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Last updated: Fri, 01 Jun 2007

readfile

(PHP 4, PHP 5)

readfile — Outputs a file

Description

int readfile ( string $filename [, bool $use_include_path [, resource $context]] )

Reads a file and writes it to the output buffer.

Returns the number of bytes read from the file. If an error occurs, FALSE is returned and unless the function was called as @readfile(), an error message is printed.

Tip

You can use a URL as a filename with this function if the fopen wrappers have been enabled. See fopen() for more details on how to specify the filename and Appendix O, List of Supported Protocols/Wrappers for a list of supported URL protocols.

You can use the optional second parameter and set it to TRUE, if you want to search for the file in the include_path, too.

Note: Context support was added with PHP 5.0.0. For a description of contexts, refer to Streams.

add a note User Contributed Notes
readfile

chad 0x40 herballure 0x2e com
17-May-2007 02:53


In reply to herbert dot fischer at NOSPAM dot gmail dot com:



The streams API in PHP5 tries to make things as efficient as possible; in php-5.1.6 on Linux, fpassthru is faster than 'echo fread($fp, 8192)' in a loop, and readfile is even faster for files on disk. I didn't benchmark further, but I'd be willing to bet non-mmap'able streams still win because they can loop in C instead of PHP.

MasterQ at 127 dot 0 dot 0 dot 1
23-Apr-2007 02:40


Do not forgot to call

exit;

after readfile else you will get trouble with the file checksum of the file, because there will be added \n at the end of the script.

mAu
10-Oct-2006 07:25


Instead of using

<?php

header('Content-Type: application/force-download');

?>

use

<?php

header('Content-Type: application/octet-stream');

?>

Some browsers have troubles with force-download.

ericlaw1979 at hotmail dot com
07-Jun-2006 07:18


It is an error to send post-check=0.  See http://blogs.msdn.com/ie/archive/2006/06/01/613132.aspx

irek at eccomes dot de
29-Mar-2006 04:35


Related to francesco at paladinux: HOW TO RESOLVE EXPLORER SAVE PROBLEM IN FORCE-DOWNLOAD.



To use "application/octetstream" instead of "application/octet-stream" may help in some cases. But the solution of this problem in most cases is to use



header ("Cache-Control: must-revalidate, post-check=0, pre-check=0");



See also message of ctemple below. This helps not only for pdf but also generally.

oryan at zareste dot com
27-Nov-2005 03:18


As Grey said below:  Readfile will send users un-executed PHP files, which makes it easy to exploit vulnerabilities.  It's common - and easy - to use GET variables pointing to downloadable files, like script.php?v=web/file.mov , but this lets users to change it to script.php?v=index.php and get damaging info.  Even POST variables can be exploited this way if the user's on a custom browser.



To keep secure, limit downloadable files to one directory, like 'web/', so that script.php?v=file.mov will send web/file.mov, and scan the variable for '..' and 'php' to make sure users can't go into other directories, or open php files you may have stupidly put under web/.  This should cover all the bases.

peavey at pixelpickers dot com
20-Oct-2005 01:38


A mime-type-independent forced download can also be conducted by using:



<?

(...)

header("Expires: Mon, 26 Jul 1997 05:00:00 GMT"); // some day in the past

header("Last-Modified: " . gmdate("D, d M Y H:i:s") . " GMT");

header("Content-type: application/x-download");

header("Content-Disposition: attachment; filename={$new_name}");

header("Content-Transfer-Encoding: binary");

?>



Cheers,



Peavey

planetmaster at planetgac dot com
17-Oct-2005 06:44


Using pieces of the forced download script, adding in MySQL database functions, and hiding the file location for security was what we needed for downloading wmv files from our members creations without prompting Media player as well as secure the file itself and use only database queries. Something to the effect below, very customizable for private access, remote files, and keeping order of your online media.





<?


