[Libguestfs] [libnbd PATCH v5 4/4] socket activation: set LISTEN_FDNAMES

Add LISTEN_FDNAMES to the child process's environment unconditionally. - If the user calls nbd_set_socket_activation_name() with a non-empty string before calling nbd_connect_systemd_socket_activation(), pass the name down to the server through LISTEN_FDNAMES. This is a feature addition. - If the user doesn't call nbd_set_socket_activation_name(), or calls it with the empty string, add "LISTEN_FDNAMES=unknown" to the environment, overwriting any potentially inherited LISTEN_FDNAMES variable. This is a bugfix: otherwise we could leak a confusing LISTEN_FDNAMES to the child process, in case the libnbd client app were itself socket-activated. Given "LISTEN_FDS=1", the setting "LISTEN_FDNAMES=unknown" has the same effect on the child as removing LISTEN_FDNAMES from the environment: <https://www.freedesktop.org/software/systemd/man/sd_listen_fds.html>;. Signed-off-by: Laszlo Ersek <lersek(a)redhat.com&gt; --- Notes: v5: - push LISTEN_FDNAMES unconditionally, with value "unknown" if the socket activation name is not set by the libnbd client application -- rewrite patch and commit message [Eric, Laszlo] - drop Rich's R-b due to the above changes v4: - pick up Rich's R-b - resolve rebase conflict near the prepare_socket_activation_environment() call site, due to keeping set_error() internal to that callee, in patch "socket activation: clean up responsibilities of prep.sock.act.env.()" generator/states-connect-socket-activation.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) diff --git a/generator/states-connect-socket-activation.c b/generator/states-connect-socket-activation.c index 10ccc3119299..b57d5d0075b0 100644 --- a/generator/states-connect-socket-activation.c +++ b/generator/states-connect-socket-activation.c @@ -185,7 +185,7 @@ CONNECT_SA.START: struct sockaddr_un addr; struct execvpe execvpe_ctx; size_t num_vars; - struct sact_var sact_var[2]; + struct sact_var sact_var[3]; size_t pid_ofs; string_vector env; pid_t pid; @@ -245,6 +245,16 @@ CONNECT_SA.START: "LISTEN_PID=", "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx", &pid_ofs); SACT_VAR_PUSH (sact_var, &num_vars, "LISTEN_FDS=", "1", NULL); + /* Push LISTEN_FDNAMES unconditionally. This ensures we overwrite any + * inherited LISTEN_FDNAMES. If "h->sact_name" is NULL, then push + * "LISTEN_FDNAMES=unknown"; it will have the same effect on the child process + * as unsetting LISTEN_FDNAMES would (with LISTEN_FDS being set to 1): + * <https://www.freedesktop.org/software/systemd/man/sd_listen_fds.html>;. + */ + SACT_VAR_PUSH (sact_var, &num_vars, + "LISTEN_FDNAMES=", + h->sact_name == NULL ? "unknown" : h->sact_name, + NULL); if (prepare_socket_activation_environment (&env, sact_var, num_vars) == -1) /* prepare_socket_activation_environment() calls set_error() internally */ goto uninit_execvpe;