On Di, 03.03.20 10:26, Łukasz Niemier (luk...@niemier.pl) wrote:
> Is there documentation for sd_notify protocol? I am working on
> pure-Erlang implementation of sd_notify (and few other systemd
> facilities) and I am looking for better description than reading C
> code which can be a little confusing without deeper knowledge of
> systemd helper functions around iocvec. Especially ucred and fds
> parts, as rest I have mostly implemented.
The sd_notify() man page says everything there is to say really under
NOTES:
"These functions send a single datagram with the state string as
payload to the AF_UNIX socket referenced in the $NOTIFY_SOCKET
environment variable. If the first character of $NOTIFY_SOCKET is
"@", the string is understood as Linux abstract namespace
socket. The datagram is accompanied by the process credentials of
the sending service, using SCM_CREDENTIALS."
There isn't much more to know.
How to use sendmsg() and iovecs you find described in the respective
man page, but that's a Linux/libc/UNIX API, not a systemd one...
The nice thing about NOTIFY_SOCKET is really that its so simple it
barely even is a protocol...
Lennart
--
Lennart Poettering, Berlin
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