This function is equivalent to calling php_stream_cast() with ret set to NULL and flags set to 0. It returns SUCCESS if the stream can be converted into the form requested, or FAILURE if the conversion cannot be performed.
Note: Although this function will not perform the conversion, some internal stream state *might* be changed by this call.
Note: You must explicitly compare the return value of this function with one of the constants, as described in php_stream_cast().
See also php_stream_cast() and php_stream_is().