make seekable s3 stream generic

Signed-off-by: Robin Appelman <robin@icewind.nl>

lib/private/Files/ObjectStore/S3ObjectTrait.php

@@ -30,6 +30,7 @@ use Aws\S3\MultipartUploader;
 use Aws\S3\ObjectUploader;
 use Aws\S3\S3Client;
 use Icewind\Streams\CallbackWrapper;
+use OC\Files\Stream\SeekableHttpStream;
 
 const S3_UPLOAD_PART_SIZE = 524288000; // 500MB
 
@@ -49,16 +50,29 @@ trait S3ObjectTrait {
 	 * @since 7.0.0
 	 */
 	function readObject($urn) {
-		$context = stream_context_create([
-			's3seek' => [
-				'client' => $this->getConnection(),
-				'bucket' => $this->bucket,
-				'urn' => $urn,
-			],
-		]);
+		return SeekableHttpStream::open(function ($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,
+				],
+			];
 
-		S3SeekableReadStream::registerIfNeeded();
-		return fopen('s3seek://', 'r', false, $context);
+			$context = stream_context_create($opts);
+			return fopen($request->getUri(), 'r', false, $context);
+		});
 	}
 
 	/**
@@ -76,7 +90,7 @@ trait S3ObjectTrait {
 		$uploader = new MultipartUploader($this->getConnection(), $countStream, [
 			'bucket' => $this->bucket,
 			'key' => $urn,
-			'part_size' => S3_UPLOAD_PART_SIZE
+			'part_size' => S3_UPLOAD_PART_SIZE,
 		]);
 
 		try {
@@ -103,7 +117,7 @@ trait S3ObjectTrait {
 	function deleteObject($urn) {
 		$this->getConnection()->deleteObject([
 			'Bucket' => $this->bucket,
-			'Key' => $urn
+			'Key' => $urn,
 		]);
 	}
 

lib/private/Files/Stream/SeekableHttpStream.php

@@ -20,34 +20,60 @@
  *
  */
 
-namespace OC\Files\ObjectStore;
+namespace OC\Files\Stream;
+
+use Icewind\Streams\File;
 
 /**
- * A stream wrapper that uses http range requests to provide a seekable
- * stream of a file in S3 storage.
+ * A stream wrapper that uses http range requests to provide a seekable stream for http reading
  */
-class S3SeekableReadStream {
+class SeekableHttpStream implements File {
+	private const PROTOCOL = 'httpseek';
+
 	private static $registered = false;
 
 	/**
-	 * Registers the stream wrapper using the `s3seek://` url scheme
+	 * Registers the stream wrapper using the `httpseek://` url scheme
 	 * $return void
 	 */
-	public static function registerIfNeeded() {
+	private static function registerIfNeeded() {
 		if (!self::$registered) {
 			stream_wrapper_register(
-				's3seek',
-				'OC\Files\ObjectStore\S3SeekableReadStream'
+				self::PROTOCOL,
+				self::class
 			);
 			self::$registered = true;
 		}
 	}
 
-	private $client;
-	private $bucket;
-	private $urn;
+	/**
+	 * 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($range) {
@@ -55,29 +81,11 @@ class S3SeekableReadStream {
 			fclose($this->current);
 		}
 
-		$command = $this->client->getCommand('GetObject', [
-			'Bucket' => $this->bucket,
-			'Key' => $this->urn,
-			'Range' => 'bytes=' . $range,
-		]);
-		$request = \Aws\serialize($command);
-		$headers = [];
-		foreach ($request->getHeaders() as $key => $values) {
-			foreach ($values as $value) {
-				$headers[] = "$key: $value";
-			}
+		$this->current = ($this->openCallback)($range);
+
+		if ($this->current === false) {
+			return false;
 		}
-		$opts = [
-			'http' => [
-				'protocol_version' => 1.1,
-				'header' => $headers,
-			],
-		];
-
-		$context = stream_context_create($opts);
-		$this->current = fopen($request->getUri(), 'r', false, $context);
-
-		if ($this->current === false) {return false;}
 
 		$responseHead = stream_get_meta_data($this->current)['wrapper_data'];
 		$contentRange = array_values(array_filter($responseHead, function ($v) {
@@ -93,30 +101,35 @@ class S3SeekableReadStream {
 	}
 
 	function stream_open($path, $mode, $options, &$opened_path) {
-		$o = stream_context_get_options($this->context)['s3seek'];
-		$this->bucket = $o['bucket'];
-		$this->urn = $o['urn'];
-		$this->client = $o['client'];
+		$options = stream_context_get_options($this->context)[self::PROTOCOL];
+		$this->openCallback = $options['callback'];
 
 		return $this->reconnect('0-');
 	}
 
 	function stream_read($count) {
+		if (!$this->current) {
+			return false;
+		}
 		$ret = fread($this->current, $count);
 		$this->offset += strlen($ret);
 		return $ret;
 	}
 
-	function stream_seek($offset, $whence) {
+	function stream_seek($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 + $offset) . '-');
-		case SEEK_END:
-			return false;
+			case SEEK_SET:
+				if ($offset === $this->offset) {
+					return true;
+				}
+				return $this->reconnect($offset . '-');
+			case SEEK_CUR:
+				if ($offset === 0) {
+					return true;
+				}
+				return $this->reconnect(($this->offset + $offset) . '-');
+			case SEEK_END:
+				return false;
 		}
 		return false;
 	}
@@ -136,4 +149,26 @@ class S3SeekableReadStream {
 	function stream_close() {
 		fclose($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
+	}
+
+
 }