/* 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); |