ssl_util_sdbm.c

mod_ssl-2.8.31-1.3.41.tar.gz 好用的ssl工具

        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;
        int got;

        c = dbit / BYTESIZ;
        dirb = c / DBLKSIZ;

        if (dirb != db->dirbno) {
                if (lseek(db->dirf, OFF_DIR(dirb), SEEK_SET) < 0
                    || (got = read(db->dirf, db->dirbuf, DBLKSIZ)) < 0)
                        return 0;
                if (got == 0) 
                        memset(db->dirbuf, 0, DBLKSIZ);
                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;
        int got;

        c = dbit / BYTESIZ;
        dirb = c / DBLKSIZ;

        if (dirb != db->dirbno) {
                if (lseek(db->dirf, OFF_DIR(dirb), SEEK_SET) < 0
                    || (got = read(db->dirf, db->dirbuf, DBLKSIZ)) < 0)
                        return 0;
                if (got == 0) 
                        memset(db->dirbuf, 0, DBLKSIZ);
                db->dirbno = dirb;

                debug(("dir read: %d\n", dirb));
        }

        db->dirbuf[c % DBLKSIZ] |= (1 << dbit % BYTESIZ);

#if 0
        if (dbit >= db->maxbno)
                db->maxbno += DBLKSIZ * BYTESIZ;
#else
        if (OFF_DIR((dirb+1))*BYTESIZ > db->maxbno) 
                db->maxbno = OFF_DIR((dirb+1)) * BYTESIZ;
#endif

        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;
}

/* ************************* */

/*
 * sdbm - ndbm work-alike hashed database library
 * based on Per-Aake Larson's Dynamic Hashing algorithms. BIT 18 (1978).
 * author: [e-mail]
 * status: public domain. keep it that way.
 *
 * hashing routine
 */

/*
 * polynomial conversion ignoring overflows
 * [this seems to work remarkably well, in fact better
 * then the ndbm hash function. Replace at your own risk]
 * use: 65599   nice.
 *      65587   even better.
 */
long
sdbm_hash(str, len)
register char *str;
register int len;
{
        register unsigned long n = 0;

#ifdef DUFF
#define HASHC   n = *str++ + 65599 * n
        if (len > 0) {
                register int loop = (len + 8 - 1) >> 3;

                switch(len & (8 - 1)) {
                case 0: do {
                        HASHC;  case 7: HASHC;
                case 6: HASHC;  case 5: HASHC;
                case 4: HASHC;  case 3: HASHC;
                case 2: HASHC;  case 1: HASHC;
                        } while (--loop);
                }

        }
#else
        while (len--)
                n = *str++ + 65599 * n;
#endif
        return n;
}

/* ************************* */

/*
 * sdbm - ndbm work-alike hashed database library
 * based on Per-Aake Larson's Dynamic Hashing algorithms. BIT 18 (1978).
 * author: [e-mail]
 * status: public domain.
 *
 * page-level routines
 */

#define exhash(item)    sdbm_hash((item).dptr, (item).dsize)

/*
 * forward
 */
static int seepair proto((char *, int, char *, int));

/*
 * page format:
 *      +------------------------------+
 * ino  | n | keyoff | datoff | keyoff |
 *      +------------+--------+--------+
 *      | datoff | - - - ---->         |
 *      +--------+---------------------+
 *      |        F R E E A R E A       |
 *      +--------------+---------------+
 *      |  <---- - - - | data          |
 *      +--------+-----+----+----------+
 *      |  key   | data     | key      |
 *      +--------+----------+----------+
 *
 * calculating the offsets for free area:  if the number
 * of entries (ino[0]) is zero, the offset to the END of
 * the free area is the block size. Otherwise, it is the
 * nth (ino[ino[0]]) entry's offset.
 */

int
fitpair(pag, need)
char *pag;
int need;
{
        register int n;
        register int off;
        register int avail;
        register short *ino = (short *) pag;

        off = ((n = ino[0]) > 0) ? ino[n] : PBLKSIZ;
        avail = off - (n + 1) * sizeof(short);
        need += 2 * sizeof(short);

        debug(("free %d need %d\n", avail, need));

        return need <= avail;
}

void
putpair(pag, key, val)
char *pag;
datum key;
datum val;
{
        register int n;
        register int off;
        register short *ino = (short *) pag;

        off = ((n = ino[0]) > 0) ? ino[n] : PBLKSIZ;
/*
 * enter the key first
 */
        off -= key.dsize;
        (void) memcpy(pag + off, key.dptr, key.dsize);
        ino[n + 1] = off;
/*
 * now the data
 */
        off -= val.dsize;
        (void) memcpy(pag + off, val.dptr, val.dsize);
        ino[n + 2] = off;
/*
 * adjust item count
 */
        ino[0] += 2;
}

datum
getpair(pag, key)
char *pag;
datum key;
{
        register int i;
        register int n;
        datum val;
        register short *ino = (short *) pag;

        if ((n = ino[0]) == 0)
                return nullitem;

        if ((i = seepair(pag, n, key.dptr, key.dsize)) == 0)
                return nullitem;

        val.dptr = pag + ino[i + 1];
        val.dsize = ino[i] - ino[i + 1];
        return val;
}