    # Protect Script against SQL-Injections


    $fileid=intval($_GET[id]);


    # setup SQL statement


    $sql = " SELECT id, fileurl, filename, filesize FROM ibf_movies WHERE id=' $fileid' ";





    # execute SQL statement


    $res = mysql_query($sql);





        # display results


        while ($row = mysql_fetch_array($res)) {


        $fileurl = $row['fileurl'];


        $filename= $row['filename'];


        $filesize= $row['filesize'];





           $file_extension = strtolower(substr(strrchr($filename,"."),1));





           switch ($file_extension) {


               case "wmv": $ctype="video/x-ms-wmv"; break;


               default: $ctype="application/force-download";


           }





// required for IE, otherwise Content-disposition is ignored


if(ini_get('zlib.output_compression'))


ini_set('zlib.output_compression', 'Off');





           header("Pragma: public");


           header("Expires: 0");


           header("Cache-Control: must-revalidate, post-check=0, pre-check=0");


           header("Cache-Control: private",false);


           header("Content-Type: video/x-ms-wmv");


           header("Content-Type: $ctype");


           header("Content-Disposition: attachment; filename=\"".basename($filename)."\";");


           header("Content-Transfer-Encoding: binary");


           header("Content-Length: ".@filesize($filename));


           set_time_limit(0);


           @readfile("$fileurl") or die("File not found."); 





}





$donwloaded = "downloads + 1";





    if ($_GET["hit"]) {


        mysql_query("UPDATE ibf_movies SET downloads = $donwloaded WHERE id=' $fileid'");





}





?>





While at it I added into download.php a hit (download) counter. Of course you need to setup the DB, table, and columns. Email me for Full setup// Session marker is also a security/logging option


Used in the context of linking:


http://www.yourdomain.com/download.php?id=xx&hit=1





[Edited by sp@php.net: Added Protection against SQL-Injection]

antispam [at] rdx page [dot] com
20-Sep-2005 09:14


Just a note:  If you're using bw_mod (current version 0.6) to limit bandwidth in Apache 2, it *will not* limit bandwidth during readfile events.

23-Aug-2005 09:39


here is a nice force download scirpt



            $filename = 'dummy.zip';

            $filename = realpath($filename);



            $file_extension = strtolower(substr(strrchr($filename,"."),1));



            switch ($file_extension) {

                case "pdf": $ctype="application/pdf"; break;

                case "exe": $ctype="application/octet-stream"; break;

                case "zip": $ctype="application/zip"; break;

                case "doc": $ctype="application/msword"; break;

                case "xls": $ctype="application/vnd.ms-excel"; break;

                case "ppt": $ctype="application/vnd.ms-powerpoint"; break;

                case "gif": $ctype="image/gif"; break;

                case "png": $ctype="image/png"; break;

                case "jpe": case "jpeg":

                case "jpg": $ctype="image/jpg"; break;

                default: $ctype="application/force-download";

            }



            if (!file_exists($filename)) {

                die("NO FILE HERE");

            }



            header("Pragma: public");

            header("Expires: 0");

            header("Cache-Control: must-revalidate, post-check=0, pre-check=0");

            header("Cache-Control: private",false);

            header("Content-Type: $ctype");

            header("Content-Disposition: attachment; filename=\"".basename($filename)."\";");

            header("Content-Transfer-Encoding: binary");

            header("Content-Length: ".@filesize($filename));

            set_time_limit(0);

            @readfile("$filename") or die("File not found.");

herbert dot fischer at NOSPAM dot gmail dot com
22-Jul-2005 03:01


readfile and fpassthru are about 55% slower than doing a loop with "feof/echo fread".

chrisputnam at gmail dot com
29-Jun-2005 08:44


In response to flowbee@gmail.com --





When using the readfile_chunked function noted here with files larger than 10MB or so I am still having memory errors. It's because the writers have left out the all important flush() after each read. So this is the proper chunked readfile (which isn't really readfile at all, and should probably be crossposted to passthru(), fopen(), and popen() just so browsers can find this information):





<?php


function readfile_chunked($filename,$retbytes=true) {


   $chunksize = 1*(1024*1024); // how many bytes per chunk


   $buffer = '';


   $cnt =0;


   // $handle = fopen($filename, 'rb');


   $handle = fopen($filename, 'rb');


   if ($handle === false) {


       return false;


   }


   while (!feof($handle)) {


       $buffer = fread($handle, $chunksize);


       echo $buffer;


       ob_flush();


       flush();


       if ($retbytes) {


           $cnt += strlen($buffer);


       }


   }


       $status = fclose($handle);


   if ($retbytes && $status) {


       return $cnt; // return num. bytes delivered like readfile() does.


