Reject write-only streams

Author: clue

README.md

@@ -714,7 +714,8 @@ $stream->on('end', function () {
 
 See also [`ReadableStreamInterface`](#readablestreaminterface) for more details.
 
-The first parameter given to the constructor MUST be a valid stream resource.
+The first parameter given to the constructor MUST be a valid stream resource
+that is opened in reading mode (e.g. `fopen()` mode `r`).
 Otherwise, it will throw an `InvalidArgumentException`:
 
 ```php

src/ReadableResourceStream.php

@@ -42,6 +42,12 @@ public function __construct($stream, LoopInterface $loop)
              throw new InvalidArgumentException('First parameter must be a valid stream resource');
         }
 
+        // ensure resource is opened for reading (fopen mode must contain "r" or "+")
+        $meta = stream_get_meta_data($stream);
+        if (isset($meta['mode']) && strpos($meta['mode'], 'r') === strpos($meta['mode'], '+')) {
+            throw new InvalidArgumentException('Given stream resource is not opened in read mode');
+        }
+
         // this class relies on non-blocking I/O in order to not interrupt the event loop
         // e.g. pipes on Windows do not support this: https://bugs.php.net/bug.php?id=47918
         if (stream_set_blocking($stream, 0) !== true) {

tests/EnforceBlockingWrapper.php

@@ -19,6 +19,11 @@ public function stream_cast($cast_as)
         return false;
     }
 
+    public function stream_eof()
+    {
+        return false;
+    }
+
     public function stream_set_option($option, $arg1, $arg2)
     {
         if ($option === STREAM_OPTION_BLOCKING) {

tests/ReadableResourceStreamTest.php

@@ -15,7 +15,7 @@ public function testConstructor()
         $stream = fopen('php://temp', 'r+');
         $loop = $this->createLoopMock();
 
-        $conn = new ReadableResourceStream($stream, $loop);
+        new ReadableResourceStream($stream, $loop);
     }
 
     /**
@@ -26,7 +26,18 @@ public function testConstructorThrowsExceptionOnInvalidStream()
         $loop = $this->createLoopMock();
 
         $this->setExpectedException('InvalidArgumentException');
-        new ReadableResourceStream('breakme', $loop);
+        new ReadableResourceStream(false, $loop);
+    }
+
+    /**
+     * @covers React\Stream\ReadableResourceStream::__construct
+     */
+    public function testConstructorThrowsExceptionOnWriteOnlyStream()
+    {
+        $loop = $this->createLoopMock();
+
+        $this->setExpectedException('InvalidArgumentException');
+        new ReadableResourceStream(STDOUT, $loop);
     }
 
     /**