Handle possible regexes defensively in NamePatternFilter

Previously, if a name contained part of a regex but wasn't actually
a regex, a PatternSyntaxException would be thrown and the request
would fail.

This commit updates NamePatternFilter to catch PatternSyntaxException
and treat the regex-like input as a name insteead.

See gh-9730

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/endpoint/mvc/NamePatternFilter.java

@@ -20,6 +20,7 @@ import java.util.HashMap;
 import java.util.LinkedHashMap;
 import java.util.Map;
 import java.util.regex.Pattern;
+import java.util.regex.PatternSyntaxException;
 
 /**
  * Utility class that can be used to filter source data using a name regular expression.
@@ -31,6 +32,7 @@ import java.util.regex.Pattern;
  * @author Phillip Webb
  * @author Sergei Egorov
  * @author Andy Wilkinson
+ * @author Dylian Bego
  * @since 1.3.0
  */
 abstract class NamePatternFilter<T> {
@@ -44,13 +46,13 @@ abstract class NamePatternFilter<T> {
 	}
 
 	public Map<String, Object> getResults(String name) {
-		if (!isRegex(name)) {
+		Pattern pattern = getRegexPattern(name);
+		if (pattern == null) { // this is not a regex
 			Object value = getValue(this.source, name);
 			Map<String, Object> result = new HashMap<String, Object>();
 			result.put(name, value);
 			return result;
 		}
-		Pattern pattern = Pattern.compile(name);
 		ResultCollectingNameCallback resultCollector = new ResultCollectingNameCallback(
 				pattern);
 		getNames(this.source, resultCollector);
@@ -58,13 +60,18 @@ abstract class NamePatternFilter<T> {
 
 	}
 
-	private boolean isRegex(String name) {
+	private Pattern getRegexPattern(String name) {
 		for (String part : REGEX_PARTS) {
 			if (name.contains(part)) {
-				return true;
+				try {
+					return Pattern.compile(name);
+				}
+				catch (PatternSyntaxException e) {
+					return null;
+				}
 			}
 		}
-		return false;
+		return null;
 	}
 
 	protected abstract void getNames(T source, NameCallback callback);

spring-boot-actuator/src/test/java/org/springframework/boot/actuate/endpoint/mvc/NamePatternFilterTests.java

@@ -27,6 +27,7 @@ import static org.assertj.core.api.Assertions.assertThat;
  *
  * @author Phillip Webb
  * @author Andy Wilkinson
+ * @author Dylian Bego
  */
 public class NamePatternFilterTests {
 
@@ -38,6 +39,13 @@ public class NamePatternFilterTests {
 		assertThat(filter.isGetNamesCalled()).isFalse();
 	}
 
+	@Test
+	public void nonRegexThatContainsRegexPart() throws Exception {
+		MockNamePatternFilter filter = new MockNamePatternFilter();
+		assertThat(filter.getResults("*")).containsEntry("*", "*");
+		assertThat(filter.isGetNamesCalled()).isFalse();
+	}
+
 	@Test
 	public void regexRepetitionZeroOrMore() {
 		MockNamePatternFilter filter = new MockNamePatternFilter();