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<?php
/**
* Functions related to the output of file content.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
* http://www.gnu.org/copyleft/gpl.html
*
* @file
*/
/**
* Functions related to the output of file content
*/
class StreamFile {
const READY_STREAM = 1;
const NOT_MODIFIED = 2;
/**
* Stream a file to the browser, adding all the headings and fun stuff.
* Headers sent include: Content-type, Content-Length, Last-Modified,
* and Content-Disposition.
*
* @param string $fname Full name and path of the file to stream
* @param array $headers Any additional headers to send
* @param bool $sendErrors Send error messages if errors occur (like 404)
* @throws MWException
* @return bool Success
*/
public static function stream( $fname, $headers = array(), $sendErrors = true ) {
if ( FileBackend::isStoragePath( $fname ) ) { // sanity
throw new MWException( __FUNCTION__ . " given storage path '$fname'." );
}
MediaWiki\suppressWarnings();
$stat = stat( $fname );
MediaWiki\restoreWarnings();
$res = self::prepareForStream( $fname, $stat, $headers, $sendErrors );
if ( $res == self::NOT_MODIFIED ) {
$ok = true; // use client cache
} elseif ( $res == self::READY_STREAM ) {
$ok = readfile( $fname );
} else {
$ok = false; // failed
}
return $ok;
}
/**
* Call this function used in preparation before streaming a file.
* This function does the following:
* (a) sends Last-Modified, Content-type, and Content-Disposition headers
* (b) cancels any PHP output buffering and automatic gzipping of output
* (c) sends Content-Length header based on HTTP_IF_MODIFIED_SINCE check
*
* @param string $path Storage path or file system path
* @param array|bool $info File stat info with 'mtime' and 'size' fields
* @param array $headers Additional headers to send
* @param bool $sendErrors Send error messages if errors occur (like 404)
* @return int|bool READY_STREAM, NOT_MODIFIED, or false on failure
*/
public static function prepareForStream(
$path, $info, $headers = array(), $sendErrors = true
) {
if ( !is_array( $info ) ) {
if ( $sendErrors ) {
HttpStatus::header( 404 );
header( 'Cache-Control: no-cache' );
header( 'Content-Type: text/html; charset=utf-8' );
$encFile = htmlspecialchars( $path );
$encScript = htmlspecialchars( $_SERVER['SCRIPT_NAME'] );
echo "<html><body>
<h1>File not found</h1>
<p>Although this PHP script ($encScript) exists, the file requested for output
($encFile) does not.</p>
</body></html>
";
}
return false;
}
// Sent Last-Modified HTTP header for client-side caching
header( 'Last-Modified: ' . wfTimestamp( TS_RFC2822, $info['mtime'] ) );
// Cancel output buffering and gzipping if set
wfResetOutputBuffers();
$type = self::contentTypeFromPath( $path );
if ( $type && $type != 'unknown/unknown' ) {
header( "Content-type: $type" );
} else {
// Send a content type which is not known to Internet Explorer, to
// avoid triggering IE's content type detection. Sending a standard
// unknown content type here essentially gives IE license to apply
// whatever content type it likes.
header( 'Content-type: application/x-wiki' );
}
// Don't stream it out as text/html if there was a PHP error
if ( headers_sent() ) {
echo "Headers already sent, terminating.\n";
return false;
}
// Send additional headers
foreach ( $headers as $header ) {
header( $header );
}
// Don't send if client has up to date cache
if ( !empty( $_SERVER['HTTP_IF_MODIFIED_SINCE'] ) ) {
$modsince = preg_replace( '/;.*$/', '', $_SERVER['HTTP_IF_MODIFIED_SINCE'] );
if ( wfTimestamp( TS_UNIX, $info['mtime'] ) <= strtotime( $modsince ) ) {
ini_set( 'zlib.output_compression', 0 );
HttpStatus::header( 304 );
return self::NOT_MODIFIED; // ok
}
}
header( 'Content-Length: ' . $info['size'] );
return self::READY_STREAM; // ok
}
/**
* Determine the file type of a file based on the path
*
* @param string $filename Storage path or file system path
* @param bool $safe Whether to do retroactive upload blacklist checks
* @return null|string
*/
public static function contentTypeFromPath( $filename, $safe = true ) {
global $wgTrivialMimeDetection;
$ext = strrchr( $filename, '.' );
$ext = $ext === false ? '' : strtolower( substr( $ext, 1 ) );
# trivial detection by file extension,
# used for thumbnails (thumb.php)
if ( $wgTrivialMimeDetection ) {
switch ( $ext ) {
case 'gif':
return 'image/gif';
case 'png':
return 'image/png';
case 'jpg':
return 'image/jpeg';
case 'jpeg':
return 'image/jpeg';
}
return 'unknown/unknown';
}
$magic = MimeMagic::singleton();
// Use the extension only, rather than magic numbers, to avoid opening
// up vulnerabilities due to uploads of files with allowed extensions
// but disallowed types.
$type = $magic->guessTypesForExtension( $ext );
/**
* Double-check some security settings that were done on upload but might
* have changed since.
*/
if ( $safe ) {
global $wgFileBlacklist, $wgCheckFileExtensions, $wgStrictFileExtensions,
$wgFileExtensions, $wgVerifyMimeType, $wgMimeTypeBlacklist;
list( , $extList ) = UploadBase::splitExtensions( $filename );
if ( UploadBase::checkFileExtensionList( $extList, $wgFileBlacklist ) ) {
return 'unknown/unknown';
}
if ( $wgCheckFileExtensions && $wgStrictFileExtensions
&& !UploadBase::checkFileExtensionList( $extList, $wgFileExtensions )
) {
return 'unknown/unknown';
}
if ( $wgVerifyMimeType && in_array( strtolower( $type ), $wgMimeTypeBlacklist ) ) {
return 'unknown/unknown';
}
}
return $type;
}
}
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