<HTML ><HEAD ><TITLE >Zlib Compression Functions</TITLE ><META NAME="GENERATOR" CONTENT="Modular DocBook HTML Stylesheet Version 1.7"><LINK REL="HOME" TITLE="PHP Manual" HREF="index.html"><LINK REL="UP" TITLE="Function Reference" HREF="funcref.html"><LINK REL="PREVIOUS" TITLE="zip_read" HREF="function.zip-read.html"><LINK REL="NEXT" TITLE="gzclose" HREF="function.gzclose.html"><META HTTP-EQUIV="Content-type" CONTENT="text/html; charset=ISO-8859-1"></HEAD ><BODY CLASS="reference" BGCOLOR="#FFFFFF" TEXT="#000000" LINK="#0000FF" VLINK="#840084" ALINK="#0000FF" ><DIV CLASS="NAVHEADER" ><TABLE SUMMARY="Header navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TH COLSPAN="3" ALIGN="center" >PHP Manual</TH ></TR ><TR ><TD WIDTH="10%" ALIGN="left" VALIGN="bottom" ><A HREF="function.zip-read.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="80%" ALIGN="center" VALIGN="bottom" ></TD ><TD WIDTH="10%" ALIGN="right" VALIGN="bottom" ><A HREF="function.gzclose.html" ACCESSKEY="N" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><DIV CLASS="reference" ><A NAME="ref.zlib" ></A ><DIV CLASS="TITLEPAGE" ><H1 CLASS="title" >CXIII. Zlib Compression Functions</H1 ><DIV CLASS="PARTINTRO" ><A NAME="AEN98820" ></A ><DIV CLASS="section" ><H1 CLASS="section" ><A NAME="zlib.intro" ></A >Introduction</H1 ><P > This module enables you to transparently read and write gzip (.gz) compressed files, through versions of most of the <A HREF="ref.filesystem.html" >filesystem</A > functions which work with gzip-compressed files (and uncompressed files, too, but not with sockets). </P ><DIV CLASS="note" ><BLOCKQUOTE CLASS="note" ><P ><B >Note: </B > Version 4.0.4 introduced 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 <A HREF="function.fopen.html" ><B CLASS="function" >fopen()</B ></A >. </P ><P > In version 4.3.0, this special prefix has been changed to 'zlib://' to prevent ambiguities with filenames containing ':'. </P ><P > This feature requires a C runtime library that provides the <TT CLASS="literal" >fopencookie()</TT > function. To my current knowledge the GNU libc is the only library that provides this feature. </P ></BLOCKQUOTE ></DIV ></DIV ><DIV CLASS="section" ><H1 CLASS="section" ><A NAME="zlib.requirements" ></A >Requirements</H1 ><P > This module uses the functions of <A HREF="http://www.gzip.org/zlib/" TARGET="_top" >zlib</A > by Jean-loup Gailly and Mark Adler. You have to use a zlib version >= 1.0.9 with this module. </P ></DIV ><DIV CLASS="section" ><H1 CLASS="section" ><A NAME="zlib.installation" ></A >Installation</H1 ><P > Zlib support in PHP is not enabled by default. You will need to configure PHP <TT CLASS="option" >--with-zlib[=DIR]</TT > </P ><P > The windows version of <TT CLASS="literal" >PHP</TT > has built in support for this extension. You do not need to load any additional extension in order to use these functions.</P ><DIV CLASS="note" ><BLOCKQUOTE CLASS="note" ><P ><B >Note: </B > Builtin support for zlib is available with PHP 4.3.0. </P ></BLOCKQUOTE ></DIV ></DIV ><DIV CLASS="section" ><H1 CLASS="section" ><A NAME="zlib.configuration" ></A >Runtime Configuration</H1 ><P > The behaviour of these functions is affected by settings in <TT CLASS="filename" >php.ini</TT >. </P ><P > The zlib extension offers the option to transparently compress your pages on-the-fly, if the requesting browser supports this. Therefore there are three options in the <A HREF="configuration.html#configuration.file" >configuration file</A > <TT CLASS="filename" >php.ini</TT >. <DIV CLASS="table" ><A NAME="AEN98850" ></A ><P ><B >Table 1. Zlib Configuration Options</B ></P ><TABLE BORDER="1" CLASS="CALSTABLE" ><THEAD ><TR ><TH