Hello Mantas.
You was right, the logic of my code kept itself away from accepting a connection, when working with the control socket passed by the systemd.
I hardcoded accept() function and this worked out - a command was read.
Thanks for your attention!
чт, 27 июн. 2019 г. в 13:44, Mantas Mikulėnas <grawity@xxxxxxxxx>:
On Thu, Jun 27, 2019 at 1:29 PM Donat Zenichev <donat.zenichev@xxxxxxxxx> wrote:Hi systemd community.
Recently I've come accross one interesting problem with API of systemd.
The problem is that, I'm not able to read commands comming to the AF_UNIX socket, that was created by systemd and passed to my program using sd_listen_fds(0) function.
What actually program requires, is AF_UNIX (AF_LOCAL) socket of type SOCK_STREAM.
In case if I create this socket manually, using socket(AF_LOCAL, SOCK_STREAM, 0) function, it works out as expected.
But, when I create a socket using systemd socket unit, reading fails with "-1" return value.
What I actually do, is that I check if there are some sockets created for me using sd_listen_fds(0), and in case it returns 1 (so 1 socket created),
program goes further and sets a file descriptor value to fd = SD_LISTEN_FDS_START + 0;
Since the SD_LISTEN_FDS_START is pre-defined to value '3', my file descriptor will always be '3'.
But when it comes to reading, with read() function, it fails with the errno EINVAL - Invalid argument.
It's not a matter of a other parameters than a file descriptor, since with manual creation of socket it works out as I said.
An initializing of the socket descriptor, when creating it by systemd passes as normal, so program starts.
But any further command received on fd fails with '-1' return value.As this is a stream socket, by default the program will receive the *listener* socket. Systemd will start your service as soon as someone connects, but your program still needs to accept() each connection first.--Mantas Mikulėnas
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BR, Donat Zenichev
BR, Donat Zenichev
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