thumb.php

<?php
/**
 * PHP script to stream out an image thumbnail.
 *
 * 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
 * @ingroup Media
 */

define( 'MW_NO_OUTPUT_COMPRESSION', 1 );
require __DIR__ . '/includes/WebStart.php';

// Don't use fancy mime detection, just check the file extension for jpg/gif/png
$wgTrivialMimeDetection = true;

if ( defined( 'THUMB_HANDLER' ) ) {
	// Called from thumb_handler.php via 404; extract params from the URI...
	wfThumbHandle404();
} else {
	// Called directly, use $_GET params
	wfThumbHandleRequest();
}

wfLogProfilingData();

//--------------------------------------------------------------------------

/**
 * Handle a thumbnail request via query parameters
 *
 * @return void
 */
function wfThumbHandleRequest() {
	$params = get_magic_quotes_gpc()
		? array_map( 'stripslashes', $_GET )
		: $_GET;

	wfStreamThumb( $params ); // stream the thumbnail
}

/**
 * Handle a thumbnail request via thumbnail file URL
 *
 * @return void
 */
function wfThumbHandle404() {
	global $wgArticlePath;

	# Set action base paths so that WebRequest::getPathInfo()
	# recognizes the "X" as the 'title' in ../thumb_handler.php/X urls.
	$wgArticlePath = false; # Don't let a "/*" article path clober our action path

	$matches = WebRequest::getPathInfo();
	if ( !isset( $matches['title'] ) ) {
		wfThumbError( 404, 'Could not determine the name of the requested thumbnail.' );
		return;
	}

	$params = wfExtractThumbParams( $matches['title'] ); // basic wiki URL param extracting
	if ( $params == null ) {
		wfThumbError( 400, 'The specified thumbnail parameters are not recognized.' );
		return;
	}

	wfStreamThumb( $params ); // stream the thumbnail
}

/**
 * Stream a thumbnail specified by parameters
 *
 * @param $params Array
 * @return void
 */
function wfStreamThumb( array $params ) {
	global $wgVaryOnXFP;

	wfProfileIn( __METHOD__ );

	$headers = array(); // HTTP headers to send

	$fileName = isset( $params['f'] ) ? $params['f'] : '';
	unset( $params['f'] );

	// Backwards compatibility parameters
	if ( isset( $params['w'] ) ) {
		$params['width'] = $params['w'];
		unset( $params['w'] );
	}
	if ( isset( $params['p'] ) ) {
		$params['page'] = $params['p'];
	}
	unset( $params['r'] ); // ignore 'r' because we unconditionally pass File::RENDER

	// Is this a thumb of an archived file?
	$isOld = ( isset( $params['archived'] ) && $params['archived'] );
	unset( $params['archived'] ); // handlers don't care

	// Is this a thumb of a temp file?
	$isTemp = ( isset( $params['temp'] ) && $params['temp'] );
	unset( $params['temp'] ); // handlers don't care

	// Some basic input validation
	$fileName = strtr( $fileName, '\\/', '__' );

	// Actually fetch the image. Method depends on whether it is archived or not.
	if ( $isTemp ) {
		$repo = RepoGroup::singleton()->getLocalRepo()->getTempRepo();
		$img = new UnregisteredLocalFile( null, $repo,
			# Temp files are hashed based on the name without the timestamp.
			# The thumbnails will be hashed based on the entire name however.
			# @todo fix this convention to actually be reasonable.
			$repo->getZonePath( 'public' ) . '/' . $repo->getTempHashPath( $fileName ) . $fileName
		);
	} elseif ( $isOld ) {
		// Format is <timestamp>!<name>
		$bits = explode( '!', $fileName, 2 );
		if ( count( $bits ) != 2 ) {
			wfThumbError( 404, wfMessage( 'badtitletext' )->text() );
			wfProfileOut( __METHOD__ );
			return;
		}
		$title = Title::makeTitleSafe( NS_FILE, $bits[1] );
		if ( !$title ) {
			wfThumbError( 404, wfMessage( 'badtitletext' )->text() );
			wfProfileOut( __METHOD__ );
			return;
		}
		$img = RepoGroup::singleton()->getLocalRepo()->newFromArchiveName( $title, $fileName );
	} else {
		$img = wfLocalFile( $fileName );
	}

	// Check the source file title
	if ( !$img ) {
		wfThumbError( 404, wfMessage( 'badtitletext' )->text() );
		wfProfileOut( __METHOD__ );
		return;
	}

