Implement Tar Global Extended Attributes API changes

src/libraries/System.Formats.Tar/ref/System.Formats.Tar.cs

@@ -13,6 +13,11 @@ public GnuTarEntry(System.Formats.Tar.TarEntryType entryType, string entryName)
         public System.DateTimeOffset AccessTime { get { throw null; } set { } }
         public System.DateTimeOffset ChangeTime { get { throw null; } set { } }
     }
+    public sealed partial class PaxGlobalExtendedAttributesTarEntry : System.Formats.Tar.PosixTarEntry
+    {
+        public PaxGlobalExtendedAttributesTarEntry(System.Collections.Generic.IEnumerable<System.Collections.Generic.KeyValuePair<string, string>> globalExtendedAttributes) { }
+        public System.Collections.Generic.IReadOnlyDictionary<string, string> GlobalExtendedAttributes { get { throw null; } }
+    }
     public sealed partial class PaxTarEntry : System.Formats.Tar.PosixTarEntry
     {
         public PaxTarEntry(System.Formats.Tar.TarEntry other) { }
@@ -101,14 +106,13 @@ public enum TarFileMode
     public sealed partial class TarReader : System.IDisposable
     {
         public TarReader(System.IO.Stream archiveStream, bool leaveOpen = false) { }
-        public System.Collections.Generic.IReadOnlyDictionary<string, string>? GlobalExtendedAttributes { get { throw null; } }
         public void Dispose() { }
         public System.Formats.Tar.TarEntry? GetNextEntry(bool copyData = false) { throw null; }
     }
     public sealed partial class TarWriter : System.IDisposable
     {
         public TarWriter(System.IO.Stream archiveStream) { }
-        public TarWriter(System.IO.Stream archiveStream, System.Collections.Generic.IEnumerable<System.Collections.Generic.KeyValuePair<string, string>>? globalExtendedAttributes = null, bool leaveOpen = false) { }
+        public TarWriter(System.IO.Stream archiveStream, bool leaveOpen = false) { }
         public TarWriter(System.IO.Stream archiveStream, System.Formats.Tar.TarEntryFormat format = System.Formats.Tar.TarEntryFormat.Pax, bool leaveOpen = false) { }
         public System.Formats.Tar.TarEntryFormat Format { get { throw null; } }
         public void Dispose() { }

src/libraries/System.Formats.Tar/src/Resources/Strings.resx

@@ -186,12 +186,12 @@
   <data name="SetLengthRequiresSeekingAndWriting" xml:space="preserve">
     <value>SetLength requires a stream that supports seeking and writing.</value>
   </data>
+  <data name="TarCannotConvertPaxGlobalExtendedAttributesEntry" xml:space="preserve">
+    <value>Cannot convert a PaxGlobalExtendedAttributesEntry into another format.</value>
+  </data>
   <data name="TarDuplicateExtendedAttribute" xml:space="preserve">
     <value>The entry '{0}' has a duplicate extended attribute.</value>
   </data>
-  <data name="TarEntriesInDifferentFormats" xml:space="preserve">
-    <value>An entry in '{0}' format was found in an archive where other entries of format '{1}' have been found.</value>
-  </data>
   <data name="TarEntryBlockOrCharacterExpected" xml:space="preserve">
     <value>Cannot set the 'DeviceMajor' or 'DeviceMinor' fields on an entry that does not represent a block or character device.</value>
   </data>
@@ -240,9 +240,6 @@
   <data name="TarSymbolicLinkTargetNotExists" xml:space="preserve">
     <value>Cannot create the symbolic link '{0}' because the specified target '{1}' does not exist.</value>
   </data>
-  <data name="TarTooManyGlobalExtendedAttributesEntries" xml:space="preserve">
-    <value>The archive has more than one global extended attributes entry.</value>
-  </data>
   <data name="TarUnexpectedMetadataEntry" xml:space="preserve">
     <value>A metadata entry of type '{0}' was unexpectedly found after a metadata entry of type '{1}'.</value>
   </data>

src/libraries/System.Formats.Tar/src/System.Formats.Tar.csproj

@@ -24,6 +24,7 @@
     <Compile Include="System\Formats\Tar\TarEntryFormat.cs" />
     <Compile Include="System\Formats\Tar\UstarTarEntry.cs" />
     <Compile Include="System\Formats\Tar\GnuTarEntry.cs" />
+    <Compile Include="System\Formats\Tar\PaxGlobalExtendedAttributesTarEntry.cs" />
     <Compile Include="System\Formats\Tar\PaxTarEntry.cs" />
     <Compile Include="System\Formats\Tar\TarEntryType.cs" />
     <Compile Include="System\Formats\Tar\TarFile.cs" />

src/libraries/System.Formats.Tar/src/System/Formats/Tar/GnuTarEntry.cs

@@ -29,7 +29,7 @@ internal GnuTarEntry(TarHeader header, TarReader readerOfOrigin)
         /// </list>
         /// </remarks>
         public GnuTarEntry(TarEntryType entryType, string entryName)
-            : base(entryType, entryName, TarEntryFormat.Gnu)
+            : base(entryType, entryName, TarEntryFormat.Gnu, isGea: false)
         {
             _header._aTime = _header._mTime; // mtime was set in base constructor
             _header._cTime = _header._mTime;

src/libraries/System.Formats.Tar/src/System/Formats/Tar/PaxGlobalExtendedAttributesTarEntry.cs

