PowerShell · Rob Holt (rjmholt) · Dec 8, 2020 · Oct 30, 2020 · Nov 11, 2020 · Dec 3, 2020
@@ -1311,35 +1311,36 @@ protected override void GetItem(string path)
                     // If we want to retrieve the file streams, retrieve them.
                     if (retrieveStreams)
                     {
-                        if (!isContainer)
+                        foreach (string desiredStream in dynamicParameters.Stream)
                         {
-                            foreach (string desiredStream in dynamicParameters.Stream)
-                            {
-                                // See that it matches the name specified
-                                WildcardPattern p = WildcardPattern.Get(desiredStream, WildcardOptions.IgnoreCase | WildcardOptions.CultureInvariant);
-                                bool foundStream = false;
+                            // See that it matches the name specified
+                            WildcardPattern p = WildcardPattern.Get(desiredStream, WildcardOptions.IgnoreCase | WildcardOptions.CultureInvariant);
+                            bool foundStream = false;
 
-                                foreach (AlternateStreamData stream in AlternateDataStreamUtilities.GetStreams(result.FullName))
+                            foreach (AlternateStreamData stream in AlternateDataStreamUtilities.GetStreams(result.FullName))
+                            {
+                                if (!p.IsMatch(stream.Stream))
                                 {
-                                    if (!p.IsMatch(stream.Stream)) { continue; }
-
-                                    string outputPath = result.FullName + ":" + stream.Stream;
-                                    WriteItemObject(stream, outputPath, isContainer);
-                                    foundStream = true;
+                                    continue;
                                 }
 
-                                if ((!WildcardPattern.ContainsWildcardCharacters(desiredStream)) && (!foundStream))
-                                {
-                                    string errorMessage = StringUtil.Format(
-                                        FileSystemProviderStrings.AlternateDataStreamNotFound, desiredStream, result.FullName);
-                                    Exception e = new FileNotFoundException(errorMessage, result.FullName);
-
-                                    WriteError(new ErrorRecord(
-                                        e,
-                                        "AlternateDataStreamNotFound",
-                                        ErrorCategory.ObjectNotFound,
-                                        path));
-                                }
+                                string outputPath = result.FullName + ":" + stream.Stream;
+                                // Alternate data streams can never be containers.
+                                WriteItemObject(stream, outputPath, isContainer: false);
+                                foundStream = true;
+                            }
+
+                            if ((!WildcardPattern.ContainsWildcardCharacters(desiredStream)) && (!foundStream))
+                            {
+                                string errorMessage = StringUtil.Format(
+                                    FileSystemProviderStrings.AlternateDataStreamNotFound, desiredStream, result.FullName);
+                                Exception e = new FileNotFoundException(errorMessage, result.FullName);
+
+                                WriteError(new ErrorRecord(
+                                    e,
+                                    "AlternateDataStreamNotFound",
+                                    ErrorCategory.ObjectNotFound,
+                                    path));
                             }
                         }
                     }
@@ -6666,7 +6667,14 @@ public IContentReader GetContentReader(string path)
 
             try
             {
-                if (Directory.Exists(path))
+                // Get-Content will write a non-terminating error if the target is a directory.
+                // On Windows, the streamName must be null or empty for it to write the error. Otherwise, the
+                // alternate data stream is not a directory, even if it's set on a directory.
+                if (Directory.Exists(path)
+#if !UNIX
+                    && string.IsNullOrEmpty(streamName)
+#endif
+                    )
                 {
                     string errMsg = StringUtil.Format(SessionStateStrings.GetContainerContentException, path);
                     ErrorRecord error = new ErrorRecord(new InvalidOperationException(errMsg), "GetContainerContentException", ErrorCategory.InvalidOperation, null);
@@ -6821,7 +6829,14 @@ public IContentWriter GetContentWriter(string path)
 
             try
             {
-                if (Directory.Exists(path))
+                // Add-Content and Set-Content will write a non-terminating error if the target is a directory.
+                // On Windows, the streamName must be null or empty for it to write the error. Otherwise, the
+                // alternate data stream is not a directory, even if it's set on a directory.
+                if (Directory.Exists(path)
+#if !UNIX
+                    && string.IsNullOrEmpty(streamName)
+#endif
+                    )
                 {
                     string errMsg = StringUtil.Format(SessionStateStrings.WriteContainerContentException, path);
                     ErrorRecord error = new ErrorRecord(new InvalidOperationException(errMsg), "WriteContainerContentException", ErrorCategory.InvalidOperation, null);
@@ -6899,13 +6914,6 @@ public void ClearContent(string path)
 
             path = NormalizePath(path);
 
