Changes following code review

Renamed Dirty and DirtyState to Changed and ChangeState.
Explicitly assigned Unchanged as a zero-value ChangeState.

src/libraries/System.IO.Compression/src/System/IO/Compression/ZipArchive.cs

@@ -170,7 +170,7 @@ public ZipArchive(Stream stream, ZipArchiveMode mode, bool leaveOpen, Encoding?
                 _entries = new List<ZipArchiveEntry>();
                 _entriesCollection = new ReadOnlyCollection<ZipArchiveEntry>(_entries);
                 _entriesDictionary = new Dictionary<string, ZipArchiveEntry>();
-                Dirty = 0;
+                Changed = ChangeState.Unchanged;
                 _readEntries = false;
                 _leaveOpen = leaveOpen;
                 _centralDirectoryStart = 0; // invalid until ReadCentralDirectory
@@ -228,7 +228,7 @@ public string Comment
             set
             {
                 _archiveComment = ZipHelper.GetEncodedTruncatedBytesFromString(value, EntryNameAndCommentEncoding, ZipEndOfCentralDirectoryBlock.ZipFileCommentMaxLength, out _);
-                Dirty |= DirtyState.DynamicLengthMetadata;
+                Changed |= ChangeState.DynamicLengthMetadata;
             }
         }
 
@@ -399,7 +399,7 @@ private set
 
         // This property's value only relates to the top-level fields of the archive (such as the archive comment.)
         // New entries in the archive won't change its state.
-        internal DirtyState Dirty { get; private set; }
+        internal ChangeState Changed { get; private set; }
 
         private ZipArchiveEntry DoCreateEntry(string entryName, CompressionLevel? compressionLevel)
         {
@@ -670,7 +670,7 @@ private void WriteFile()
                 {
                     if (entry._originallyInArchive)
                     {
-                        if (entry.Dirty == 0)
+                        if (entry.Changed == ChangeState.Unchanged)
                         {
                             // Keep track of the expected position of the file entry after the final untouched file entry so that when the loop completes,
                             // we'll know which position to start writing new entries from.
@@ -688,7 +688,7 @@ private void WriteFile()
                         {
                             // If the pending data to write is fixed-length metadata in the header, there's no need to load the full file for
                             // inflation and deflation.
-                            if ((entry.Dirty & (DirtyState.DynamicLengthMetadata | DirtyState.StoredData)) != 0)
+                            if ((entry.Changed & (ChangeState.DynamicLengthMetadata | ChangeState.StoredData)) != 0)
                             {
                                 dynamicDirtyStartingOffset = Math.Min(dynamicDirtyStartingOffset, entry._offsetOfLocalHeader);
                             }
@@ -781,7 +781,7 @@ private void WriteArchiveEpilogue(long startOfCentralDirectory, long sizeOfCentr
             }
 
             // write normal eocd
-            if (centralDirectoryChanged | (Dirty != 0))
+            if (centralDirectoryChanged | (Changed != ChangeState.Unchanged))
             {
                 ZipEndOfCentralDirectoryBlock.WriteBlock(_archiveStream, _entries.Count, startOfCentralDirectory, sizeOfCentralDirectory, _archiveComment);
             }
@@ -792,8 +792,9 @@ private void WriteArchiveEpilogue(long startOfCentralDirectory, long sizeOfCentr
         }
 
         [Flags]
-        internal enum DirtyState
+        internal enum ChangeState
         {
+            Unchanged = 0x0,
             FixedLengthMetadata = 0x1,
             DynamicLengthMetadata = 0x2,
             StoredData = 0x4

src/libraries/System.IO.Compression/src/System/IO/Compression/ZipArchiveEntry.cs

@@ -88,7 +88,7 @@ internal ZipArchiveEntry(ZipArchive archive, ZipCentralDirectoryFileHeader cd)
 
             _compressionLevel = MapCompressionLevel(_generalPurposeBitFlag, CompressionMethod);
 