@@ -0,0 +1,50 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.Collections.Generic;
+using System.Collections.ObjectModel;
+using System.Diagnostics;
+
+namespace System.Formats.Tar
+{
+    /// <summary>
+    /// Represents a Global Extended Attributes TAR entry from an archive of the PAX format.
+    /// </summary>
+    public sealed class PaxGlobalExtendedAttributesTarEntry : PosixTarEntry
+    {
+        private ReadOnlyDictionary<string, string>? _readOnlyGlobalExtendedAttributes;
+
+        // Constructor used when reading an existing archive.
+        internal PaxGlobalExtendedAttributesTarEntry(TarHeader header, TarReader readerOfOrigin)
+            : base(header, readerOfOrigin, TarEntryFormat.Pax)
+        {
+        }
+
+        /// <summary>
+        /// Initializes a new <see cref="PaxGlobalExtendedAttributesTarEntry"/> instance with the specified Global Extended Attributes enumeration.
+        /// </summary>
+        /// <param name="globalExtendedAttributes">An enumeration of string key-value pairs that represents the metadata to include as Global Extended Attributes.</param>
+        /// <exception cref="ArgumentNullException"><paramref name="globalExtendedAttributes"/> is <see langword="null"/>.</exception>
+        public PaxGlobalExtendedAttributesTarEntry(IEnumerable<KeyValuePair<string, string>> globalExtendedAttributes)
+            : base(TarEntryType.GlobalExtendedAttributes, TarHeader.GlobalHeadFormatPrefix, TarEntryFormat.Pax, isGea: true)
+        {
+            ArgumentNullException.ThrowIfNull(globalExtendedAttributes);
+            _header._extendedAttributes = new Dictionary<string, string>(globalExtendedAttributes);
+        }
+
+        /// <summary>
+        /// Returns the global extended attributes stored in this entry.
+        /// </summary>
+        public IReadOnlyDictionary<string, string> GlobalExtendedAttributes
+        {
+            get
+            {
+                _header._extendedAttributes ??= new Dictionary<string, string>();
+                return _readOnlyGlobalExtendedAttributes ??= _header._extendedAttributes.AsReadOnly();
+            }
+        }
+
+        // Determines if the current instance's entry type supports setting a data stream.
+        internal override bool IsDataStreamSetterSupported() => false;
+    }
+}

src/libraries/System.Formats.Tar/src/System/Formats/Tar/PaxTarEntry.cs

@@ -48,7 +48,7 @@ internal PaxTarEntry(TarHeader header, TarReader readerOfOrigin)
         /// </list>
         /// </remarks>
         public PaxTarEntry(TarEntryType entryType, string entryName)
-            : base(entryType, entryName, TarEntryFormat.Pax)
+            : base(entryType, entryName, TarEntryFormat.Pax, isGea: false)
         {
             _header._prefix = string.Empty;
             _header._extendedAttributes = new Dictionary<string, string>();
@@ -87,7 +87,7 @@ public PaxTarEntry(TarEntryType entryType, string entryName)
         /// </list>
         /// </remarks>
         public PaxTarEntry(TarEntryType entryType, string entryName, IEnumerable<KeyValuePair<string, string>> extendedAttributes)
-            : base(entryType, entryName, TarEntryFormat.Pax)
+            : base(entryType, entryName, TarEntryFormat.Pax, isGea: false)
         {
             ArgumentNullException.ThrowIfNull(extendedAttributes);
 

src/libraries/System.Formats.Tar/src/System/Formats/Tar/PosixTarEntry.cs

@@ -19,8 +19,8 @@ internal PosixTarEntry(TarHeader header, TarReader readerOfOrigin, TarEntryForma
         }
 
         // Constructor called when the user creates a TarEntry instance from scratch.
-        internal PosixTarEntry(TarEntryType entryType, string entryName, TarEntryFormat format)
-            : base(entryType, entryName, format)
+        internal PosixTarEntry(TarEntryType entryType, string entryName, TarEntryFormat format, bool isGea)
+            : base(entryType, entryName, format, isGea)
         {
             _header._uName = string.Empty;
             _header._gName = string.Empty;

src/libraries/System.Formats.Tar/src/System/Formats/Tar/TarEntry.cs

@@ -29,10 +29,16 @@ internal TarEntry(TarHeader header, TarReader readerOfOrigin, TarEntryFormat for
         }
 
