Mercurial > hg > CbC > CbC_gcc
annotate zlib/examples/gzlog.h @ 158:494b0b89df80 default tip
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author | Shinji KONO <kono@ie.u-ryukyu.ac.jp> |
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date | Mon, 25 May 2020 18:13:55 +0900 |
parents | 04ced10e8804 |
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rev | line source |
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1 /* gzlog.h |
111 | 2 Copyright (C) 2004, 2008, 2012 Mark Adler, all rights reserved |
3 version 2.2, 14 Aug 2012 | |
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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 |
111 | 24 /* Version History: |
25 1.0 26 Nov 2004 First version | |
26 2.0 25 Apr 2008 Complete redesign for recovery of interrupted operations | |
27 Interface changed slightly in that now path is a prefix | |
28 Compression now occurs as needed during gzlog_write() | |
29 gzlog_write() now always leaves the log file as valid gzip | |
30 2.1 8 Jul 2012 Fix argument checks in gzlog_compress() and gzlog_write() | |
31 2.2 14 Aug 2012 Clean up signed comparisons | |
32 */ | |
33 | |
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34 /* |
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35 The gzlog object allows writing short messages to a gzipped log file, |
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36 opening the log file locked for small bursts, and then closing it. The log |
111 | 37 object works by appending stored (uncompressed) data to the gzip file until |
38 1 MB has been accumulated. At that time, the stored data is compressed, and | |
39 replaces the uncompressed data in the file. The log file is truncated to | |
40 its new size at that time. After each write operation, the log file is a | |
41 valid gzip file that can decompressed to recover what was written. | |
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42 |
111 | 43 The gzlog operations can be interupted at any point due to an application or |
44 system crash, and the log file will be recovered the next time the log is | |
45 opened with gzlog_open(). | |
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46 */ |
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47 |
111 | 48 #ifndef GZLOG_H |
49 #define GZLOG_H | |
50 | |
51 /* gzlog object type */ | |
52 typedef void gzlog; | |
53 | |
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54 /* Open a gzlog object, creating the log file if it does not exist. Return |
111 | 55 NULL on error. Note that gzlog_open() could take a while to complete if it |
56 has to wait to verify that a lock is stale (possibly for five minutes), or | |
57 if there is significant contention with other instantiations of this object | |
58 when locking the resource. path is the prefix of the file names created by | |
59 this object. If path is "foo", then the log file will be "foo.gz", and | |
60 other auxiliary files will be created and destroyed during the process: | |
61 "foo.dict" for a compression dictionary, "foo.temp" for a temporary (next) | |
62 dictionary, "foo.add" for data being added or compressed, "foo.lock" for the | |
63 lock file, and "foo.repairs" to log recovery operations performed due to | |
64 interrupted gzlog operations. A gzlog_open() followed by a gzlog_close() | |
65 will recover a previously interrupted operation, if any. */ | |
66 gzlog *gzlog_open(char *path); | |
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67 |
111 | 68 /* Write to a gzlog object. Return zero on success, -1 if there is a file i/o |
69 error on any of the gzlog files (this should not happen if gzlog_open() | |
70 succeeded, unless the device has run out of space or leftover auxiliary | |
71 files have permissions or ownership that prevent their use), -2 if there is | |
72 a memory allocation failure, or -3 if the log argument is invalid (e.g. if | |
73 it was not created by gzlog_open()). This function will write data to the | |
74 file uncompressed, until 1 MB has been accumulated, at which time that data | |
75 will be compressed. The log file will be a valid gzip file upon successful | |
76 return. */ | |
77 int gzlog_write(gzlog *log, void *data, size_t len); | |
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78 |
111 | 79 /* Force compression of any uncompressed data in the log. This should be used |
80 sparingly, if at all. The main application would be when a log file will | |
81 not be appended to again. If this is used to compress frequently while | |
82 appending, it will both significantly increase the execution time and | |
83 reduce the compression ratio. The return codes are the same as for | |
84 gzlog_write(). */ | |
85 int gzlog_compress(gzlog *log); | |
86 | |
87 /* Close a gzlog object. Return zero on success, -3 if the log argument is | |
88 invalid. The log object is freed, and so cannot be referenced again. */ | |
89 int gzlog_close(gzlog *log); | |
90 | |
91 #endif |