Add PSApplicationOutputEncoding variable

src/System.Management.Automation/engine/InitialSessionState.cs

@@ -4527,6 +4527,14 @@ static InitialSessionState()
                     ScopedItemOptions.None,
                     new ArgumentTypeConverterAttribute(typeof(System.Text.Encoding))),
 
+                // Variable which controls the encoding for decoding data from a NativeCommand
+                new SessionStateVariableEntry(
+                    SpecialVariables.PSApplicationOutputEncoding,
+                    null,
+                    RunspaceInit.PSApplicationOutputEncodingDescription,
+                    ScopedItemOptions.None,
+                    new ArgumentTypeConverterAttribute(typeof(Encoding))),
+
                 // Preferences
                 //
                 // NTRAID#Windows Out Of Band Releases-931461-2006/03/13

src/System.Management.Automation/engine/NativeCommandProcessor.cs

@@ -1433,16 +1433,17 @@ NativeParameterBinderController.ArgumentPassingStyle switch
                 startInfo.UseShellExecute = false;
                 startInfo.RedirectStandardInput = redirectInput;
 
+                Encoding outputEncoding = GetOutputEncoding();
                 if (redirectOutput)
                 {
                     startInfo.RedirectStandardOutput = true;
-                    startInfo.StandardOutputEncoding = Console.OutputEncoding;
+                    startInfo.StandardOutputEncoding = outputEncoding;
                 }
 
                 if (redirectError)
                 {
                     startInfo.RedirectStandardError = true;
-                    startInfo.StandardErrorEncoding = Console.OutputEncoding;
+                    startInfo.StandardErrorEncoding = outputEncoding;
                 }
             }
 
@@ -1499,6 +1500,20 @@ NativeParameterBinderController.ArgumentPassingStyle switch
             return startInfo;
         }
 
+#nullable enable
+        /// <summary>
+        /// Gets the encoding to use for a process' output/error pipes.
+        /// </summary>
+        /// <returns>The encoding to use for the process output.</returns>
+        private Encoding GetOutputEncoding()
+        {
+            Encoding? applicationOutputEncoding = Context.GetVariableValue(
+                    SpecialVariables.PSApplicationOutputEncodingVarPath) as Encoding;
+
+            return applicationOutputEncoding ?? Console.OutputEncoding;
+        }
+#nullable disable
+
         /// <summary>
         /// Determine if we have a special file which will change the way native argument passing
         /// is done on Windows. We use legacy behavior for cmd.exe, .bat, .cmd files.

src/System.Management.Automation/engine/SpecialVariables.cs

@@ -41,6 +41,10 @@ internal static class SpecialVariables
 
         internal static readonly VariablePath OutputEncodingVarPath = new VariablePath(OutputEncoding);
 
+        internal const string PSApplicationOutputEncoding = nameof(PSApplicationOutputEncoding);
+
+        internal static readonly VariablePath PSApplicationOutputEncodingVarPath = new VariablePath(PSApplicationOutputEncoding);
+
         internal const string VerboseHelpErrors = "VerboseHelpErrors";
 
         internal static readonly VariablePath VerboseHelpErrorsVarPath = new VariablePath(VerboseHelpErrors);
@@ -386,6 +390,7 @@ internal static class SpecialVariables
                     SpecialVariables.NestedPromptLevel,
                     SpecialVariables.pwd,
                     SpecialVariables.Matches,
+                    SpecialVariables.PSApplicationOutputEncoding,
                 },
                 StringComparer.OrdinalIgnoreCase
             );

src/System.Management.Automation/resources/RunspaceInit.resx

@@ -153,6 +153,9 @@
   <data name="OutputEncodingDescription" xml:space="preserve">
     <value>The text encoding used when piping text to a native executable file</value>
   </data>
+  <data name="PSApplicationOutputEncodingDescription" xml:space="preserve">
+    <value>The text encoding used when reading output text from a native executable file</value>
+  </data>
   <data name="PSStyleDescription" xml:space="preserve">
     <value>Configuration controlling how text is rendered.</value>
   </data>

test/powershell/engine/Basic/NativeCommandEncoding.Tests.ps1

@@ -0,0 +1,62 @@
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT License.
+
+Describe 'Native command output encoding tests' -Tags 'CI' {
+    BeforeAll {
+        $WriteConsoleOutPath = Join-Path $PSScriptRoot assets WriteConsoleOut.ps1
+        $defaultEncoding = [Console]::OutputEncoding.WebName
+    }
+
+    BeforeEach {
+        Clear-Variable -Name PSApplicationOutputEncoding
+    }
+
+    AfterEach {
+        Clear-Variable -Name PSApplicationOutputEncoding
+    }
+
+    It 'Defaults to [Console]::OutputEncoding if not set' {
+        $actual = pwsh -File $WriteConsoleOutPath -Value café -Encoding $defaultEncoding
+        $actual | Should -Be café
+    }
+
+    It 'Defaults to [Console]::OutputEncoding if set to $null' {
+        $PSApplicationOutputEncoding = $null
+        $actual = pwsh -File $WriteConsoleOutPath -Value café -Encoding $defaultEncoding
+        $actual | Should -Be café
+    }
+
+    It 'Uses scoped $PSApplicationOutputEncoding value' {
+        $PSApplicationOutputEncoding = [System.Text.Encoding]::Unicode
+        $actual = & {
+            $PSApplicationOutputEncoding = [System.Text.UTF8Encoding]::new()
+            pwsh -File $WriteConsoleOutPath -Value café -Encoding utf-8
+        }
+
+        $actual | Should -Be café
+
+        # Will use UTF-16-LE hence the different values
+        $actual = pwsh -File $WriteConsoleOutPath -Value café -Encoding Unicode
+        $actual | Should -Be café
+    }
+
+    It 'Uses variable in class method' {
+        class NativeEncodingTestClass {
+            static [string] RunTest([string]$Script) {
+                $PSApplicationOutputEncoding = [System.Text.Encoding]::Unicode
+                return pwsh -File $Script -Value café -Encoding unicode
+            }
+        }
+
+        $actual = [NativeEncodingTestClass]::RunTest($WriteConsoleOutPath)
+        $actual | Should -Be café
+    }
+
+    It 'Fails to set variable with invalid encoding object' {
+        $ps = [PowerShell]::Create()
+        $ps.AddScript('$PSApplicationOutputEncoding = "utf-8"').Invoke()
+
+        $ps.Streams.Error.Count | Should -Be 1
+        [string]$ps.Streams.Error[0] | Should -Be 'Cannot convert the "utf-8" value of type "System.String" to type "System.Text.Encoding".'
+    }
+}

test/powershell/engine/Basic/assets/WriteConsoleOut.ps1

@@ -0,0 +1,23 @@
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT License.
+
+[CmdletBinding()]
+param (
+    [Parameter(Mandatory)]
+    [string]
+    $Value,
+
+    [Parameter(Mandatory)]
+    [string]
+    $Encoding
+)
+
+$enc = [System.Text.Encoding]::GetEncoding($Encoding)
+$data = $enc.GetBytes($Value)
+
+$outStream = [System.Console]::OpenStandardOutput()
+try {
+    $outStream.Write($data, 0, $data.Length)
+} finally {
+    $outStream.Dispose()
+}