Update to drupal 8.0.0-rc1. For more information, see https://www.drupal.org/node/2582663

vendor/guzzlehttp/psr7/src/CachingStream.php

@@ -0,0 +1,136 @@
+<?php
+namespace GuzzleHttp\Psr7;
+
+use Psr\Http\Message\StreamInterface;
+
+/**
+ * Stream decorator that can cache previously read bytes from a sequentially
+ * read stream.
+ */
+class CachingStream implements StreamInterface
+{
+    use StreamDecoratorTrait;
+
+    /** @var StreamInterface Stream being wrapped */
+    private $remoteStream;
+
+    /** @var int Number of bytes to skip reading due to a write on the buffer */
+    private $skipReadBytes = 0;
+
+    /**
+     * We will treat the buffer object as the body of the stream
+     *
+     * @param StreamInterface $stream Stream to cache
+     * @param StreamInterface $target Optionally specify where data is cached
+     */
+    public function __construct(
+        StreamInterface $stream,
+        StreamInterface $target = null
+    ) {
+        $this->remoteStream = $stream;
+        $this->stream = $target ?: new Stream(fopen('php://temp', 'r+'));
+    }
+
+    public function getSize()
+    {
+        return max($this->stream->getSize(), $this->remoteStream->getSize());
+    }
+
+    public function rewind()
+    {
+        $this->seek(0);
+    }
+
+    public function seek($offset, $whence = SEEK_SET)
+    {
+        if ($whence == SEEK_SET) {
+            $byte = $offset;
+        } elseif ($whence == SEEK_CUR) {
+            $byte = $offset + $this->tell();
+        } elseif ($whence == SEEK_END) {
+            $size = $this->remoteStream->getSize();
+            if ($size === null) {
+                $size = $this->cacheEntireStream();
+            }
+            // Because 0 is the first byte, we seek to size - 1.
+            $byte = $size - 1 - $offset;
+        } else {
+            throw new \InvalidArgumentException('Invalid whence');
+        }
+
+        $diff = $byte - $this->stream->getSize();
+
+        if ($diff > 0) {
+            // If the seek byte is greater the number of read bytes, then read
+            // the difference of bytes to cache the bytes and inherently seek.
+            $this->read($diff);
+        } else {
+            // We can just do a normal seek since we've already seen this byte.
+            $this->stream->seek($byte);
+        }
+    }
+
+    public function read($length)
+    {
+        // Perform a regular read on any previously read data from the buffer
+        $data = $this->stream->read($length);
+        $remaining = $length - strlen($data);
+
+        // More data was requested so read from the remote stream
+        if ($remaining) {
+            // If data was written to the buffer in a position that would have
+            // been filled from the remote stream, then we must skip bytes on
+            // the remote stream to emulate overwriting bytes from that
+            // position. This mimics the behavior of other PHP stream wrappers.
+            $remoteData = $this->remoteStream->read(
+                $remaining + $this->skipReadBytes
+            );
+
+            if ($this->skipReadBytes) {
+                $len = strlen($remoteData);
+                $remoteData = substr($remoteData, $this->skipReadBytes);
+                $this->skipReadBytes = max(0, $this->skipReadBytes - $len);
+            }
+
+            $data .= $remoteData;
+            $this->stream->write($remoteData);
+        }
+
+        return $data;
+    }
+
+    public function write($string)
+    {
+        // When appending to the end of the currently read stream, you'll want
+        // to skip bytes from being read from the remote stream to emulate
+        // other stream wrappers. Basically replacing bytes of data of a fixed
+        // length.
+        $overflow = (strlen($string) + $this->tell()) - $this->remoteStream->tell();
+        if ($overflow > 0) {
+            $this->skipReadBytes += $overflow;
+        }
+
+        return $this->stream->write($string);
+    }
+
+    public function eof()
+    {
+        return $this->stream->eof() && $this->remoteStream->eof();
+    }
+
+    /**
+     * Close both the remote stream and buffer stream
+     */
+    public function close()
+    {
+        $this->remoteStream->close() && $this->stream->close();
+    }
+
+    private function cacheEntireStream()
+    {
+        $target = new FnStream(['write' => 'strlen']);
+        copy_to_stream($this, $target);
+
+        return $this->tell();
+    }
+}