ALIGN="LEFT" VALIGN="MIDDLE" >Name</TH ><TH ALIGN="LEFT" VALIGN="MIDDLE" >Default</TH ><TH ALIGN="LEFT" VALIGN="MIDDLE" >Changeable</TH ></TR ></THEAD ><TBODY ><TR ><TD ALIGN="LEFT" VALIGN="MIDDLE" >zlib.output_compression</TD ><TD ALIGN="LEFT" VALIGN="MIDDLE" >"Off"</TD ><TD ALIGN="LEFT" VALIGN="MIDDLE" >PHP_INI_ALL</TD ></TR ><TR ><TD ALIGN="LEFT" VALIGN="MIDDLE" >zlib.output_compression_level</TD ><TD ALIGN="LEFT" VALIGN="MIDDLE" >"-1"</TD ><TD ALIGN="LEFT" VALIGN="MIDDLE" >PHP_INI_ALL</TD ></TR ><TR ><TD ALIGN="LEFT" VALIGN="MIDDLE" >zlib.output_handler</TD ><TD ALIGN="LEFT" VALIGN="MIDDLE" >""</TD ><TD ALIGN="LEFT" VALIGN="MIDDLE" >PHP_INI_ALL</TD ></TR ></TBODY ></TABLE ></DIV > For further details and definition of the PHP_INI_* constants see <A HREF="function.ini-set.html" ><B CLASS="function" >ini_set()</B ></A >. </P ><P > Here is a short explanation of the configuration directives. <P ></P ><DIV CLASS="variablelist" ><DL ><DT ><A NAME="ini.zlib.output-compression" ></A ><TT CLASS="parameter" ><I >zlib.output_compression</I ></TT > <A HREF="language.types.boolean.html" ><B CLASS="type" >boolean</B ></A >/<A HREF="language.types.integer.html" ><B CLASS="type" >integer</B ></A ></DT ><DD ><P > Whether to transparently compress pages. If this option is set to "On" in <TT CLASS="filename" >php.ini</TT > or the Apache configuration, pages are compressed if the browser sends an "Accept-Encoding: gzip" or "deflate" header. "Content-Encoding: gzip" (respectively "deflate") and "Vary: Accept-Encoding" headers are added to the output. </P ><P > You can use <A HREF="function.ini-set.html" ><B CLASS="function" >ini_set()</B ></A > to disable this in your script if the headers aren't already sent. If you output a "Content-Type: image/" header the compression is disabled, too (in order to circumvent a Netscape bug). You can reenable it, if you add "ini_set('zlib.output_compression', 'On')" after the header call which added the image content-type. </P ><P > This option also accepts integer values instead of boolean "On"/"Off", using this you can set the output buffer size (default is 4KB). </P ><DIV CLASS="note" ><BLOCKQUOTE CLASS="note" ><P ><B >Note: </B > <A HREF="ref.outcontrol.html#ini.output-handler" >output_handler</A > must be empty if this is set 'On' ! Instead you must use zlib.output_handler. </P ></BLOCKQUOTE ></DIV ></DD ><DT ><A NAME="ini.zlib.output-compression-level" ></A ><TT CLASS="parameter" ><I >zlib.output_compression_level</I ></TT > <A HREF="language.types.integer.html" ><B CLASS="type" >integer</B ></A ></DT ><DD ><P > Compression level used for transparent output compression. </P ></DD ><DT ><A NAME="ini.zlib.output-handler" ></A ><TT CLASS="parameter" ><I >zlib.output_handler</I ></TT > <A HREF="language.types.string.html" ><B CLASS="type" >string</B ></A ></DT ><DD ><P > You cannot specify additional output handlers if zlib.output_compression is activated here. This setting does the same as <A HREF="ref.outcontrol.html#ini.output-handler" > output_handler</A > but in a different order. </P ></DD ></DL ></DIV > </P ></DIV ><DIV CLASS="section" ><H1 CLASS="section" ><A NAME="zlib.resources" ></A >Resource Types</H1 ><P >This extension has no resource types defined.