1 files changed, 84 insertions, 0 deletions
diff --git a/lib/private/Files/Stream/Quota.php b/lib/private/Files/Stream/Quota.php
new file mode 100644
index 00000000000..cc737910fd8
--- /dev/null
+++ b/lib/private/Files/Stream/Quota.php
@@ -0,0 +1,84 @@
+<?php
+
+/**
+ * SPDX-FileCopyrightText: 2016-2024 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-FileCopyrightText: 2016 ownCloud, Inc.
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+namespace OC\Files\Stream;
+
+use Icewind\Streams\Wrapper;
+
+/**
+ * stream wrapper limits the amount of data that can be written to a stream
+ *
+ * usage: resource \OC\Files\Stream\Quota::wrap($stream, $limit)
+ */
+class Quota extends Wrapper {
+	/**
+	 * @var int $limit
+	 */
+	private $limit;
+
+	/**
+	 * @param resource $stream
+	 * @param int $limit
+	 * @return resource|false
+	 */
+	public static function wrap($stream, $limit) {
+		$context = stream_context_create([
+			'quota' => [
+				'source' => $stream,
+				'limit' => $limit
+			]
+		]);
+		return Wrapper::wrapSource($stream, $context, 'quota', self::class);
+	}
+
+	public function stream_open($path, $mode, $options, &$opened_path) {
+		$context = $this->loadContext('quota');
+		$this->source = $context['source'];
+		$this->limit = $context['limit'];
+
+		return true;
+	}
+
+	public function dir_opendir($path, $options) {
+		return false;
+	}
+
+	public function stream_seek($offset, $whence = SEEK_SET) {
+		if ($whence === SEEK_END) {
+			// go to the end to find out last position's offset
+			$oldOffset = $this->stream_tell();
+			if (fseek($this->source, 0, $whence) !== 0) {
+				return false;
+			}
+			$whence = SEEK_SET;
+			$offset = $this->stream_tell() + $offset;
+			$this->limit += $oldOffset - $offset;
+		} elseif ($whence === SEEK_SET) {
+			$this->limit += $this->stream_tell() - $offset;
+		} else {
+			$this->limit -= $offset;
+		}
+		// this wrapper needs to return "true" for success.
+		// the fseek call itself returns 0 on succeess
+		return fseek($this->source, $offset, $whence) === 0;
+	}
+
+	public function stream_read($count) {
+		$this->limit -= $count;
+		return fread($this->source, $count);
+	}
+
+	public function stream_write($data) {
+		$size = strlen($data);
+		if ($size > $this->limit) {
+			$data = substr($data, 0, $this->limit);
+			$size = $this->limit;
+		}
+		$this->limit -= $size;
+		return fwrite($this->source, $data);
+	}
+}