Create hardened versions of Get and Mutable for repeated_field.

Create `CheckedGetOrAbort` and `CheckedMutableOrAbort` for repeated_field.h. This is already similarly done for repeated_ptr_field.h.

PiperOrigin-RevId: 723591137

Author: protobuf-github-bot

src/google/protobuf/repeated_field.h

@@ -1437,6 +1437,28 @@ internal::RepeatedFieldBackInsertIterator<T> RepeatedFieldBackInserter(
   return internal::RepeatedFieldBackInsertIterator<T>(mutable_field);
 }
 
+namespace internal {
+template <typename T>
+inline void CheckIndexInBoundsOrAbort(const RepeatedField<T>& field,
+                                      int index) {
+  if (ABSL_PREDICT_FALSE(index < 0 || index >= field.size())) {
+    LogIndexOutOfBoundsAndAbort(index, field.size());
+  }
+}
+
+template <typename T>
+const T& CheckedGetOrAbort(const RepeatedField<T>& field, int index) {
+  CheckIndexInBoundsOrAbort(field, index);
+  return field.Get(index);
+}
+
+template <typename T>
+inline T* CheckedMutableOrAbort(RepeatedField<T>* field, int index) {
+  CheckIndexInBoundsOrAbort(*field, index);
+  return field->Mutable(index);
+}
+}  // namespace internal
+
 
 }  // namespace protobuf
 }  // namespace google

src/google/protobuf/repeated_field_unittest.cc

@@ -1343,6 +1343,35 @@ TEST_F(RepeatedFieldInsertionIteratorsTest, Halves) {
                          protobuffer.repeated_double().end(), halves.begin()));
 }
 
+TEST(RepeatedField, CheckedGetOrAbortTest) {
+  RepeatedField<int> field;
+
+  // Empty container tests.
+  EXPECT_DEATH(CheckedGetOrAbort(field, -1), "index: -1, size: 0");
+  EXPECT_DEATH(CheckedGetOrAbort(field, field.size()), "index: 0, size: 0");
+
+  // Non-empty container tests
+  field.Add(5);
+  field.Add(4);
+  EXPECT_DEATH(CheckedGetOrAbort(field, 2), "index: 2, size: 2");
+  EXPECT_DEATH(CheckedGetOrAbort(field, -1), "index: -1, size: 2");
+}
+
+TEST(RepeatedField, CheckedMutableOrAbortTest) {
+  RepeatedField<int> field;
+
+  // Empty container tests.
+  EXPECT_DEATH(CheckedMutableOrAbort(&field, -1), "index: -1, size: 0");
+  EXPECT_DEATH(CheckedMutableOrAbort(&field, field.size()),
+               "index: 0, size: 0");
+
+  // Non-empty container tests
+  field.Add(5);
+  field.Add(4);
+  EXPECT_DEATH(CheckedMutableOrAbort(&field, 2), "index: 2, size: 2");
+  EXPECT_DEATH(CheckedMutableOrAbort(&field, -1), "index: -1, size: 2");
+}
+
 }  // namespace
 
 }  // namespace protobuf