net/passt: Don't try to read the pidfile if passt got a signal

g_subprocess_get_if_exited returns false if passt was killed by a signal, so we fall through to trying to read the pidfile.

Update the error when passt exits to include the exit code.

Reviewed-by: Laurent Vivier <lvivier@redhat.com>
Signed-off-by: Peter Foley <pefoley@google.com>
Message-ID: <20260305-passt-v2-2-f0582198afc0@google.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>

net/passt.c

@@ -270,8 +270,17 @@ static int net_passt_start_daemon(NetPasstState *s, int sock, Error **errp)
         return -1;
     }
 
-    if (g_subprocess_get_if_exited(daemon) &&
+    if (g_subprocess_get_if_exited(daemon)) {
-        g_subprocess_get_exit_status(daemon)) {
+        gint status = g_subprocess_get_exit_status(daemon);
+        if (status) {
+            error_setg(errp, "Passt exited with code %d", status);
+            return -1;
+        }
+    }
+
+    if (g_subprocess_get_if_signaled(daemon)) {
+        error_setg(errp, "Passt killed with signal %d",
+                   g_subprocess_get_term_sig(daemon));
         return -1;
     }