1 files changed, 72 insertions, 0 deletions
diff --git a/lib/private/Files/Stream/HashWrapper.php b/lib/private/Files/Stream/HashWrapper.php
new file mode 100644
index 00000000000..048e50794e8
--- /dev/null
+++ b/lib/private/Files/Stream/HashWrapper.php
@@ -0,0 +1,72 @@
+<?php declare(strict_types=1);
+/**
+ * @copyright Copyright (c) 2020 Robin Appelman <robin@icewind.nl>
+ *
+ * @license GNU AGPL version 3 or any later version
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+namespace OC\Files\Stream;
+
+use Icewind\Streams\Wrapper;
+
+class HashWrapper extends Wrapper {
+	protected $callback;
+	protected $hash;
+
+	public static function wrap($source, string $algo, callable $callback) {
+		$hash = hash_init($algo);
+		$context = stream_context_create([
+			'hash' => [
+				'source' => $source,
+				'callback' => $callback,
+				'hash' => $hash,
+			],
+		]);
+		return Wrapper::wrapSource($source, $context, 'hash', self::class);
+	}
+
+	protected function open() {
+		$context = $this->loadContext('hash');
+
+		$this->callback = $context['callback'];
+		$this->hash = $context['hash'];
+		return true;
+	}
+
+	public function dir_opendir($path, $options) {
+		return $this->open();
+	}
+
+	public function stream_open($path, $mode, $options, &$opened_path) {
+		return $this->open();
+	}
+
+	public function stream_read($count) {
+		$result = parent::stream_read($count);
+		hash_update($this->hash, $result);
+		return $result;
+	}
+
+	public function stream_close() {
+		if (is_callable($this->callback)) {
+			call_user_func($this->callback, hash_final($this->hash));
+			// prevent further calls by potential PHP 7 GC ghosts
+			$this->callback = null;
+		}
+		return parent::stream_close();
+	}
+}