Checks if @stream can be read.

Note that some stream types may not be able to implement this 100% reliably, and it is possible that a call to g_input_stream_read() after this returns %TRUE would still block. To guarantee non-blocking behavior, you should always use g_pollable_input_stream_read_nonblocking(), which will return a %G_IO_ERROR_WOULD_BLOCK error rather than blocking.

The behaviour of this method is undefined if g_pollable_input_stream_can_poll() returns %FALSE for @stream.

Checks if @stream is actually pollable. Some classes may implement #GPollableInputStream but have only certain instances of that class be pollable. If this method returns %FALSE, then the behavior of other #GPollableInputStream methods is undefined.

For any given stream, the value returned by this method is constant; a stream cannot switch from pollable to non-pollable or vice versa.