src: Fix NullReferenceException and static initialization issues in some cases due to mixing of static readonly and consts in some block types by setting Signature value to the fixed number 4, which will most likely never change.

carlossanlop · carlossanlop · commit 0b6e6feb0cdb · 2025-04-16T23:04:28.000-07:00
diff --git a/src/libraries/System.IO.Compression/src/System/IO/Compression/ZipBlocks.FieldLengths.cs b/src/libraries/System.IO.Compression/src/System/IO/Compression/ZipBlocks.FieldLengths.cs
@@ -27,7 +27,9 @@ internal sealed partial class Zip64EndOfCentralDirectoryLocator
     {
         internal static class FieldLengths
         {
-            public static readonly int Signature = SignatureConstantBytes.Length;
+            // Must match the signature constant bytes length, but should stay a const int or sometimes
+            // static initialization of FieldLengths and NullReferenceException occurs.
+            public const int Signature = 4;
             public const int NumberOfDiskWithZip64EOCD = sizeof(uint);
             public const int OffsetOfZip64EOCD = sizeof(ulong);
             public const int TotalNumberOfDisks = sizeof(uint);
@@ -38,7 +40,9 @@ internal sealed partial class Zip64EndOfCentralDirectoryRecord
     {
         private static class FieldLengths
         {
-            public static readonly int Signature = SignatureConstantBytes.Length;
+            // Must match the signature constant bytes length, but should stay a const int or sometimes
+            // static initialization of FieldLengths and NullReferenceException occurs.
+            public const int Signature = 4;
             public const int SizeOfThisRecord = sizeof(ulong);
             public const int VersionMadeBy = sizeof(ushort);
             public const int VersionNeededToExtract = sizeof(ushort);
@@ -55,7 +59,9 @@ internal readonly partial struct ZipLocalFileHeader
     {
         internal static class FieldLengths
         {
-            public static readonly int Signature = SignatureConstantBytes.Length;
+            // Must match the signature constant bytes length, but should stay a const int or sometimes
+            // static initialization of FieldLengths and NullReferenceException occurs.
+            public const int Signature = 4;
             public const int VersionNeededToExtract = sizeof(ushort);
             public const int GeneralPurposeBitFlags = sizeof(ushort);
             public const int CompressionMethod = sizeof(ushort);
@@ -71,7 +77,9 @@ internal sealed partial class ZipDataDescriptor
         {
             internal static class FieldLengths
             {
-                public static readonly int Signature = DataDescriptorSignatureConstantBytes.Length;
+                // Must match the data descriptor signature constant bytes length, but should stay a const int or sometimes
+                // static initialization of FieldLengths and NullReferenceException occurs.
+                public const int Signature = 4;
                 public const int Crc32 = sizeof(uint);
                 public const int CompressedSize = sizeof(uint);
                 public const int UncompressedSize = sizeof(uint);
@@ -82,7 +90,9 @@ internal sealed partial class Zip64DataDescriptor
         {
             internal static class FieldLengths
             {
-                public static readonly int Signature = DataDescriptorSignatureConstantBytes.Length;
+                // Must match the data descriptor signature constant bytes length, but should stay a const int or sometimes
+                // static initialization of FieldLengths and NullReferenceException occurs.
+                public const int Signature = 4;
                 public const int Crc32 = sizeof(uint);
                 public const int CompressedSize = sizeof(long);
                 public const int UncompressedSize = sizeof(long);
@@ -94,7 +104,9 @@ internal sealed partial class ZipCentralDirectoryFileHeader
     {
         internal static class FieldLengths
         {
-            public static readonly int Signature = SignatureConstantBytes.Length;
+            // Must match the signature constant bytes length, but should stay a const int or sometimes
+            // static initialization of FieldLengths and NullReferenceException occurs.
+            public const int Signature = 4;
             public const int VersionMadeBySpecification = sizeof(byte);
             public const int VersionMadeByCompatibility = sizeof(byte);
             public const int VersionNeededToExtract = sizeof(ushort);
@@ -118,7 +130,9 @@ internal sealed partial class ZipEndOfCentralDirectoryBlock
     {
         internal static class FieldLengths
         {
-            public static readonly int Signature = SignatureConstantBytes.Length;
+            // Must match the signature constant bytes length, but should stay a const int or sometimes
+            // static initialization of FieldLengths and NullReferenceException occurs.
+            public const int Signature = 4;
             public const int NumberOfThisDisk = sizeof(ushort);
             public const int NumberOfTheDiskWithTheStartOfTheCentralDirectory = sizeof(ushort);
             public const int NumberOfEntriesInTheCentralDirectoryOnThisDisk = sizeof(ushort);
diff --git a/src/libraries/System.IO.Compression/src/System/IO/Compression/ZipBlocks.FieldLocations.cs b/src/libraries/System.IO.Compression/src/System/IO/Compression/ZipBlocks.FieldLocations.cs
@@ -31,9 +31,9 @@ internal sealed partial class Zip64EndOfCentralDirectoryLocator
         private static class FieldLocations
         {
             public const int Signature = 0;
-            public static readonly int NumberOfDiskWithZip64EOCD = Signature + FieldLengths.Signature;
-            public static readonly int OffsetOfZip64EOCD = NumberOfDiskWithZip64EOCD + FieldLengths.NumberOfDiskWithZip64EOCD;
-            public static readonly int TotalNumberOfDisks = OffsetOfZip64EOCD + FieldLengths.OffsetOfZip64EOCD;
+            public const int NumberOfDiskWithZip64EOCD = Signature + FieldLengths.Signature;
+            public const int OffsetOfZip64EOCD = NumberOfDiskWithZip64EOCD + FieldLengths.NumberOfDiskWithZip64EOCD;
+            public const int TotalNumberOfDisks = OffsetOfZip64EOCD + FieldLengths.OffsetOfZip64EOCD;
         }
     }
 