	// Check permissions if there are read restrictions
	$varyHeader = array();
	if ( !in_array( 'read', User::getGroupPermissions( array( '*' ) ), true ) ) {
		if ( !$img->getTitle() || !$img->getTitle()->userCan( 'read' ) ) {
			wfThumbError( 403, 'Access denied. You do not have permission to access ' .
				'the source file.' );
			wfProfileOut( __METHOD__ );
			return;
		}
		$headers[] = 'Cache-Control: private';
		$varyHeader[] = 'Cookie';
	}

	// Check the source file storage path
	if ( !$img->exists() ) {
		wfThumbError( 404, "The source file '$fileName' does not exist." );
		wfProfileOut( __METHOD__ );
		return;
	} elseif ( $img->getPath() === false ) {
		wfThumbError( 500, "The source file '$fileName' is not locally accessible." );
		wfProfileOut( __METHOD__ );
		return;
	}

	// Check IMS against the source file
	// This means that clients can keep a cached copy even after it has been deleted on the server
	if ( !empty( $_SERVER['HTTP_IF_MODIFIED_SINCE'] ) ) {
		// Fix IE brokenness
		$imsString = preg_replace( '/;.*$/', '', $_SERVER["HTTP_IF_MODIFIED_SINCE"] );
		// Calculate time
		wfSuppressWarnings();
		$imsUnix = strtotime( $imsString );
		wfRestoreWarnings();
		if ( wfTimestamp( TS_UNIX, $img->getTimestamp() ) <= $imsUnix ) {
			header( 'HTTP/1.1 304 Not Modified' );
			wfProfileOut( __METHOD__ );
			return;
		}
	}

	// Get the normalized thumbnail name from the parameters...
	try {
		$thumbName = $img->thumbName( $params );
		if ( !strlen( $thumbName ) ) { // invalid params?
			wfThumbError( 400, 'The specified thumbnail parameters are not valid.' );
			wfProfileOut( __METHOD__ );
			return;
		}
		$thumbName2 = $img->thumbName( $params, File::THUMB_FULL_NAME ); // b/c; "long" style
	} catch ( MWException $e ) {
		wfThumbError( 500, $e->getHTML() );
		wfProfileOut( __METHOD__ );
		return;
	}

	// For 404 handled thumbnails, we only use the the base name of the URI
	// for the thumb params and the parent directory for the source file name.
	// Check that the zone relative path matches up so squid caches won't pick
	// up thumbs that would not be purged on source file deletion (bug 34231).
	if ( isset( $params['rel404'] ) ) { // thumbnail was handled via 404
		if ( rawurldecode( $params['rel404'] ) === $img->getThumbRel( $thumbName ) ) {
			// Request for the canonical thumbnail name
		} elseif ( rawurldecode( $params['rel404'] ) === $img->getThumbRel( $thumbName2 ) ) {
			// Request for the "long" thumbnail name; redirect to canonical name
			$response = RequestContext::getMain()->getRequest()->response();
			$response->header( "HTTP/1.1 301 " . HttpStatus::getMessage( 301 ) );
			$response->header( 'Location: ' .
				wfExpandUrl( $img->getThumbUrl( $thumbName ), PROTO_CURRENT ) );
			$response->header( 'Expires: ' .
				gmdate( 'D, d M Y H:i:s', time() + 7 * 86400 ) . ' GMT' );
			if ( $wgVaryOnXFP ) {
				$varyHeader[] = 'X-Forwarded-Proto';
			}
			if ( count( $varyHeader ) ) {
				$response->header( 'Vary: ' . implode( ', ', $varyHeader ) );
			}
			wfProfileOut( __METHOD__ );
			return;
		} else {
			wfThumbError( 404, "The given path of the specified thumbnail is incorrect;
				expected '" . $img->getThumbRel( $thumbName ) . "' but got '" .
				rawurldecode( $params['rel404'] ) . "'." );
			wfProfileOut( __METHOD__ );
			return;
		}
	}

	// Suggest a good name for users downloading this thumbnail
	$headers[] = "Content-Disposition: {$img->getThumbDisposition( $thumbName )}";

	if ( count( $varyHeader ) ) {
		$headers[] = 'Vary: ' . implode( ', ', $varyHeader );
	}

	// Stream the file if it exists already...
	$thumbPath = $img->getThumbPath( $thumbName );
	if ( $img->getRepo()->fileExists( $thumbPath ) ) {
		$img->getRepo()->streamFile( $thumbPath, $headers );
		wfProfileOut( __METHOD__ );
		return;
	}

