/*- * See the file LICENSE for redistribution information. * * Copyright (c) 1996, 1997, 1998 * Sleepycat Software. All rights reserved. */ /* * Copyright (c) 1990, 1993, 1994, 1995, 1996 * Keith Bostic. All rights reserved. */ /* * Copyright (c) 1990, 1993, 1994, 1995 * The Regents of the University of California. All rights reserved. * * This code is derived from software contributed to Berkeley by * Mike Olson. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by the University of * California, Berkeley and its contributors. * 4. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ #include "config.h" #ifndef lint static const char sccsid[] = "@(#)bt_compare.c 10.14 (Sleepycat) 10/9/98"; #endif /* not lint */ #ifndef NO_SYSTEM_INCLUDES #include <sys/types.h> #include <string.h> #endif #include "db_int.h" #include "db_page.h" #include "btree.h" /* * __bam_cmp -- * Compare a key to a given record. * * PUBLIC: int __bam_cmp __P((DB *, const DBT *, * PUBLIC: PAGE *, u_int32_t, int (*)(const DBT *, const DBT *))); */ int __bam_cmp(dbp, dbt, h, indx, func) DB *dbp; const DBT *dbt; PAGE *h; u_int32_t indx; int (*func)__P((const DBT *, const DBT *)); { BINTERNAL *bi; BKEYDATA *bk; BOVERFLOW *bo; DBT pg_dbt; int ret; /* * Returns: * < 0 if dbt is < page record * = 0 if dbt is = page record * > 0 if dbt is > page record * * !!! * We do not clear the pg_dbt DBT even though it's likely to contain * random bits. That should be okay, because the app's comparison * routine had better not be looking at fields other than data/size. * We don't clear it because we go through this path a lot and it's * expensive. */ if (TYPE(h) == P_LBTREE || TYPE(h) == P_DUPLICATE) { bk = GET_BKEYDATA(h, indx); if (B_TYPE(bk->type) == B_OVERFLOW) bo = (BOVERFLOW *)bk; else { pg_dbt.data = bk->data; pg_dbt.size = bk->len; return (func(dbt, &pg_dbt)); } } else { /* * The following code guarantees that the left-most key on an * internal page at any level of the btree is less than any * user specified key. This saves us from having to update the * leftmost key on an internal page when the user inserts a new * key in the tree smaller than anything we've seen before. */ if (indx == 0 && h->prev_pgno == PGNO_INVALID) return (1); bi = GET_BINTERNAL(h, indx); if (B_TYPE(bi->type) == B_OVERFLOW) bo = (BOVERFLOW *)(bi->data); else { pg_dbt.data = bi->data; pg_dbt.size = bi->len; return (func(dbt, &pg_dbt)); } } /* * Overflow. * * XXX * We ignore __db_moff() errors, because we have no way of returning * them. */ (void) __db_moff(dbp, dbt, bo->pgno, bo->tlen, func == __bam_defcmp ? NULL : func, &ret); return (ret); } /* * __bam_defcmp -- * Default comparison routine. * * PUBLIC: int __bam_defcmp __P((const DBT *, const DBT *)); */ int __bam_defcmp(a, b) const DBT *a, *b; { size_t len; u_int8_t *p1, *p2; /* * Returns: * < 0 if a is < b * = 0 if a is = b * > 0 if a is > b * * XXX * If a size_t doesn't fit into a long, or if the difference between * any two characters doesn't fit into an int, this routine can lose. * What we need is a signed integral type that's guaranteed to be at * least as large as a size_t, and there is no such thing. */ len = a->size > b->size ? b->size : a->size; for (p1 = a->data, p2 = b->data; len--; ++p1, ++p2) if (*p1 != *p2) return ((long)*p1 - (long)*p2); return ((long)a->size - (long)b->size); } /* * __bam_defpfx -- * Default prefix routine. * * PUBLIC: size_t __bam_defpfx __P((const DBT *, const DBT *)); */ size_t __bam_defpfx(a, b) const DBT *a, *b; { size_t cnt, len; u_int8_t *p1, *p2; cnt = 1; len = a->size > b->size ? b->size : a->size; for (p1 = a->data, p2 = b->data; len--; ++p1, ++p2, ++cnt) if (*p1 != *p2) return (cnt); /* * We know that a->size must be <= b->size, or they wouldn't be * in this order. */ return (a->size < b->size ? a->size + 1 : a->size); }
