Skip removing read only attribute for Symlinks AB#2248480 (#5144)

Author: praval-microsoft

src/Agent.Sdk/Util/IOUtil.cs

@@ -146,8 +146,11 @@ public static void DeleteDirectory(string path, bool contentsOnly, bool continue
                             bool success = false;
                             try
                             {
-                                // Remove the readonly attribute.
-                                RemoveReadOnly(item);
+                                // Skip for Symlinks
+                                if (!item.Attributes.HasFlag(FileAttributes.ReparsePoint)) {
+                                    // Remove the readonly attribute.
+                                    RemoveReadOnly(item);
+                                }
 
                                 // Check if the item is a file.
                                 if (item is FileInfo)

src/Test/L0/Util/IOUtilL0.cs

@@ -82,6 +82,47 @@ public void Delete_DeletesFile()
             }
         }
 
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Common")]
+        public async void DeleteDirectory_DeleteTargetFileWithASymlink()
+        {
+            using (TestHostContext hc = new TestHostContext(this))
+            {
+                Tracing trace = hc.GetTrace();
+
+                // Arrange: Create a directory with a file.
+                string directory = Path.Combine(hc.GetDirectory(WellKnownDirectory.Bin), Path.GetRandomFileName());
+                string targetFile = Path.Combine(directory, "somefile");
+                string symlink = Path.Combine(directory, "symlink");
+                try
+                {
+                    Directory.CreateDirectory(directory);
+                    File.WriteAllText(path: targetFile, contents: "some contents");
+                    File.SetAttributes(targetFile, File.GetAttributes(targetFile) | FileAttributes.ReadOnly);
+
+                    await CreateFileReparsePoint(context: hc, link: symlink, target: targetFile);
+
+                    // Act.
+                    IOUtil.DeleteFile(targetFile);
+                    IOUtil.DeleteDirectory(directory, CancellationToken.None);
+
+                    // Assert.
+                    Assert.False(File.Exists(targetFile));
+                    Assert.False(File.Exists(symlink));
+
+                }
+                finally
+                {
+                    // Cleanup.
+                    if (Directory.Exists(directory))
+                    {
+                        Directory.Delete(directory, recursive: true);
+                    }
+                }
+            }
+        }
+
         [Fact]
         [Trait("Level", "L0")]
         [Trait("Category", "Common")]
@@ -1269,5 +1310,28 @@ public void GetDirectoryName_WindowsStyle()
                 }
             }
         }
+
+        private static async Task CreateFileReparsePoint(IHostContext context, string link, string target)
+        {
+            string fileName = (TestUtil.IsWindows())
+                ? Environment.GetEnvironmentVariable("ComSpec")
+                : "/bin/ln";
+            string arguments = (TestUtil.IsWindows())
+                ? $@"/c ""mklink ""{link}"" ""{target}"""""
+                : $@"-s ""{target}"" ""{link}""";
+
+            ArgUtil.File(fileName, nameof(fileName));
+            using (var processInvoker = new ProcessInvokerWrapper())
+            {
+                processInvoker.Initialize(context);
+                await processInvoker.ExecuteAsync(
+                    workingDirectory: context.GetDirectory(WellKnownDirectory.Bin),
+                    fileName: fileName,
+                    arguments: arguments,
+                    environment: null,
+                    requireExitCodeZero: true,
+                    cancellationToken: CancellationToken.None);
+            }
+        }
     }
 }