installed plugin W3 Total Cache version 2.3.2

wp-content/plugins/w3-total-cache/lib/Azure/GuzzleHttp/Psr7/InflateStream.php

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+<?php
+namespace GuzzleHttp\Psr7;
+
+use Psr\Http\Message\StreamInterface;
+
+/**
+ * Uses PHP's zlib.inflate filter to inflate deflate or gzipped content.
+ *
+ * This stream decorator skips the first 10 bytes of the given stream to remove
+ * the gzip header, converts the provided stream to a PHP stream resource,
+ * then appends the zlib.inflate filter. The stream is then converted back
+ * to a Guzzle stream resource to be used as a Guzzle stream.
+ *
+ * @link http://tools.ietf.org/html/rfc1952
+ * @link http://php.net/manual/en/filters.compression.php
+ */
+class InflateStream implements StreamInterface
+{
+    use StreamDecoratorTrait;
+
+    public function __construct(StreamInterface $stream)
+    {
+        // read the first 10 bytes, ie. gzip header
+        $header = $stream->read(10);
+        $filenameHeaderLength = $this->getLengthOfPossibleFilenameHeader($stream, $header);
+        // Skip the header, that is 10 + length of filename + 1 (nil) bytes
+        $stream = new LimitStream($stream, -1, 10 + $filenameHeaderLength);
+        $resource = StreamWrapper::getResource($stream);
+        stream_filter_append($resource, 'zlib.inflate', STREAM_FILTER_READ);
+        $this->stream = new Stream($resource);
+    }
+
+    /**
+     * @param StreamInterface $stream
+     * @param $header
+     * @return int
+     */
+    private function getLengthOfPossibleFilenameHeader(StreamInterface $stream, $header)
+    {
+        $filename_header_length = 0;
+
+        if (substr(bin2hex($header), 6, 2) === '08') {
+            // we have a filename, read until nil
+            $filename_header_length = 1;
+            while ($stream->read(1) !== chr(0)) {
+                $filename_header_length++;
+            }
+        }
+
+        return $filename_header_length;
+    }
+}