symbian-qemu-0.9.1-12/zlib-1.2.3/examples/gzlog.h
author martin.trojer@nokia.com
Fri, 31 Jul 2009 15:01:17 +0100
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/* gzlog.h
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  Copyright (C) 2004 Mark Adler, all rights reserved
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  version 1.0, 26 Nov 2004
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  This software is provided 'as-is', without any express or implied
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  warranty.  In no event will the author be held liable for any damages
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  arising from the use of this software.
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  Permission is granted to anyone to use this software for any purpose,
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  including commercial applications, and to alter it and redistribute it
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  freely, subject to the following restrictions:
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  1. The origin of this software must not be misrepresented; you must not
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     claim that you wrote the original software. If you use this software
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     in a product, an acknowledgment in the product documentation would be
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     appreciated but is not required.
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  2. Altered source versions must be plainly marked as such, and must not be
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     misrepresented as being the original software.
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  3. This notice may not be removed or altered from any source distribution.
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  Mark Adler    madler@alumni.caltech.edu
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 */
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/*
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   The gzlog object allows writing short messages to a gzipped log file,
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   opening the log file locked for small bursts, and then closing it.  The log
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   object works by appending stored data to the gzip file until 1 MB has been
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   accumulated.  At that time, the stored data is compressed, and replaces the
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   uncompressed data in the file.  The log file is truncated to its new size at
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   that time.  After closing, the log file is always valid gzip file that can
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   decompressed to recover what was written.
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   A gzip header "extra" field contains two file offsets for appending.  The
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   first points to just after the last compressed data.  The second points to
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   the last stored block in the deflate stream, which is empty.  All of the
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   data between those pointers is uncompressed.
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 */
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/* Open a gzlog object, creating the log file if it does not exist.  Return
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   NULL on error.  Note that gzlog_open() could take a long time to return if
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   there is difficulty in locking the file. */
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void *gzlog_open(char *path);
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/* Write to a gzlog object.  Return non-zero on error.  This function will
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   simply write data to the file uncompressed.  Compression of the data
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   will not occur until gzlog_close() is called.  It is expected that
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   gzlog_write() is used for a short message, and then gzlog_close() is
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   called.  If a large amount of data is to be written, then the application
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   should write no more than 1 MB at a time with gzlog_write() before
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   calling gzlog_close() and then gzlog_open() again. */
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int gzlog_write(void *log, char *data, size_t len);
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/* Close a gzlog object.  Return non-zero on error.  The log file is locked
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   until this function is called.  This function will compress stored data
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   at the end of the gzip file if at least 1 MB has been accumulated.  Note
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   that the file will not be a valid gzip file until this function completes.
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 */
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int gzlog_close(void *log);