Create warnings when UTF7 is specified as an encoding (#13430)

src/Microsoft.PowerShell.Commands.Utility/commands/utility/CsvCommands.cs

@@ -217,7 +217,21 @@ namespace Microsoft.PowerShell.Commands
         [ArgumentToEncodingTransformationAttribute]
         [ArgumentEncodingCompletionsAttribute]
         [ValidateNotNullOrEmpty]
-        public Encoding Encoding { get; set; } = ClrFacade.GetDefaultEncoding();
+        public Encoding Encoding
+        {
+            get
+            {
+                return _encoding;
+            }
+
+            set
+            {
+                EncodingConversion.WarnIfObsolete(this, value);
+                _encoding = value;
+            }
+        }
+
+        private Encoding _encoding = ClrFacade.GetDefaultEncoding();
 
         /// <summary>
         /// Gets or sets property that sets append parameter.
@@ -592,7 +606,21 @@ namespace Microsoft.PowerShell.Commands
         [ArgumentToEncodingTransformationAttribute]
         [ArgumentEncodingCompletionsAttribute]
         [ValidateNotNullOrEmpty]
-        public Encoding Encoding { get; set; } = ClrFacade.GetDefaultEncoding();
+        public Encoding Encoding
+        {
+            get
+            {
+                return _encoding;
+            }
+
+            set
+            {
+                EncodingConversion.WarnIfObsolete(this, value);
+                _encoding = value;
+            }
+        }
+
+        private Encoding _encoding = ClrFacade.GetDefaultEncoding();
 
         /// <summary>
         /// Avoid writing out duplicate warning messages when there are one or more unspecified names.

src/Microsoft.PowerShell.Commands.Utility/commands/utility/FormatAndOutput/format-hex/Format-Hex.cs

@@ -71,7 +71,20 @@ namespace Microsoft.PowerShell.Commands
         [ArgumentToEncodingTransformationAttribute()]
         [ArgumentEncodingCompletionsAttribute]
         [ValidateNotNullOrEmpty]
-        public Encoding Encoding { get; set; } = ClrFacade.GetDefaultEncoding();
+        public Encoding Encoding
+        {
+            get
+            {
+                return _encoding;
+            }
+            set
+            {
+                EncodingConversion.WarnIfObsolete(this, value);
+                _encoding = value;
+            }
+        }
+
+        private Encoding _encoding = ClrFacade.GetDefaultEncoding();
 
         /// <summary>
         /// Gets or sets count of bytes to read from the input stream.

src/Microsoft.PowerShell.Commands.Utility/commands/utility/FormatAndOutput/out-file/Out-File.cs

@@ -78,7 +78,21 @@ namespace Microsoft.PowerShell.Commands
         [ArgumentToEncodingTransformationAttribute()]
         [ArgumentEncodingCompletionsAttribute]
         [ValidateNotNullOrEmpty]
-        public Encoding Encoding { get; set; } = ClrFacade.GetDefaultEncoding();
+        public Encoding Encoding
+        {
+            get
+            {
+                return _encoding;
+            }
+
+            set
+            {
+                EncodingConversion.WarnIfObsolete(this, value);
+                _encoding = value;
+            }
+        }
+
+        private Encoding _encoding = ClrFacade.GetDefaultEncoding();
 
         /// <summary>
         /// Property that sets append parameter.

src/Microsoft.PowerShell.Commands.Utility/commands/utility/ImplicitRemotingCommands.cs

@@ -76,7 +76,21 @@ namespace Microsoft.PowerShell.Commands
         [ArgumentToEncodingTransformationAttribute()]
         [ArgumentEncodingCompletionsAttribute]
         [ValidateNotNullOrEmpty]
-        public Encoding Encoding { get; set; } = ClrFacade.GetDefaultEncoding();
+        public Encoding Encoding
+        {
+            get
+            {
+                return _encoding;
+            }
+
+            set
+            {
+                EncodingConversion.WarnIfObsolete(this, value);
+                _encoding = value;
+            }
+        }
+
+        private Encoding _encoding = ClrFacade.GetDefaultEncoding();
 
