Enable fseek for files in S3 storage

lib/composer/composer/autoload_classmap.php

@@ -1023,6 +1023,7 @@
     'OC\\Files\\Storage\\Wrapper\\Wrapper' => $baseDir . '/lib/private/Files/Storage/Wrapper/Wrapper.php',
     'OC\\Files\\Stream\\Encryption' => $baseDir . '/lib/private/Files/Stream/Encryption.php',
     'OC\\Files\\Stream\\Quota' => $baseDir . '/lib/private/Files/Stream/Quota.php',
+    'OC\\Files\\Stream\\SeekableHttpStream' => $baseDir . '/lib/private/Files/Stream/SeekableHttpStream.php',
     'OC\\Files\\Type\\Detection' => $baseDir . '/lib/private/Files/Type/Detection.php',
     'OC\\Files\\Type\\Loader' => $baseDir . '/lib/private/Files/Type/Loader.php',
     'OC\\Files\\Type\\TemplateManager' => $baseDir . '/lib/private/Files/Type/TemplateManager.php',

lib/composer/composer/autoload_static.php

@@ -1052,6 +1052,7 @@ class ComposerStaticInit53792487c5a8370acc0b06b1a864ff4c
         'OC\\Files\\Storage\\Wrapper\\Wrapper' => __DIR__ . '/../../..' . '/lib/private/Files/Storage/Wrapper/Wrapper.php',
         'OC\\Files\\Stream\\Encryption' => __DIR__ . '/../../..' . '/lib/private/Files/Stream/Encryption.php',
         'OC\\Files\\Stream\\Quota' => __DIR__ . '/../../..' . '/lib/private/Files/Stream/Quota.php',
+        'OC\\Files\\Stream\\SeekableHttpStream' => __DIR__ . '/../../..' . '/lib/private/Files/Stream/SeekableHttpStream.php',
         'OC\\Files\\Type\\Detection' => __DIR__ . '/../../..' . '/lib/private/Files/Type/Detection.php',
         'OC\\Files\\Type\\Loader' => __DIR__ . '/../../..' . '/lib/private/Files/Type/Loader.php',
         'OC\\Files\\Type\\TemplateManager' => __DIR__ . '/../../..' . '/lib/private/Files/Type/TemplateManager.php',

lib/private/Files/ObjectStore/S3ObjectTrait.php

@@ -30,6 +30,7 @@
 use Aws\S3\ObjectUploader;
 use Aws\S3\S3Client;
 use Icewind\Streams\CallbackWrapper;
+use OC\Files\Stream\SeekableHttpStream;
 
 const S3_UPLOAD_PART_SIZE = 524288000; // 500MB
 
@@ -49,27 +50,29 @@ abstract protected function getConnection();
 	 * @since 7.0.0
 	 */
 	function readObject($urn) {
-		$client = $this->getConnection();
-		$command = $client->getCommand('GetObject', [
-			'Bucket' => $this->bucket,
-			'Key' => $urn
-		]);
-		$request = \Aws\serialize($command);
-		$headers = [];
-		foreach ($request->getHeaders() as $key => $values) {
-			foreach ($values as $value) {
-				$headers[] = "$key: $value";
+		return SeekableHttpStream::open(function ($range) use ($urn) {
+			$command = $this->getConnection()->getCommand('GetObject', [
+				'Bucket' => $this->bucket,
+				'Key' => $urn,
+				'Range' => 'bytes=' . $range,
+			]);
+			$request = \Aws\serialize($command);
+			$headers = [];
+			foreach ($request->getHeaders() as $key => $values) {
+				foreach ($values as $value) {
+					$headers[] = "$key: $value";
+				}
 			}
-		}
-		$opts = [
-			'http' => [
-				'protocol_version'  => 1.1,
-				'header' => $headers
-			]
-		];
+			$opts = [
+				'http' => [
+					'protocol_version' => 1.1,
+					'header' => $headers,
+				],
+			];
 
-		$context = stream_context_create($opts);
-		return fopen($request->getUri(), 'r', false, $context);
+			$context = stream_context_create($opts);
+			return fopen($request->getUri(), 'r', false, $context);
+		});
 	}
 
 	/**
@@ -87,7 +90,7 @@ function writeObject($urn, $stream) {
 		$uploader = new MultipartUploader($this->getConnection(), $countStream, [
 			'bucket' => $this->bucket,
 			'key' => $urn,
-			'part_size' => S3_UPLOAD_PART_SIZE
+			'part_size' => S3_UPLOAD_PART_SIZE,
 		]);
 
 		try {
@@ -114,7 +117,7 @@ function writeObject($urn, $stream) {
 	function deleteObject($urn) {
 		$this->getConnection()->deleteObject([
 			'Bucket' => $this->bucket,
-			'Key' => $urn
+			'Key' => $urn,
 		]);
 	}
 