</P ></DIV ><DIV CLASS="section" ><H1 CLASS="section" ><A NAME="zlib.constants" ></A >Predefined Constants</H1 ><P > The constants below are defined by this extension, and will only be available when the extension has either been compiled into PHP or dynamically loaded at runtime. </P ><P ></P ><DIV CLASS="variablelist" ><DL ><DT ><TT CLASS="constant" ><B >FORCE_GZIP</B ></TT > (<A HREF="language.types.integer.html" >integer</A >)</DT ><DD ><P > </P ></DD ><DT ><TT CLASS="constant" ><B >FORCE_DEFLATE</B ></TT > (<A HREF="language.types.integer.html" >integer</A >)</DT ><DD ><P > </P ></DD ></DL ></DIV ></DIV ><DIV CLASS="section" ><H1 CLASS="section" ><A NAME="zlib.examples" ></A >Examples</H1 ><P > This example opens a temporary file and writes a test string to it, then it prints out the content of this file twice. </P ><TABLE WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" CLASS="EXAMPLE" ><TR ><TD ><DIV CLASS="example" ><A NAME="AEN98923" ></A ><P ><B >Example 1. Small Zlib Example</B ></P ><TABLE BORDER="0" BGCOLOR="#E0E0E0" CELLPADDING="5" ><TR ><TD ><PRE CLASS="php" ><?php $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, $s); // close file gzclose($zp); // open file for reading $zp = gzopen($filename, "r"); // read 3 char print gzread($zp, 3); // output until end of the file and close it. gzpassthru($zp); print "\n"; // open file and print content (the 2nd time). if (readgzfile($filename) != strlen($s)) { echo "Error with zlib functions!"; } unlink($filename); print "</pre>\n</h1></body>\n</html>\n"; ?></PRE ></TD ></TR ></TABLE ></DIV ></TD ></TR ></TABLE ></DIV ></DIV ><DIV CLASS="TOC" ><DL ><DT ><B >Table of Contents</B ></DT ><DT ><A HREF="function.gzclose.html" >gzclose</A > -- Close an open gz-file pointer</DT ><DT ><A HREF="function.gzcompress.html" >gzcompress</A > -- Compress a string</DT ><DT ><A HREF="function.gzdeflate.html" >gzdeflate</A > -- Deflate a string</DT ><DT ><A HREF="function.gzencode.html" >gzencode</A > -- Create a gzip compressed string</DT ><DT ><A HREF="function.gzeof.html" >gzeof</A > -- Test for end-of-file on a gz-file pointer</DT ><DT ><A HREF="function.gzfile.html" >gzfile</A > -- Read entire gz-file into an array</DT ><DT ><A HREF="function.gzgetc.html" >gzgetc</A > -- Get character from gz-file pointer</DT ><DT ><A HREF="function.gzgets.html" >gzgets</A > -- Get line from file pointer</DT ><DT ><A HREF="function.gzgetss.html" >gzgetss</A > -- Get line from gz-file pointer and strip HTML tags </DT ><DT ><A HREF="function.gzinflate.html" >gzinflate</A > -- Inflate a deflated string</DT ><DT ><A HREF="function.gzopen.html" >gzopen</A > -- Open gz-file</DT ><DT ><A HREF="function.gzpassthru.html" >gzpassthru</A > -- Output all remaining data on a gz-file pointer </DT ><DT ><A HREF="function.gzputs.html" >gzputs</A > -- Write to a gz-file pointer</DT ><DT ><A HREF="function.gzread.html" >gzread</A > -- Binary-safe gz-file read</DT ><DT ><A HREF="function.gzrewind.html" >gzrewind</A > -- Rewind the position of a gz-file pointer</DT ><DT ><A HREF="function.gzseek.html" >gzseek</A > -- Seek on a gz-file pointer</DT ><DT ><A HREF="function.gztell.html" >gztell</A > -- Tell gz-file pointer read/write position</DT ><DT ><A HREF="function.gzuncompress.html" >gzuncompress</A > -- Uncompress a deflated string</DT ><DT ><A HREF="function.gzwrite.html" >gzwrite</A > -- Binary-safe gz-file write</DT ><DT ><A HREF="function.readgzfile.html" >readgzfile</A > -- Output a gz-file</DT ></DL ></DIV ></DIV ></DIV ><DIV CLASS="NAVFOOTER" ><HR ALIGN="LEFT" WIDTH="100%"><TABLE SUMMARY="Footer navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" ><A HREF="function.zip-read.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="index.html" ACCESSKEY="H" >Home</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" ><A HREF="function.gzclose.html" ACCESSKEY="N" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >zip_read</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="funcref.html" ACCESSKEY="U" >Up</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >gzclose</TD ></TR ></TABLE ></DIV ></BODY ></HTML >