@@ -42,15 +42,15 @@ internal sealed partial class Zip64EndOfCentralDirectoryRecord
         private static class FieldLocations
         {
             public const int Signature = 0;
-            public static readonly int SizeOfThisRecord = Signature + FieldLengths.Signature;
-            public static readonly int VersionMadeBy = SizeOfThisRecord + FieldLengths.SizeOfThisRecord;
-            public static readonly int VersionNeededToExtract = VersionMadeBy + FieldLengths.VersionMadeBy;
-            public static readonly int NumberOfThisDisk = VersionNeededToExtract + FieldLengths.VersionNeededToExtract;
-            public static readonly int NumberOfDiskWithStartOfCD = NumberOfThisDisk + FieldLengths.NumberOfThisDisk;
-            public static readonly int NumberOfEntriesOnThisDisk = NumberOfDiskWithStartOfCD + FieldLengths.NumberOfDiskWithStartOfCD;
-            public static readonly int NumberOfEntriesTotal = NumberOfEntriesOnThisDisk + FieldLengths.NumberOfEntriesOnThisDisk;
-            public static readonly int SizeOfCentralDirectory = NumberOfEntriesTotal + FieldLengths.NumberOfEntriesTotal;
-            public static readonly int OffsetOfCentralDirectory = SizeOfCentralDirectory + FieldLengths.SizeOfCentralDirectory;
+            public const int SizeOfThisRecord = Signature + FieldLengths.Signature;
+            public const int VersionMadeBy = SizeOfThisRecord + FieldLengths.SizeOfThisRecord;
+            public const int VersionNeededToExtract = VersionMadeBy + FieldLengths.VersionMadeBy;
+            public const int NumberOfThisDisk = VersionNeededToExtract + FieldLengths.VersionNeededToExtract;
+            public const int NumberOfDiskWithStartOfCD = NumberOfThisDisk + FieldLengths.NumberOfThisDisk;
+            public const int NumberOfEntriesOnThisDisk = NumberOfDiskWithStartOfCD + FieldLengths.NumberOfDiskWithStartOfCD;
+            public const int NumberOfEntriesTotal = NumberOfEntriesOnThisDisk + FieldLengths.NumberOfEntriesOnThisDisk;
+            public const int SizeOfCentralDirectory = NumberOfEntriesTotal + FieldLengths.NumberOfEntriesTotal;
+            public const int OffsetOfCentralDirectory = SizeOfCentralDirectory + FieldLengths.SizeOfCentralDirectory;
         }
     }
 