-            if (Directory.Exists(path))
-            {
-                string errorMsg = StringUtil.Format(SessionStateStrings.ClearDirectoryContent, path);
-                WriteError(new ErrorRecord(new NotSupportedException(errorMsg), "ClearDirectoryContent", ErrorCategory.InvalidOperation, path));
-                return;
-            }
-
             try
             {
 #if !UNIX
@@ -6957,6 +6965,26 @@ public void ClearContent(string path)
                     clearStream = false;
                 }
 
+#endif
+                // On Windows, determine if our argument is a directory only after we determine if
+                // we're being asked to work with an alternate data stream, because directories can have
+                // alternate data streams on them that are not child items. These alternate data streams
+                // must be treated as data streams, even if they're attached to directories. However,
+                // if asked to work with a directory without a data stream specified, write a non-terminating
+                // error instead of clearing all child items of the directory. (On non-Windows, alternate
+                // data streams don't exist, so in that environment always write the error when addressing
+                // a directory.)
+                if (Directory.Exists(path)
+#if !UNIX
+                    && !clearStream
+#endif
+                    )
+                {
+                    string errorMsg = StringUtil.Format(SessionStateStrings.ClearDirectoryContent, path);
+                    WriteError(new ErrorRecord(new NotSupportedException(errorMsg), "ClearDirectoryContent", ErrorCategory.InvalidOperation, path));
+                    return;
+                }
+#if !UNIX
                 if (clearStream)
                 {
                     FileStream fileStream = null;
@@ -8622,7 +8650,22 @@ internal static List<AlternateStreamData> GetStreams(string path)
             SafeFindHandle handle = NativeMethods.FindFirstStreamW(
                 path, NativeMethods.StreamInfoLevels.FindStreamInfoStandard,
                 findStreamData, 0);
-            if (handle.IsInvalid) throw new Win32Exception();
+
+            if (handle.IsInvalid)
+            {
+                int error = Marshal.GetLastWin32Error();
+
+                // Directories don't normally have alternate streams, so this is not an exceptional state.
+                // If a directory has no alternate data streams, FindFirstStreamW returns ERROR_HANDLE_EOF.
+                if (error == NativeMethods.ERROR_HANDLE_EOF)
+                {
+                    return alternateStreams;
+                }
+
+                // An unexpected error was returned, that we don't know how to interpret. The most helpful
+                // thing we can do at this point is simply throw the raw Win32 exception.
+                throw new Win32Exception(error);
+            }
 
             try
             {
@@ -8757,6 +8800,7 @@ internal static void SetZoneOfOrigin(string path, SecurityZone securityZone)
         internal static class NativeMethods
         {
             internal const int ERROR_HANDLE_EOF = 38;
+            internal const int ERROR_INVALID_PARAMETER = 87;
 
             internal enum StreamInfoLevels { FindStreamInfoStandard = 0 }
 

@@ -5,6 +5,7 @@ Describe "Add-Content cmdlet tests" -Tags "CI" {
   BeforeAll {
     $file1 = "file1.txt"
     Setup -File "$file1"
+    $streamContent = "ShouldWork"
   }
 
   Context "Add-Content should actually add content" {
@@ -47,6 +48,29 @@ Describe "Add-Content cmdlet tests" -Tags "CI" {
       { Add-Content -Path . -Value "WriteContainerContentException" -ErrorAction Stop } | Should -Throw -ErrorId "WriteContainerContentException,Microsoft.PowerShell.Commands.AddContentCommand"
     }
 
