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zlib/examples/gzlog.c  view on Meta::CPAN

    /* write the modified stored block header and lengths, move the file
       pointer to after the last stored block data */
    PUT2(buf + 2, log->stored);
    PUT2(buf + 4, log->stored ^ 0xffff);
    return lseek(log->fd, log->last - len, SEEK_SET) < 0 ||
           write(log->fd, buf + 2 - len, len + 4) != len + 4 ||
           lseek(log->fd, log->stored, SEEK_CUR) < 0 ? -1 : 0;
}

/* Append len bytes from data to the locked and open log file.  len may be zero
   if recovering and no .add file was found.  In that case, the previous state
   of the foo.gz file is restored.  The data is appended uncompressed in
   deflate stored blocks.  Return -1 if there was an error reading or writing
   the foo.gz file. */
local int log_append(struct log *log, unsigned char *data, size_t len)
{
    uint put;
    off_t end;
    unsigned char buf[8];

zlib/examples/gzlog.h  view on Meta::CPAN

   2.0  25 Apr 2008  Complete redesign for recovery of interrupted operations
                     Interface changed slightly in that now path is a prefix
                     Compression now occurs as needed during gzlog_write()
                     gzlog_write() now always leaves the log file as valid gzip
   2.1   8 Jul 2012  Fix argument checks in gzlog_compress() and gzlog_write()
   2.2  14 Aug 2012  Clean up signed comparisons
 */

/*
   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 (uncompressed) 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 each write operation, the log file is a
   valid gzip file that can decompressed to recover what was written.

   The gzlog operations can be interrupted at any point due to an application or
   system crash, and the log file will be recovered the next time the log is
   opened with gzlog_open().
 */