Attempts to read up to @count bytes from @stream into @buffer, as
with g_input_stream_read(). If @stream is not currently readable,
this will immediately return %G_IO_ERROR_WOULD_BLOCK, and you can
use g_pollable_input_stream_create_source() to create a #GSource
that will be triggered when @stream is readable.
Note that since this method never blocks, you cannot actually
use @cancellable to cancel it. However, it will return an error
if @cancellable has already been cancelled when you call, which
may happen if you call this method after a source triggers due
to having been cancelled.
Attempts to read up to @count bytes from @stream into @buffer, as with g_input_stream_read(). If @stream is not currently readable, this will immediately return %G_IO_ERROR_WOULD_BLOCK, and you can use g_pollable_input_stream_create_source() to create a #GSource that will be triggered when @stream is readable.
Note that since this method never blocks, you cannot actually use @cancellable to cancel it. However, it will return an error if @cancellable has already been cancelled when you call, which may happen if you call this method after a source triggers due to having been cancelled.