io.h" #include "apr_strings.h" #include "apr_errno.h" #include "apr_sdbm.h" #include "sdbm_tune.h" #include "sdbm_pair.h" #include "sdbm_private.h" #include <string.h> /* for memset() */ #include <stdlib.h> /* for malloc() and free() */ /* * forward */ static int getdbit (apr_sdbm_t *, long); static apr_status_t setdbit(apr_sdbm_t *, long); static apr_status_t getpage(apr_sdbm_t *db, long); static apr_status_t getnext(apr_sdbm_datum_t *key, apr_sdbm_t *db); static apr_status_t makroom(apr_sdbm_t *, long, int); /* * useful macros */ #define bad(x) ((x).dptr == NULL || (x).dsize <= 0) #define exhash(item) sdbm_hash((item).dptr, (item).dsize) #define OFF_PAG(off) (apr_off_t) (off) * PBLKSIZ #define OFF_DIR(off) (apr_off_t) (off) * DBLKSIZ static const long masks[] = { 000000000000, 000000000001, 000000000003, 000000000007, 000000000017, 000000000037, 000000000077, 000000000177, 000000000377, 000000000777, 000000001777, 000000003777, 000000007777, 000000017777, 000000037777, 000000077777, 000000177777, 000000377777, 000000777777, 000001777777, 000003777777, 000007777777, 000017777777, 000037777777, 000077777777, 000177777777, 000377777777, 000777777777, 001777777777, 003777777777, 007777777777, 017777777777 }; const apr_sdbm_datum_t sdbm_nullitem = { NULL, 0 }; static apr_status_t database_cleanup(void *data) { apr_sdbm_t *db = data; /* * Can't rely on apr_sdbm_unlock, since it will merely * decrement the refcnt if several locks are held. */ if (db->flags & (SDBM_SHARED_LOCK | SDBM_EXCLUSIVE_LOCK)) (void) apr_file_unlock(db->dirf); (void) apr_file_close(db->dirf); (void) apr_file_close(db->pagf); free(db); return APR_SUCCESS; } static apr_status_t prep(apr_sdbm_t **pdb, const char *dirname, const char *pagname, apr_int32_t flags, apr_fileperms_t perms, apr_pool_t *p) { apr_sdbm_t *db; apr_status_t status; *pdb = NULL; db = malloc(sizeof(*db)); memset(db, 0, sizeof(*db)); db->pool = p; /* * adjust user flags so that WRONLY becomes RDWR, * as required by this package. Also set our internal * flag for RDONLY if needed. */ if (!(flags & APR_WRITE)) { db->flags |= SDBM_RDONLY; } /* * adjust the file open flags so that we handle locking * on our own (don't rely on any locking behavior within * an apr_file_t, in case it's ever introduced, and set * our own flag. */ if (flags & APR_SHARELOCK) { db->flags |= SDBM_SHARED; flags &= ~APR_SHARELOCK; } flags |= APR_BINARY | APR_READ; /* * open the files in sequence, and stat the dirfile. * If we fail anywhere, undo everything, return NULL. */ if ((status = apr_file_open(&db->dirf, dirname, flags, perms, p)) != APR_SUCCESS) goto error; if ((status = apr_file_open(&db->pagf, pagname, flags, perms, p)) != APR_SUCCESS) goto error; if ((status = apr_sdbm_lock(db, (db->flags & SDBM_RDONLY) ? APR_FLOCK_SHARED : APR_FLOCK_EXCLUSIVE)) != APR_SUCCESS) goto error; /* apr_pcalloc zeroed the buffers * apr_sdbm_lock stated the dirf->size and invalidated the cache */ /* * if we are opened in SHARED mode, unlock ourself */ if (db->flags & SDBM_SHARED) if ((status = apr_sdbm_unlock(db)) != APR_SUCCESS) goto error; /* make sure that we close the database at some point */ apr_pool_cleanup_register(p, db, database_cleanup, apr_pool_cleanup_null); /* Done! */ *pdb = db; return APR_SUCCESS; error: if (db->dirf && db->pagf) (void) apr_sdbm_unlock(db); if (db->dirf != NULL) (void) apr_file_close(db->dirf); if (db->pagf != NULL) { (void) apr_file_close(db->pagf); } free(db); return status; } APU_DECLARE(apr_status_t) apr_sdbm_open(apr_sdbm_t **db, const char *file, apr_int32_t flags, apr_fileperms_t perms, apr_pool_t *p) { char *dirname = apr_pstrcat(p, file, APR_SDBM_DIRFEXT, NULL); char *pagname = apr_pstrcat(p, file, APR_SDBM_PAGFEXT, NULL); return prep(db, dirname, pagname, flags, perms, p); } APU_DECLARE(apr_status_t) apr_sdbm_close(apr_sdbm_t *db) { return apr_pool_cleanup_run(db->pool, db, database_cleanup); } APU_DECLARE(apr_status_t) apr_sdbm_fetch(apr_sdbm_t *db, apr_sdbm_datum_t *val, apr_sdbm_datum_t key) { apr_status_t status; if (db == NULL || bad(key)) return APR_EINVAL; if ((status = apr_sdbm_lock(db, APR_FLOCK_SHARED)) != APR_SUCCESS) return status; if ((status = getpage(db, exhash(key))) == APR_SUCCESS) { *val = getpair(db->pagbuf, key); /* ### do we want a not-found result? */ } (void) apr_sdbm_unlock(db); return status; } static apr_status_t write_page(apr_sdbm_t *db, const char *buf, long pagno) { apr_status_t status; apr_off_t off = OFF_PAG(pagno); if ((status = apr_file_seek(db->pagf, APR_SET, &off)) == APR_SUCCESS) status = apr_file_write_full(db->pagf, buf, PBLKSIZ, NULL); return status; } APU_DECLARE(apr_status_t) apr_sdbm_delete(apr_sdbm_t *db, const apr_sdbm_datum_t key) { apr_status_t status; if (db == NULL || bad(key)) return APR_EINVAL; if (apr_sdbm_rdonly(db)) return APR_EINVAL; if ((status = apr_sdbm_lock(db, APR_FLOCK_EXCLUSIVE)) != APR_SUCCESS) return status; if ((status = getpage(db, exhash(key))) == APR_SUCCESS) { if (!delpair(db->pagbuf, key)) /* ### should we define some APRUTIL codes? */ status = APR_EGENERAL; else status = write_page(db, db->pagbuf, db->pagbno); } (void) apr_sdbm_unlock(db); return status; } APU_DECLARE(apr_status_t) apr_sdbm_store(apr_sdbm_t *db, apr_sdbm_datum_t key, apr_sdbm_datum_t val, int flags) { int need; register long hash; apr_status_t status; if (db == NULL || bad(key)) return APR_EINVAL; if (apr_sdbm_rdonly(db)) return APR_EINVAL; need = key.dsize + val.dsize; /* * is the pair too big (or too small) for this database ?? */ if (need < 0 || need > PAIRMAX) return APR_EINVAL; if ((status = apr_sdbm_lock(db, APR_FLOCK_EXCLUSIVE)) != APR_SUCCESS) return status; if ((status = getpage(db, (hash = exhash(key)))) == APR_SUCCESS) { /* * if we need to replace, delete the key/data pair * first. If it is not there, ignore. */ if (flags == APR_SDBM_REPLACE) (void) delpair(db->pagbuf, key); else if (!(flags & APR_SDBM_INSERTDUP) && duppair(db->pagbuf, key)) { status = APR_EEXIST; goto error; } /* * if we do not have enough room, we have to split. */ if (!fitpair(db->pagbuf, need)) if ((status = makroom(db, hash, need)) != APR_SUCCESS) goto error; /* * we have enough room or split is successful. insert the key, * and update the page file. */ (void) putpair(db->pagbuf, key, val); status = write_page(db, db->pagbuf, db->pagbno); } error: (void) apr_sdbm_unlock(db); return status; } /* * makroom - make room by splitting the overfull