From dd6207e99ab45fa85073d60ca22fdd9c7527f8ff Mon Sep 17 00:00:00 2001
From: ydynnikov <ydynnikov@yandex-team.com>
Date: Fri, 27 Feb 2026 11:19:31 +0300
Subject: Enhance library/cpp/monlib exception verbosity for debugging
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Этот эксепшн ронял YDB RU PRESTABLE минимум дважды:
\- 2025-09-10 <https://nda.ya.ru/t/VerKgHXk7VTLyV>
\- 2026-02-19 <https://nda.ya.ru/t/uhTY2yqK7UtBen>

Патч призван упростить отладку падений и поиски руткоза
commit_hash:72d859bae3ab265a2807e566c763bfb70a92a61a
---
 library/cpp/monlib/dynamic_counters/encode_ut.cpp | 31 +++++++++++++++++++++++
 1 file changed, 31 insertions(+)

(limited to 'library/cpp/monlib/dynamic_counters/encode_ut.cpp')

diff --git a/library/cpp/monlib/dynamic_counters/encode_ut.cpp b/library/cpp/monlib/dynamic_counters/encode_ut.cpp
index 52d77b6b413..b1ef7df93a8 100644
--- a/library/cpp/monlib/dynamic_counters/encode_ut.cpp
+++ b/library/cpp/monlib/dynamic_counters/encode_ut.cpp
@@ -8,6 +8,7 @@
 #include <library/cpp/testing/unittest/registar.h>
 
 #include <util/generic/buffer.h>
+#include <util/generic/yexception.h>
 #include <util/stream/buffer.h>
 
 namespace NMonitoring {
@@ -221,6 +222,36 @@ namespace NMonitoring {
 
             AssertResult(samples);
         }
+
+        Y_UNIT_TEST(InvalidUtf8) {
+            TDynamicCounterPtr rootGroup1(new TDynamicCounters());
+            rootGroup1->GetNamedCounter("invalid\x80Utf8Name", "validUtf8");
+
+            {
+                TString result;
+                TStringOutput out(result);
+                auto encoder = CreateEncoder(&out, EFormat::JSON);
+                UNIT_ASSERT_EXCEPTION_CONTAINS(
+                    rootGroup1->Accept(TString(), TString(), *encoder),
+                    yexception,
+                    "label name is not valid UTF-8 string: 'invalid\\x80Utf8Name'"
+                );
+            }
+
+            TDynamicCounterPtr rootGroup2(new TDynamicCounters());
+            rootGroup2->GetNamedCounter("validUtf8Name", "invalid\x80Utf8");
+
+            {
+                TString result;
+                TStringOutput out(result);
+                auto encoder = CreateEncoder(&out, EFormat::JSON);
+                UNIT_ASSERT_EXCEPTION_CONTAINS(
+                    rootGroup2->Accept(TString(), TString(), *encoder),
+                    yexception,
+                    "label value is not valid UTF-8 string, name: 'validUtf8Name', value: 'invalid\\x80Utf8'"
+                );
+            }
+        }
     }
 
 }
-- 
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