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.
%TRUE if @stream is readable, %FALSE if not. If an error
has occurred on @stream, this will result in
g_pollable_input_stream_is_readable() returning %TRUE, and the
next attempt to read will return the error.
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.