+    Context "Add-Content should work with alternate data streams on Windows" {
+      BeforeAll {
+        if (!$isWindows) {
+          return
+        }
+        $ADSTestDir = "addcontentadstest"
+        $ADSTestFile = "addcontentads.txt"
+        $streamContent = "This is a test stream."
+        Setup -Directory "$ADSTestDir"
+        Setup -File "$ADSTestFile"
+      }
+
+      It "Should add an alternate data stream on a directory" -Skip:(!$IsWindows) {
+        Add-Content -Path TestDrive:\$ADSTestDir -Stream Add-Content-Test-Stream -Value $streamContent -ErrorAction Stop        
+        Get-Content -Path TestDrive:\$ADSTestDir -Stream Add-Content-Test-Stream | Should -BeExactly $streamContent
+      }
+
+      It "Should add an alternate data stream on a file" -Skip:(!$IsWindows) {
+        Add-Content -Path TestDrive:\$ADSTestFile -Stream Add-Content-Test-Stream -Value $streamContent -ErrorAction Stop        
+        Get-Content -Path TestDrive:\$ADSTestFile -Stream Add-Content-Test-Stream | Should -BeExactly $streamContent
+      }
+    }
+
     #[BugId(BugDatabase.WindowsOutOfBandReleases, 906022)]
     It "should throw 'NotSupportedException' when you add-content to an unsupported provider" -Skip:($IsLinux -Or $IsMacOS) {
       { Add-Content -Path HKLM:\\software\\microsoft -Value "ShouldNotWorkBecausePathIsUnsupported" -ErrorAction Stop } | Should -Throw -ErrorId "NotSupported,Microsoft.PowerShell.Commands.AddContentCommand"

@@ -51,6 +51,8 @@ Describe "Clear-Content cmdlet tests" -Tags "CI" {
     Setup -File "$file3" -Content $content2
     $streamContent = "content for alternate stream"
     $streamName = "altStream1"
+    $dirName = "clearcontent"
+    Setup -Directory "$dirName"
   }
 
   Context "Clear-Content should actually clear content" {
@@ -75,32 +77,50 @@ Describe "Clear-Content cmdlet tests" -Tags "CI" {
       $cci.SupportsShouldProcess | Should -BeTrue
     }
 
-    It "Alternate streams should be cleared with clear-content" -Skip:(!$IsWindows) {
-      # make sure that the content is correct
-      # this is here rather than BeforeAll because only windows can write to an alternate stream
-      Set-Content -Path "TestDrive:/$file3" -Stream $streamName -Value $streamContent
-      Get-Content -Path "TestDrive:/$file3" | Should -BeExactly $content2
-      Get-Content -Path "TestDrive:/$file3" -Stream $streamName | Should -BeExactly $streamContent
-      Clear-Content -Path "TestDrive:/$file3" -Stream $streamName
-      Get-Content -Path "TestDrive:/$file3" | Should -BeExactly $content2
-      Get-Content -Path "TestDrive:/$file3" -Stream $streamName | Should -BeNullOrEmpty
-    }
+    Context "Clear-Content should work with alternate data streams on Windows" {
+      It "Alternate streams should be cleared with Clear-Content on a file" -Skip:(!$IsWindows) {
+
+        Set-Content           -Path "TestDrive:/$file3" -Stream $streamName -Value $streamContent
+        Get-Content           -Path "TestDrive:/$file3" -Stream $streamName | Should -BeExactly $streamContent
+
+        Clear-Content         -Path "TestDrive:/$file3" -Stream $streamName -ErrorAction Stop
+
+        $result = Get-Item -Path "TestDrive:/$file3" -Stream $streamName
+        $result | Should -BeOfType System.Management.Automation.Internal.AlternateStreamData
+        $result.length | Should -Be 0
+      }
 
-    It "the '-Stream' dynamic parameter is visible to get-command in the filesystem" -Skip:(!$IsWindows) {
-      try {
-        Push-Location -Path TestDrive:
-        (Get-Command Clear-Content -Stream foo).parameters.keys -eq "stream" | Should -Be "stream"
+      It "Alternate streams should be cleared with Clear-Content on a directory" -Skip:(!$IsWindows) {
+        Set-Content           -Path "TestDrive:/$dirName" -Stream $streamName -Value $streamContent
+
+        Get-Content           -Path "TestDrive:/$dirName" -Stream $streamName | Should -BeExactly $streamContent
+        Clear-Content         -Path "TestDrive:/$dirName" -Stream $streamName -ErrorAction Stop
+
+        $result = Get-Item -Path "TestDrive:/$dirName" -Stream $streamName
+        $result | Should -BeOfType System.Management.Automation.Internal.AlternateStreamData
+        $result.length | Should -Be 0
       }
-      finally {
-        Pop-Location
+
+      It "the '-Stream' dynamic parameter is visible to get-command in the filesystem" -Skip:(!$IsWindows) {
+        try {
+          Push-Location -Path TestDrive:
+          (Get-Command Clear-Content -Stream foo).parameters.keys -eq "Stream" | Should -BeExactly "Stream"
+        }
+        finally {
+          Pop-Location
+        }
       }
-    }
 