@@ -59,26 +59,26 @@ internal readonly partial struct ZipLocalFileHeader
         internal static class FieldLocations
         {
             public const int Signature = 0;
-            public static readonly int VersionNeededToExtract = Signature + FieldLengths.Signature;
-            public static readonly int GeneralPurposeBitFlags = VersionNeededToExtract + FieldLengths.VersionNeededToExtract;
-            public static readonly int CompressionMethod = GeneralPurposeBitFlags + FieldLengths.GeneralPurposeBitFlags;
-            public static readonly int LastModified = CompressionMethod + FieldLengths.CompressionMethod;
-            public static readonly int Crc32 = LastModified + FieldLengths.LastModified;
-            public static readonly int CompressedSize = Crc32 + FieldLengths.Crc32;
-            public static readonly int UncompressedSize = CompressedSize + FieldLengths.CompressedSize;
-            public static readonly int FilenameLength = UncompressedSize + FieldLengths.UncompressedSize;
-            public static readonly int ExtraFieldLength = FilenameLength + FieldLengths.FilenameLength;
-            public static readonly int DynamicData = ExtraFieldLength + FieldLengths.ExtraFieldLength;
+            public const int VersionNeededToExtract = Signature + FieldLengths.Signature;
+            public const int GeneralPurposeBitFlags = VersionNeededToExtract + FieldLengths.VersionNeededToExtract;
+            public const int CompressionMethod = GeneralPurposeBitFlags + FieldLengths.GeneralPurposeBitFlags;
+            public const int LastModified = CompressionMethod + FieldLengths.CompressionMethod;
+            public const int Crc32 = LastModified + FieldLengths.LastModified;
+            public const int CompressedSize = Crc32 + FieldLengths.Crc32;
+            public const int UncompressedSize = CompressedSize + FieldLengths.CompressedSize;
+            public const int FilenameLength = UncompressedSize + FieldLengths.UncompressedSize;
+            public const int ExtraFieldLength = FilenameLength + FieldLengths.FilenameLength;
+            public const int DynamicData = ExtraFieldLength + FieldLengths.ExtraFieldLength;
         }
 
         internal sealed partial class ZipDataDescriptor
         {
             internal static class FieldLocations
             {
                 public const int Signature = 0;
-                public static readonly int Crc32 = Signature + FieldLengths.Signature;
-                public static readonly int CompressedSize = Crc32 + FieldLengths.Crc32;
-                public static readonly int UncompressedSize = CompressedSize + FieldLengths.CompressedSize;
+                public const int Crc32 = Signature + FieldLengths.Signature;
+                public const int CompressedSize = Crc32 + FieldLengths.Crc32;
+                public const int UncompressedSize = CompressedSize + FieldLengths.CompressedSize;
             }
         }
 
