mirror of https://github.com/madler/zlib.git
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
91 lines
4.5 KiB
91 lines
4.5 KiB
/* gzlog.h |
|
Copyright (C) 2004, 2008, 2012 Mark Adler, all rights reserved |
|
version 2.2, 14 Aug 2012 |
|
|
|
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 |
|
*/ |
|
|
|
/* Version History: |
|
1.0 26 Nov 2004 First version |
|
2.0 25 Apr 2008 Complete redesign for recovery of interrupted operations |
|
Interface changed slightly in that now path is a prefix |
|
Compression now occurs as needed during gzlog_write() |
|
gzlog_write() now always leaves the log file as valid gzip |
|
2.1 8 Jul 2012 Fix argument checks in gzlog_compress() and gzlog_write() |
|
2.2 14 Aug 2012 Clean up signed comparisons |
|
*/ |
|
|
|
/* |
|
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 (uncompressed) 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 each write operation, the log file is a |
|
valid gzip file that can decompressed to recover what was written. |
|
|
|
The gzlog operations can be interupted at any point due to an application or |
|
system crash, and the log file will be recovered the next time the log is |
|
opened with gzlog_open(). |
|
*/ |
|
|
|
#ifndef GZLOG_H |
|
#define GZLOG_H |
|
|
|
/* gzlog object type */ |
|
typedef void gzlog; |
|
|
|
/* Open a gzlog object, creating the log file if it does not exist. Return |
|
NULL on error. Note that gzlog_open() could take a while to complete if it |
|
has to wait to verify that a lock is stale (possibly for five minutes), or |
|
if there is significant contention with other instantiations of this object |
|
when locking the resource. path is the prefix of the file names created by |
|
this object. If path is "foo", then the log file will be "foo.gz", and |
|
other auxiliary files will be created and destroyed during the process: |
|
"foo.dict" for a compression dictionary, "foo.temp" for a temporary (next) |
|
dictionary, "foo.add" for data being added or compressed, "foo.lock" for the |
|
lock file, and "foo.repairs" to log recovery operations performed due to |
|
interrupted gzlog operations. A gzlog_open() followed by a gzlog_close() |
|
will recover a previously interrupted operation, if any. */ |
|
gzlog *gzlog_open(char *path); |
|
|
|
/* Write to a gzlog object. Return zero on success, -1 if there is a file i/o |
|
error on any of the gzlog files (this should not happen if gzlog_open() |
|
succeeded, unless the device has run out of space or leftover auxiliary |
|
files have permissions or ownership that prevent their use), -2 if there is |
|
a memory allocation failure, or -3 if the log argument is invalid (e.g. if |
|
it was not created by gzlog_open()). This function will write data to the |
|
file uncompressed, until 1 MB has been accumulated, at which time that data |
|
will be compressed. The log file will be a valid gzip file upon successful |
|
return. */ |
|
int gzlog_write(gzlog *log, void *data, size_t len); |
|
|
|
/* Force compression of any uncompressed data in the log. This should be used |
|
sparingly, if at all. The main application would be when a log file will |
|
not be appended to again. If this is used to compress frequently while |
|
appending, it will both significantly increase the execution time and |
|
reduce the compression ratio. The return codes are the same as for |
|
gzlog_write(). */ |
|
int gzlog_compress(gzlog *log); |
|
|
|
/* Close a gzlog object. Return zero on success, -3 if the log argument is |
|
invalid. The log object is freed, and so cannot be referenced again. */ |
|
int gzlog_close(gzlog *log); |
|
|
|
#endif
|
|
|