1176998Sphk/*- 2176998Sphk * Copyright (c) 2005-2008 Poul-Henning Kamp 3176998Sphk * All rights reserved. 4176998Sphk * 5176998Sphk * Redistribution and use in source and binary forms, with or without 6176998Sphk * modification, are permitted provided that the following conditions 7176998Sphk * are met: 8176998Sphk * 1. Redistributions of source code must retain the above copyright 9176998Sphk * notice, this list of conditions and the following disclaimer. 10176998Sphk * 2. Redistributions in binary form must reproduce the above copyright 11176998Sphk * notice, this list of conditions and the following disclaimer in the 12176998Sphk * documentation and/or other materials provided with the distribution. 13176998Sphk * 14176998Sphk * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15176998Sphk * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16176998Sphk * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17176998Sphk * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18176998Sphk * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19176998Sphk * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20176998Sphk * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21176998Sphk * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22176998Sphk * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23176998Sphk * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24176998Sphk * SUCH DAMAGE. 25176998Sphk * 26176998Sphk * $FreeBSD$ 27176998Sphk */ 28176998Sphk 29176998Sphk#ifndef __LOCAL_FIFOLOG_H_ 30176998Sphk#define __LOCAL_FIFOLOG_H_ 31176998Sphk 32176998Sphk/* 33176998Sphk * Definitions for fifolog "protocol": the on-media layout. 34176998Sphk * 35176998Sphk * The fifolog on-media record has three layers: 36210930Suqs * The outer timestamping and synchronization layer. 37210930Suqs * The zlib implemented data compression. 38176998Sphk * The inner sequencing and identification layer. 39176998Sphk * 40210930Suqs * All three layers are synchronized at a subset of the outer layer 41176998Sphk * record boundaries, from where reading can be initiated. 42176998Sphk * 43176998Sphk * 44210930Suqs * The outer layer: 45176998Sphk * ----------------- 46176998Sphk * The first record in a fifolog contains a magic string and version 47176998Sphk * information along with a 32be encoded recordsize for all records 48176998Sphk * in the fifolog, including the first. 49176998Sphk * The recordsize is explicit to avoid ambiguities when a media is 50176998Sphk * moved from one machine to another. 51176998Sphk * 52176998Sphk * Each record in the fifolog has the following contents: 53176998Sphk * offset type contents 54176998Sphk * -------------------------------------------------------------- 55176998Sphk * 0 32be sequence_number 56176998Sphk * The sequence number is randomly chosen for the 57176998Sphk * fifolog and increments once for each record written. 58210930Suqs * It's presence allow quick identification of the next 59176998Sphk * record to be written using a binary search for the 60176998Sphk * first place where a discontinuity in the sequence 61176998Sphk * numbers occur. 62176998Sphk * 4 8 flags (FIFOLOG_FLG_*) 63176998Sphk * 64176998Sphk * If (flags & (FIFOLOG_FLG_SYNC)) the record is a synchronization point 65176998Sphk * at which the inner layers are aligned so that reading can be started 66176998Sphk * at this point. 67176998Sphk * To enable seeks into the file based on timestamps, a third field is 68176998Sphk * present in these records as well: 69176998Sphk * 5 32be time_t containing POSIX's understanding of UTC. 70176998Sphk * 71219027Sphk * These fields are immediately followed by the inner layer payload as 72176998Sphk * described below, which has variable length. 73176998Sphk * 74176998Sphk * If the inner layer payload is shorter than the available space in 75176998Sphk * the record, it is padded with zero bytes, and the number of unused 76176998Sphk * bytes, including the encoded length thereof is recorded at the end 77176998Sphk * of the record as follows: 78176998Sphk * 79176998Sphk * If (flags & FIFOLOG_FLG_1BYTE) 80176998Sphk * n-1 8 number of unused bytes 81176998Sphk * else if (flags & FIFOLOG_FLG_4BYTE) 82176998Sphk * n-4 32be number of unused bytes 83176998Sphk * 84176998Sphk * 85176998Sphk * The gzip layer 86176998Sphk * -------------- 87176998Sphk * Is just output from zlib, nothing special here. FIFOLOG_FLG_SYNC 88176998Sphk * corresponds to Z_FINISH flags to zlib. 89176998Sphk * In most cases, the timer will expire before zlib has filled an entire 90176998Sphk * record in which case Z_SYNC_FLUSH will be used to force as much as 91176998Sphk * possible into the buffer before it is written. This is not marked 92210930Suqs * in outer layer (apart from a natural correlation with padding) since 93176998Sphk * zlibs data stream handles this without help. 94176998Sphk * 95176998Sphk * 96176998Sphk * The inner layer: 97176998Sphk * ---------------- 98219027Sphk * The inner layer contains data identification and to the second 99219027Sphk * timestamping (the timestamp in the outer layer only marks the 100176998Sphk * first possible timestamp for content in the SYNC record). 101219027Sphk * 102176998Sphk * offset type contents 103176998Sphk * -------------------------------------------------------------- 104176998Sphk * 0 32be ident 105176998Sphk * 106176998Sphk * The bottom 30 bits of the identification word are application defined, 107176998Sphk * presently unused in the stand-alone fifolog tools, but used in the 108176998Sphk * original "measured" application that originated the fifolog format. 109176998Sphk * Should for instance syslogd(8) grow native support for fifolog format, 110176998Sphk * it could store the message priority here. 111176998Sphk * 112176998Sphk * If (ident & FIFOLOG_TIMESTAMP) the record is prefixed by: 113176998Sphk * 4 32be time_t containing POSIX's understanding of UTC. 114176998Sphk * 115176998Sphk * Then follows the content, either as a NUL terminated string or as 116210930Suqs * a length encoded binary sequence: 117176998Sphk * 118176998Sphk * If (ident & FIFOLOG_LENGTH) the record is prefixed by: 119176998Sphk * {0|4} 8 length of binary data 120176998Sphk * 121176998Sphk */ 122176998Sphk 123176998Sphk/* Magic identification string */ 124176998Sphk#define FIFOLOG_FMT_MAGIC "Measured FIFOLOG Ver 1.01\n" 125176998Sphk 126176998Sphk/* Offset of the 32be encoded recordsize in the first sector */ 127176998Sphk#define FIFOLOG_OFF_BS 0x20 128176998Sphk 129176998Sphk#define FIFOLOG_FLG_1BYTE 0x01 130176998Sphk#define FIFOLOG_FLG_4BYTE 0x02 131176998Sphk#define FIFOLOG_FLG_RESTART 0x40 132176998Sphk#define FIFOLOG_FLG_SYNC 0x80 133176998Sphk 134176998Sphk#define FIFOLOG_TIMESTAMP 0x80000000 135176998Sphk#define FIFOLOG_LENGTH 0x40000000 136176998Sphk#define FIFOLOG_IDENT 0x3fffffff 137176998Sphk 138176998Sphk#endif /* __LOCAL_FIFOLOG_H_ */ 139