-            Dirty = 0;
+            Changed = ZipArchive.ChangeState.Unchanged;
         }
 
         // Initializes a ZipArchiveEntry instance for a new archive entry with a specified compression level.
@@ -151,7 +151,7 @@ internal ZipArchiveEntry(ZipArchive archive, string entryName)
                 _archive.AcquireArchiveStream(this);
             }
 
-            Dirty = 0;
+            Changed = ZipArchive.ChangeState.Unchanged;
         }
 
         /// <summary>
@@ -191,7 +191,7 @@ public int ExternalAttributes
             {
                 ThrowIfInvalidArchive();
                 _externalFileAttr = (uint)value;
-                Dirty |= ZipArchive.DirtyState.FixedLengthMetadata;
+                Changed |= ZipArchive.ChangeState.FixedLengthMetadata;
             }
         }
 
@@ -214,7 +214,7 @@ public string Comment
                 {
                     _generalPurposeBitFlag |= BitFlagValues.UnicodeFileNameAndComment;
                 }
-                Dirty |= ZipArchive.DirtyState.DynamicLengthMetadata;
+                Changed |= ZipArchive.ChangeState.DynamicLengthMetadata;
             }
         }
 
@@ -279,7 +279,7 @@ public DateTimeOffset LastWriteTime
                     throw new ArgumentOutOfRangeException(nameof(value), SR.DateTimeOutOfRange);
 
                 _lastModified = value;
-                Dirty |= ZipArchive.DirtyState.FixedLengthMetadata;
+                Changed |= ZipArchive.ChangeState.FixedLengthMetadata;
             }
         }
 
@@ -302,7 +302,7 @@ public long Length
         /// </summary>
         public string Name => ParseFileName(FullName, _versionMadeByPlatform);
 
-        internal ZipArchive.DirtyState Dirty { get; private set; }
+        internal ZipArchive.ChangeState Changed { get; private set; }
 
         /// <summary>
         /// Deletes the entry from the archive.
@@ -533,7 +533,7 @@ internal void WriteCentralDirectoryFileHeader(bool forceWrite)
                 extraFieldLength = (ushort)bigExtraFieldLength;
             }
 
-            if (_originallyInArchive && Dirty == 0 && !forceWrite)
+            if (_originallyInArchive && Changed == ZipArchive.ChangeState.Unchanged && !forceWrite)
             {
                 long centralDirectoryHeaderLength = 46
                     + _storedEntryNameBytes.Length
@@ -716,7 +716,7 @@ private WrappedStream OpenInWriteMode()
             _archive.DebugAssertIsStillArchiveStreamOwner(this);
 
             _everOpenedForWrite = true;
-            Dirty |= ZipArchive.DirtyState.StoredData;
+            Changed |= ZipArchive.ChangeState.StoredData;
             CheckSumAndSizeWriteStream crcSizeStream = GetDataCompressor(_archive.ArchiveStream, true, (object? o, EventArgs e) =>
             {
                 // release the archive stream
@@ -737,7 +737,7 @@ private WrappedStream OpenInUpdateMode()
             ThrowIfNotOpenable(needToUncompress: true, needToLoadIntoMemory: true);
 
             _everOpenedForWrite = true;
-            Dirty |= ZipArchive.DirtyState.StoredData;
+            Changed |= ZipArchive.ChangeState.StoredData;
             _currentlyOpenForWrite = true;
             // always put it at the beginning for them
             UncompressedData.Seek(0, SeekOrigin.Begin);
@@ -946,7 +946,7 @@ private bool WriteLocalFileHeader(bool isEmptyFile, bool forceWrite)
 
             // If this is an existing, unchanged entry then silently skip forwards.
             // If it's new or changed, write the header.
-            if (_originallyInArchive && Dirty == 0 && !forceWrite)
+            if (_originallyInArchive && Changed == ZipArchive.ChangeState.Unchanged && !forceWrite)
             {
                 writer.Seek(30 + _storedEntryNameBytes.Length, SeekOrigin.Current);