HADOOP-17088.Failed to load XInclude files with relative path. (#2097)

Contributed by Yushi Hayasaka.

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/conf/Configuration.java

@@ -40,6 +40,8 @@ import java.io.Writer;
 import java.lang.ref.WeakReference;
 import java.net.InetSocketAddress;
 import java.net.JarURLConnection;
+import java.net.URI;
+import java.net.URISyntaxException;
 import java.net.URL;
 import java.net.URLConnection;
 import java.nio.file.Files;
@@ -3247,7 +3249,15 @@ public class Configuration implements Iterable<Map.Entry<String,String>>,
           File href = new File(confInclude);
           if (!href.isAbsolute()) {
             // Included resources are relative to the current resource
-            File baseFile = new File(name).getParentFile();
+            File baseFile;
+
+            try {
+              baseFile = new File(new URI(name));
+            } catch (IllegalArgumentException | URISyntaxException e) {
+              baseFile = new File(name);
+            }
+
+            baseFile = baseFile.getParentFile();
             href = new File(baseFile, href.getPath());
           }
           if (!href.exists()) {

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/conf/TestConfiguration.java

@@ -1062,6 +1062,38 @@ public class TestConfiguration {
     new File(new File(relConfig).getParent()).delete();
   }
 
+  @Test
+  public void testRelativeIncludesWithLoadingViaUri() throws Exception {
+    tearDown();
+    File configFile = new File("./tmp/test-config.xml");
+    File configFile2 = new File("./tmp/test-config2.xml");
+
+    new File(configFile.getParent()).mkdirs();
+    out = new BufferedWriter(new FileWriter(configFile2));
+    startConfig();
+    appendProperty("a", "b");
+    endConfig();
+
+    out = new BufferedWriter(new FileWriter(configFile));
+    startConfig();
+    // Add the relative path instead of the absolute one.
+    startInclude(configFile2.getName());
+    endInclude();
+    appendProperty("c", "d");
+    endConfig();
+
+    // verify that the includes file contains all properties
+    Path fileResource = new Path(configFile.toURI());
+    conf.addResource(fileResource);
+    assertEquals("b", conf.get("a"));
+    assertEquals("d", conf.get("c"));
+
+    // Cleanup
+    configFile.delete();
+    configFile2.delete();
+    new File(configFile.getParent()).delete();
+  }
+
   @Test
   public void testIntegerRanges() {
     Configuration conf = new Configuration();