@@ -87,9 +87,9 @@ internal sealed partial class Zip64DataDescriptor
             internal static class FieldLocations
             {
                 public const int Signature = 0;
-                public static readonly int Crc32 = Signature + FieldLengths.Signature;
-                public static readonly int CompressedSize = Crc32 + FieldLengths.Crc32;
-                public static readonly int UncompressedSize = CompressedSize + FieldLengths.CompressedSize;
+                public const int Crc32 = Signature + FieldLengths.Signature;
+                public const int CompressedSize = Crc32 + FieldLengths.Crc32;
+                public const int UncompressedSize = CompressedSize + FieldLengths.CompressedSize;
             }
         }
     }
@@ -99,23 +99,23 @@ internal sealed partial class ZipCentralDirectoryFileHeader
         internal static class FieldLocations
         {
             public const int Signature = 0;
-            public static readonly int VersionMadeBySpecification = Signature + FieldLengths.Signature;
-            public static readonly int VersionMadeByCompatibility = VersionMadeBySpecification + FieldLengths.VersionMadeBySpecification;
-            public static readonly int VersionNeededToExtract = VersionMadeByCompatibility + FieldLengths.VersionMadeByCompatibility;
-            public static readonly int GeneralPurposeBitFlags = VersionNeededToExtract + FieldLengths.VersionNeededToExtract;
-            public static readonly int CompressionMethod = GeneralPurposeBitFlags + FieldLengths.GeneralPurposeBitFlags;
-            public static readonly int LastModified = CompressionMethod + FieldLengths.CompressionMethod;
-            public static readonly int Crc32 = LastModified + FieldLengths.LastModified;
-            public static readonly int CompressedSize = Crc32 + FieldLengths.Crc32;
-            public static readonly int UncompressedSize = CompressedSize + FieldLengths.CompressedSize;
-            public static readonly int FilenameLength = UncompressedSize + FieldLengths.UncompressedSize;
-            public static readonly int ExtraFieldLength = FilenameLength + FieldLengths.FilenameLength;
-            public static readonly int FileCommentLength = ExtraFieldLength + FieldLengths.ExtraFieldLength;
-            public static readonly int DiskNumberStart = FileCommentLength + FieldLengths.FileCommentLength;
-            public static readonly int InternalFileAttributes = DiskNumberStart + FieldLengths.DiskNumberStart;
-            public static readonly int ExternalFileAttributes = InternalFileAttributes + FieldLengths.InternalFileAttributes;
-            public static readonly int RelativeOffsetOfLocalHeader = ExternalFileAttributes + FieldLengths.ExternalFileAttributes;
-            public static readonly int DynamicData = RelativeOffsetOfLocalHeader + FieldLengths.RelativeOffsetOfLocalHeader;
+            public const int VersionMadeBySpecification = Signature + FieldLengths.Signature;
+            public const int VersionMadeByCompatibility = VersionMadeBySpecification + FieldLengths.VersionMadeBySpecification;
+            public const int VersionNeededToExtract = VersionMadeByCompatibility + FieldLengths.VersionMadeByCompatibility;
+            public const int GeneralPurposeBitFlags = VersionNeededToExtract + FieldLengths.VersionNeededToExtract;
+            public const int CompressionMethod = GeneralPurposeBitFlags + FieldLengths.GeneralPurposeBitFlags;
+            public const int LastModified = CompressionMethod + FieldLengths.CompressionMethod;
+            public const int Crc32 = LastModified + FieldLengths.LastModified;
+            public const int CompressedSize = Crc32 + FieldLengths.Crc32;
+            public const int UncompressedSize = CompressedSize + FieldLengths.CompressedSize;
+            public const int FilenameLength = UncompressedSize + FieldLengths.UncompressedSize;
+            public const int ExtraFieldLength = FilenameLength + FieldLengths.FilenameLength;
+            public const int FileCommentLength = ExtraFieldLength + FieldLengths.ExtraFieldLength;
+            public const int DiskNumberStart = FileCommentLength + FieldLengths.FileCommentLength;
+            public const int InternalFileAttributes = DiskNumberStart + FieldLengths.DiskNumberStart;
+            public const int ExternalFileAttributes = InternalFileAttributes + FieldLengths.InternalFileAttributes;
+            public const int RelativeOffsetOfLocalHeader = ExternalFileAttributes + FieldLengths.ExternalFileAttributes;
+            public const int DynamicData = RelativeOffsetOfLocalHeader + FieldLengths.RelativeOffsetOfLocalHeader;
         }
     }
 
@@ -124,14 +124,14 @@ internal sealed partial class ZipEndOfCentralDirectoryBlock
         private static class FieldLocations
         {
             public const int Signature = 0;
-            public static readonly int NumberOfThisDisk = Signature + FieldLengths.Signature;
-            public static readonly int NumberOfTheDiskWithTheStartOfTheCentralDirectory = NumberOfThisDisk + FieldLengths.NumberOfThisDisk;
-            public static readonly int NumberOfEntriesInTheCentralDirectoryOnThisDisk = NumberOfTheDiskWithTheStartOfTheCentralDirectory + FieldLengths.NumberOfTheDiskWithTheStartOfTheCentralDirectory;
-            public static readonly int NumberOfEntriesInTheCentralDirectory = NumberOfEntriesInTheCentralDirectoryOnThisDisk + FieldLengths.NumberOfEntriesInTheCentralDirectoryOnThisDisk;
-            public static readonly int SizeOfCentralDirectory = NumberOfEntriesInTheCentralDirectory + FieldLengths.NumberOfEntriesInTheCentralDirectory;
-            public static readonly int OffsetOfStartOfCentralDirectoryWithRespectToTheStartingDiskNumber = SizeOfCentralDirectory + FieldLengths.SizeOfCentralDirectory;
-            public static readonly int ArchiveCommentLength = OffsetOfStartOfCentralDirectoryWithRespectToTheStartingDiskNumber + FieldLengths.OffsetOfStartOfCentralDirectoryWithRespectToTheStartingDiskNumber;
-            public static readonly int DynamicData = ArchiveCommentLength + FieldLengths.ArchiveCommentLength;
+            public const int NumberOfThisDisk = Signature + FieldLengths.Signature;
+            public const int NumberOfTheDiskWithTheStartOfTheCentralDirectory = NumberOfThisDisk + FieldLengths.NumberOfThisDisk;
+            public const int NumberOfEntriesInTheCentralDirectoryOnThisDisk = NumberOfTheDiskWithTheStartOfTheCentralDirectory + FieldLengths.NumberOfTheDiskWithTheStartOfTheCentralDirectory;
+            public const int NumberOfEntriesInTheCentralDirectory = NumberOfEntriesInTheCentralDirectoryOnThisDisk + FieldLengths.NumberOfEntriesInTheCentralDirectoryOnThisDisk;
+            public const int SizeOfCentralDirectory = NumberOfEntriesInTheCentralDirectory + FieldLengths.NumberOfEntriesInTheCentralDirectory;
+            public const int OffsetOfStartOfCentralDirectoryWithRespectToTheStartingDiskNumber = SizeOfCentralDirectory + FieldLengths.SizeOfCentralDirectory;
+            public const int ArchiveCommentLength = OffsetOfStartOfCentralDirectoryWithRespectToTheStartingDiskNumber + FieldLengths.OffsetOfStartOfCentralDirectoryWithRespectToTheStartingDiskNumber;
+            public const int DynamicData = ArchiveCommentLength + FieldLengths.ArchiveCommentLength;
         }
     }
 }
diff --git a/src/libraries/System.IO.Compression/src/System/IO/Compression/ZipBlocks.cs b/src/libraries/System.IO.Compression/src/System/IO/Compression/ZipBlocks.cs
@@ -409,8 +409,8 @@ internal sealed partial class Zip64EndOfCentralDirectoryLocator
         // ZIP files store values in little endian, so this is reversed.
         public static readonly byte[] SignatureConstantBytes = [0x50, 0x4B, 0x06, 0x07];
 
