includes/Html/TemplateParser.php
<?php
namespace MediaWiki\Html;
use FileContentsHasher;
use LightnCandy\LightnCandy;
use MediaWiki\MainConfigNames;
use MediaWiki\MediaWikiServices;
use RuntimeException;
use UnexpectedValueException;
use Wikimedia\ObjectCache\BagOStuff;
/**
* 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 {
private const CACHE_VERSION = '2.2.0';
private const CACHE_TTL = BagOStuff::TTL_WEEK;
/**
* @var BagOStuff
*/
private $cache;
/**
* @var string The path to the Mustache templates
*/
protected $templateDir;
/**
* @var callable[] Array of cached rendering functions
*/
protected $renderers;
/**
* @var int Compilation flags passed to LightnCandy
*/
protected $compileFlags;
/**
* @param string|null $templateDir
* @param BagOStuff|null $cache Read-write cache
*/
public function __construct( $templateDir = null, ?BagOStuff $cache = null ) {
$this->templateDir = $templateDir ?: __DIR__ . '/../templates';
$this->cache = $cache ?: MediaWikiServices::getInstance()->getObjectCacheFactory()
->getLocalServerInstance( CACHE_ANYTHING );
// Do not add more flags here without discussion.
// If you do add more flags, be sure to update unit tests as well.
$this->compileFlags = LightnCandy::FLAG_ERROR_EXCEPTION | LightnCandy::FLAG_MUSTACHELOOKUP;
}
/**
* Enable/disable the use of recursive partials.
* @param bool $enable
*/
public function enableRecursivePartials( $enable ) {
if ( $enable ) {
$this->compileFlags |= LightnCandy::FLAG_RUNTIMEPARTIAL;
} else {
$this->compileFlags &= ~LightnCandy::FLAG_RUNTIMEPARTIAL;
}
}
/**
* Constructs the location of 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 LanguageNameUtils::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 When the template file cannot be found
* @throws RuntimeException When the compiled template isn't callable. This is indicative of a
* bug in LightnCandy
*/
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];
}
// Fetch a secret key for building a keyed hash of the PHP code.
// Note that this may be called before MediaWiki is fully initialized.
$secretKey = MediaWikiServices::hasInstance()
? MediaWikiServices::getInstance()->getMainConfig()->get( MainConfigNames::SecretKey )
: null;
if ( $secretKey ) {
// See if the compiled PHP code is stored in the server-local cache.
$key = $this->cache->makeKey(
'lightncandy-compiled',
self::CACHE_VERSION,
$this->compileFlags,
$this->templateDir,
$templateName
);
$compiledTemplate = $this->cache->get( $key );
// 1. Has the template changed since the compiled template was cached? If so, don't use
// the cached code.
if ( $compiledTemplate ) {
$filesHash = FileContentsHasher::getFileContentsHash( $compiledTemplate['files'] );
if ( $filesHash !== $compiledTemplate['filesHash'] ) {
$compiledTemplate = null;
}
}
// 2. Is the integrity of the cached PHP code compromised? If so, don't use the cached
// code.
if ( $compiledTemplate ) {
$integrityHash = hash_hmac( 'sha256', $compiledTemplate['phpCode'], $secretKey );
if ( $integrityHash !== $compiledTemplate['integrityHash'] ) {
$compiledTemplate = null;
}
}
// We're not using the cached code for whatever reason. Recompile the template and
// cache it.
if ( !$compiledTemplate ) {
$compiledTemplate = $this->compile( $templateName );
$compiledTemplate['integrityHash'] = hash_hmac(
'sha256',
$compiledTemplate['phpCode'],
$secretKey
);
$this->cache->set( $key, $compiledTemplate, self::CACHE_TTL );
}
// If there is no secret key available, don't use cache
} else {
$compiledTemplate = $this->compile( $templateName );
}
// phpcs:ignore MediaWiki.Usage.ForbiddenFunctions.eval
$renderer = eval( $compiledTemplate['phpCode'] );
if ( !is_callable( $renderer ) ) {
throw new RuntimeException( "Compiled template `{$templateName}` is not callable" );
}
$this->renderers[$templateKey] = $renderer;
return $renderer;
}
/**
* Compile the Mustache template into PHP code using LightnCandy.
*
* The compilation step generates both PHP code and metadata, which is also returned in the
* result. An example result looks as follows:
*
* ```php
* [
* 'phpCode' => '...',
* 'files' => [
* '/path/to/template.mustache',
* '/path/to/partial1.mustache',
* '/path/to/partial2.mustache',
* 'filesHash' => '...'
* ]
* ```
*
* The `files` entry is a list of the files read during the compilation of the template. Each
* entry is the fully-qualified filename, i.e. it includes path information.
*
* The `filesHash` entry can be used to determine whether the template has changed since it was
* last compiled without compiling the template again. Currently, the `filesHash` entry is
* generated with FileContentsHasher::getFileContentsHash.
*
* @param string $templateName The name of the template
* @return array An associative array containing the PHP code and metadata about its compilation
* @throws \Exception Thrown by LightnCandy if it could not compile the Mustache code
* @throws RuntimeException If LightnCandy could not compile the Mustache code but did not throw
* an exception. This exception is indicative of a bug in LightnCandy
* @suppress PhanTypeMismatchArgument
*/
protected function compile( $templateName ) {
$filename = $this->getTemplateFilename( $templateName );
if ( !file_exists( $filename ) ) {
throw new RuntimeException( "Could not find template `{$templateName}` at {$filename}" );
}
$files = [ $filename ];
$contents = file_get_contents( $filename );
$compiled = LightnCandy::compile(
$contents,
[
'flags' => $this->compileFlags,
'basedir' => $this->templateDir,
'fileext' => '.mustache',
'partialresolver' => function ( $cx, $partialName ) use ( $templateName, &$files ) {
$filename = "{$this->templateDir}/{$partialName}.mustache";
if ( !file_exists( $filename ) ) {
throw new RuntimeException( sprintf(
'Could not compile template `%s`: Could not find partial `%s` at %s',
$templateName,
$partialName,
$filename
) );
}
$fileContents = file_get_contents( $filename );
if ( $fileContents === false ) {
throw new RuntimeException( sprintf(
'Could not compile template `%s`: Could not find partial `%s` at %s',
$templateName,
$partialName,
$filename
) );
}
$files[] = $filename;
return $fileContents;
}
]
);
if ( !$compiled ) {
// This shouldn't happen because LightnCandy::FLAG_ERROR_EXCEPTION is set
// Errors should throw exceptions instead of returning false
// Check anyway for paranoia
throw new RuntimeException( "Could not compile template `{$filename}`" );
}
$files = array_values( array_unique( $files ) );
return [
'phpCode' => $compiled,
'files' => $files,
'filesHash' => FileContentsHasher::getFileContentsHash( $files ),
];
}
/**
* 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-taint $templateName exec_path
* @param mixed $args
* @param-taint $args none
* @param array $scopes
* @param-taint $scopes none
* @return string
*/
public function processTemplate( $templateName, $args, array $scopes = [] ) {
$template = $this->getTemplate( $templateName );
return $template( $args, $scopes );
}
}
/** @deprecated class alias since 1.40 */
class_alias( TemplateParser::class, 'TemplateParser' );