| /* |
| * sdbm - ndbm work-alike hashed database library |
| * based on Per-Aake Larson's Dynamic Hashing algorithms. BIT 18 (1978). |
| * author: oz@nexus.yorku.ca |
| * status: public domain. |
| * |
| * core routines |
| */ |
| |
| #include "sdbm.h" |
| #include "sdbm_tune.h" |
| #include "sdbm_pair.h" |
| |
| #include <sys/types.h> |
| #include <sys/stat.h> |
| #include <fcntl.h> |
| #include <errno.h> |
| #include <string.h> |
| #include <stdlib.h> |
| #ifdef WIN32 |
| #include <io.h> |
| #include <stdio.h> |
| #else |
| #include <unistd.h> /* for lseek() */ |
| #endif |
| #ifdef NETWARE |
| #include <nwsemaph.h> |
| #endif |
| |
| |
| /* |
| * forward |
| */ |
| static int getdbit proto((DBM *, long)); |
| static int setdbit proto((DBM *, long)); |
| static int getpage proto((DBM *, long)); |
| static datum getnext proto((DBM *)); |
| static int makroom proto((DBM *, long, int)); |
| |
| /* |
| * useful macros |
| */ |
| #define bad(x) ((x).dptr == NULL || (x).dsize <= 0) |
| #define exhash(item) sdbm_hash((item).dptr, (item).dsize) |
| #define ioerr(db) ((db)->flags |= DBM_IOERR) |
| |
| #define OFF_PAG(off) (long) (off) * PBLKSIZ |
| #define OFF_DIR(off) (long) (off) * DBLKSIZ |
| |
| static 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 |
| }; |
| |
| datum nullitem = {NULL, 0}; |
| #ifdef NETWARE |
| extern LONG locking_sem; |
| #endif |
| |
| DBM * |
| sdbm_open(file, flags, mode) |
| register char *file; |
| register int flags; |
| register int mode; |
| { |
| register DBM *db; |
| register char *dirname; |
| register char *pagname; |
| register int n; |
| |
| if (file == NULL || !*file) |
| return errno = EINVAL, (DBM *) NULL; |
| /* |
| * need space for two seperate filenames |
| */ |
| n = strlen(file) * 2 + strlen(DIRFEXT) + strlen(PAGFEXT) + 2; |
| |
| if ((dirname = malloc((unsigned) n)) == NULL) |
| return errno = ENOMEM, (DBM *) NULL; |
| /* |
| * build the file names |
| */ |
| dirname = strcat(strcpy(dirname, file), DIRFEXT); |
| pagname = strcpy(dirname + strlen(dirname) + 1, file); |
| pagname = strcat(pagname, PAGFEXT); |
| |
| #ifdef NETWARE |
| locking_sem = OpenLocalSemaphore (1); |
| #endif |
| |
| db = sdbm_prep(dirname, pagname, flags, mode); |
| free((char *) dirname); |
| return db; |
| } |
| |
| DBM * |
| sdbm_prep(dirname, pagname, flags, mode) |
| char *dirname; |
| char *pagname; |
| int flags; |
| int mode; |
| { |
| register DBM *db; |
| struct stat dstat; |
| |
| if ((db = (DBM *) malloc(sizeof(DBM))) == NULL) |
| return errno = ENOMEM, (DBM *) NULL; |
| |
| db->flags = 0; |
| db->hmask = 0; |
| db->blkptr = 0; |
| db->keyptr = 0; |
| /* |
| * adjust user flags so that WRONLY becomes RDWR, |
| * as required by this package. Also set our internal |
| * flag for RDONLY if needed. |
| */ |
| if (flags & O_WRONLY) |
| flags = (flags & ~O_WRONLY) | O_RDWR; |
| |
| else if ((flags & 03) == O_RDONLY) |
| db->flags = DBM_RDONLY; |
| /* |
| * open the files in sequence, and stat the dirfile. |
| * If we fail anywhere, undo everything, return NULL. |
| */ |
| #if defined(OS2) || defined(MSDOS) || defined(WIN32) || defined(NETWARE) |
| flags |= O_BINARY; |
| #endif |
| if ((db->pagf = open(pagname, flags, mode)) > -1) { |
| if ( sdbm_fd_lock(db->pagf, sdbm_rdonly(db)) > -1 ) { |
| if ((db->dirf = open(dirname, flags, mode)) > -1) { |
| /* |
| * need the dirfile size to establish max bit number. |
| */ |
| if (fstat(db->dirf, &dstat) == 0) { |
| /* |
| * zero size: either a fresh database, or one with a single, |
| * unsplit data page: dirpage is all zeros. |
| */ |
