systemd,systemctl: export condition status and show failing condition

$ systemctl --user status hoohoo
hoohoo.service
   Loaded: loaded (/home/zbyszek/.config/systemd/user/hoohoo.service; static)
   Active: inactive (dead)
           start condition failed at Tue 2013-06-25 18:08:42 EDT; 1s ago
           ConditionPathExists=/tmp/hoo was not met

Full information is exported over D-Bus:
  [(condition, trigger, negate, param, state),...]
where state is one of "failed" (<0), "untested" (0), "OK" (>0).
I've decided to use 0 for "untested", because it might be useful to
differentiate different types of failure later on, without breaking
compatibility.

systemctl shows the failing condition, if there was a non-trigger
failing condition, or says "none of the trigger conditions were met",
because there're often many trigger conditions, and they must all
fail for the condition to fail, so printing them all would consume
a lot of space, and bring unnecessary attention to something that is
quite low-level.

1 files changed, 53 insertions, 9 deletions

diff --git a/src/systemctl/systemctl.c b/src/systemctl/systemctl.c
index 6fdbc417b6..b3b679e0af 100644
--- a/src/systemctl/systemctl.c
+++ b/src/systemctl/systemctl.c
@@ -2534,6 +2534,10 @@ typedef struct UnitStatusInfo {
 
         usec_t condition_timestamp;
         bool condition_result;
+        bool failed_condition_trigger;
+        bool failed_condition_negate;
+        const char *failed_condition;
+        const char *failed_condition_param;
 
         /* Socket */
         unsigned n_accepted;
@@ -2676,10 +2680,15 @@ static void print_status_info(UnitStatusInfo *i) {
                 s1 = format_timestamp_relative(since1, sizeof(since1), i->condition_timestamp);
                 s2 = format_timestamp(since2, sizeof(since2), i->condition_timestamp);
 
-                if (s1)
-                        printf("          start condition failed at %s; %s\n", s2, s1);
-                else if (s2)
-                        printf("          start condition failed at %s\n", s2);
+                printf("           start condition failed at %s%s%s\n",
+                       s2, s1 ? "; " : "", s1 ? s1 : "");
+                if (i->failed_condition_trigger)
+                        printf("           none of the trigger conditions were met\n");
+                else if (i->failed_condition)
+                        printf("           %s=%s%s was not met\n",
+                               i->failed_condition,
+                               i->failed_condition_negate ? "!" : "",
+                               i->failed_condition_param);
         }
 
         if (i->sysfs_path)
@@ -3038,15 +3047,18 @@ static int status_property(const char *name, DBusMessageIter *iter, UnitStatusIn
                                 ExecStatusInfo *info;
                                 int r;
 
-                                if (!(info = new0(ExecStatusInfo, 1)))
+                                info = new0(ExecStatusInfo, 1);
+                                if (!info)
                                         return -ENOMEM;
 
-                                if (!(info->name = strdup(name))) {
+                                info->name = strdup(name);
+                                if (!info->name) {
                                         free(info);
                                         return -ENOMEM;
                                 }
 
-                                if ((r = exec_status_info_deserialize(&sub, info)) < 0) {
+                                r = exec_status_info_deserialize(&sub, info);
+                                if (r < 0) {
                                         free(info);
                                         return r;
                                 }
@@ -3056,7 +3068,8 @@ static int status_property(const char *name, DBusMessageIter *iter, UnitStatusIn
                                 dbus_message_iter_next(&sub);
                         }
 
-                } else if (dbus_message_iter_get_element_type(iter) == DBUS_TYPE_STRUCT && streq(name, "Listen")) {
+                } else if (dbus_message_iter_get_element_type(iter) == DBUS_TYPE_STRUCT &&
+                           streq(name, "Listen")) {
                         DBusMessageIter sub, sub2;
 
                         dbus_message_iter_recurse(iter, &sub);
@@ -3082,7 +3095,8 @@ static int status_property(const char *name, DBusMessageIter *iter, UnitStatusIn
 
                         return 0;
 
-                } else if (dbus_message_iter_get_element_type(iter) == DBUS_TYPE_STRING && streq(name, "DropInPaths")) {
+                } else if (dbus_message_iter_get_element_type(iter) == DBUS_TYPE_STRING &&
+                           streq(name, "DropInPaths")) {
                         int r = bus_parse_strv_iter(iter, &i->dropin_paths);
                         if (r < 0)
                                 return r;
@@ -3105,6 +3119,36 @@ static int status_property(const char *name, DBusMessageIter *iter, UnitStatusIn
 
                                 dbus_message_iter_next(&sub);
                         }
+
+                } else if (dbus_message_iter_get_element_type(iter) == DBUS_TYPE_STRUCT &&
+                           streq(name, "Conditions")) {
+                        DBusMessageIter sub, sub2;
+
+                        dbus_message_iter_recurse(iter, &sub);
+                        while (dbus_message_iter_get_arg_type(&sub) == DBUS_TYPE_STRUCT) {
+                                const char *cond, *param;
+                                dbus_bool_t trigger, negate;
+                                dbus_int32_t state;
+
+                                dbus_message_iter_recurse(&sub, &sub2);
+                                log_debug("here");
+
+                                if(bus_iter_get_basic_and_next(&sub2, DBUS_TYPE_STRING, &cond, true) >= 0 &&
+                                   bus_iter_get_basic_and_next(&sub2, DBUS_TYPE_BOOLEAN, &trigger, true) >= 0 &&
+                                   bus_iter_get_basic_and_next(&sub2, DBUS_TYPE_BOOLEAN, &negate, true) >= 0 &&
+                                   bus_iter_get_basic_and_next(&sub2, DBUS_TYPE_STRING, &param, true) >= 0 &&
+                                   bus_iter_get_basic_and_next(&sub2, DBUS_TYPE_INT32, &state, false) >= 0) {
+                                        log_debug("%s %d %d %s %d", cond, trigger, negate, param, state);
+                                        if (state < 0 && (!trigger || !i->failed_condition)) {
+                                                i->failed_condition = cond;
+                                                i->failed_condition_trigger = trigger;
+                                                i->failed_condition_negate = negate;
+                                                i->failed_condition_param = param;
+                                        }
+                                }
+
+                                dbus_message_iter_next(&sub);
+                        }
                 }
 
                 break;