   }


   return $status;





}


?>





All I've added is a flush(); after the echo line. Be sure to include this!

Hern�n Pereira
17-May-2005 06:21


I saw in previous contributed notes that in content-disposition the file is not a quoted-string, there is no problem if the filename have no spaces but if it has in IE it works but in Firefox not.



The RFC 2616 puts as an example this:

Content-Disposition: attachment; filename="fname.ext"



You can see http://www.faqs.org/rfcs/rfc2616.html section "19.5.1 Content-Disposition" for more details.



The correct header then is this:

header("Content-Disposition: attachment; filename=\"$filename\"");

Philipp Heckel
10-May-2005 11:58


To use readfile() it is absolutely necessary to set the mime-type before. If you are using an Apache, it's quite simple to figure out the correct mime type. Apache has a file called "mime.types" which can (in normal case) be read by all users.



Use this (or another) function to get a list of mime-types:



<?php



    function mimeTypes($file) {

        if (!is_file($file) || !is_readable($file)) return false;

        $types = array();

        $fp = fopen($file,"r");

        while (false != ($line = fgets($fp,4096))) {

            if (!preg_match("/^\s*(?!#)\s*(\S+)\s+(?=\S)(.+)/",$line,$match)) continue;

            $tmp = preg_split("/\s/",trim($match[2]));

            foreach($tmp as $type) $types[strtolower($type)] = $match[1];

        }

        fclose ($fp);

        

        return $types;

    }



    # [...]



    # read the mime-types

    $mimes = mimeTypes('/usr/local/apache/current/conf/mime.types');



    # use them ($ext is the extension of your file)

    if (isset($mimes[$ext])) header("Content-Type: ".$mimes[$ext]);

    header("Content-Length: ".@filesize($fullpath));

    readfile($fullpath); exit;



?>



If you do not want to read from the mime.types file directly, you can of course make a copy in another folder!

Cheers Philipp Heckel

flobee at gmail dot com
06-May-2005 06:17


regarding php5:

i found out that there is already a disscussion @php-dev  about readfile() and fpassthru() where only exactly 2 MB will be delivered.



so you may use this on php5 to get lager files

<?php

function readfile_chunked($filename,$retbytes=true) {

    $chunksize = 1*(1024*1024); // how many bytes per chunk

    $buffer = '';

    $cnt =0;

    // $handle = fopen($filename, 'rb');

    $handle = fopen($filename, 'rb');

    if ($handle === false) {

        return false;

    }

    while (!feof($handle)) {

        $buffer = fread($handle, $chunksize);

        echo $buffer;

        if ($retbytes) {

            $cnt += strlen($buffer);

        }

    }

        $status = fclose($handle);

    if ($retbytes && $status) {

        return $cnt; // return num. bytes delivered like readfile() does.

    } 

    return $status;



} 

?>

TheDayOfCondor
27-Apr-2005 01:24


I think that readfile suffers from the maximum script execution time. The readfile is always completed even if it exceed the default 30 seconds limit, then the script is aborted.

Be warned that you can get very odd behaviour not only on large files, but also on small files if the user has a slow connection.



The best thing to do is to use 



<?

  set_time_limit(0);

?>



just before the readfile, to disable completely the watchdog if you intend to use the readfile call to tranfer a file to the user.

comicforum at lelon dot net
22-Apr-2005 06:22


The problem with using readfile on large files isn't caused by your memory_limit setting.  Setting it to 4x the size of the file can still cause the file to be truncated.  Use the readfile_chunked found below.