         #endregion Parameters
 

src/Microsoft.PowerShell.Commands.Utility/commands/utility/MatchString.cs

@@ -1349,7 +1349,21 @@ namespace Microsoft.PowerShell.Commands
         [ArgumentToEncodingTransformationAttribute()]
         [ArgumentEncodingCompletionsAttribute]
         [ValidateNotNullOrEmpty]
-        public Encoding Encoding { get; set; } = ClrFacade.GetDefaultEncoding();
+        public Encoding Encoding
+        {
+            get
+            {
+                return _encoding;
+            }
+
+            set
+            {
+                EncodingConversion.WarnIfObsolete(this, value);
+                _encoding = value;
+            }
+        }
+
+        private Encoding _encoding = ClrFacade.GetDefaultEncoding();
 
         /// <summary>
         /// Gets or sets the number of context lines to collect. If set to a

src/Microsoft.PowerShell.Commands.Utility/commands/utility/Send-MailMessage.cs

@@ -63,7 +63,21 @@ namespace Microsoft.PowerShell.Commands
         [ValidateNotNullOrEmpty]
         [ArgumentEncodingCompletionsAttribute]
         [ArgumentToEncodingTransformationAttribute]
-        public Encoding Encoding { get; set; } = Encoding.ASCII;
+        public Encoding Encoding
+        {
+            get
+            {
+                return _encoding;
+            }
+
+            set
+            {
+                EncodingConversion.WarnIfObsolete(this, value);
+                _encoding = value;
+            }
+        }
+
+        private Encoding _encoding = Encoding.ASCII;
 
         /// <summary>
         /// Gets or sets the address collection that contains the

src/Microsoft.PowerShell.Commands.Utility/commands/utility/XmlCommands.cs

@@ -114,7 +114,21 @@ namespace Microsoft.PowerShell.Commands
         [ArgumentToEncodingTransformationAttribute()]
         [ArgumentEncodingCompletionsAttribute]
         [ValidateNotNullOrEmpty]
-        public Encoding Encoding { get; set; } = ClrFacade.GetDefaultEncoding();
+        public Encoding Encoding
+        {
+            get
+            {
+                return _encoding;
+            }
+
+            set
+            {
+                EncodingConversion.WarnIfObsolete(this, value);
+                _encoding = value;
+            }
+        }
+
+        private Encoding _encoding = ClrFacade.GetDefaultEncoding();
 
         #endregion Command Line Parameters
 

src/System.Management.Automation/namespaces/FileSystemProvider.cs

@@ -6744,7 +6744,7 @@ namespace Microsoft.PowerShell.Commands
         /// </returns>
         public object GetContentReaderDynamicParameters(string path)
         {
-            return new FileSystemContentReaderDynamicParameters();
+            return new FileSystemContentReaderDynamicParameters(this);
         }
 
         /// <summary>
@@ -6878,7 +6878,7 @@ namespace Microsoft.PowerShell.Commands
         /// </returns>
         public object GetContentWriterDynamicParameters(string path)
         {
-            return new FileSystemContentWriterDynamicParameters();
+            return new FileSystemContentWriterDynamicParameters(this);
         }
 
         /// <summary>
@@ -7593,6 +7593,13 @@ namespace Microsoft.PowerShell.Commands
     /// </summary>
     public class FileSystemContentDynamicParametersBase
     {
+        internal FileSystemContentDynamicParametersBase(FileSystemProvider provider)
+        {
+            _provider = provider;
+        }
+
+        private FileSystemProvider _provider;
+
         /// <summary>
         /// Gets or sets the encoding method used when
         /// reading data from the file.
@@ -7610,6 +7617,10 @@ namespace Microsoft.PowerShell.Commands
 
             set
             {
+                if (value == System.Text.Encoding.UTF7)
+                {
+                    _provider.WriteWarning(PathUtilsStrings.Utf7EncodingObsolete);
+                }
                 _encoding = value;
                 // If an encoding was explicitly set, be sure to capture that.
                 WasStreamTypeSpecified = true;
@@ -7659,6 +7670,8 @@ namespace Microsoft.PowerShell.Commands
     /// </summary>
     public class FileSystemContentWriterDynamicParameters : FileSystemContentDynamicParametersBase
     {
+        internal FileSystemContentWriterDynamicParameters(FileSystemProvider provider) : base(provider) { }
+
         /// <summary>
         /// False to add a newline to the end of the output string, true if not.
         /// </summary>
@@ -7684,6 +7697,8 @@ namespace Microsoft.PowerShell.Commands
     /// </summary>
     public class FileSystemContentReaderDynamicParameters : FileSystemContentDynamicParametersBase
     {
+        internal FileSystemContentReaderDynamicParameters(FileSystemProvider provider) : base (provider) { }
+
         /// <summary>
         /// Gets or sets the delimiter to use when reading the file.  Custom delimiters
         /// may not be used when the file is opened with a "Byte" encoding.