| db->dirbno = (!dstat.st_size) ? 0 : -1; |
| db->pagbno = -1; |
| db->maxbno = dstat.st_size * BYTESIZ; |
| |
| (void) memset(db->pagbuf, 0, PBLKSIZ); |
| (void) memset(db->dirbuf, 0, DBLKSIZ); |
| /* |
| * success |
| */ |
| return db; |
| } |
| (void) close(db->dirf); |
| } |
| (void) sdbm_fd_unlock(db->pagf); |
| } |
| (void) close(db->pagf); |
| } |
| free((char *) db); |
| return (DBM *) NULL; |
| } |
| |
| void |
| sdbm_close(db) |
| register DBM *db; |
| { |
| if (db == NULL) |
| errno = EINVAL; |
| else { |
| (void) close(db->dirf); |
| (void) sdbm_fd_unlock(db->pagf); |
| (void) close(db->pagf); |
| free((char *) db); |
| #ifdef NETWARE |
| CloseLocalSemaphore (locking_sem); |
| #endif |
| } |
| } |
| |
| datum |
| sdbm_fetch(db, key) |
| register DBM *db; |
| datum key; |
| { |
| if (db == NULL || bad(key)) |
| return errno = EINVAL, nullitem; |
| |
| if (getpage(db, exhash(key))) |
| return getpair(db->pagbuf, key); |
| |
| return ioerr(db), nullitem; |
| } |
| |
| int |
| sdbm_delete(db, key) |
| register DBM *db; |
| datum key; |
| { |
| if (db == NULL || bad(key)) |
| return errno = EINVAL, -1; |
| if (sdbm_rdonly(db)) |
| return errno = EPERM, -1; |
| |
| if (getpage(db, exhash(key))) { |
| if (!delpair(db->pagbuf, key)) |
| return -1; |
| /* |
| * update the page file |
| */ |
| if (lseek(db->pagf, OFF_PAG(db->pagbno), SEEK_SET) < 0 |
| || write(db->pagf, db->pagbuf, PBLKSIZ) < 0) |
| return ioerr(db), -1; |
| |
| return 0; |
| } |
| |
| return ioerr(db), -1; |
| } |
| |
| int |
| sdbm_store(db, key, val, flags) |
| register DBM *db; |
| datum key; |
| datum val; |
| int flags; |
| { |
| int need; |
| register long hash; |
| |
| if (db == NULL || bad(key)) |
| return errno = EINVAL, -1; |
| if (sdbm_rdonly(db)) |
| return errno = EPERM, -1; |
| |
| need = key.dsize + val.dsize; |
| /* |
| * is the pair too big (or too small) for this database ?? |
| */ |
| if (need < 0 || need > PAIRMAX) |
| return errno = EINVAL, -1; |
| |
| if (getpage(db, (hash = exhash(key)))) { |
| /* |
| * if we need to replace, delete the key/data pair |
| * first. If it is not there, ignore. |
| */ |
| if (flags == DBM_REPLACE) |
| (void) delpair(db->pagbuf, key); |
| #ifdef SEEDUPS |
| else if (duppair(db->pagbuf, key)) |
| return 1; |
| #endif |
| /* |
| * if we do not have enough room, we have to split. |
| */ |
| if (!fitpair(db->pagbuf, need)) |
| if (!makroom(db, hash, need)) |
| return ioerr(db), -1; |
| /* |
| * we have enough room or split is successful. insert the key, |
| * and update the page file. |
| */ |
| (void) putpair(db->pagbuf, key, val); |
| |
| if (lseek(db->pagf, OFF_PAG(db->pagbno), SEEK_SET) < 0 |
| || write(db->pagf, db->pagbuf, PBLKSIZ) < 0) |
| return ioerr(db), -1; |
| /* |
| * success |
| */ |
| return 0; |
| } |
| |
| return ioerr(db), -1; |
| } |
| |
| /* |
| * makroom - make room by splitting the overfull page |
| * this routine will attempt to make room for SPLTMAX times before |
| * giving up. |
| */ |
| static int |
| makroom(db, hash, need) |
| register DBM *db; |
| long hash; |
| int need; |
| { |
| long newp; |
| char twin[PBLKSIZ]; |
| char *pag = db->pagbuf; |
| char *new = twin; |
| register int smax = SPLTMAX; |
| |
| 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 (lseek(db->pagf, OFF_PAG(db->pagbno), SEEK_SET) < 0 |
| || write(db->pagf, db->pagbuf, PBLKSIZ) < 0) |
| return 0; |
| db->pagbno = newp; |
| (void) memcpy(pag, new, PBLKSIZ); |
| } |
| else if (lseek(db->pagf, OFF_PAG(newp), SEEK_SET) < 0 |
| || write(db->pagf, new, PBLKSIZ) < 0) |
| return 0; |
| |
| if (!setdbit(db, db->curbit)) |
