Possible bug in the implementation of php://input streams?

We've noticed something odd about the "php://input" stream. This type of stream resource reports itself as seekable: assert(stream_get_meta_data(fopen("php://input", "r"))["seekable"] === true); https://3v4l.org/EFLiO If you attempt to rewind() it after reading the stream, rewind() returns true, and ftell() subequently returns 0. However, attempting to read the stream again after that returns nothing. On the other hand, if you fopen() a new resource, it is readable again after all. So it seems, either the "php://input" stream implementation is somehow broken - or it's incorrectly reporting as seekable? Any idea?