Further restrict configuration wildcard patterns

Extend wildcard restrictions to the `spring.config.name` property. Also
refine exception messages to include the property value.

Closes gh-21217

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/context/config/ConfigFileApplicationListener.java

@@ -703,16 +703,18 @@ public class ConfigFileApplicationListener implements EnvironmentPostProcessor,
 		private void validateWildcardLocation(String path) {
 			if (path.contains("*")) {
 				Assert.state(StringUtils.countOccurrencesOf(path, "*") == 1,
-						"Wildard pattern with multiple '*'s cannot be used as search location");
+						() -> "Search location '" + path + "' cannot contain multiple wildcards");
 				String directoryPath = path.substring(0, path.lastIndexOf("/") + 1);
-				Assert.state(directoryPath.endsWith("*/"), "Wildcard patterns must end with '*/'");
+				Assert.state(directoryPath.endsWith("*/"), () -> "Search location '" + path + "' must end with '*/'");
 			}
 		}
 
 		private Set<String> getSearchNames() {
 			if (this.environment.containsProperty(CONFIG_NAME_PROPERTY)) {
 				String property = this.environment.getProperty(CONFIG_NAME_PROPERTY);
-				return asResolvedSet(property, null);
+				Set<String> names = asResolvedSet(property, null);
+				names.forEach(this::assertValidConfigName);
+				return names;
 			}
 			return asResolvedSet(ConfigFileApplicationListener.this.names, DEFAULT_NAMES);
 		}
@@ -724,6 +726,12 @@ public class ConfigFileApplicationListener implements EnvironmentPostProcessor,
 			return new LinkedHashSet<>(list);
 		}
 
+		private void assertValidConfigName(String name) {
+			Assert.state(!name.contains("*"), () -> "Config name '" + name + "' cannot contain wildcards");
+			Assert.state(!name.contains("/") && !name.contains("\\"),
+					() -> "Config name '" + name + "' cannot contain slashes");
+		}
+
 		private void addLoadedPropertySources() {
 			MutablePropertySources destination = this.environment.getPropertySources();
 			List<MutablePropertySources> loaded = new ArrayList<>(this.loaded.values());

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/context/config/ConfigFileApplicationListenerTests.java

@@ -1039,7 +1039,16 @@ class ConfigFileApplicationListenerTests {
 				"spring.config.location=" + location);
 		assertThatIllegalStateException()
 				.isThrownBy(() -> this.initializer.postProcessEnvironment(this.environment, this.application))
-				.withMessage("Wildcard patterns must end with '*/'");
+				.withMessageStartingWith("Search location '").withMessageEndingWith("' must end with '*/'");
+	}
+
+	@Test
+	void configNameCannotContainWildcard() {
+		TestPropertySourceUtils.addInlinedPropertiesToEnvironment(this.environment,
+				"spring.config.location=file:src/test/resources/", "spring.config.name=*/application");
+		assertThatIllegalStateException()
+				.isThrownBy(() -> this.initializer.postProcessEnvironment(this.environment, this.application))
+				.withMessage("Config name '*/application' cannot contain wildcards");
 	}
 
 	@Test
@@ -1049,7 +1058,8 @@ class ConfigFileApplicationListenerTests {
 				"spring.config.location=" + location);
 		assertThatIllegalStateException()
 				.isThrownBy(() -> this.initializer.postProcessEnvironment(this.environment, this.application))
-				.withMessage("Wildard pattern with multiple '*'s cannot be used as search location");
+				.withMessageStartingWith("Search location '")
+				.withMessageEndingWith("' cannot contain multiple wildcards");
 	}
 
 	@Test