         // Constructor called when the user creates a TarEntry instance from scratch.
-        internal TarEntry(TarEntryType entryType, string entryName, TarEntryFormat format)
+        internal TarEntry(TarEntryType entryType, string entryName, TarEntryFormat format, bool isGea)
         {
             ArgumentException.ThrowIfNullOrEmpty(entryName);
-            TarHelpers.ThrowIfEntryTypeNotSupported(entryType, format);
+
+            Debug.Assert(!isGea || entryType is TarEntryType.GlobalExtendedAttributes);
+
+            if (!isGea)
+            {
+                TarHelpers.ThrowIfEntryTypeNotSupported(entryType, format);
+            }
 
             _header = default;
             _header._format = format;
@@ -48,6 +54,11 @@ internal TarEntry(TarEntryType entryType, string entryName, TarEntryFormat forma
         // Constructor called when converting an entry to the selected format.
         internal TarEntry(TarEntry other, TarEntryFormat format)
         {
+            if (other is PaxGlobalExtendedAttributesTarEntry)
+            {
+                throw new InvalidOperationException(SR.TarCannotConvertPaxGlobalExtendedAttributesEntry);
+            }
+
             TarEntryType compatibleEntryType;
             if (other.Format is TarEntryFormat.V7 && other.EntryType is TarEntryType.V7RegularFile && format is TarEntryFormat.Ustar or TarEntryFormat.Pax or TarEntryFormat.Gnu)
             {
@@ -208,7 +219,7 @@ public int Uid
         /// <exception cref="UnauthorizedAccessException">Operation not permitted due to insufficient permissions.</exception>
         public void ExtractToFile(string destinationFileName, bool overwrite)
         {
-            if (EntryType is TarEntryType.SymbolicLink or TarEntryType.HardLink)
+            if (EntryType is TarEntryType.SymbolicLink or TarEntryType.HardLink or TarEntryType.GlobalExtendedAttributes)
             {
                 throw new InvalidOperationException(string.Format(SR.TarEntryTypeNotSupportedForExtracting, EntryType));
             }

src/libraries/System.Formats.Tar/src/System/Formats/Tar/TarFile.cs

@@ -255,7 +255,10 @@ private static void ExtractToDirectoryInternal(Stream source, string destination
             TarEntry? entry;
             while ((entry = reader.GetNextEntry()) != null)
             {
-                entry.ExtractRelativeToDirectory(destinationDirectoryPath, overwriteFiles);
+                if (entry is not PaxGlobalExtendedAttributesTarEntry)
+                {
+                    entry.ExtractRelativeToDirectory(destinationDirectoryPath, overwriteFiles);
+                }
             }
         }
     }

src/libraries/System.Formats.Tar/src/System/Formats/Tar/TarHeader.Write.cs

@@ -22,28 +22,9 @@ internal partial struct TarHeader
         // "{dirName}/PaxHeaders.{processId}/{fileName}{trailingSeparator}"
         private const string PaxHeadersFormat = "{0}/PaxHeaders.{1}/{2}{3}";
 
-        // Global Extended Attribute entries have a special format in the Name field:
-        // "{tmpFolder}/GlobalHead.{processId}.1"
-        private const string GlobalHeadFormat = "{0}/GlobalHead.{1}.1";
-
         // Predefined text for the Name field of a GNU long metadata entry. Applies for both LongPath ('L') and LongLink ('K').
         private const string GnuLongMetadataName = "././@LongLink";
 
-        // Creates a PAX Global Extended Attributes header and writes it into the specified archive stream.
-        internal static void WriteGlobalExtendedAttributesHeader(Stream archiveStream, Span<byte> buffer, IEnumerable<KeyValuePair<string, string>> globalExtendedAttributes)
-        {
-            TarHeader geaHeader = default;
-            geaHeader._name = GenerateGlobalExtendedAttributeName();
-            geaHeader._mode = (int)TarHelpers.DefaultMode;
-            geaHeader._typeFlag = TarEntryType.GlobalExtendedAttributes;
-            geaHeader._linkName = string.Empty;
-            geaHeader._magic = string.Empty;
-            geaHeader._version = string.Empty;
-            geaHeader._gName = string.Empty;
-            geaHeader._uName = string.Empty;
-            geaHeader.WriteAsPaxExtendedAttributes(archiveStream, buffer, globalExtendedAttributes, isGea: true);
-        }
-
         // Writes the current header as a V7 entry into the archive stream.
         internal void WriteAsV7(Stream archiveStream, Span<byte> buffer)
         {
@@ -82,14 +63,27 @@ internal void WriteAsUstar(Stream archiveStream, Span<byte> buffer)
             }
         }
 
