[stable30] improve handling of large single-part s3 uploads

apps/dav/lib/Upload/AssemblyStream.php

@@ -75,6 +75,10 @@ public function stream_seek($offset, $whence = SEEK_SET) {
 			$offset = $this->size + $offset;
 		}
 
+		if ($offset === $this->pos) {
+			return true;
+		}
+
 		if ($offset > $this->size) {
 			return false;
 		}
@@ -95,7 +99,7 @@ public function stream_seek($offset, $whence = SEEK_SET) {
 
 		$stream = $this->getStream($this->nodes[$nodeIndex]);
 		$nodeOffset = $offset - $nodeStart;
-		if (fseek($stream, $nodeOffset) === -1) {
+		if ($nodeOffset > 0 && fseek($stream, $nodeOffset) === -1) {
 			return false;
 		}
 		$this->currentNode = $nodeIndex;
@@ -126,9 +130,14 @@ public function stream_read($count) {
 			}
 		}
 
-		do {
+		$collectedData = '';
+		// read data until we either got all the data requested or there is no more stream left
+		while ($count > 0 && !is_null($this->currentStream)) {
 			$data = fread($this->currentStream, $count);
 			$read = strlen($data);
+
+			$count -= $read;
+			$collectedData .= $data;
 			$this->currentNodeRead += $read;
 
 			if (feof($this->currentStream)) {
@@ -145,14 +154,11 @@ public function stream_read($count) {
 					$this->currentStream = null;
 				}
 			}
-			// if no data read, try again with the next node because
-			// returning empty data can make the caller think there is no more
-			// data left to read
-		} while ($read === 0 && !is_null($this->currentStream));
+		}
 
 		// update position
-		$this->pos += $read;
-		return $data;
+		$this->pos += strlen($collectedData);
+		return $collectedData;
 	}
 
 	/**

apps/dav/tests/unit/Upload/AssemblyStreamTest.php

@@ -24,12 +24,16 @@ public function testGetContents($expected, $nodes): void {
 	/**
 	 * @dataProvider providesNodes()
 	 */
-	public function testGetContentsFread($expected, $nodes): void {
+	public function testGetContentsFread($expected, $nodes, $chunkLength = 3): void {
 		$stream = \OCA\DAV\Upload\AssemblyStream::wrap($nodes);
 
 		$content = '';
 		while (!feof($stream)) {
-			$content .= fread($stream, 3);
+			$chunk = fread($stream, $chunkLength);
+			$content .= $chunk;
+			if ($chunkLength !== 3) {
+				$this->assertEquals($chunkLength, strlen($chunk));
+			}
 		}
 
 		$this->assertEquals($expected, $content);
@@ -102,7 +106,19 @@ public function providesNodes() {
 				]],
 			'a ton of nodes' => [
 				$tonofdata, $tonofnodes
-			]
+			],
+			'one read over multiple nodes' => [
+				'1234567890', [
+					$this->buildNode('0', '1234'),
+					$this->buildNode('1', '5678'),
+					$this->buildNode('2', '90'),
+				], 10],
+			'two reads over multiple nodes' => [
+				'1234567890', [
+					$this->buildNode('0', '1234'),
+					$this->buildNode('1', '5678'),
+					$this->buildNode('2', '90'),
+				], 5],
 		];
 	}
 

lib/private/Files/ObjectStore/ObjectStoreStorage.php

@@ -474,6 +474,13 @@ public function file_put_contents($path, $data) {
 	}
 
 	public function writeStream(string $path, $stream, ?int $size = null): int {
+		if ($size === null) {
+			$stats = fstat($stream);
+			if (is_array($stats) && isset($stats['size'])) {
+				$size = $stats['size'];
+			}
+		}
+
 		$stat = $this->stat($path);
 		if (empty($stat)) {
 			// create new file

lib/private/Files/ObjectStore/S3ObjectTrait.php

@@ -140,20 +140,33 @@ protected function writeMultiPart(string $urn, StreamInterface $stream, ?string
 	 * @since 7.0.0
 	 */
 	public function writeObject($urn, $stream, ?string $mimetype = null) {
+		$canSeek = fseek($stream, 0, SEEK_CUR) === 0;
 		$psrStream = Utils::streamFor($stream);
 
-		// ($psrStream->isSeekable() && $psrStream->getSize() !== null) evaluates to true for a On-Seekable stream
-		// so the optimisation does not apply
-		$buffer = new Psr7\Stream(fopen('php://memory', 'rwb+'));
-		Utils::copyToStream($psrStream, $buffer, $this->putSizeLimit);
-		$buffer->seek(0);
-		if ($buffer->getSize() < $this->putSizeLimit) {
-			// buffer is fully seekable, so use it directly for the small upload
-			$this->writeSingle($urn, $buffer, $mimetype);
+
+		$size = $psrStream->getSize();
+		if ($size === null || !$canSeek) {
+			// The s3 single-part upload requires the size to be known for the stream.
+			// So for input streams that don't have a known size, we need to copy (part of)
+			// the input into a temporary stream so the size can be determined
+			$buffer = new Psr7\Stream(fopen('php://temp', 'rw+'));
+			Utils::copyToStream($psrStream, $buffer, $this->putSizeLimit);
+			$buffer->seek(0);
+			if ($buffer->getSize() < $this->putSizeLimit) {
+				// buffer is fully seekable, so use it directly for the small upload
+				$this->writeSingle($urn, $buffer, $mimetype);
+			} else {
+				$loadStream = new Psr7\AppendStream([$buffer, $psrStream]);
+				$this->writeMultiPart($urn, $loadStream, $mimetype);
+			}
 		} else {
-			$loadStream = new Psr7\AppendStream([$buffer, $psrStream]);
-			$this->writeMultiPart($urn, $loadStream, $mimetype);
+			if ($size < $this->putSizeLimit) {
+				$this->writeSingle($urn, $psrStream, $mimetype);
+			} else {
+				$this->writeMultiPart($urn, $psrStream, $mimetype);
+			}
 		}
+		$psrStream->close();
 	}
 
 	/**