page * this routine will attempt to make room for SPLTMAX times before * giving up. */ static apr_status_t makroom(apr_sdbm_t *db, long hash, int need) { long newp; char twin[PBLKSIZ]; char *pag = db->pagbuf; char *new = twin; register int smax = SPLTMAX; apr_status_t status; do { /* * split the current page */ (void) splpage(pag, new, db->hmask + 1); /* * address of the new page */ newp = (hash & db->hmask) | (db->hmask + 1); /* * write delay, read avoidence/cache shuffle: * select the page for incoming pair: if key is to go to the new page, * write out the previous one, and copy the new one over, thus making * it the current page. If not, simply write the new page, and we are * still looking at the page of interest. current page is not updated * here, as sdbm_store will do so, after it inserts the incoming pair. */ if (hash & (db->hmask + 1)) { if ((status = write_page(db, db->pagbuf, db->pagbno)) != APR_SUCCESS) return status; db->pagbno = newp; (void) memcpy(pag, new, PBLKSIZ); } else { if ((status = write_page(db, new, newp)) != APR_SUCCESS) return status; } if ((status = setdbit(db, db->curbit)) != APR_SUCCESS) return status; /* * see if we have enough room now */ if (fitpair(pag, need)) return APR_SUCCESS; /* * try again... update curbit and hmask as getpage would have * done. because of our update of the current page, we do not * need to read in anything. BUT we have to write the current * [deferred] page out, as the window of failure is too great. */ db->curbit = 2 * db->curbit + ((hash & (db->hmask + 1)) ? 2 : 1); db->hmask |= db->hmask + 1; if ((status = write_page(db, db->pagbuf, db->pagbno)) != APR_SUCCESS) return status; } while (--smax); /* * if we are here, this is real bad news. After SPLTMAX splits, * we still cannot fit the key. say goodnight. */ #if 0 (void) write(2, "sdbm: cannot insert after SPLTMAX attempts.\n", 44); #endif /* ### ENOSPC not really appropriate but better than nothing */ return APR_ENOSPC; } /* Reads 'len' bytes from file 'f' at offset 'off' into buf. * 'off' is given relative to the start of the file. * If EOF is returned while reading, this is taken as success. */ static apr_status_t read_from(apr_file_t *f, void *buf, apr_off_t off, apr_size_t len) { apr_status_t status; if ((status = apr_file_seek(f, APR_SET, &off)) != APR_SUCCESS || ((status = apr_file_read_full(f, buf, len, NULL)) != APR_SUCCESS)) { /* if EOF is reached, pretend we read all zero's */ if (status == APR_EOF) { memset(buf, 0, len); status = APR_SUCCESS; } } return status; } /* * the following two routines will break if * deletions aren't taken into account. (ndbm bug) */ APU_DECLARE(apr_status_t) apr_sdbm_firstkey(apr_sdbm_t *db, apr_sdbm_datum_t *key) { apr_status_t status; if ((status = apr_sdbm_lock(db, APR_FLOCK_SHARED)) != APR_SUCCESS) return status; /* * start at page 0 */ if ((status = read_from(db->pagf, db->pagbuf, OFF_PAG(0), PBLKSIZ)) == APR_SUCCESS) { db->pagbno = 0; db->blkptr = 0; db->keyptr = 0; status = getnext(key, db); } (void) apr_sdbm_unlock(db); return status; } APU_DECLARE(apr_status_t) apr_sdbm_nextkey(apr_sdbm_t *db, apr_sdbm_datum_t *key) { apr_status_t status; if ((status = apr_sdbm_lock(db, APR_FLOCK_SHARED)) != APR_SUCCESS) return status; status = getnext(key, db); (void) apr_sdbm_unlock(db); return status; } /* * all important binary tree traversal */ static apr_status_t getpage(apr_sdbm_t *db, long hash) { register int hbit; register long dbit; register long pagb; apr_status_t status; dbit = 0; hbit = 0; while (dbit < db->maxbno && getdbit(db, dbit)) dbit = 2 * dbit + ((hash & (1 << hbit++)) ? 