| return 0; |
| /* |
| * see if we have enough room now |
| */ |
| if (fitpair(pag, need)) |
| return 1; |
| /* |
| * 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 (lseek(db->pagf, OFF_PAG(db->pagbno), SEEK_SET) < 0 |
| || write(db->pagf, db->pagbuf, PBLKSIZ) < 0) |
| return 0; |
| |
| } while (--smax); |
| /* |
| * if we are here, this is real bad news. After SPLTMAX splits, |
| * we still cannot fit the key. say goodnight. |
| */ |
| #ifdef BADMESS |
| (void) write(2, "sdbm: cannot insert after SPLTMAX attempts.\n", 44); |
| #endif |
| return 0; |
| |
| } |
| |
| /* |
| * the following two routines will break if |
| * deletions aren't taken into account. (ndbm bug) |
| */ |
| datum |
| sdbm_firstkey(db) |
| register DBM *db; |
| { |
| if (db == NULL) |
| return errno = EINVAL, nullitem; |
| /* |
| * start at page 0 |
| */ |
| if (lseek(db->pagf, OFF_PAG(0), SEEK_SET) < 0 |
| || read(db->pagf, db->pagbuf, PBLKSIZ) < 0) |
| return ioerr(db), nullitem; |
| db->pagbno = 0; |
| db->blkptr = 0; |
| db->keyptr = 0; |
| |
| return getnext(db); |
| } |
| |
| datum |
| sdbm_nextkey(db) |
| register DBM *db; |
| { |
| if (db == NULL) |
| return errno = EINVAL, nullitem; |
| return getnext(db); |
| } |
| |
| /* |
| * all important binary trie traversal |
| */ |
| static int |
| getpage(db, hash) |
| register DBM *db; |
| register long hash; |
| { |
| register int hbit; |
| register long dbit; |
| register long pagb; |
| |
| 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. |
| */ |
| if (lseek(db->pagf, OFF_PAG(pagb), SEEK_SET) < 0 |
| || read(db->pagf, db->pagbuf, PBLKSIZ) < 0) |
| return 0; |
| if (!chkpage(db->pagbuf)) |
| return 0; |
| db->pagbno = pagb; |
| |
| debug(("pag read: %d\n", pagb)); |
| } |
| return 1; |
| } |
| |
| static int |
| getdbit(db, dbit) |
| register DBM *db; |
| register long dbit; |
| { |
| register long c; |
| register long dirb; |
| |
| c = dbit / BYTESIZ; |
| dirb = c / DBLKSIZ; |
| |
| if (dirb != db->dirbno) { |
| if (lseek(db->dirf, OFF_DIR(dirb), SEEK_SET) < 0 |
| || read(db->dirf, db->dirbuf, DBLKSIZ) < 0) |
| return 0; |
| db->dirbno = dirb; |
| |
| debug(("dir read: %d\n", dirb)); |
| } |
| |
| return db->dirbuf[c % DBLKSIZ] & (1 << dbit % BYTESIZ); |
| } |
| |
| static int |
| setdbit(db, dbit) |
| register DBM *db; |
| register long dbit; |
| { |
| register long c; |
| register long dirb; |
| |
| c = dbit / BYTESIZ; |
| dirb = c / DBLKSIZ; |
| |
| if (dirb != db->dirbno) { |
| if (lseek(db->dirf, OFF_DIR(dirb), SEEK_SET) < 0 |
| || read(db->dirf, db->dirbuf, DBLKSIZ) < 0) |
| return 0; |
| db->dirbno = dirb; |
| |
| debug(("dir read: %d\n", dirb)); |
| } |
| |
| db->dirbuf[c % DBLKSIZ] |= (1 << dbit % BYTESIZ); |
| |
| if (dbit >= db->maxbno) |
| db->maxbno += DBLKSIZ * BYTESIZ; |
| |
| if (lseek(db->dirf, OFF_DIR(dirb), SEEK_SET) < 0 |
| || write(db->dirf, db->dirbuf, DBLKSIZ) < 0) |
| return 0; |
| |
| return 1; |
| } |
| |
| /* |
| * getnext - get the next key in the page, and if done with |
| * the page, try the next page in sequence |
| */ |
| static datum |
| getnext(db) |
| register DBM *db; |
| { |
| datum key; |
| |
| for (;;) { |
| db->keyptr++; |
| key = getnkey(db->pagbuf, db->keyptr); |
| if (key.dptr != NULL) |
| return key; |
| /* |
| * 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++) |
| if (lseek(db->pagf, OFF_PAG(db->blkptr), SEEK_SET) < 0) |
| break; |
| db->pagbno = db->blkptr; |
| if (read(db->pagf, db->pagbuf, PBLKSIZ) <= 0) |
| break; |
| if (!chkpage(db->pagbuf)) |
| break; |
| } |
| |
| return ioerr(db), nullitem; |
| } |