#ifdef SEEDUPS
int
duppair(pag, key)
char *pag;
datum key;
{
        register short *ino = (short *) pag;
        return ino[0] > 0 && seepair(pag, ino[0], key.dptr, key.dsize) > 0;
}
#endif

datum
getnkey(pag, num)
char *pag;
int num;
{
        datum key;
        register int off;
        register short *ino = (short *) pag;

        num = num * 2 - 1;
        if (ino[0] == 0 || num > ino[0])
                return nullitem;

        off = (num > 1) ? ino[num - 1] : PBLKSIZ;

        key.dptr = pag + ino[num];
        key.dsize = off - ino[num];

        return key;
}

int
delpair(pag, key)
char *pag;
datum key;
{
        register int n;
        register int i;
        register short *ino = (short *) pag;

        if ((n = ino[0]) == 0)
                return 0;

        if ((i = seepair(pag, n, key.dptr, key.dsize)) == 0)
                return 0;
/*
 * found the key. if it is the last entry
 * [i.e. i == n - 1] we just adjust the entry count.
 * hard case: move all data down onto the deleted pair,
 * shift offsets onto deleted offsets, and adjust them.
 * [note: 0 < i < n]
 */
        if (i < n - 1) {
                register int m;
                register char *dst = pag + (i == 1 ? PBLKSIZ : ino[i - 1]);
                register char *src = pag + ino[i + 1];
                register int   zoo = dst - src;

                debug(("free-up %d ", zoo));
/*
 * shift data/keys down
 */
                m = ino[i + 1] - ino[n];
#ifdef DUFF
#define MOVB    *--dst = *--src
                if (m > 0) {
                        register int loop = (m + 8 - 1) >> 3;

                        switch (m & (8 - 1)) {
                        case 0: do {
                                MOVB;   case 7: MOVB;
                        case 6: MOVB;   case 5: MOVB;
                        case 4: MOVB;   case 3: MOVB;
                        case 2: MOVB;   case 1: MOVB;
                                } while (--loop);
                        }
                }
#else
                dst -= m;
                src -= m;
                memmove(dst, src, m);
#endif
/*
 * adjust offset index up
 */
                while (i < n - 1) {
                        ino[i] = ino[i + 2] + zoo;
                        i++;
                }
        }
        ino[0] -= 2;
        return 1;
}

/*
 * search for the key in the page.
 * return offset index in the range 0 < i < n.
 * return 0 if not found.
 */
static int
seepair(pag, n, key, siz)
char *pag;
register int n;
register char *key;
register int siz;
{
        register int i;
        register int off = PBLKSIZ;
        register short *ino = (short *) pag;

        for (i = 1; i < n; i += 2) {
                if (siz == off - ino[i] &&
                    memcmp(key, pag + ino[i], siz) == 0)
                        return i;
                off = ino[i + 1];
        }
        return 0;
}

void
splpage(pag, new, sbit)
char *pag;
char *new;
long sbit;
{
        datum key;
        datum val;

        register int n;
        register int off = PBLKSIZ;
        char cur[PBLKSIZ];
        register short *ino = (short *) cur;

        (void) memcpy(cur, pag, PBLKSIZ);
        (void) memset(pag, 0, PBLKSIZ);
        (void) memset(new, 0, PBLKSIZ);

        n = ino[0];
        for (ino++; n > 0; ino += 2) {
                key.dptr = cur + ino[0];
                key.dsize = off - ino[0];
                val.dptr = cur + ino[1];
                val.dsize = ino[0] - ino[1];
/*
 * select the page pointer (by looking at sbit) and insert
 */
                (void) putpair((exhash(key) & sbit) ? new : pag, key, val);

                off = ino[1];
                n -= 2;
        }

        debug(("%d split %d/%d\n", ((short *) cur)[0] / 2,
               ((short *) new)[0] / 2,
               ((short *) pag)[0] / 2));
}

/*
 * check page sanity:
 * number of entries should be something
 * reasonable, and all offsets in the index should be in order.
 * this could be made more rigorous.
 */
int
chkpage(pag)
char *pag;
{
        register int n;
        register int off;
        register short *ino = (short *) pag;

        if ((n = ino[0]) < 0 || n > PBLKSIZ / sizeof(short))
                return 0;

        if (n > 0) {
                off = PBLKSIZ;
                for (ino++; n > 0; ino += 2) {
                        if (ino[0] > off || ino[1] > off ||
                            ino[1] > ino[0])
                                return 0;
                        off = ino[1];
                        n -= 2;
                }
        }
        return 1;
}

#endif /* SSL_USE_SDBM */