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59 lines
2.8 KiB
C
59 lines
2.8 KiB
C
/* 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);
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