| 1 | /* gzlog.h
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| 2 | Copyright (C) 2004 Mark Adler, all rights reserved
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| 3 | version 1.0, 26 Nov 2004
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| 4 |
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| 5 | This software is provided 'as-is', without any express or implied
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| 6 | warranty. In no event will the author be held liable for any damages
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| 7 | arising from the use of this software.
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| 8 |
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| 9 | Permission is granted to anyone to use this software for any purpose,
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| 10 | including commercial applications, and to alter it and redistribute it
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| 11 | freely, subject to the following restrictions:
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| 12 |
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| 13 | 1. The origin of this software must not be misrepresented; you must not
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| 14 | claim that you wrote the original software. If you use this software
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| 15 | in a product, an acknowledgment in the product documentation would be
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| 16 | appreciated but is not required.
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| 17 | 2. Altered source versions must be plainly marked as such, and must not be
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| 18 | misrepresented as being the original software.
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| 19 | 3. This notice may not be removed or altered from any source distribution.
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| 20 |
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| 21 | Mark Adler madler@alumni.caltech.edu
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| 22 | */
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| 23 |
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| 24 | /*
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| 25 | The gzlog object allows writing short messages to a gzipped log file,
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| 26 | opening the log file locked for small bursts, and then closing it. The log
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| 27 | object works by appending stored data to the gzip file until 1 MB has been
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| 28 | accumulated. At that time, the stored data is compressed, and replaces the
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| 29 | uncompressed data in the file. The log file is truncated to its new size at
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| 30 | that time. After closing, the log file is always valid gzip file that can
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| 31 | decompressed to recover what was written.
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| 32 |
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| 33 | A gzip header "extra" field contains two file offsets for appending. The
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| 34 | first points to just after the last compressed data. The second points to
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| 35 | the last stored block in the deflate stream, which is empty. All of the
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| 36 | data between those pointers is uncompressed.
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| 37 | */
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| 38 |
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| 39 | /* Open a gzlog object, creating the log file if it does not exist. Return
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| 40 | NULL on error. Note that gzlog_open() could take a long time to return if
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| 41 | there is difficulty in locking the file. */
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| 42 | void *gzlog_open(char *path);
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| 43 |
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| 44 | /* Write to a gzlog object. Return non-zero on error. This function will
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| 45 | simply write data to the file uncompressed. Compression of the data
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| 46 | will not occur until gzlog_close() is called. It is expected that
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| 47 | gzlog_write() is used for a short message, and then gzlog_close() is
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| 48 | called. If a large amount of data is to be written, then the application
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| 49 | should write no more than 1 MB at a time with gzlog_write() before
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| 50 | calling gzlog_close() and then gzlog_open() again. */
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| 51 | int gzlog_write(void *log, char *data, size_t len);
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| 52 |
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| 53 | /* Close a gzlog object. Return non-zero on error. The log file is locked
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| 54 | until this function is called. This function will compress stored data
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| 55 | at the end of the gzip file if at least 1 MB has been accumulated. Note
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| 56 | that the file will not be a valid gzip file until this function completes.
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| 57 | */
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| 58 | int gzlog_close(void *log);
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