zlib 1.2.2.2v1.2.2.2

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+/* gzlog.h
+  Copyright (C) 2004 Mark Adler, all rights reserved
+  version 1.0, 26 Nov 2004
+
+  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
+ */
+
+/*
+   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 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 closing, the log file is always valid gzip file that can
+   decompressed to recover what was written.
+
+   A gzip header "extra" field contains two file offsets for appending.  The
+   first points to just after the last compressed data.  The second points to
+   the last stored block in the deflate stream, which is empty.  All of the
+   data between those pointers is uncompressed.
+ */
+
+/* Open a gzlog object, creating the log file if it does not exist.  Return
+   NULL on error.  Note that gzlog_open() could take a long time to return if
+   there is difficulty in locking the file. */
+void *gzlog_open(char *path);
+
+/* Write to a gzlog object.  Return non-zero on error.  This function will
+   simply write data to the file uncompressed.  Compression of the data
+   will not occur until gzlog_close() is called.  It is expected that
+   gzlog_write() is used for a short message, and then gzlog_close() is
+   called.  If a large amount of data is to be written, then the application
+   should write no more than 1 MB at a time with gzlog_write() before
+   calling gzlog_close() and then gzlog_open() again. */
+int gzlog_write(void *log, char *data, size_t len);
+
+/* Close a gzlog object.  Return non-zero on error.  The log file is locked
+   until this function is called.  This function will compress stored data
+   at the end of the gzip file if at least 1 MB has been accumulated.  Note
+   that the file will not be a valid gzip file until this function completes.
+ */
+int gzlog_close(void *log);