From f8aa659ddd55a7f1e40d713678cfd99e09434158 Mon Sep 17 00:00:00 2001
From: Gautham Banasandra <gautham.bangalore@gmail.com>
Date: Sat, 28 Jun 2025 23:14:04 +0530
Subject: [PATCH] HADOOP-19599. Fix file permission errors as per the platform

* The file permission denial error message in Linux
  systems end with `(Permission denied)` particularly.
* However, an error message in the same scenario on
  Windows ends with an `(Access is denied)` error.
* This PR fixes the resulting bug in
  `org.apache.hadoop.fs.ChecksumFileSystem.ChecksumFSInputChecker`
  and also fixes the unit test failure
  `org.apache.hadoop.fs.TestFsShellCopy#testPutSrcFileNoPerm`
  by making the appropriate check in accordance with the platform.
---
 .../apache/hadoop/fs/ChecksumFileSystem.java  | 20 +++++++++++++++++--
 .../org/apache/hadoop/fs/TestFsShellCopy.java | 19 ++++++++++++++++--
 2 files changed, 35 insertions(+), 4 deletions(-)

diff --git a/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/ChecksumFileSystem.java b/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/ChecksumFileSystem.java
index 66d9b628fa3f2..b6341ff3479c6 100644
--- a/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/ChecksumFileSystem.java
+++ b/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/ChecksumFileSystem.java
@@ -205,8 +205,7 @@ public ChecksumFSInputChecker(ChecksumFileSystem fs, Path file, int bufferSize)
       } catch (IOException e) {
         // mincing the message is terrible, but java throws permission
         // exceptions as FNF because that's all the method signatures allow!
-        if (!(e instanceof FileNotFoundException) ||
-            e.getMessage().endsWith(" (Permission denied)")) {
+        if (!(e instanceof FileNotFoundException) || isPermissionDenied(e)) {
           LOG.warn("Problem opening checksum file: "+ file +
               ".  Ignoring exception: " , e);
         }
@@ -214,6 +213,23 @@ public ChecksumFSInputChecker(ChecksumFileSystem fs, Path file, int bufferSize)
       }
     }
 
+    /**
+     * Check if the exception is a permission denied error.
+     * This is used to differentiate between a missing checksum file
+     * and a permission denied error when trying to read it.
+     *
+     * @param e the IOException to check
+     * @return true if the exception indicates a permission denied error
+     */
+    private static boolean isPermissionDenied(IOException e) {
+      String errorMessage = e.getMessage();
+      if (Path.WINDOWS) {
+        return errorMessage.endsWith(" (Access is denied)");
+      }
+
+      return errorMessage.endsWith(" (Permission denied)");
+    }
+
     private long getChecksumFilePos( long dataPos ) {
       return HEADER_LENGTH + FSInputChecker.CHECKSUM_SIZE*(dataPos/bytesPerSum);
     }
diff --git a/hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/fs/TestFsShellCopy.java b/hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/fs/TestFsShellCopy.java
index 319ae0e2d8a5b..c51b7add06078 100644
--- a/hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/fs/TestFsShellCopy.java
+++ b/hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/fs/TestFsShellCopy.java
@@ -676,14 +676,29 @@ public void testPutSrcFileNoPerm()
       System.setErr(new PrintStream(err));
       shellRun(1, "-put", src.toString(), dst.toString());
       System.setErr(oldErr);
-      System.err.print(err.toString());
-      assertTrue(err.toString().contains("(Permission denied)"));
+      System.err.print(err);
+      assertPermissionDenied(err);
     } finally {
       // make sure the test file can be deleted
       lfs.setPermission(src, new FsPermission((short)0755));
     }
   }
 
+  /**
+   * Assert that the error message contains the expected permission denied
+   * message, which varies by platform.
+   *
+   * @param err the ByteArrayOutputStream containing the error output
+   */
+  private static void assertPermissionDenied(ByteArrayOutputStream err) {
+    String errorMessage = err.toString();
+    if (Path.WINDOWS) {
+      assertTrue(errorMessage.contains("(Access is denied)"));
+    } else {
+      assertTrue(errorMessage.contains("(Permission denied)"));
+    }
+  }
+
   @Test
   public void testLazyPersistDirectOverwrite() throws Exception {
     Path testRoot = new Path(testRootDir, "testLazyPersistDirectOverwrite");