io.ReadFull cannot be used on a serial port, and it was.
On Windows a serial read that times out returns (0, nil) — on this transport a
timeout is not an error. io.ReadFull loops while err == nil, so a controller
that goes quiet for one poll, or answers with a truncated frame, spins it
forever. It holds ioMu throughout, and that is the whole failure the operator
sees:
- the poll goroutine never returns, so nothing is ever logged about a fault
and the cached status keeps the antenna looking connected;
- every command blocks on the same mutex, and the trace line sat AFTER the
lock, so even the attempt left no trace.
One dropped reply on a 4800-baud link therefore stopped the antenna responding
until OpsLog was restarted, with a log that showed the antenna starting, a few
status frames, and then nothing — which is exactly how it was reported.
Reads are now bounded: three seconds for an 11-byte frame that takes 23 ms on
the wire. Giving up returns an error, and the poll loop already knows what to do
with one — say so and reconnect. The command trace moved ahead of the lock, so
what the operator asked for is in the log even when the answer is not.
The SPE driver reads through a bufio.Reader, whose ErrNoProgress guard already
covers this; the ADIF parser reads a file. This was the only exposed one.
rouggy
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