-        public static readonly int TotalSize = FieldLocations.TotalNumberOfDisks + FieldLengths.TotalNumberOfDisks;
-        public static readonly int SizeOfBlockWithoutSignature = TotalSize - FieldLengths.Signature;
+        public const int TotalSize = FieldLocations.TotalNumberOfDisks + FieldLengths.TotalNumberOfDisks;
+        public const int SizeOfBlockWithoutSignature = TotalSize - FieldLengths.Signature;
 
         public uint NumberOfDiskWithZip64EOCD;
         public ulong OffsetOfZip64EOCD;
@@ -850,9 +850,9 @@ internal sealed partial class ZipEndOfCentralDirectoryBlock
         public static readonly byte[] SignatureConstantBytes = [0x50, 0x4B, 0x05, 0x06];
 
         // This also assumes a zero-length comment.
-        public static readonly int TotalSize = FieldLocations.ArchiveCommentLength + FieldLengths.ArchiveCommentLength;
+        public const int TotalSize = FieldLocations.ArchiveCommentLength + FieldLengths.ArchiveCommentLength;
         // These are the minimum possible size, assuming the zip file comments variable section is empty
-        public static readonly int SizeOfBlockWithoutSignature = TotalSize - FieldLengths.Signature;
+        public const int SizeOfBlockWithoutSignature = TotalSize - FieldLengths.Signature;
 
         // The end of central directory can have a variable size zip file comment at the end, but its max length can be 64K
         // The Zip File Format Specification does not explicitly mention a max size for this field, but we are assuming this