-    It "the '-Stream' dynamic parameter should not be visible to get-command in the function provider" {
-      Push-Location -Path function:
-      { Get-Command Clear-Content -Stream $streamName } |
-        Should -Throw -ErrorId "NamedParameterNotFound,Microsoft.PowerShell.Commands.GetCommandCommand"
-      Pop-Location
+      It "the '-Stream' dynamic parameter should not be visible to get-command in the function provider" -Skip:(!$IsWindows) {
+        try {
+        Push-Location -Path function:
+          { Get-Command Clear-Content -Stream $streamName } |
+            Should -Throw -ErrorId "NamedParameterNotFound,Microsoft.PowerShell.Commands.GetCommandCommand"
+        }
+        finally {
+          Pop-Location
+        }
+      }
     }
   }
 

@@ -221,25 +221,27 @@ Describe "Get-Content" -Tags "CI" {
         $expected = 'He', 'o,', '', 'Wor', "d${nl}He", 'o2,', '', 'Wor', "d2${nl}"
         for ($i = 0; $i -lt $result.Length ; $i++) { $result[$i]    | Should -BeExactly $expected[$i]}
     }
+
+    Context "Alternate Data Stream support on Windows" {
+        It "Should support NTFS streams using colon syntax" -Skip:(!$IsWindows) {
+            Set-Content "${testPath}:Stream" -Value "Foo"
+            { Test-Path "${testPath}:Stream" | Should -Throw -ErrorId "ItemExistsNotSupportedError,Microsoft.PowerShell.Commands,TestPathCommand" }
+            Get-Content "${testPath}:Stream" | Should -BeExactly "Foo"
+            Get-Content $testPath | Should -BeExactly $testString
+        }
 
-    It "Should support NTFS streams using colon syntax" -Skip:(!$IsWindows) {
-        Set-Content "${testPath}:Stream" -Value "Foo"
-        { Test-Path "${testPath}:Stream" | Should -Throw -ErrorId "ItemExistsNotSupportedError,Microsoft.PowerShell.Commands,TestPathCommand" }
-        Get-Content "${testPath}:Stream" | Should -BeExactly "Foo"
-        Get-Content $testPath | Should -BeExactly $testString
-    }
-
-    It "Should support NTFS streams using -Stream" -Skip:(!$IsWindows) {
-        Set-Content -Path $testPath -Stream hello -Value World
-        Get-Content -Path $testPath | Should -BeExactly $testString
-        Get-Content -Path $testPath -Stream hello | Should -BeExactly "World"
-        $item = Get-Item -Path $testPath -Stream hello
-        $item | Should -BeOfType System.Management.Automation.Internal.AlternateStreamData
-        $item.Stream | Should -BeExactly "hello"
-        Clear-Content -Path $testPath -Stream hello
-        Get-Content -Path $testPath -Stream hello | Should -BeNullOrEmpty
-        Remove-Item -Path $testPath -Stream hello
-        { Get-Content -Path $testPath -Stream hello | Should -Throw -ErrorId "GetContentReaderFileNotFoundError,Microsoft.PowerShell.Commands.GetContentCommand" }
+        It "Should support NTFS streams using -Stream" -Skip:(!$IsWindows) {
+            Set-Content -Path $testPath -Stream hello -Value World
+            Get-Content -Path $testPath | Should -BeExactly $testString
+            Get-Content -Path $testPath -Stream hello | Should -BeExactly "World"
+            $item = Get-Item -Path $testPath -Stream hello
+            $item | Should -BeOfType System.Management.Automation.Internal.AlternateStreamData
+            $item.Stream | Should -BeExactly "hello"
+            Clear-Content -Path $testPath -Stream hello
+            Get-Content -Path $testPath -Stream hello | Should -BeNullOrEmpty
+            Remove-Item -Path $testPath -Stream hello
+            { Get-Content -Path $testPath -Stream hello -ErrorAction stop} | Should -Throw -ErrorId "GetContentReaderFileNotFoundError,Microsoft.PowerShell.Commands.GetContentCommand"
+        }
     }
 
     It "Should support colons in filename on Linux/Mac" -Skip:($IsWindows) {