1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 1990, 1993, 1994 5 * The Regents of the University of California. All rights reserved. 6 * 7 * This code is derived from software contributed to Berkeley by 8 * Margo Seltzer. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 * 34 * @(#)page.h 8.2 (Berkeley) 5/31/94 35 * $FreeBSD$ 36 */ 37 38 /* 39 * Definitions for hashing page file format. 40 */ 41 42 /* 43 * routines dealing with a data page 44 * 45 * page format: 46 * +------------------------------+ 47 * p | n | keyoff | datoff | keyoff | 48 * +------------+--------+--------+ 49 * | datoff | free | ptr | --> | 50 * +--------+---------------------+ 51 * | F R E E A R E A | 52 * +--------------+---------------+ 53 * | <---- - - - | data | 54 * +--------+-----+----+----------+ 55 * | key | data | key | 56 * +--------+----------+----------+ 57 * 58 * Pointer to the free space is always: p[p[0] + 2] 59 * Amount of free space on the page is: p[p[0] + 1] 60 */ 61 62 /* 63 * How many bytes required for this pair? 64 * 2 shorts in the table at the top of the page + room for the 65 * key and room for the data 66 * 67 * We prohibit entering a pair on a page unless there is also room to append 68 * an overflow page. The reason for this it that you can get in a situation 69 * where a single key/data pair fits on a page, but you can't append an 70 * overflow page and later you'd have to split the key/data and handle like 71 * a big pair. 72 * You might as well do this up front. 73 */ 74 75 #define PAIRSIZE(K,D) (2*sizeof(u_int16_t) + (K)->size + (D)->size) 76 #define BIGOVERHEAD (4*sizeof(u_int16_t)) 77 #define KEYSIZE(K) (4*sizeof(u_int16_t) + (K)->size); 78 #define OVFLSIZE (2*sizeof(u_int16_t)) 79 #define FREESPACE(P) ((P)[(P)[0]+1]) 80 #define OFFSET(P) ((P)[(P)[0]+2]) 81 #define PAIRFITS(P,K,D) \ 82 (((P)[2] >= REAL_KEY) && \ 83 (PAIRSIZE((K),(D)) + OVFLSIZE) <= FREESPACE((P))) 84 #define PAGE_META(N) (((N)+3) * sizeof(u_int16_t)) 85 86 typedef struct { 87 BUFHEAD *newp; 88 BUFHEAD *oldp; 89 BUFHEAD *nextp; 90 u_int16_t next_addr; 91 } SPLIT_RETURN; 92