Attempts to read up to size 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.
Virtual: read_nonblocking
Attempts to read up to size 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. Virtual: read_nonblocking