Fix panic with unicode counter names in win_perf_counters (#4255)

plugins/inputs/win_perf_counters/performance_query.go

@@ -181,7 +181,7 @@ func UTF16ToStringArray(buf []uint16) []string {
 	stringLine := UTF16PtrToString(&buf[0])
 	for stringLine != "" {
 		strings = append(strings, stringLine)
-		nextLineStart += len(stringLine) + 1
+		nextLineStart += len([]rune(stringLine)) + 1
 		remainingBuf := buf[nextLineStart:]
 		stringLine = UTF16PtrToString(&remainingBuf[0])
 	}

plugins/inputs/win_perf_counters/win_perf_counters_test.go

@@ -463,3 +463,37 @@ func TestGatherRefreshing(t *testing.T) {
 	acc3.AssertContainsTaggedFields(t, measurement, fields3, tags3)
 
 }
+
+// list of nul terminated strings from WinAPI
+var unicodeStringListWithEnglishChars = []uint16{0x5c, 0x5c, 0x54, 0x34, 0x38, 0x30, 0x5c, 0x50, 0x68, 0x79, 0x73, 0x69, 0x63, 0x61, 0x6c, 0x44, 0x69, 0x73, 0x6b, 0x28, 0x30, 0x20, 0x43, 0x3a, 0x29, 0x5c, 0x43, 0x75, 0x72, 0x72, 0x65, 0x6e, 0x74, 0x20, 0x44, 0x69, 0x73, 0x6b, 0x20, 0x51, 0x75, 0x65, 0x75, 0x65, 0x20, 0x4c, 0x65, 0x6e, 0x67, 0x74, 0x68, 0x0, 0x5c, 0x5c, 0x54, 0x34, 0x38, 0x30, 0x5c, 0x50, 0x68, 0x79, 0x73, 0x69, 0x63, 0x61, 0x6c, 0x44, 0x69, 0x73, 0x6b, 0x28, 0x5f, 0x54, 0x6f, 0x74, 0x61, 0x6c, 0x29, 0x5c, 0x43, 0x75, 0x72, 0x72, 0x65, 0x6e, 0x74, 0x20, 0x44, 0x69, 0x73, 0x6b, 0x20, 0x51, 0x75, 0x65, 0x75, 0x65, 0x20, 0x4c, 0x65, 0x6e, 0x67, 0x74, 0x68, 0x0, 0x0}
+var unicodeStringListWithCzechChars = []uint16{0x5c, 0x5c, 0x54, 0x34, 0x38, 0x30, 0x5c, 0x46, 0x79, 0x7a, 0x69, 0x63, 0x6b, 0xfd, 0x20, 0x64, 0x69, 0x73, 0x6b, 0x28, 0x30, 0x20, 0x43, 0x3a, 0x29, 0x5c, 0x41, 0x6b, 0x74, 0x75, 0xe1, 0x6c, 0x6e, 0xed, 0x20, 0x64, 0xe9, 0x6c, 0x6b, 0x61, 0x20, 0x66, 0x72, 0x6f, 0x6e, 0x74, 0x79, 0x20, 0x64, 0x69, 0x73, 0x6b, 0x75, 0x0, 0x5c, 0x5c, 0x54, 0x34, 0x38, 0x30, 0x5c, 0x46, 0x79, 0x7a, 0x69, 0x63, 0x6b, 0xfd, 0x20, 0x64, 0x69, 0x73, 0x6b, 0x28, 0x5f, 0x54, 0x6f, 0x74, 0x61, 0x6c, 0x29, 0x5c, 0x41, 0x6b, 0x74, 0x75, 0xe1, 0x6c, 0x6e, 0xed, 0x20, 0x64, 0xe9, 0x6c, 0x6b, 0x61, 0x20, 0x66, 0x72, 0x6f, 0x6e, 0x74, 0x79, 0x20, 0x64, 0x69, 0x73, 0x6b, 0x75, 0x0, 0x0}
+var unicodeStringListSingleItem = []uint16{0x5c, 0x5c, 0x54, 0x34, 0x38, 0x30, 0x5c, 0x50, 0x68, 0x79, 0x73, 0x69, 0x63, 0x61, 0x6c, 0x44, 0x69, 0x73, 0x6b, 0x28, 0x30, 0x20, 0x43, 0x3a, 0x29, 0x5c, 0x43, 0x75, 0x72, 0x72, 0x65, 0x6e, 0x74, 0x20, 0x44, 0x69, 0x73, 0x6b, 0x20, 0x51, 0x75, 0x65, 0x75, 0x65, 0x20, 0x4c, 0x65, 0x6e, 0x67, 0x74, 0x68, 0x0, 0x0}
+var unicodeStringListNoItem = []uint16{0x0}
+
+var stringArrayWithEnglishChars = []string{
+	"\\\\T480\\PhysicalDisk(0 C:)\\Current Disk Queue Length",
+	"\\\\T480\\PhysicalDisk(_Total)\\Current Disk Queue Length",
+}
+var stringArrayWithCzechChars = []string{
+	"\\\\T480\\Fyzick\u00fd disk(0 C:)\\Aktu\u00e1ln\u00ed d\u00e9lka fronty disku",
+	"\\\\T480\\Fyzick\u00fd disk(_Total)\\Aktu\u00e1ln\u00ed d\u00e9lka fronty disku",
+}
+
+var stringArraySingleItem = []string{
+	"\\\\T480\\PhysicalDisk(0 C:)\\Current Disk Queue Length",
+}
+
+func TestUTF16ToStringArray(t *testing.T) {
+	singleItem := UTF16ToStringArray(unicodeStringListSingleItem)
+	assert.True(t, assert.ObjectsAreEqual(singleItem, stringArraySingleItem), "Not equal single arrays")
+
+	noItem := UTF16ToStringArray(unicodeStringListNoItem)
+	assert.Nil(t, noItem)
+
+	engStrings := UTF16ToStringArray(unicodeStringListWithEnglishChars)
+	assert.True(t, assert.ObjectsAreEqual(engStrings, stringArrayWithEnglishChars), "Not equal eng arrays")
+
+	czechStrings := UTF16ToStringArray(unicodeStringListWithCzechChars)
+	assert.True(t, assert.ObjectsAreEqual(czechStrings, stringArrayWithCzechChars), "Not equal czech arrays")
+
+}