v2: fix TarHeader

Author: sator-imaging

src/TarHeader.cs

@@ -9,7 +9,7 @@ namespace SatorImaging.TarArchiver
     public class TarHeader
     {
         const int BLOCK_SIZE = 512;
-        static readonly DateTime EPOCH = new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc);
+        static readonly DateTime EPOCH = new(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc);
         static readonly Encoding ArchiveEncoding = Encoding.UTF8;
 
         enum EEntryType : byte
@@ -30,14 +30,14 @@ enum EEntryType : byte
         }
 
 
-        internal string Name { get; set; }
+        internal string Name { get; set; } = string.Empty;
         internal long Size { get; set; }
         internal DateTime LastModifiedTime { get; set; }
 
 
         internal void Write(Stream output)
         {
-            byte[] buffer = stackalloc byte[BLOCK_SIZE];
+            var buffer = (stackalloc byte[BLOCK_SIZE]);
 
             WriteOctalBytes(511, buffer, 100, 8); // file mode
             WriteOctalBytes(0, buffer, 108, 8); // owner ID
@@ -65,14 +65,14 @@ internal void Write(Stream output)
                     Span<byte> bytes12 = stackalloc byte[12];
                     BinaryPrimitives_WriteInt64BigEndian(bytes12.Slice(4), Size);
                     bytes12[0] |= 0x80;
-                    bytes12.CopyTo(buffer.AsSpan(124));
+                    bytes12.CopyTo(buffer.Slice(124));
                 }
             }
 
             int crc = RecalculateChecksum(buffer);
             WriteOctalBytes(crc, buffer, 148, 8);
 
-            output.Write(buffer, 0, buffer.Length);
+            output.Write(buffer);
 
             if (nameByteCount > 100)
             {
@@ -103,7 +103,7 @@ static void BinaryPrimitives_WriteInt64BigEndian(Span<byte> destination, long va
         }
 
 
-        static void WriteOctalBytes(long value, byte[] buffer, int offset, int length)
+        static void WriteOctalBytes(long value, Span<byte> buffer, int offset, int length)
         {
             var val = Convert.ToString(value, 8);
             var shift = length - val.Length - 1;
@@ -125,7 +125,7 @@ static void WriteStringBytes(ReadOnlySpan<byte> name, Span<byte> buffer, int len
             buffer.Slice(i, length - i).Clear();
         }
 
-        static void WriteStringBytes(string name, byte[] buffer, int offset, int length)
+        static void WriteStringBytes(string name, Span<byte> buffer, int offset, int length)
         {
             int i;
 
@@ -168,10 +168,10 @@ void WriteLongFilenameHeader(Stream output)
                 (byte)' ',
             };
 
-        static int RecalculateChecksum(byte[] buf)
+        static int RecalculateChecksum(Span<byte> buf)
         {
             // Set default value for checksum. That is 8 spaces.
-            eightSpaces.CopyTo(buf, 148);
+            eightSpaces.CopyTo(buf.Slice(148));
 
             // Calculate checksum
             var headerChecksum = 0;