Commands on the head of the queue can be canceled if none of its bytes
have actually been written to the modem. This is tracked by
cmd_bytes_written variable.
This patch adds debugging support to GAtChat (specifically of what's going
across the serial line). Callbacks can be set via g_at_chat_set_debugging,
and that callback is called after any channel reads or writes.
When a line comes in from the modem, we check against prefixes
in outstanding commands and unsolicited notifications. If the
outstanding command has not yet been sent (cmd_bytes_written == 0),
we still check it resulting in access violation.
The previous fix did not take into account the logic in have_line
function, which takes care of certain modems that do not prefix
their responses by <cr><lf> at all. This fix should take both
into consideration
The standard is a bit fuzzy on how multiline responses are returned
GAtChat assumed that they will always start with <cr><lf>, however
this doesn't seem to be correct. Add a new state which is entered
when a response is obtained. If <cr> is encountered, then it
is processed regularly, otherwise the parser assumes that the
next line is part of the multiline response