+        // Writes the current header as a PAX Global Extended Attributes entry into the archive stream.
+        internal void WriteAsPaxGlobalExtendedAttributes(Stream archiveStream, Span<byte> buffer, int globalExtendedAttributesEntryNumber)
+        {
+            Debug.Assert(_typeFlag is TarEntryType.GlobalExtendedAttributes);
+
+            _name = GenerateGlobalExtendedAttributeName(globalExtendedAttributesEntryNumber);
+            _extendedAttributes ??= new Dictionary<string, string>();
+            WriteAsPaxExtendedAttributes(archiveStream, buffer, _extendedAttributes, isGea: true);
+        }
+
         // Writes the current header as a PAX entry into the archive stream.
-        // Makes sure to add the preceding exteded attributes entry before the actual entry.
+        // Makes sure to add the preceding extended attributes entry before the actual entry.
         internal void WriteAsPax(Stream archiveStream, Span<byte> buffer)
         {
+            Debug.Assert(_typeFlag is not TarEntryType.GlobalExtendedAttributes);
+
             // First, we write the preceding extended attributes header
             TarHeader extendedAttributesHeader = default;
             // Fill the current header's dict
             CollectExtendedAttributesFromStandardFieldsIfNeeded();
+            // And pass the attributes to the preceding extended attributes header for writing
             Debug.Assert(_extendedAttributes != null);
             extendedAttributesHeader.WriteAsPaxExtendedAttributes(archiveStream, buffer, _extendedAttributes, isGea: false);
 
@@ -611,30 +605,30 @@ private string GenerateExtendedAttributeName()
         }
 
         // Gets the special name for the 'name' field in a global extended attribute entry.
-        // Format: "%d/GlobalHead.%p/%f"
+        // Format: "%d/GlobalHead.%p/%n"
         // - %d: The path of the $TMPDIR variable, if found. Otherwise, the value is '/tmp'.
         // - %p: The current process ID.
         // - %n: The sequence number of the global extended header record of the archive, starting at 1. In our case, since we only generate one, the value is always 1.
         // If the path of $TMPDIR makes the final string too long to fit in the 'name' field,
         // then the TMPDIR='/tmp' is used.
-        private static string GenerateGlobalExtendedAttributeName()
+        private static string GenerateGlobalExtendedAttributeName(int globalExtendedAttributesEntryNumber)
         {
-            string? tmpDir = Environment.GetEnvironmentVariable("TMPDIR");
-            if (string.IsNullOrWhiteSpace(tmpDir))
-            {
-                tmpDir = "/tmp";
-            }
-            else if (Path.EndsInDirectorySeparator(tmpDir))
+            Debug.Assert(globalExtendedAttributesEntryNumber >= 1);
+
+            string tmpDir = Path.GetTempPath();
+            if (Path.EndsInDirectorySeparator(tmpDir))
             {
                 tmpDir = Path.TrimEndingDirectorySeparator(tmpDir);
             }
             int processId = Environment.ProcessId;
 
-            string result = string.Format(GlobalHeadFormat, tmpDir, processId);
-            if (result.Length >= FieldLengths.Name)
+            string result = string.Format(GlobalHeadFormatPrefix, tmpDir, processId);
+            string suffix = $".{globalExtendedAttributesEntryNumber}"; // GEA sequence number
+            if (result.Length + suffix.Length >= FieldLengths.Name)
             {
-                result = string.Format(GlobalHeadFormat, "/tmp", processId);
+                result = string.Format(GlobalHeadFormatPrefix, "/tmp", processId);
             }
+            result += suffix;
 
             return result;
         }

src/libraries/System.Formats.Tar/src/System/Formats/Tar/TarHeader.cs

@@ -38,6 +38,11 @@ internal partial struct TarHeader
         private const string PaxEaDevMajor = "devmajor";
         private const string PaxEaDevMinor = "devminor";
 
+        // Global Extended Attribute entries have a special format in the Name field:
+        // "{tmpFolder}/GlobalHead.{processId}.{GEAEntryNumber}"
+        // Excludes ".{GEAEntryNumber}" because the number gets added on write.
+        internal const string GlobalHeadFormatPrefix = "{0}/GlobalHead.{1}";
+
         internal Stream? _dataStream;
 
         // Position in the stream where the data ends in this header.

src/libraries/System.Formats.Tar/src/System/Formats/Tar/TarHelpers.cs

@@ -252,9 +252,10 @@ TarEntryType.HardLink or
                         TarEntryType.RegularFile or
                         TarEntryType.SymbolicLink)
                     {
+                        // GlobalExtendedAttributes is handled via PaxGlobalExtendedAttributesEntry
+
                         // Not supported for writing - internally autogenerated:
                         // - ExtendedAttributes
-                        // - GlobalExtendedAttributes
                         return;
                     }
                     break;