Fix DataReader.findNewLine with lone EOL character (helidon-io#9325)

Add a missing check to keep the internal toIndex within bounds.
Fixes helidon-io#9287

Author: romain-grecourt

common/buffers/src/main/java/io/helidon/common/buffers/DataReader.java

@@ -445,6 +445,9 @@ public int findNewLine(int max) throws IncorrectNewLineException {
                     }
                     indexWithinNode = crIndex + 1;
                     idx += indexWithinNode;
+                    if (idx >= max) {
+                        return max;
+                    }
                     continue;
                 }
             }

common/buffers/src/test/java/io/helidon/common/buffers/DataReaderTest.java

@@ -0,0 +1,44 @@
+/*
+ * Copyright (c) 2024 Oracle and/or its affiliates.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.helidon.common.buffers;
+
+import java.util.concurrent.atomic.AtomicReference;
+
+import org.junit.jupiter.api.Test;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.is;
+
+class DataReaderTest {
+
+    @Test
+    void testFindNewLineWithLoneCR() {
+        // reading N bytes at a time until a new line is found
+        // with data containing a lone CR
+
+        byte[] data = new byte[] {0, 0, (byte) '\r', 0, (byte) '\r', (byte) '\n'};
+        AtomicReference<byte[]> ref = new AtomicReference<>(data);
+        DataReader dataReader = new DataReader(() -> ref.getAndSet(null), true);
+
+        int n = 2;
+        assertThat(dataReader.findNewLine(n), is(n));
+        dataReader.skip(n);
+        assertThat(dataReader.findNewLine(n), is(n));
+        dataReader.skip(n);
+        assertThat(dataReader.findNewLine(n), is(0));
+    }
+}