HDFS-9472. concat() API does not give proper exception messages on ./reserved relative path (Rakesh R via umamahesh)

(cherry picked from commit e363417e7b)

hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt

@@ -868,6 +868,9 @@ Release 2.8.0 - UNRELEASED
     HDFS-9527. The return type of FSNamesystem.getBlockCollection should be
     changed to INodeFile. (szetszwo)
 
+    HDFS-9472. concat() API does not give proper exception messages on ./reserved 
+    relative path (Rakesh R via umamahesh)
+
   OPTIMIZATIONS
 
     HDFS-8026. Trace FSOutputSummer#writeChecksumChunks rather than

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSDirConcatOp.java

@@ -49,14 +49,11 @@ class FSDirConcatOp {
 
   static HdfsFileStatus concat(FSDirectory fsd, String target, String[] srcs,
     boolean logRetryCache) throws IOException {
-    Preconditions.checkArgument(!target.isEmpty(), "Target file name is empty");
+    validatePath(target, srcs);
-    Preconditions.checkArgument(srcs != null && srcs.length > 0,
-      "No sources given");
     assert srcs != null;
     if (FSDirectory.LOG.isDebugEnabled()) {
       FSDirectory.LOG.debug("concat {} to {}", Arrays.toString(srcs), target);
     }
-
     final INodesInPath targetIIP = fsd.getINodesInPath4Write(target);
     // write permission for the target
     FSPermissionChecker pc = null;
@@ -86,6 +83,25 @@ class FSDirConcatOp {
     return fsd.getAuditFileInfo(targetIIP);
   }
 
+  private static void validatePath(String target, String[] srcs)
+      throws IOException {
+    Preconditions.checkArgument(!target.isEmpty(), "Target file name is empty");
+    Preconditions.checkArgument(srcs != null && srcs.length > 0,
+        "No sources given");
+    if (FSDirectory.isReservedRawName(target)
+        || FSDirectory.isReservedInodesName(target)) {
+      throw new IOException("Concat operation doesn't support "
+          + FSDirectory.DOT_RESERVED_STRING + " relative path : " + target);
+    }
+    for (String srcPath : srcs) {
+      if (FSDirectory.isReservedRawName(srcPath)
+          || FSDirectory.isReservedInodesName(srcPath)) {
+        throw new IOException("Concat operation doesn't support "
+            + FSDirectory.DOT_RESERVED_STRING + " relative path : " + srcPath);
+      }
+    }
+  }
+
   private static void verifyTargetFile(FSDirectory fsd, final String target,
       final INodesInPath targetIIP) throws IOException {
     // check the target

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestHDFSConcat.java

@@ -503,4 +503,23 @@ public class TestHDFSConcat {
     assertEquals(blockSize * 2, dfs.getFileStatus(trg).getLen());
     assertFalse(dfs.exists(src));
   }
+
+  @Test(timeout = 30000)
+  public void testConcatReservedRelativePaths() throws IOException {
+    String testPathDir = "/.reserved/raw/ezone";
+    Path dir = new Path(testPathDir);
+    dfs.mkdirs(dir);
+    Path trg = new Path(testPathDir, "trg");
+    Path src = new Path(testPathDir, "src");
+    DFSTestUtil.createFile(dfs, trg, blockSize, REPL_FACTOR, 1);
+    DFSTestUtil.createFile(dfs, src, blockSize, REPL_FACTOR, 1);
+    try {
+      dfs.concat(trg, new Path[] { src });
+      Assert.fail("Must throw Exception!");
+    } catch (IOException e) {
+      String errMsg = "Concat operation doesn't support "
+          + FSDirectory.DOT_RESERVED_STRING + " relative path : " + trg;
+      GenericTestUtils.assertExceptionContains(errMsg, e);
+    }
+  }
 }