lib/private/Files/Stream/SeekableHttpStream.php

@@ -0,0 +1,182 @@
+<?php
+/**
+ *
+ * @copyright Copyright (c) 2020, Lukas Stabe (lukas@stabe.de)
+ *
+ * @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\File;
+
+/**
+ * A stream wrapper that uses http range requests to provide a seekable stream for http reading
+ */
+class SeekableHttpStream implements File {
+	private const PROTOCOL = 'httpseek';
+
+	private static $registered = false;
+
+	/**
+	 * Registers the stream wrapper using the `httpseek://` url scheme
+	 * $return void
+	 */
+	private static function registerIfNeeded() {
+		if (!self::$registered) {
+			stream_wrapper_register(
+				self::PROTOCOL,
+				self::class
+			);
+			self::$registered = true;
+		}
+	}
+
+	/**
+	 * Open a readonly-seekable http stream
+	 *
+	 * The provided callback will be called with byte range and should return an http stream for the requested range
+	 *
+	 * @param callable $callback
+	 * @return false|resource
+	 */
+	public static function open(callable $callback) {
+		$context = stream_context_create([
+			SeekableHttpStream::PROTOCOL => [
+				'callback' => $callback
+			],
+		]);
+
+		SeekableHttpStream::registerIfNeeded();
+		return fopen(SeekableHttpStream::PROTOCOL . '://', 'r', false, $context);
+	}
+
+	/** @var resource */
+	public $context;
+
+	/** @var callable */
+	private $openCallback;
+
+	/** @var resource */
+	private $current;
+	/** @var int */
+	private $offset = 0;
+
+	private function reconnect(int $start) {
+		$range = $start . '-';
+		if ($this->current != null) {
+			fclose($this->current);
+		}
+
+		$this->current = ($this->openCallback)($range);
+
+		if ($this->current === false) {
+			return false;
+		}
+
+		$responseHead = stream_get_meta_data($this->current)['wrapper_data'];
+		$rangeHeaders = array_values(array_filter($responseHead, function ($v) {
+			return preg_match('#^content-range:#i', $v) === 1;
+		}));
+		if (!$rangeHeaders) {
+			return false;
+		}
+		$contentRange = $rangeHeaders[0];
+
+		$content = trim(explode(':', $contentRange)[1]);
+		$range = trim(explode(' ', $content)[1]);
+		$begin = intval(explode('-', $range)[0]);
+
+		if ($begin !== $start) {
+			return false;
+		}
+
+		$this->offset = $begin;
+
+		return true;
+	}
+
+	public function stream_open($path, $mode, $options, &$opened_path) {
+		$options = stream_context_get_options($this->context)[self::PROTOCOL];
+		$this->openCallback = $options['callback'];
+
+		return $this->reconnect(0);
+	}
+
+	public function stream_read($count) {
+		if (!$this->current) {
+			return false;
+		}
+		$ret = fread($this->current, $count);
+		$this->offset += strlen($ret);
+		return $ret;
+	}
+
+	public function stream_seek($offset, $whence = SEEK_SET) {
+		switch ($whence) {
+			case SEEK_SET:
+				if ($offset === $this->offset) {
+					return true;
+				}
+				return $this->reconnect($offset);
+			case SEEK_CUR:
+				if ($offset === 0) {
+					return true;
+				}
+				return $this->reconnect($this->offset + $offset);
+			case SEEK_END:
+				return false;
+		}
+		return false;
+	}
+
+	public function stream_tell() {
+		return $this->offset;
+	}
+
+	public function stream_stat() {
+		return fstat($this->current);
+	}
+
+	public function stream_eof() {
+		return feof($this->current);
+	}
+
+	public function stream_close() {
+		fclose($this->current);
+	}
+
+	public function stream_write($data) {
+		return false;
+	}
+
+	public function stream_set_option($option, $arg1, $arg2) {
+		return false;
+	}
+
+	public function stream_truncate($size) {
+		return false;
+	}
+
+	public function stream_lock($operation) {
+		return false;
+	}
+
+	public function stream_flush() {
+		return; //noop because readonly stream
+	}
+}

tests/lib/Files/ObjectStore/ObjectStoreTest.php

@@ -31,7 +31,7 @@ abstract class ObjectStoreTest extends TestCase {
 	 */
 	abstract protected function getInstance();
 
-	private function stringToStream($data) {
+	protected function stringToStream($data) {
 		$stream = fopen('php://temp', 'w+');
 		fwrite($stream, $data);
 		rewind($stream);

tests/lib/Files/ObjectStore/S3Test.php

@@ -27,7 +27,7 @@
 class MultiPartUploadS3 extends S3 {
 	function writeObject($urn, $stream) {
 		$this->getConnection()->upload($this->bucket, $urn, $stream, 'private', [
-			'mup_threshold' => 1
+			'mup_threshold' => 1,
 		]);
 	}
 }
@@ -36,8 +36,8 @@ class NonSeekableStream extends Wrapper {
 	public static function wrap($source) {
 		$context = stream_context_create([
 			'nonseek' => [
-				'source' => $source
-			]
+				'source' => $source,
+			],
 		]);
 		return Wrapper::wrapSource($source, $context, 'nonseek', self::class);
 	}
@@ -83,4 +83,20 @@ public function testUploadNonSeekable() {
 
 		$this->assertEquals(file_get_contents(__FILE__), stream_get_contents($result));
 	}
+
+	public function testSeek() {
+		$data = file_get_contents(__FILE__);
+
+		$instance = $this->getInstance();
+		$instance->writeObject('seek', $this->stringToStream($data));
+
+		$read = $instance->readObject('seek');
+		$this->assertEquals(substr($data, 0, 100), fread($read, 100));
+
+		fseek($read, 10);
+		$this->assertEquals(substr($data, 10, 100), fread($read, 100));
+
+		fseek($read, 100, SEEK_CUR);
+		$this->assertEquals(substr($data, 210, 100), fread($read, 100));
+	}
 }