61 lines
2.9 KiB
C
61 lines
2.9 KiB
C
|
/* $NetBSD: gzlog.h,v 1.1.1.1 2006/01/14 20:11:09 christos Exp $ */
|
||
|
|
|
||
|
|
/* gzlog.h
|
||
|
|
Copyright (C) 2004 Mark Adler, all rights reserved
|
||
|
|
version 1.0, 26 Nov 2004
|
||
|
|
|
||
|
|
This software is provided 'as-is', without any express or implied
|
||
|
|
warranty. In no event will the author be held liable for any damages
|
||
|
|
arising from the use of this software.
|
||
|
|
|
||
|
|
Permission is granted to anyone to use this software for any purpose,
|
||
|
|
including commercial applications, and to alter it and redistribute it
|
||
|
|
freely, subject to the following restrictions:
|
||
|
|
|
||
|
|
1. The origin of this software must not be misrepresented; you must not
|
||
|
|
claim that you wrote the original software. If you use this software
|
||
|
|
in a product, an acknowledgment in the product documentation would be
|
||
|
|
appreciated but is not required.
|
||
|
|
2. Altered source versions must be plainly marked as such, and must not be
|
||
|
|
misrepresented as being the original software.
|
||
|
|
3. This notice may not be removed or altered from any source distribution.
|
||
|
|
|
||
|
|
Mark Adler madler@alumni.caltech.edu
|
||
|
|
*/
|
||
|
|
|
||
|
|
/*
|
||
|
|
The gzlog object allows writing short messages to a gzipped log file,
|
||
|
|
opening the log file locked for small bursts, and then closing it. The log
|
||
|
|
object works by appending stored data to the gzip file until 1 MB has been
|
||
|
|
accumulated. At that time, the stored data is compressed, and replaces the
|
||
|
|
uncompressed data in the file. The log file is truncated to its new size at
|
||
|
|
that time. After closing, the log file is always valid gzip file that can
|
||
|
|
decompressed to recover what was written.
|
||
|
|
|
||
|
|
A gzip header "extra" field contains two file offsets for appending. The
|
||
|
|
first points to just after the last compressed data. The second points to
|
||
|
|
the last stored block in the deflate stream, which is empty. All of the
|
||
|
|
data between those pointers is uncompressed.
|
||
|
|
*/
|
||
|
|
|
||
|
|
/* Open a gzlog object, creating the log file if it does not exist. Return
|
||
|
|
NULL on error. Note that gzlog_open() could take a long time to return if
|
||
|
|
there is difficulty in locking the file. */
|
||
|
|
void *gzlog_open(char *path);
|
||
|
|
|
||
|
|
/* Write to a gzlog object. Return non-zero on error. This function will
|
||
|
|
simply write data to the file uncompressed. Compression of the data
|
||
|
|
will not occur until gzlog_close() is called. It is expected that
|
||
|
|
gzlog_write() is used for a short message, and then gzlog_close() is
|
||
|
|
called. If a large amount of data is to be written, then the application
|
||
|
|
should write no more than 1 MB at a time with gzlog_write() before
|
||
|
|
calling gzlog_close() and then gzlog_open() again. */
|
||
|
|
int gzlog_write(void *log, char *data, size_t len);
|
||
|
|
|
||
|
|
/* Close a gzlog object. Return non-zero on error. The log file is locked
|
||
|
|
until this function is called. This function will compress stored data
|
||
|
|
at the end of the gzip file if at least 1 MB has been accumulated. Note
|
||
|
|
that the file will not be a valid gzip file until this function completes.
|
||
|
|
*/
|
||
|
|
int gzlog_close(void *log);
|