	// Thumbnail isn't already there, so create the new thumbnail...
	try {
		$thumb = $img->transform( $params, File::RENDER_NOW );
	} catch ( Exception $ex ) {
		// Tried to select a page on a non-paged file?
		$thumb = false;
	}

	// Check for thumbnail generation errors...
	$errorMsg = false;
	$msg = wfMessage( 'thumbnail_error' );
	if ( !$thumb ) {
		$errorMsg = $msg->rawParams( 'File::transform() returned false' )->escaped();
	} elseif ( $thumb->isError() ) {
		$errorMsg = $thumb->getHtmlMsg();
	} elseif ( !$thumb->hasFile() ) {
		$errorMsg = $msg->rawParams( 'No path supplied in thumbnail object' )->escaped();
	} elseif ( $thumb->fileIsSource() ) {
		$errorMsg = $msg->
			rawParams( 'Image was not scaled, is the requested width bigger than the source?' )->escaped();
	}

	if ( $errorMsg !== false ) {
		wfThumbError( 500, $errorMsg );
	} else {
		// Stream the file if there were no errors
		$thumb->streamFile( $headers );
	}

	wfProfileOut( __METHOD__ );
}

/**
 * Extract the required params for thumb.php from the thumbnail request URI.
 * At least 'width' and 'f' should be set if the result is an array.
 *
 * @param $thumbRel String Thumbnail path relative to the thumb zone
 * @return Array|null associative params array or null
 */
function wfExtractThumbParams( $thumbRel ) {
	$repo = RepoGroup::singleton()->getLocalRepo();

	$hashDirReg = $subdirReg = '';
	for ( $i = 0; $i < $repo->getHashLevels(); $i++ ) {
		$subdirReg .= '[0-9a-f]';
		$hashDirReg .= "$subdirReg/";
	}

	// Check if this is a thumbnail of an original in the local file repo
	if ( preg_match( "!^((archive/)?$hashDirReg([^/]*)/([^/]*))$!", $thumbRel, $m ) ) {
		list( /*all*/, $rel, $archOrTemp, $filename, $thumbname ) = $m;
	// Check if this is a thumbnail of an temp file in the local file repo
	} elseif ( preg_match( "!^(temp/)($hashDirReg([^/]*)/([^/]*))$!", $thumbRel, $m ) ) {
		list( /*all*/, $archOrTemp, $rel, $filename, $thumbname ) = $m;
	} else {
		return null; // not a valid looking thumbnail request
	}

	$params = array( 'f' => $filename, 'rel404' => $rel );
	if ( $archOrTemp === 'archive/' ) {
		$params['archived'] = 1;
	} elseif ( $archOrTemp === 'temp/' ) {
		$params['temp'] = 1;
	}

	// Check hooks if parameters can be extracted
	// Hooks return false if they manage to *resolve* the parameters
	if ( !wfRunHooks( 'ExtractThumbParameters', array( $thumbname, &$params ) ) ) {
		return $params; // valid thumbnail URL (via extension or config)
	// Check if the parameters can be extracted from the thumbnail name...
	} elseif ( preg_match( '!^(page(\d*)-)*(\d*)px-[^/]*$!', $thumbname, $matches ) ) {
		list( /* all */, $pagefull, $pagenum, $size ) = $matches;
		$params['width'] = $size;
		if ( $pagenum ) {
			$params['page'] = $pagenum;
		}
		return $params; // valid thumbnail URL
	}

	return null; // not a valid thumbnail URL
}

/**
 * Output a thumbnail generation error message
 *
 * @param $status integer
 * @param $msg string
 * @return void
 */
function wfThumbError( $status, $msg ) {
	global $wgShowHostnames;

	header( 'Cache-Control: no-cache' );
	header( 'Content-Type: text/html; charset=utf-8' );
	if ( $status == 404 ) {
		header( 'HTTP/1.1 404 Not found' );
	} elseif ( $status == 403 ) {
		header( 'HTTP/1.1 403 Forbidden' );
		header( 'Vary: Cookie' );
	} else {
		header( 'HTTP/1.1 500 Internal server error' );
	}
	if ( $wgShowHostnames ) {
		$url = htmlspecialchars( isset( $_SERVER['REQUEST_URI'] ) ? $_SERVER['REQUEST_URI'] : '' );
		$hostname = htmlspecialchars( wfHostname() );
		$debug = "<!-- $url -->\n<!-- $hostname -->\n";
	} else {
		$debug = '';
	}
	echo <<<EOT
<html><head><title>Error generating thumbnail</title></head>
<body>
<h1>Error generating thumbnail</h1>
<p>
$msg
</p>
$debug
</body>
</html>

EOT;
}