diff options
Diffstat (limited to 'ext/SDBM_File/sdbm/sdbm.c')
| -rw-r--r-- | ext/SDBM_File/sdbm/sdbm.c | 520 |
1 files changed, 520 insertions, 0 deletions
diff --git a/ext/SDBM_File/sdbm/sdbm.c b/ext/SDBM_File/sdbm/sdbm.c new file mode 100644 index 0000000000..d09adccdd3 --- /dev/null +++ b/ext/SDBM_File/sdbm/sdbm.c @@ -0,0 +1,520 @@ +/* + * 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 + */ + +#ifndef lint +static char rcsid[] = "$Id: sdbm.c,v 1.16 90/12/13 13:01:31 oz Exp $"; +#endif + +#include "config.h" +#include "sdbm.h" +#include "tune.h" +#include "pair.h" + +#ifdef I_FCNTL +# include <fcntl.h> +#endif +#ifdef I_SYS_FILE +# include <sys/file.h> +#endif + +#ifdef I_STRING +# include <string.h> +#else +# include <strings.h> +#endif + +/* + * externals + */ +#ifndef sun +extern int errno; +#endif + +extern Malloc_t malloc proto((MEM_SIZE)); +extern void free proto((void *)); +extern Off_t lseek(); + +/* + * 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}; + +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); + + 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 ((db->pagf = open(pagname, flags, mode)) > -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) 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) close(db->pagf); + free((char *) db); + } +} + +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; +} + |