If blocking is false, then stream must be a
#GPollableInputStream for which gio.pollable_input_stream.PollableInputStream.canPoll
returns true, or else the behavior is undefined. If blocking is
true, then stream does not need to be a #GPollableInputStream.
Tries to read from stream, as with gio.input_stream.InputStream.read (if blocking is true) or gio.pollable_input_stream.PollableInputStream.readNonblocking (if blocking is false). This can be used to more easily share code between blocking and non-blocking implementations of a method.
If blocking is false, then stream must be a #GPollableInputStream for which gio.pollable_input_stream.PollableInputStream.canPoll returns true, or else the behavior is undefined. If blocking is true, then stream does not need to be a #GPollableInputStream.