Enable fseek for files in S3 storage

Signed-off-by: Lukas Stabe <lukas@stabe.de>

diff --git a/lib/private/Files/ObjectStore/S3ObjectTrait.php b/lib/private/Files/ObjectStore/S3ObjectTrait.php
index a63415c7f4334299489f21814f2af8829f6f5e72..79a0c0a87afd228b87d3daca6a43c5116530e0a1 100644 (file)
--- a/lib/private/Files/ObjectStore/S3ObjectTrait.php
+++ b/lib/private/Files/ObjectStore/S3ObjectTrait.php
@@ -47,27 +47,16 @@ trait S3ObjectTrait {
         * @since 7.0.0
         */
        function readObject($urn) {
-               $client = $this->getConnection();
-               $command = $client->getCommand('GetObject', [
-                       'Bucket' => $this->bucket,
-                       'Key' => $urn
+               $context = stream_context_create([
+                       's3seek' => [
+                               'client' => $this->getConnection(),
+                               'bucket' => $this->bucket,
+                               'urn' => $urn,
+                       ],
                ]);
-               $request = \Aws\serialize($command);
-               $headers = [];
-               foreach ($request->getHeaders() as $key => $values) {
-                       foreach ($values as $value) {
-                               $headers[] = "$key: $value";
-                       }
-               }
-               $opts = [
-                       'http' => [
-                               'protocol_version'  => 1.1,
-                               'header' => $headers
-                       ]
-               ];
 
-               $context = stream_context_create($opts);
-               return fopen($request->getUri(), 'r', false, $context);
+               S3SeekableReadStream::registerIfNeeded();
+               return fopen('s3seek://', 'r', false, $context);
        }
 
        /**

diff --git a/lib/private/Files/ObjectStore/S3SeekableReadStream.php b/lib/private/Files/ObjectStore/S3SeekableReadStream.php
new file mode 100644 (file)
index 0000000..7085553
--- /dev/null
+++ b/lib/private/Files/ObjectStore/S3SeekableReadStream.php
@@ -0,0 +1,139 @@
+<?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\ObjectStore;
+
+/**
+ * A stream wrapper that uses http range requests to provide a seekable
+ * stream of a file in S3 storage.
+ */
+class S3SeekableReadStream {
+       private static $registered = false;
+
+       /**
+        * Registers the stream wrapper using the `s3seek://` url scheme
+        * $return void
+        */
+       public static function registerIfNeeded() {
+               if (!self::$registered) {
+                       stream_wrapper_register(
+                               's3seek',
+                               'OC\Files\ObjectStore\S3SeekableReadStream'
+                       );
+                       self::$registered = true;
+               }
+       }
+
+       private $client;
+       private $bucket;
+       private $urn;
+
+       private $current;
+       private $offset = 0;
+
+       private function reconnect($range) {
+               if ($this->current != null) {
+                       fclose($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";
+                       }
+               }
+               $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) {
+                       return preg_match('#^content-range:#i', $v) === 1;
+               }))[0];
+
+               $content = trim(explode(':', $contentRange)[1]);
+               $range = trim(explode(' ', $content)[1]);
+               $begin = explode('-', $range)[0];
+               $this->offset = intval($begin);
+
+               return true;
+       }
+
+       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'];
+
+               return $this->reconnect('0-');
+       }
+
+       function stream_read($count) {
+               $ret = fread($this->current, $count);
+               $this->offset += strlen($ret);
+               return $ret;
+       }
+
+       function stream_seek($offset, $whence) {
+               switch ($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;
+       }
+
+       function stream_tell() {
+               return $this->offset;
+       }
+
+       function stream_stat() {
+               return fstat($this->current);
+       }
+
+       function stream_eof() {
+               return feof($this->current);
+       }
+
+       function stream_close() {
+               fclose($this->current);
+       }
+}