sd-daemon: introduce sd_watchdog_enabled() for parsing $WATCHDOG_USEC

Also, introduce a new environment variable named $WATCHDOG_PID which
cotnains the PID of the process that is supposed to send the keep-alive
events. This is similar how $LISTEN_FDS and $LISTEN_PID work together,
and protects against confusing processes further down the process tree
due to inherited environment.

1 files changed, 2 insertions, 9 deletions

diff --git a/src/libsystemd-bus/sd-event.c b/src/libsystemd-bus/sd-event.c
index a1baac52aa..bfc798ca6e 100644
--- a/src/libsystemd-bus/sd-event.c
+++ b/src/libsystemd-bus/sd-event.c
@@ -2164,17 +2164,10 @@ _public_ int sd_event_set_watchdog(sd_event *e, int b) {
 
         if (b) {
                 struct epoll_event ev = {};
-                const char *env;
 
-                env = getenv("WATCHDOG_USEC");
-                if (!env)
-                        return false;
-
-                r = safe_atou64(env, &e->watchdog_period);
-                if (r < 0)
+                r = sd_watchdog_enabled(false, &e->watchdog_period);
+                if (r <= 0)
                         return r;
-                if (e->watchdog_period <= 0)
-                        return -EIO;
 
                 /* Issue first ping immediately */
                 sd_notify(false, "WATCHDOG=1");