66102bd54c
This isn't used anywhere. Theoretical code using would gracefully fallback to 'md4' given extra params are ignored by PHP. In terms of future roadmap, I do expect that this algo may have to change one day based on information that might come to light around whether MD4 will remain sufficiently fast and/or sufficiently unique. However, I do not expect that to be so significant in difference that we'd have to remain some callers on MD4 whilst others adopt something else. It seems fine that, if that time comes, to simply switch it and thus consider the algo an implementation detail. Bug: T32956 Change-Id: Ia9e1366b802ac18f439ce0c802189ede0a2c63f0
108 lines
3.2 KiB
PHP
108 lines
3.2 KiB
PHP
<?php
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/**
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* Generate hash digests of file contents to help with cache invalidation.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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* http://www.gnu.org/copyleft/gpl.html
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*
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* @file
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*/
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class FileContentsHasher {
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private const ALGO = 'md4';
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/** @var BagOStuff */
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protected $cache;
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/** @var FileContentsHasher */
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private static $instance;
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public function __construct() {
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$this->cache = function_exists( 'apcu_fetch' ) ? new APCUBagOStuff() : new EmptyBagOStuff();
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}
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/**
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* Get the singleton instance of this class.
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*
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* @return FileContentsHasher
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*/
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public static function singleton() {
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if ( !self::$instance ) {
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self::$instance = new self;
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}
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return self::$instance;
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}
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/**
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* Get a hash of a file's contents, either by retrieving a previously-
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* computed hash from the cache, or by computing a hash from the file.
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*
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* @param string $filePath Full path to the file.
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* @return string|bool Hash of file contents, or false if the file could not be read.
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*/
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private function getFileContentsHashInternal( $filePath ) {
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// phpcs:ignore Generic.PHP.NoSilencedErrors.Discouraged
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$mtime = @filemtime( $filePath );
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if ( $mtime === false ) {
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return false;
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}
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$cacheKey = $this->cache->makeGlobalKey( __CLASS__, $filePath, $mtime, self::ALGO );
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return $this->cache->getWithSetCallback(
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$cacheKey,
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$this->cache::TTL_DAY,
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static function () use ( $filePath ) {
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// phpcs:ignore Generic.PHP.NoSilencedErrors.Discouraged
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$contents = @file_get_contents( $filePath );
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if ( $contents === false ) {
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// Don't cache false
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return false;
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}
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return hash( self::ALGO, $contents );
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}
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);
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}
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/**
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* Get a hash of the combined contents of one or more files, either by
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* retrieving a previously-computed hash from the cache, or by computing
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* a hash from the files.
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*
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* @param string|string[] $filePaths One or more file paths.
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* @return string|bool Hash of files' contents, or false if no file could not be read.
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*/
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public static function getFileContentsHash( $filePaths ) {
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$instance = self::singleton();
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if ( !is_array( $filePaths ) ) {
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$filePaths = (array)$filePaths;
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}
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if ( count( $filePaths ) === 1 ) {
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$hash = $instance->getFileContentsHashInternal( $filePaths[0] );
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return $hash;
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}
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sort( $filePaths );
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$hashes = [];
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foreach ( $filePaths as $filePath ) {
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$hashes[] = $instance->getFileContentsHashInternal( $filePath ) ?: '';
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}
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$hashes = implode( '', $hashes );
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return $hashes ? hash( self::ALGO, $hashes ) : false;
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}
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}
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