118334Speter/*- 2117395Skan * Copyright (c) 2005-2008 Poul-Henning Kamp 318334Speter * All rights reserved. 4132718Skan * 518334Speter * Redistribution and use in source and binary forms, with or without 6132718Skan * modification, are permitted provided that the following conditions 718334Speter * are met: 818334Speter * 1. Redistributions of source code must retain the above copyright 918334Speter * notice, this list of conditions and the following disclaimer. 1018334Speter * 2. Redistributions in binary form must reproduce the above copyright 11132718Skan * notice, this list of conditions and the following disclaimer in the 1218334Speter * documentation and/or other materials provided with the distribution. 1318334Speter * 1418334Speter * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 1518334Speter * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 1618334Speter * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17132718Skan * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18169689Skan * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19169689Skan * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 2018334Speter * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 2118334Speter * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 2218334Speter * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 2318334Speter * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 2418334Speter * SUCH DAMAGE. 2518334Speter * 2618334Speter * $FreeBSD: releng/10.3/usr.sbin/fifolog/lib/fifolog.h 219027 2011-02-25 09:40:17Z phk $ 2718334Speter */ 2818334Speter 2950397Sobrien#ifndef __LOCAL_FIFOLOG_H_ 3018334Speter#define __LOCAL_FIFOLOG_H_ 3118334Speter 3218334Speter/* 3318334Speter * Definitions for fifolog "protocol": the on-media layout. 3418334Speter * 3518334Speter * The fifolog on-media record has three layers: 3618334Speter * The outer timestamping and synchronization layer. 3718334Speter * The zlib implemented data compression. 3818334Speter * The inner sequencing and identification layer. 3918334Speter * 4018334Speter * All three layers are synchronized at a subset of the outer layer 4118334Speter * record boundaries, from where reading can be initiated. 4218334Speter * 4318334Speter * 4418334Speter * The outer layer: 4518334Speter * ----------------- 4618334Speter * The first record in a fifolog contains a magic string and version 4718334Speter * information along with a 32be encoded recordsize for all records 4818334Speter * in the fifolog, including the first. 4990075Sobrien * The recordsize is explicit to avoid ambiguities when a media is 5018334Speter * moved from one machine to another. 5118334Speter * 5218334Speter * Each record in the fifolog has the following contents: 5390075Sobrien * offset type contents 5418334Speter * -------------------------------------------------------------- 5518334Speter * 0 32be sequence_number 5618334Speter * The sequence number is randomly chosen for the 5790075Sobrien * fifolog and increments once for each record written. 5818334Speter * It's presence allow quick identification of the next 59117395Skan * record to be written using a binary search for the 60117395Skan * first place where a discontinuity in the sequence 6118334Speter * numbers occur. 6218334Speter * 4 8 flags (FIFOLOG_FLG_*) 6352284Sobrien * 6418334Speter * If (flags & (FIFOLOG_FLG_SYNC)) the record is a synchronization point 6590075Sobrien * at which the inner layers are aligned so that reading can be started 66 * at this point. 67 * To enable seeks into the file based on timestamps, a third field is 68 * present in these records as well: 69 * 5 32be time_t containing POSIX's understanding of UTC. 70 * 71 * These fields are immediately followed by the inner layer payload as 72 * described below, which has variable length. 73 * 74 * If the inner layer payload is shorter than the available space in 75 * the record, it is padded with zero bytes, and the number of unused 76 * bytes, including the encoded length thereof is recorded at the end 77 * of the record as follows: 78 * 79 * If (flags & FIFOLOG_FLG_1BYTE) 80 * n-1 8 number of unused bytes 81 * else if (flags & FIFOLOG_FLG_4BYTE) 82 * n-4 32be number of unused bytes 83 * 84 * 85 * The gzip layer 86 * -------------- 87 * Is just output from zlib, nothing special here. FIFOLOG_FLG_SYNC 88 * corresponds to Z_FINISH flags to zlib. 89 * In most cases, the timer will expire before zlib has filled an entire 90 * record in which case Z_SYNC_FLUSH will be used to force as much as 91 * possible into the buffer before it is written. This is not marked 92 * in outer layer (apart from a natural correlation with padding) since 93 * zlibs data stream handles this without help. 94 * 95 * 96 * The inner layer: 97 * ---------------- 98 * The inner layer contains data identification and to the second 99 * timestamping (the timestamp in the outer layer only marks the 100 * first possible timestamp for content in the SYNC record). 101 * 102 * offset type contents 103 * -------------------------------------------------------------- 104 * 0 32be ident 105 * 106 * The bottom 30 bits of the identification word are application defined, 107 * presently unused in the stand-alone fifolog tools, but used in the 108 * original "measured" application that originated the fifolog format. 109 * Should for instance syslogd(8) grow native support for fifolog format, 110 * it could store the message priority here. 111 * 112 * If (ident & FIFOLOG_TIMESTAMP) the record is prefixed by: 113 * 4 32be time_t containing POSIX's understanding of UTC. 114 * 115 * Then follows the content, either as a NUL terminated string or as 116 * a length encoded binary sequence: 117 * 118 * If (ident & FIFOLOG_LENGTH) the record is prefixed by: 119 * {0|4} 8 length of binary data 120 * 121 */ 122 123/* Magic identification string */ 124#define FIFOLOG_FMT_MAGIC "Measured FIFOLOG Ver 1.01\n" 125 126/* Offset of the 32be encoded recordsize in the first sector */ 127#define FIFOLOG_OFF_BS 0x20 128 129#define FIFOLOG_FLG_1BYTE 0x01 130#define FIFOLOG_FLG_4BYTE 0x02 131#define FIFOLOG_FLG_RESTART 0x40 132#define FIFOLOG_FLG_SYNC 0x80 133 134#define FIFOLOG_TIMESTAMP 0x80000000 135#define FIFOLOG_LENGTH 0x40000000 136#define FIFOLOG_IDENT 0x3fffffff 137 138#endif /* __LOCAL_FIFOLOG_H_ */ 139