XCIV. Zlib Compression Functions

This module uses the functions of zlib by Jean-loup Gailly and Mark Adler to transparently read and write gzip (.gz) compressed files. You have to use a zlib version >= 1.0.9 with this module.

This module contains versions of most of the filesystem functions which work with gzip-compressed files (and uncompressed files, too, but not with sockets).

Note: The current CVS version 4.0.4-dev introduces a fopen-wrapper for .gz-files, so that you can use a special 'zlib:' URL to access compressed files transparently using the normal f*() file access functions if you prepend the filename or path with a 'zlib:' prefix when calling fopen().

This feature requires a C runtime library that provides the fopencookie() function. To my current knowledge the GNU libc is the only library that provides this feature.

Small code example

Opens a temporary file and writes a test string to it, then it prints out the content of this file twice.

Example 1. Small Zlib Example


$filename = tempnam ('/tmp', 'zlibtest').'.gz';
print "<html>\n<head></head>\n<body>\n<pre>\n";
$s = "Only a test, test, test, test, test, test, test, test!\n";

// open file for writing with maximum compression
$zp = gzopen($filename, "w9");

// write string to file
gzwrite($zp, $s);

// close file

// open file for reading
$zp = gzopen($filename, "r");

// read 3 char
print gzread($zp, 3);

// output until end of the file and close it.

print "\n";

// open file and print content (the 2nd time).
if (readgzfile($filename) != strlen($s)) {
        echo "Error with zlib functions!";
print "</pre>\n</h1></body>\n</html>\n";

Table of Contents
gzclose -- Close an open gz-file pointer
gzeof -- Test for end-of-file on a gz-file pointer
gzfile -- Read entire gz-file into an array
gzgetc -- Get character from gz-file pointer
gzgets -- Get line from file pointer
gzgetss --  Get line from gz-file pointer and strip HTML tags
gzopen -- Open gz-file
gzpassthru --  Output all remaining data on a gz-file pointer
gzputs -- Write to a gz-file pointer
gzread -- Binary-safe gz-file read
gzrewind -- Rewind the position of a gz-file pointer
gzseek -- Seek on a gz-file pointer
gztell -- Tell gz-file pointer read/write position
gzwrite -- Binary-safe gz-file write
readgzfile -- Output a gz-file
gzcompress -- Compress a string
gzuncompress -- Uncompress a deflated string
gzdeflate -- Deflate a string
gzinflate -- Inflate a deflated string
gzencode -- Create a gzip compressed string