Make final kill signal configurable

Usecase is to allow changing the final kill from SIGKILL to SIGQUIT which
should create a core dump useful for debugging why the service didn't stop
with the SIGTERM

src/core/dbus-kill.c

@@ -12,6 +12,7 @@ const sd_bus_vtable bus_kill_vtable[] = {
         SD_BUS_VTABLE_START(0),
         SD_BUS_PROPERTY("KillMode", "s", property_get_kill_mode, offsetof(KillContext, kill_mode), SD_BUS_VTABLE_PROPERTY_CONST),
         SD_BUS_PROPERTY("KillSignal", "i", bus_property_get_int, offsetof(KillContext, kill_signal), SD_BUS_VTABLE_PROPERTY_CONST),
+        SD_BUS_PROPERTY("FinalKillSignal", "i", bus_property_get_int, offsetof(KillContext, final_kill_signal), SD_BUS_VTABLE_PROPERTY_CONST),
         SD_BUS_PROPERTY("SendSIGKILL", "b", bus_property_get_bool, offsetof(KillContext, send_sigkill), SD_BUS_VTABLE_PROPERTY_CONST),
         SD_BUS_PROPERTY("SendSIGHUP", "b", bus_property_get_bool,  offsetof(KillContext, send_sighup), SD_BUS_VTABLE_PROPERTY_CONST),
         SD_BUS_VTABLE_END
@@ -19,6 +20,7 @@ const sd_bus_vtable bus_kill_vtable[] = {
 
 static BUS_DEFINE_SET_TRANSIENT_PARSE(kill_mode, KillMode, kill_mode_from_string);
 static BUS_DEFINE_SET_TRANSIENT_TO_STRING(kill_signal, "i", int32_t, int, "%" PRIi32, signal_to_string_with_check);
+static BUS_DEFINE_SET_TRANSIENT_TO_STRING(final_kill_signal, "i", int32_t, int, "%" PRIi32, signal_to_string_with_check);
 
 int bus_kill_context_set_transient_property(
                 Unit *u,
@@ -47,5 +49,8 @@ int bus_kill_context_set_transient_property(
         if (streq(name, "KillSignal"))
                 return bus_set_transient_kill_signal(u, name, &c->kill_signal, message, flags, error);
 
+        if (streq(name, "FinalKillSignal"))
+                return bus_set_transient_final_kill_signal(u, name, &c->final_kill_signal, message, flags, error);
+
         return 0;
 }

src/core/kill.c

@@ -9,6 +9,7 @@ void kill_context_init(KillContext *c) {
         assert(c);
 
         c->kill_signal = SIGTERM;
+        c->final_kill_signal = SIGKILL;
         c->send_sigkill = true;
         c->send_sighup = false;
 }
@@ -21,10 +22,12 @@ void kill_context_dump(KillContext *c, FILE *f, const char *prefix) {
         fprintf(f,
                 "%sKillMode: %s\n"
                 "%sKillSignal: SIG%s\n"
+                "%sFinalKillSignal: SIG%s\n"
                 "%sSendSIGKILL: %s\n"
                 "%sSendSIGHUP:  %s\n",
                 prefix, kill_mode_to_string(c->kill_mode),
                 prefix, signal_to_string(c->kill_signal),
+                prefix, signal_to_string(c->final_kill_signal),
                 prefix, yes_no(c->send_sigkill),
                 prefix, yes_no(c->send_sighup));
 }

src/core/kill.h

@@ -21,6 +21,7 @@ typedef enum KillMode {
 struct KillContext {
         KillMode kill_mode;
         int kill_signal;
+        int final_kill_signal;
         bool send_sigkill;
         bool send_sighup;
 };

src/core/load-fragment-gperf.gperf.m4

@@ -151,7 +151,8 @@ m4_define(`KILL_CONTEXT_CONFIG_ITEMS',
 `$1.SendSIGKILL,                 config_parse_bool,                  0,                             offsetof($1, kill_context.send_sigkill)
 $1.SendSIGHUP,                   config_parse_bool,                  0,                             offsetof($1, kill_context.send_sighup)
 $1.KillMode,                     config_parse_kill_mode,             0,                             offsetof($1, kill_context.kill_mode)
-$1.KillSignal,                   config_parse_signal,                0,                             offsetof($1, kill_context.kill_signal)'
+$1.KillSignal,                   config_parse_signal,                0,                             offsetof($1, kill_context.kill_signal)
+$1.FinalKillSignal,              config_parse_signal,                0,                             offsetof($1, kill_context.final_kill_signal)'
 )m4_dnl
 m4_define(`CGROUP_CONTEXT_CONFIG_ITEMS',
 `$1.Slice,                       config_parse_unit_slice,            0,                             0

src/core/load-fragment.h

@@ -39,6 +39,7 @@ CONFIG_PARSER_PROTOTYPE(config_parse_exec_cpu_affinity);
 CONFIG_PARSER_PROTOTYPE(config_parse_exec_secure_bits);
 CONFIG_PARSER_PROTOTYPE(config_parse_capability_set);
 CONFIG_PARSER_PROTOTYPE(config_parse_kill_signal);
+CONFIG_PARSER_PROTOTYPE(config_parse_final_kill_signal);
 CONFIG_PARSER_PROTOTYPE(config_parse_exec_mount_flags);
 CONFIG_PARSER_PROTOTYPE(config_parse_timer);
 CONFIG_PARSER_PROTOTYPE(config_parse_trigger_unit);

src/core/unit.c

@@ -4479,7 +4479,7 @@ static int operation_to_signal(KillContext *c, KillOperation k) {
                 return c->kill_signal;
 
         case KILL_KILL:
-                return SIGKILL;
+                return c->final_kill_signal;
 
         case KILL_ABORT:
                 return SIGABRT;

src/shared/bus-unit-util.c

@@ -1189,7 +1189,7 @@ static int bus_append_kill_property(sd_bus_message *m, const char *field, const
 
                 return bus_append_parse_boolean(m, field, eq);
 
-        if (streq(field, "KillSignal"))
+        if (STR_IN_SET(field, "KillSignal", "FinalKillSignal"))
 
                 return bus_append_signal_from_string(m, field, eq);