Error summary (#2259)HEADmaster

* lib: properly name function to set summary

* lib: set first non-ok subcheck as the summary for the overall check

* Fetch summarily recursively from failed subchecks

---------

Co-authored-by: Lorenz Kästle <lorenz.kaestle@netways.de>

2 files changed, 130 insertions, 12 deletions

diff --git a/lib/output.c b/lib/output.c
index 3c04d63d..9bcd02d9 100644
--- a/lib/output.c
+++ b/lib/output.c
@@ -20,8 +20,53 @@ static char *fmt_subcheck_output(mp_output_format output_format, mp_subcheck che
                                                                  unsigned int indentation);
 static inline cJSON *json_serialize_subcheck(mp_subcheck subcheck);
 
+// mp_compare_state compares two state arguments
+// if *first* is WORSE than *second*, the result is < 0
+// if *first* is equal to *second*, the result is 0
+// if *first* is BETTER (less bad) the result is > 0
+static int mp_compare_state(mp_state_enum first, mp_state_enum second);
+
 // == Implementation ==
 
+// get_subcheck_failed_output retrieves the output of the
+// worst and first leave node in a subcheck tree
+// or NULL if no such message exists
+// the return string is a copy of the original
+static char *get_subcheck_failed_output(const mp_subcheck tree) {
+        if (tree.subchecks == NULL) {
+                // this is a leave node
+                if (mp_compute_subcheck_state(tree) == STATE_OK) {
+                        // ALL OK, nothing to return
+                        return NULL;
+                }
+
+                char *result = strdup(tree.output);
+                return result;
+        }
+
+        // not a leave node, go through tree
+        mp_subcheck_list *subcheck = tree.subchecks;
+        mp_subcheck *worst_first_node = NULL;
+        mp_state_enum worst_state = STATE_OK;
+        while (subcheck != NULL) {
+                mp_state_enum current = mp_compute_subcheck_state(subcheck->subcheck);
+                if (mp_compare_state(current, worst_state) < 0) {
+                        worst_first_node = &subcheck->subcheck;
+                }
+
+                subcheck = subcheck->next;
+        }
+
+        if (worst_first_node == NULL) {
+                // we did not find a failed subcheck, return the output
+                // of the current node
+                char *result = strdup(tree.output);
+                return result;
+        }
+
+        return get_subcheck_failed_output(*worst_first_node);
+}
+
 /*
  * Generate output string for a mp_subcheck object
  */
@@ -164,7 +209,7 @@ int mp_add_subcheck_to_subcheck(mp_subcheck check[static 1], mp_subcheck subchec
  * Add a manual summary to a mp_check object, effectively replacing
  * the autogenerated one
  */
-void mp_add_summary(mp_check check[static 1], char *summary) { check->summary = summary; }
+void mp_set_summary(mp_check check[static 1], char *summary) { check->summary = strdup(summary); }
 
 /*
  * Generate the summary string of a mp_check object based on its subchecks
@@ -172,31 +217,61 @@ void mp_add_summary(mp_check check[static 1], char *summary) { check->summary =
 char *get_subcheck_summary(mp_check check) {
         mp_subcheck_list *subchecks = check.subchecks;
 
-        unsigned int ok = 0;
-        unsigned int warning = 0;
-        unsigned int critical = 0;
-        unsigned int unknown = 0;
+        unsigned int ok_count = 0;
+        unsigned int warning_count = 0;
+        unsigned int critical_count = 0;
+        unsigned int unknown_count = 0;
+        char *result = NULL;
         while (subchecks != NULL) {
                 switch (mp_compute_subcheck_state(subchecks->subcheck)) {
                 case STATE_OK:
-                        ok++;
+                        ok_count++;
                         break;
                 case STATE_WARNING:
-                        warning++;
+                        if (critical_count == 0 && unknown_count == 0 && warning_count == 0) {
+                                // set summary to first warning subcheck output
+                                asprintf(&result, "%s", get_subcheck_failed_output(subchecks->subcheck));
+                        }
+                        warning_count++;
                         break;
                 case STATE_CRITICAL:
-                        critical++;
+                        if (critical_count == 0) {
+                                // set summary to first critical subcheck output
+                                asprintf(&result, "%s", get_subcheck_failed_output(subchecks->subcheck));
+                        }
+                        critical_count++;
                         break;
                 case STATE_UNKNOWN:
-                        unknown++;
+                        if (critical_count == 0 && unknown_count == 0) {
+                                // set summary to first unknown subcheck output
+                                asprintf(&result, "%s", get_subcheck_failed_output(subchecks->subcheck));
+                        }
+                        unknown_count++;
                         break;
                 default:
                         die(STATE_UNKNOWN, "Unknown state in get_subcheck_summary");
                 }
                 subchecks = subchecks->next;
         }
-        char *result = NULL;
-        asprintf(&result, "ok=%d, warning=%d, critical=%d, unknown=%d", ok, warning, critical, unknown);
+
+        if (result == NULL) {
+                if (ok_count > 0) {
+                        asprintf(&result, "ok=%d", ok_count);
+                }
+
+                if (warning_count > 0) {
+                        asprintf(&result, "%swarning=%d", (result == NULL ? "" : ", "), warning_count);
+                }
+
+                if (critical_count > 0) {
+                        asprintf(&result, "%scritical=%d", (result == NULL ? "" : ", "), critical_count);
+                }
+
+                if (unknown_count > 0) {
+                        asprintf(&result, "%sunknown=%d", (result == NULL ? "" : ", "), unknown_count);
+                }
+        }
+
         return result;
 }
 
@@ -658,3 +733,46 @@ mp_state_enum mp_eval_unknown(mp_check overall) {
         (void)overall;
         return STATE_UNKNOWN;
 }
+
+static int mp_compare_state(mp_state_enum first, mp_state_enum second) {
+        switch (first) {
+        case STATE_OK:
+                switch (second) {
+                case STATE_OK:
+                        return 0;
+                case STATE_WARNING:
+                case STATE_UNKNOWN:
+                case STATE_CRITICAL:
+                        return 1;
+                }
+        case STATE_WARNING:
+                switch (second) {
+                case STATE_OK:
+                        return -1;
+                case STATE_WARNING:
+                        return 0;
+                case STATE_UNKNOWN:
+                case STATE_CRITICAL:
+                        return 1;
+                }
+        case STATE_UNKNOWN:
+                switch (second) {
+                case STATE_OK:
+                case STATE_WARNING:
+                        return -1;
+                case STATE_UNKNOWN:
+                        return 0;
+                case STATE_CRITICAL:
+                        return 1;
+                }
+        case STATE_CRITICAL:
+                switch (second) {
+                case STATE_OK:
+                case STATE_WARNING:
+                case STATE_UNKNOWN:
+                        return -1;
+                case STATE_CRITICAL:
+                        return 0;
+                }
+        }
+}
diff --git a/lib/output.h b/lib/output.h
index f5011268..6ca63cfe 100644
--- a/lib/output.h
+++ b/lib/output.h
@@ -87,7 +87,7 @@ int mp_add_subcheck_to_subcheck(mp_subcheck check[static 1], mp_subcheck);
 
 void mp_add_perfdata_to_subcheck(mp_subcheck check[static 1], mp_perfdata);
 
-void mp_add_summary(mp_check check[static 1], char *summary);
+void mp_set_summary(mp_check check[static 1], char *summary);
 
 mp_state_enum mp_compute_check_state(mp_check);
 mp_state_enum mp_compute_subcheck_state(mp_subcheck);