Validate axes and led labels correctly

Before this CL, a number of checks for kl file validity were incorrect.
Some of the APIs were supposed to return an invalid value, but instead
were always returning a valid value, no matter what the input was.

Correct these values by switching to std::optional.

Bug: 266400536
Test: m libinput_tests && adb sync data && adb shell -t /data/nativetest64/libinput_tests/libinput_tests
Change-Id: I4ef45f3249dca4f4f033fb85e9fecbc2ad1f1395
diff --git a/libs/input/InputEventLabels.cpp b/libs/input/InputEventLabels.cpp
index 7159e27..d97c1bb 100644
--- a/libs/input/InputEventLabels.cpp
+++ b/libs/input/InputEventLabels.cpp
@@ -438,11 +438,11 @@
 
 const std::unordered_map<std::string, int> InputEventLookup::FLAGS = {FLAGS_SEQUENCE};
 
-int InputEventLookup::lookupValueByLabel(const std::unordered_map<std::string, int>& map,
-                                         const char* literal) {
+std::optional<int> InputEventLookup::lookupValueByLabel(
+        const std::unordered_map<std::string, int>& map, const char* literal) {
     std::string str(literal);
     auto it = map.find(str);
-    return it != map.end() ? it->second : 0;
+    return it != map.end() ? std::make_optional(it->second) : std::nullopt;
 }
 
 const char* InputEventLookup::lookupLabelByValue(const std::vector<InputEventLabel>& vec,
@@ -453,8 +453,8 @@
     return nullptr;
 }
 
-int32_t InputEventLookup::getKeyCodeByLabel(const char* label) {
-    return int32_t(lookupValueByLabel(KEYCODES, label));
+std::optional<int> InputEventLookup::getKeyCodeByLabel(const char* label) {
+    return lookupValueByLabel(KEYCODES, label);
 }
 
 const char* InputEventLookup::getLabelByKeyCode(int32_t keyCode) {
@@ -464,20 +464,20 @@
     return nullptr;
 }
 
-uint32_t InputEventLookup::getKeyFlagByLabel(const char* label) {
-    return uint32_t(lookupValueByLabel(FLAGS, label));
+std::optional<int> InputEventLookup::getKeyFlagByLabel(const char* label) {
+    return lookupValueByLabel(FLAGS, label);
 }
 
-int32_t InputEventLookup::getAxisByLabel(const char* label) {
-    return int32_t(lookupValueByLabel(AXES, label));
+std::optional<int> InputEventLookup::getAxisByLabel(const char* label) {
+    return lookupValueByLabel(AXES, label);
 }
 
 const char* InputEventLookup::getAxisLabel(int32_t axisId) {
     return lookupLabelByValue(AXES_NAMES, axisId);
 }
 
-int32_t InputEventLookup::getLedByLabel(const char* label) {
-    return int32_t(lookupValueByLabel(LEDS, label));
+std::optional<int> InputEventLookup::getLedByLabel(const char* label) {
+    return lookupValueByLabel(LEDS, label);
 }
 
 } // namespace android