mirror of
https://git.FreeBSD.org/src.git
synced 2024-12-20 11:11:24 +00:00
139 lines
5.3 KiB
C
139 lines
5.3 KiB
C
/*-
|
|
* Copyright (c) 2005-2008 Poul-Henning Kamp
|
|
* All rights reserved.
|
|
*
|
|
* 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.
|
|
*
|
|
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
|
|
*
|
|
* $FreeBSD$
|
|
*/
|
|
|
|
#ifndef __LOCAL_FIFOLOG_H_
|
|
#define __LOCAL_FIFOLOG_H_
|
|
|
|
/*
|
|
* Definitions for fifolog "protocol": the on-media layout.
|
|
*
|
|
* The fifolog on-media record has three layers:
|
|
* The outer timestamping and synchronization layer.
|
|
* The zlib implemented data compression.
|
|
* The inner sequencing and identification layer.
|
|
*
|
|
* All three layers are synchronized at a subset of the outer layer
|
|
* record boundaries, from where reading can be initiated.
|
|
*
|
|
*
|
|
* The outer layer:
|
|
* -----------------
|
|
* The first record in a fifolog contains a magic string and version
|
|
* information along with a 32be encoded recordsize for all records
|
|
* in the fifolog, including the first.
|
|
* The recordsize is explicit to avoid ambiguities when a media is
|
|
* moved from one machine to another.
|
|
*
|
|
* Each record in the fifolog has the following contents:
|
|
* offset type contents
|
|
* --------------------------------------------------------------
|
|
* 0 32be sequence_number
|
|
* The sequence number is randomly chosen for the
|
|
* fifolog and increments once for each record written.
|
|
* It's presence allow quick identification of the next
|
|
* record to be written using a binary search for the
|
|
* first place where a discontinuity in the sequence
|
|
* numbers occur.
|
|
* 4 8 flags (FIFOLOG_FLG_*)
|
|
*
|
|
* If (flags & (FIFOLOG_FLG_SYNC)) the record is a synchronization point
|
|
* at which the inner layers are aligned so that reading can be started
|
|
* at this point.
|
|
* To enable seeks into the file based on timestamps, a third field is
|
|
* present in these records as well:
|
|
* 5 32be time_t containing POSIX's understanding of UTC.
|
|
*
|
|
* These fields are immediately followed by the inner layer payload as
|
|
* described below, which has variable length.
|
|
*
|
|
* If the inner layer payload is shorter than the available space in
|
|
* the record, it is padded with zero bytes, and the number of unused
|
|
* bytes, including the encoded length thereof is recorded at the end
|
|
* of the record as follows:
|
|
*
|
|
* If (flags & FIFOLOG_FLG_1BYTE)
|
|
* n-1 8 number of unused bytes
|
|
* else if (flags & FIFOLOG_FLG_4BYTE)
|
|
* n-4 32be number of unused bytes
|
|
*
|
|
*
|
|
* The gzip layer
|
|
* --------------
|
|
* Is just output from zlib, nothing special here. FIFOLOG_FLG_SYNC
|
|
* corresponds to Z_FINISH flags to zlib.
|
|
* In most cases, the timer will expire before zlib has filled an entire
|
|
* record in which case Z_SYNC_FLUSH will be used to force as much as
|
|
* possible into the buffer before it is written. This is not marked
|
|
* in outer layer (apart from a natural correlation with padding) since
|
|
* zlibs data stream handles this without help.
|
|
*
|
|
*
|
|
* The inner layer:
|
|
* ----------------
|
|
* The inner layer contains data identification and to the second
|
|
* timestamping (the timestamp in the outer layer only marks the
|
|
* first possible timestamp for content in the SYNC record).
|
|
*
|
|
* offset type contents
|
|
* --------------------------------------------------------------
|
|
* 0 32be ident
|
|
*
|
|
* The bottom 30 bits of the identification word are application defined,
|
|
* presently unused in the stand-alone fifolog tools, but used in the
|
|
* original "measured" application that originated the fifolog format.
|
|
* Should for instance syslogd(8) grow native support for fifolog format,
|
|
* it could store the message priority here.
|
|
*
|
|
* If (ident & FIFOLOG_TIMESTAMP) the record is prefixed by:
|
|
* 4 32be time_t containing POSIX's understanding of UTC.
|
|
*
|
|
* Then follows the content, either as a NUL terminated string or as
|
|
* a length encoded binary sequence:
|
|
*
|
|
* If (ident & FIFOLOG_LENGTH) the record is prefixed by:
|
|
* {0|4} 8 length of binary data
|
|
*
|
|
*/
|
|
|
|
/* Magic identification string */
|
|
#define FIFOLOG_FMT_MAGIC "Measured FIFOLOG Ver 1.01\n"
|
|
|
|
/* Offset of the 32be encoded recordsize in the first sector */
|
|
#define FIFOLOG_OFF_BS 0x20
|
|
|
|
#define FIFOLOG_FLG_1BYTE 0x01
|
|
#define FIFOLOG_FLG_4BYTE 0x02
|
|
#define FIFOLOG_FLG_RESTART 0x40
|
|
#define FIFOLOG_FLG_SYNC 0x80
|
|
|
|
#define FIFOLOG_TIMESTAMP 0x80000000
|
|
#define FIFOLOG_LENGTH 0x40000000
|
|
#define FIFOLOG_IDENT 0x3fffffff
|
|
|
|
#endif /* __LOCAL_FIFOLOG_H_ */
|