OpenStack SWIFT: fseek(): stream does not support seeking

[solracsf]

Duplicate of #8275 or #14617 but for OpenStack SWIFT, as #20033 does NOT fix it (it is intended for S3 only).

[PHP] Error: Error: fseek(): stream does not support seeking at /public/3rdparty/icewind/streams/src/Wrapper.php#82 at <<closure>>

 0. <<closure>>
    OC\Log\ErrorHandler::onError(2, "fseek(): stream ... g", "/srv/users/ ... p", 82, {offset: 32768,whence: 0})
 1. /public/3rdparty/icewind/streams/src/Wrapper.php line 82
    fseek(null, 32768, 0)
 2. <<closure>>
    Icewind\Streams\Wrapper->stream_seek(32768, 0)
 3. /public/3rdparty/icewind/streams/src/Wrapper.php line 82
    fseek(null, 32768, 0)
 4. <<closure>>
    Icewind\Streams\Wrapper->stream_seek(32768, 0)
 5. /public/3rdparty/sabre/dav/lib/DAV/CorePlugin.php line 184
    fseek(null, 32768, 0)
 6. /public/3rdparty/sabre/event/lib/WildcardEmitterTrait.php line 89
    Sabre\DAV\CorePlugin->httpGet(Sabre\HTTP\Request {}, Sabre\HTTP\Response {})
 7. /public/3rdparty/sabre/dav/lib/DAV/Server.php line 474
    Sabre\DAV\Server->emit("method:GET", [Sabre\HTTP\Requ ... }])
 8. /public/3rdparty/sabre/dav/lib/DAV/Server.php line 251
    Sabre\DAV\Server->invokeMethod(Sabre\HTTP\Request {}, Sabre\HTTP\Response {})
 9. /public/3rdparty/sabre/dav/lib/DAV/Server.php line 319
    Sabre\DAV\Server->start()
10. /public/apps/dav/lib/Server.php line 332
    Sabre\DAV\Server->exec()
11. /public/apps/dav/appinfo/v2/remote.php line 35
    OCA\DAV\Server->exec()
12. /public/remote.php line 167
    require_once("/srv/users/ ... p")

GET /remote.php/dav/files/user/Videos/40590592_2138161566405349_5883589116544679936_n.mp4

[vpecinka]

My traceback says also a problem arised in nextcloud/3rdparty/sabre/dav/lib/DAV/CorePlugin.php:184

The code says

            // Streams may advertise themselves as seekable, but still not
            // actually allow fseek.  We'll manually go forward in the stream
            // if fseek failed.
            if (!stream_get_meta_data($body)['seekable'] || -1 === fseek($body, $start, SEEK_SET)) {
                $consumeBlock = 8192;
                for ($consumed = 0; $start - $consumed > 0;) {
                    if (feof($body)) {
                        throw new Exception\RequestedRangeNotSatisfiable('The start offset ('.$start.') exceeded the size of the entity ('.$consumed.')');
                    }
                    $consumed += strlen(fread($body, min($start - $consumed, $consumeBlock)));
                }
            }

however as seen the stream_seek() is called via wrapper nextcloud/3rdparty/icewind/streams/src/Wrapper.php:82

        public function stream_seek($offset, $whence = SEEK_SET) {
                $result = fseek($this->source, $offset, $whence);
                return $result == 0 ? true : false;
        }

that returns false or true (not -1)

[vpecinka]

Ok, i discovered there is Icewind\Streams\SeekableWrapper , replacing it in the Swift.php seems working

--- lib/private/Files/ObjectStore/Swift.php.orig	2021-02-24 20:07:09.000000000 +0100
+++ lib/private/Files/ObjectStore/Swift.php	2021-03-17 17:27:04.987925583 +0100
@@ -29,12 +29,13 @@
 use GuzzleHttp\Client;
 use GuzzleHttp\Exception\BadResponseException;
 use function GuzzleHttp\Psr7\stream_for;
-use Icewind\Streams\RetryWrapper;
+use Icewind\Streams\SeekableWrapper;
 use OCP\Files\NotFoundException;
 use OCP\Files\ObjectStore\IObjectStore;
 use OCP\Files\StorageAuthException;
 
-const SWIFT_SEGMENT_SIZE = 1073741824; // 1GB
+
+const SWIFT_SEGMENT_SIZE = 209715200;
 
 class Swift implements IObjectStore {
 	/**
@@ -126,7 +127,7 @@
 			}
 		}
 
-		return RetryWrapper::wrap($response->getBody()->detach());
+		return SeekableWrapper::wrap($response->getBody()->detach());
 	}
 
 	/**

Can anybody confirm?

[solracsf]

I can try it next week.
cc @icewind1991 if you can give us your opinion before submit any PR.

[vpecinka]

Still, I think the approach as in #20033 is better, as Swift supports Range: bytes=.... The SeekableWrapper seems always reading only forwards, not backwards.

[q-wertz]

Still valid on NC 23.0.4