2 : 1); debug(("dbit: %d...", dbit)); db->curbit = dbit; db->hmask = masks[hbit]; pagb = hash & db->hmask; /* * see if the block we need is already in memory. * note: this lookaside cache has about 10% hit rate. */ if (pagb != db->pagbno) { /* * note: here, we assume a "hole" is read as 0s. * if not, must zero pagbuf first. * ### joe: this assumption was surely never correct? but * ### we make it so in read_from anyway. */ if ((status = read_from(db->pagf, db->pagbuf, OFF_PAG(pagb), PBLKSIZ)) != APR_SUCCESS) return status; if (!chkpage(db->pagbuf)) return APR_ENOSPC; /* ### better error? */ db->pagbno = pagb; debug(("pag read: %d\n", pagb)); } return APR_SUCCESS; } static int getdbit(apr_sdbm_t *db, long dbit) { register long c; register long dirb; c = dbit / BYTESIZ; dirb = c / DBLKSIZ; if (dirb != db->dirbno) { if (read_from(db->dirf, db->dirbuf, OFF_DIR(dirb), DBLKSIZ) != APR_SUCCESS) return 0; db->dirbno = dirb; debug(("dir read: %d\n", dirb)); } return db->dirbuf[c % DBLKSIZ] & (1 << dbit % BYTESIZ); } static apr_status_t setdbit(apr_sdbm_t *db, long dbit) { register long c; register long dirb; apr_status_t status; apr_off_t off; c = dbit / BYTESIZ; dirb = c / DBLKSIZ; if (dirb != db->dirbno) { if ((status = read_from(db->dirf, db->dirbuf, OFF_DIR(dirb), DBLKSIZ)) != APR_SUCCESS) return status; db->dirbno = dirb; debug(("dir read: %d\n", dirb)); } db->dirbuf[c % DBLKSIZ] |= (1 << dbit % BYTESIZ); if (dbit >= db->maxbno) db->maxbno += DBLKSIZ * BYTESIZ; off = OFF_DIR(dirb); if ((status = apr_file_seek(db->dirf, APR_SET, &off)) == APR_SUCCESS) status = apr_file_write_full(db->dirf, db->dirbuf, DBLKSIZ, NULL); return status; } /* * getnext - get the next key in the page, and if done with * the page, try the next page in sequence */ static apr_status_t getnext(apr_sdbm_datum_t *key, apr_sdbm_t *db) { apr_status_t status; for (;;) { db->keyptr++; *key = getnkey(db->pagbuf, db->keyptr); if (key->dptr != NULL) return APR_SUCCESS; /* * we either run out, or there is nothing on this page.. * try the next one... If we lost our position on the * file, we will have to seek. */ db->keyptr = 0; if (db->pagbno != db->blkptr++) { apr_off_t off = OFF_PAG(db->blkptr); if ((status = apr_file_seek(db->pagf, APR_SET, &off)) != APR_SUCCESS) return status; } db->pagbno = db->blkptr; /* ### EOF acceptable here too? */ if ((status = apr_file_read_full(db->pagf, db->pagbuf, PBLKSIZ, NULL)) != APR_SUCCESS) return status; if (!chkpage(db->pagbuf)) return APR_EGENERAL; /* ### need better error */ } /* NOTREACHED */ } APU_DECLARE(int) apr_sdbm_rdonly(apr_sdbm_t *db) { /* ### Should we return true if the first lock is a share lock, * to reflect that apr_sdbm_store and apr_sdbm_delete will fail? */ return (db->flags & SDBM_RDONLY) != 0; }
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