TheDayOfCondor
20-Apr-2005 04:10


Beware - the chunky readfile suggested by Rob Funk can easily exceed you maximum script execution time (30 seconds by default).



I suggest you to use the set_time_limit function inside the while loop to reset the php watchdog.

php at cNhOiSpPpAlMe dot net
22-Feb-2005 02:25


For some reason, readfile seems to reset the file's modified time (filemtime). Using fopen and fpassthru avoids this.



<?

$fp = @fopen($file,"rb");

fpassthru($fp);

fclose($fp);

?>



(PHP version: 4.3.10)

Rob Funk
04-Jan-2005 06:31


When using readfile() with very large files, it's possible to run into problems due to the memory_limit setting; apparently readfile() pulls the whole file into memory at once.





One solution is to make sure memory_limit is larger than the largest file you'll use with readfile().  A better solution is to write a chunking readfile.  Here's a simple one that doesn't exactly conform to the API, but is close enough for most purposes:





<?php


function readfile_chunked ($filename) {


  $chunksize = 1*(1024*1024); // how many bytes per chunk


  $buffer = '';


  $handle = fopen($filename, 'rb');


  if ($handle === false) {


    return false;


  }


  while (!feof($handle)) {


    $buffer = fread($handle, $chunksize);


    print $buffer;


  }


  return fclose($handle);


}


?>

Justin Dearing
29-Dec-2004 11:38


Word for word copy of a comment on session_start() posted by Kevin. Might be relevant here.



If you're having a problem with a file download script not working with IE if you call session_start() before sending the file, then try adding a session_cache_limiter() call before session_start().



I use session_cache_limiter('none'), but 'public' and 'private' seem to fix the problem too; use whichever suits your application.

grey - greywyvern - com
29-Dec-2004 04:29


readfile() makes a handy include for what you know should be plain HTML or text.  Sloppy and/or lazy scripters can introduce security risks when using include() and require() in such a way that users can tell the script what file(s) to include.  This is because the PHP code contained in any file they refer to is executed with PHP's privledges.



With readfile(), any PHP code is passed to the output buffer as-is, without being executed.

ctemple at n-able dot com
15-Nov-2004 08:12


If you're passing files through a script, you may want to include this header:



        header ("Cache-Control: must-revalidate, post-check=0, pre-check=0");



Otherwise, some programs such as Adobe Reader may have problems opening files directly.



<?php

        header ("Cache-Control: must-revalidate, post-check=0, pre-check=0");

        header ("Content-Type: application/octet-stream");

        header ("Content-Length: " . filesize($theFile));

        header ("Content-Disposition: attachment; filename=$theFileName");

        readfile($theFile);

?>

Thomas Jespersen
25-Oct-2004 01:06


Remember if you make a "force download" script like mentioned below that you SANITIZE YOUR INPUT!



I have seen a lot of  download scripts that does not test so you are able to download anything you want on the server.



Test especially for strings like ".." which makes directory traversal possible. If possible only permit characters a-z, A-Z and 0-9 and make it possible to only download from one "download-folder".

flobee at gmail dot com
04-Oct-2004 12:33


you may try the statemants below with

header("Content-Type: application/octet-stream");

// insteat OF: header('Content-Type: application/force-download');

MAC OSX / IE: has problems to find the right mime type and do not accept spaces in filenames. then all plattforms should work

nobody at localhost
23-Sep-2004 09:03


If you want to force a download:





<?php


$file = '/var/www/html/file-to-download.xyz';


header('Content-Description: File Transfer');


header('Content-Type: application/force-download');


header('Content-Length: ' . filesize($filename));


header('Content-Disposition: attachment; filename=' . basename($file));


readfile($file);


?>

kschenke at datafreight dot com
15-Oct-2003 04:43


If your site visitors are having problems with Internet Explorer downloading files over an SSL connection, see the manual page for the session_cache_limiter() function.

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Last updated: Fri, 01 Jun 2007