Original file line number	Diff line number	Diff line change
`@@ -27,7 +27,9 @@ internal sealed partial class Zip64EndOfCentralDirectoryLocator`
`27`	`27`	`{`
`28`	`28`	`internal static class FieldLengths`
`29`	`29`	`{`
`30`		`- public static readonly int Signature = SignatureConstantBytes.Length;`
	`30`	`+ // Must match the signature constant bytes length, but should stay a const int or sometimes`
	`31`	`+ // static initialization of FieldLengths and NullReferenceException occurs.`
	`32`	`+ public const int Signature = 4;`
`31`	`33`	`public const int NumberOfDiskWithZip64EOCD = sizeof(uint);`
`32`	`34`	`public const int OffsetOfZip64EOCD = sizeof(ulong);`
`33`	`35`	`public const int TotalNumberOfDisks = sizeof(uint);`
`@@ -38,7 +40,9 @@ internal sealed partial class Zip64EndOfCentralDirectoryRecord`
`38`	`40`	`{`
`39`	`41`	`private static class FieldLengths`
`40`	`42`	`{`
`41`		`- public static readonly int Signature = SignatureConstantBytes.Length;`
	`43`	`+ // Must match the signature constant bytes length, but should stay a const int or sometimes`
	`44`	`+ // static initialization of FieldLengths and NullReferenceException occurs.`
	`45`	`+ public const int Signature = 4;`
`42`	`46`	`public const int SizeOfThisRecord = sizeof(ulong);`
`43`	`47`	`public const int VersionMadeBy = sizeof(ushort);`
`44`	`48`	`public const int VersionNeededToExtract = sizeof(ushort);`
`@@ -55,7 +59,9 @@ internal readonly partial struct ZipLocalFileHeader`
`55`	`59`	`{`
`56`	`60`	`internal static class FieldLengths`
`57`	`61`	`{`
`58`		`- public static readonly int Signature = SignatureConstantBytes.Length;`
	`62`	`+ // Must match the signature constant bytes length, but should stay a const int or sometimes`
	`63`	`+ // static initialization of FieldLengths and NullReferenceException occurs.`
	`64`	`+ public const int Signature = 4;`
`59`	`65`	`public const int VersionNeededToExtract = sizeof(ushort);`
`60`	`66`	`public const int GeneralPurposeBitFlags = sizeof(ushort);`
`61`	`67`	`public const int CompressionMethod = sizeof(ushort);`
`@@ -71,7 +77,9 @@ internal sealed partial class ZipDataDescriptor`
`71`	`77`	`{`
`72`	`78`	`internal static class FieldLengths`
`73`	`79`	`{`
`74`		`- public static readonly int Signature = DataDescriptorSignatureConstantBytes.Length;`
	`80`	`+ // Must match the data descriptor signature constant bytes length, but should stay a const int or sometimes`
	`81`	`+ // static initialization of FieldLengths and NullReferenceException occurs.`
	`82`	`+ public const int Signature = 4;`
`75`	`83`	`public const int Crc32 = sizeof(uint);`
`76`	`84`	`public const int CompressedSize = sizeof(uint);`
`77`	`85`	`public const int UncompressedSize = sizeof(uint);`
`@@ -82,7 +90,9 @@ internal sealed partial class Zip64DataDescriptor`
`82`	`90`	`{`
`83`	`91`	`internal static class FieldLengths`
`84`	`92`	`{`
`85`		`- public static readonly int Signature = DataDescriptorSignatureConstantBytes.Length;`
	`93`	`+ // Must match the data descriptor signature constant bytes length, but should stay a const int or sometimes`
	`94`	`+ // static initialization of FieldLengths and NullReferenceException occurs.`
	`95`	`+ public const int Signature = 4;`
`86`	`96`	`public const int Crc32 = sizeof(uint);`
`87`	`97`	`public const int CompressedSize = sizeof(long);`
`88`	`98`	`public const int UncompressedSize = sizeof(long);`
`@@ -94,7 +104,9 @@ internal sealed partial class ZipCentralDirectoryFileHeader`
`94`	`104`	`{`
`95`	`105`	`internal static class FieldLengths`
`96`	`106`	`{`
`97`		`- public static readonly int Signature = SignatureConstantBytes.Length;`
	`107`	`+ // Must match the signature constant bytes length, but should stay a const int or sometimes`
	`108`	`+ // static initialization of FieldLengths and NullReferenceException occurs.`
	`109`	`+ public const int Signature = 4;`
`98`	`110`	`public const int VersionMadeBySpecification = sizeof(byte);`
`99`	`111`	`public const int VersionMadeByCompatibility = sizeof(byte);`
`100`	`112`	`public const int VersionNeededToExtract = sizeof(ushort);`
`@@ -118,7 +130,9 @@ internal sealed partial class ZipEndOfCentralDirectoryBlock`
`118`	`130`	`{`
`119`	`131`	`internal static class FieldLengths`
`120`	`132`	`{`
`121`		`- public static readonly int Signature = SignatureConstantBytes.Length;`
	`133`	`+ // Must match the signature constant bytes length, but should stay a const int or sometimes`
	`134`	`+ // static initialization of FieldLengths and NullReferenceException occurs.`
	`135`	`+ public const int Signature = 4;`
`122`	`136`	`public const int NumberOfThisDisk = sizeof(ushort);`
`123`	`137`	`public const int NumberOfTheDiskWithTheStartOfTheCentralDirectory = sizeof(ushort);`
`124`	`138`	`public const int NumberOfEntriesInTheCentralDirectoryOnThisDisk = sizeof(ushort);`