This uses a single fd for both status and control.
To make this work, we enforce the convention that replies are the same
as requests + 100, and that their name ends in "_REPLY".
This also means that various daemons can simply exit when done; there's
no race between reading request and closing status fds.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Or for blackbox tests --gdb1=<subdaemon> / --gdb2=<subdaemon>.
This makes the subdaemon wait as soon as it's execed, so we can attach
the debugger.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
It's a bit messy, since some status messages are accompanied by an FD:
in this case, the handler returns STATUS_NEED_FD and we read that then
re-call the handler.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>