src/Stream.php
public function isReadable()
    {
        if (is_resource($this->fp) && !is_null($mode = $this->getMetadata('mode'))) {
            foreach (['r', 'r+', 'w+', 'a+', 'x+', 'c+'] as $rMode) {
                if (stripos($mode, $rMode) === 0) {
                    return true;
                }
            }

            return false;
        } else {
            return false;
        }
    }
public function isReadable()
    {
        if (is_resource($this->fp) && !is_null($mode = $this->getMetadata('mode'))) {
            foreach (['r', 'r+', 'w+', 'a+', 'x+', 'c+'] as $rMode) {
                if (stripos($mode, $rMode) === 0) {
                    return true;
                }
            }

            return false;
        } else {
            return false;
        }
    }
Returns whether or not the stream is readable.

@return bool