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

@@ -117,6 +117,9 @@
   <resheader name="writer">
     <value>System.Resources.ResXResourceWriter, System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</value>
   </resheader>
+  <data name="Utf7EncodingObsolete" xml:space="preserve">
+    <value>Encoding 'UTF-7' is obsolete, please use UTF-8.</value>
+  </data>
   <data name="UtilityFileExistsNoClobber" xml:space="preserve">
     <value>File {0} already exists and {1} was specified.</value>
   </data>

src/System.Management.Automation/utils/EncodingUtils.cs

@@ -63,6 +63,12 @@ namespace System.Management.Automation
             Encoding foundEncoding;
             if (encodingMap.TryGetValue(encoding, out foundEncoding))
             {
+                // Write a warning if using utf7 as it is obsolete in .NET5
+                if (string.Compare(encoding, Utf7, StringComparison.OrdinalIgnoreCase) == 0)
+                {
+                    cmdlet.WriteWarning(PathUtilsStrings.Utf7EncodingObsolete);
+                }
+
                 return foundEncoding;
             }
 
@@ -81,6 +87,19 @@ namespace System.Management.Automation
 
             return null;
         }
+
+        /// <summary>
+        /// Warn if the encoding has been designated as obsolete.
+        /// </summary>
+        /// <param name="cmdlet">A cmdlet instance which is used to emit the warning.</param>
+        /// <param name="encoding">The encoding to check for obsolescence.</param>
+        internal static void WarnIfObsolete(Cmdlet cmdlet, Encoding encoding)
+        {
+            if (encoding == System.Text.Encoding.UTF7)
+            {
+                cmdlet.WriteWarning(PathUtilsStrings.Utf7EncodingObsolete);
+            }
+        }
     }
 
     /// <summary>

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

@@ -99,4 +99,30 @@ Describe "File encoding tests" -Tag CI {
             (Get-Content $testFile -AsByteStream) -join "-" | Should -BeExactly $expectedBytes
         }
     }
+
+    Context "Using encoding utf7 results in a warning" {
+        BeforeAll {
+            $expectedString = "Encoding 'UTF-7' is obsolete, please use UTF-8."
+            $testCases = @(
+                @{ Command = 'Add-Content';   Script = { "test" | Add-Content -Encoding utf7 -Path TESTDRIVE:/file 3>TESTDRIVE:/warning } }
+                @{ Command = 'Export-CliXml'; Script = { "test" | Export-Clixml -Path TESTDRIVE:/file.ps1xml -Encoding utf7 3>TESTDRIVE:/warning } }
+                @{ Command = 'Export-Csv';    Script = { "test" | Export-Csv -Path TESTDRIVE:/export.csv -Encoding utf7 3>TESTDRIVE:/warning } }
+                @{ Command = 'Format-Hex';    Script = { "test" | Format-Hex -Encoding utf7 > TESTDRIVE:/output 3>TESTDRIVE:/warning } }
+                @{ Command = 'Get-Content';   Script = { "output" > TESTDRIVE:/input; $null = Get-Content -Path TESTDRIVE:/input -Encoding utf7 3>TESTDRIVE:/warning } }
+                @{ Command = 'Import-Csv';    Script = { "test" | Export-Csv -Path TESTDRIVE:/output.csv; $null = Import-Csv -Path TESTDRIVE:/output.csv -Encoding utf7 3>TESTDRIVE:/warning } }
+                @{ Command = 'Out-File';      Script = { "test" | Out-File -Path TESTDRIVE:/output.txt -Encoding utf7 3>TESTDRIVE:/warning } }
+                @{ Command = 'Select-String'; Script = { "aa" | Select-String -pattern bb -Encoding utf7 3>TESTDRIVE:/warning } }
+                @{ Command = 'Set-Content';   Script = { "aa" | Set-Content -Path TESTDRIVE:/output.txt -Encoding utf7 3>TESTDRIVE:/warning } }
+            )
+        }
+        BeforeEach {
+            Remove-Item TESTDRIVE:/* -force -ErrorAction Ignore
+        }
+        It "'<command> has a warning when '-Encoding utf7' is used" -TestCases $testCases {
+            param ($command, $script)
+            & $script
+            $observed = Get-Content TESTDRIVE:/warning
+            $observed | Should -BeExactly $expectedString
+        }
+    }
 }