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<?php
use MediaWiki\MediaWikiServices;
/**
* Handles compiling Mustache templates into PHP rendering functions
*
* 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
* @since 1.25
*/
class TemplateParser {
/**
* @var string The path to the Mustache templates
*/
protected $templateDir;
/**
* @var callable[] Array of cached rendering functions
*/
protected $renderers;
/**
* @var bool Always compile template files
*/
protected $forceRecompile = false;
/**
* @var int Compilation flags passed to LightnCandy
*/
// Do not add more flags here without discussion.
// If you do add more flags, be sure to update unit tests as well.
protected $compileFlags = LightnCandy::FLAG_ERROR_EXCEPTION;
/**
* @param string $templateDir
* @param bool $forceRecompile
*/
public function __construct( $templateDir = null, $forceRecompile = false ) {
$this->templateDir = $templateDir ?: __DIR__ . '/templates';
$this->forceRecompile = $forceRecompile;
}
/**
* Enable/disable the use of recursive partials.
* @param bool $enable
*/
public function enableRecursivePartials( $enable ) {
if ( $enable ) {
$this->compileFlags = $this->compileFlags | LightnCandy::FLAG_RUNTIMEPARTIAL;
} else {
$this->compileFlags = $this->compileFlags & ~LightnCandy::FLAG_RUNTIMEPARTIAL;
}
}
/**
* Constructs the location of the the source Mustache template
* @param string $templateName The name of the template
* @return string
* @throws UnexpectedValueException If $templateName attempts upwards directory traversal
*/
protected function getTemplateFilename( $templateName ) {
// Prevent path traversal. Based on Language::isValidCode().
// This is for paranoia. The $templateName should never come from
// untrusted input.
if (
strcspn( $templateName, ":/\\\000&<>'\"%" ) !== strlen( $templateName )
) {
throw new UnexpectedValueException( "Malformed \$templateName: $templateName" );
}
return "{$this->templateDir}/{$templateName}.mustache";
}
/**
* Returns a given template function if found, otherwise throws an exception.
* @param string $templateName The name of the template (without file suffix)
* @return callable
* @throws RuntimeException
*/
protected function getTemplate( $templateName ) {
$templateKey = $templateName . '|' . $this->compileFlags;
// If a renderer has already been defined for this template, reuse it
if ( isset( $this->renderers[$templateKey] ) &&
is_callable( $this->renderers[$templateKey] )
) {
return $this->renderers[$templateKey];
}
$filename = $this->getTemplateFilename( $templateName );
if ( !file_exists( $filename ) ) {
throw new RuntimeException( "Could not locate template: {$filename}" );
}
// Read the template file
$fileContents = file_get_contents( $filename );
// Generate a quick hash for cache invalidation
$fastHash = md5( $this->compileFlags . '|' . $fileContents );
// Fetch a secret key for building a keyed hash of the PHP code
$config = MediaWikiServices::getInstance()->getMainConfig();
$secretKey = $config->get( 'SecretKey' );
if ( $secretKey ) {
// See if the compiled PHP code is stored in cache.
$cache = ObjectCache::getLocalServerInstance( CACHE_ANYTHING );
$key = $cache->makeKey( 'template', $templateName, $fastHash );
$code = $this->forceRecompile ? null : $cache->get( $key );
if ( $code ) {
// Verify the integrity of the cached PHP code
$keyedHash = substr( $code, 0, 64 );
$code = substr( $code, 64 );
if ( $keyedHash !== hash_hmac( 'sha256', $code, $secretKey ) ) {
// If the integrity check fails, don't use the cached code
// We'll update the invalid cache below
$code = null;
}
}
if ( !$code ) {
$code = $this->compileForEval( $fileContents, $filename );
// Prefix the cached code with a keyed hash (64 hex chars) as an integrity check
$cache->set( $key, hash_hmac( 'sha256', $code, $secretKey ) . $code );
}
// If there is no secret key available, don't use cache
} else {
$code = $this->compileForEval( $fileContents, $filename );
}
$renderer = eval( $code );
if ( !is_callable( $renderer ) ) {
throw new RuntimeException( "Requested template, {$templateName}, is not callable" );
}
$this->renderers[$templateKey] = $renderer;
return $renderer;
}
/**
* Wrapper for compile() function that verifies successful compilation and strips
* out the '<?php' part so that the code is ready for eval()
* @param string $fileContents Mustache code
* @param string $filename Name of the template
* @return string PHP code (without '<?php')
* @throws RuntimeException
*/
protected function compileForEval( $fileContents, $filename ) {
// Compile the template into PHP code
$code = $this->compile( $fileContents );
if ( !$code ) {
throw new RuntimeException( "Could not compile template: {$filename}" );
}
// Strip the "<?php" added by lightncandy so that it can be eval()ed
if ( substr( $code, 0, 5 ) === '<?php' ) {
$code = substr( $code, 5 );
}
return $code;
}
/**
* Compile the Mustache code into PHP code using LightnCandy
* @param string $code Mustache code
* @return string PHP code (with '<?php')
* @throws RuntimeException
*/
protected function compile( $code ) {
if ( !class_exists( 'LightnCandy' ) ) {
throw new RuntimeException( 'LightnCandy class not defined' );
}
return LightnCandy::compile(
$code,
[
'flags' => $this->compileFlags,
'basedir' => $this->templateDir,
'fileext' => '.mustache',
]
);
}
/**
* Returns HTML for a given template by calling the template function with the given args
*
* @code
* echo $templateParser->processTemplate(
* 'ExampleTemplate',
* [
* 'username' => $user->getName(),
* 'message' => 'Hello!'
* ]
* );
* @endcode
* @param string $templateName The name of the template
* @param mixed $args
* @param array $scopes
* @return string
*/
public function processTemplate( $templateName, $args, array $scopes = [] ) {
$template = $this->getTemplate( $templateName );
return call_user_func( $template, $args, $scopes );
}
}
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