Revert "Fix deterministic MVID and add PdbChecksum (#31)"

This reverts commit ff616bf90e3aff2292a0b1536f7af13cd8810276.

12 files changed, 107 insertions, 500 deletions

diff --git a/Mono.Cecil.Cil/PortablePdb.cs b/Mono.Cecil.Cil/PortablePdb.cs
index d8c43f6..aff6b29 100644
--- a/Mono.Cecil.Cil/PortablePdb.cs
+++ b/Mono.Cecil.Cil/PortablePdb.cs
@@ -12,7 +12,7 @@ using System;
 using System.Collections.Generic;
 using System.IO;
 using System.IO.Compression;
-using System.Security.Cryptography;
+
 using Mono.Cecil.Metadata;
 using Mono.Cecil.PE;
 
@@ -39,7 +39,7 @@ namespace Mono.Cecil.Cil {
 
 		ISymbolReader GetSymbolReader (ModuleDefinition module, Disposable<Stream> symbolStream, string fileName)
 		{
-			return new PortablePdbReader (ImageReader.ReadPortablePdb (symbolStream, fileName, out _), module);
+			return new PortablePdbReader (ImageReader.ReadPortablePdb (symbolStream, fileName), module);
 		}
 	}
 
@@ -234,8 +234,8 @@ namespace Mono.Cecil.Cil {
 			Mixin.CheckModule (module);
 			Mixin.CheckFileName (fileName);
 
-			var file = File.Open (Mixin.GetPdbFileName (fileName), FileMode.OpenOrCreate, FileAccess.ReadWrite);
-			return GetSymbolWriter (module, Disposable.Owned (file as Stream), Disposable.NotOwned ((Stream)null));
+			var file = File.OpenWrite (Mixin.GetPdbFileName (fileName));
+			return GetSymbolWriter (module, Disposable.Owned (file as Stream));
 		}
 
 		public ISymbolWriter GetSymbolWriter (ModuleDefinition module, Stream symbolStream)
@@ -243,18 +243,15 @@ namespace Mono.Cecil.Cil {
 			Mixin.CheckModule (module);
 			Mixin.CheckStream (symbolStream);
 
-			// In order to compute the PDB checksum, the stream we're writing to needs to be able to
-			// seek and read as well. We can't assume this about a stream provided by the user.
-			// So in this case, create a memory stream to cache the PDB.
-			return GetSymbolWriter (module, Disposable.Owned (new MemoryStream() as Stream), Disposable.NotOwned (symbolStream));
+			return GetSymbolWriter (module, Disposable.NotOwned (symbolStream));
 		}
 
-		ISymbolWriter GetSymbolWriter (ModuleDefinition module, Disposable<Stream> stream, Disposable<Stream> final_stream)
+		ISymbolWriter GetSymbolWriter (ModuleDefinition module, Disposable<Stream> stream)
 		{
 			var metadata = new MetadataBuilder (module, this);
 			var writer = ImageWriter.CreateDebugWriter (module, metadata, stream);
 
-			return new PortablePdbWriter (metadata, module, writer, final_stream);
+			return new PortablePdbWriter (metadata, module, writer);
 		}
 	}
 
@@ -263,14 +260,9 @@ namespace Mono.Cecil.Cil {
 		readonly MetadataBuilder pdb_metadata;
 		readonly ModuleDefinition module;
 		readonly ImageWriter writer;
-		readonly Disposable<Stream> final_stream;
 
 		MetadataBuilder module_metadata;
 
-		internal byte [] pdb_checksum;
-		internal Guid pdb_id_guid;
-		internal uint pdb_id_age;
-
 		bool IsEmbedded { get { return writer == null; } }
 
 		internal PortablePdbWriter (MetadataBuilder pdb_metadata, ModuleDefinition module)
@@ -286,11 +278,10 @@ namespace Mono.Cecil.Cil {
 			pdb_metadata.AddCustomDebugInformations (module);
 		}
 
-		internal PortablePdbWriter (MetadataBuilder pdb_metadata, ModuleDefinition module, ImageWriter writer, Disposable<Stream> final_stream)
+		internal PortablePdbWriter (MetadataBuilder pdb_metadata, ModuleDefinition module, ImageWriter writer)
 			: this (pdb_metadata, module)
 		{
 			this.writer = writer;
-			this.final_stream = final_stream;
 		}
 
 		public ISymbolReaderProvider GetReaderProvider ()
@@ -298,82 +289,45 @@ namespace Mono.Cecil.Cil {
 			return new PortablePdbReaderProvider ();
 		}
 
-		public void Write (MethodDebugInformation info)
-		{
-			CheckMethodDebugInformationTable ();
-
-			pdb_metadata.AddMethodDebugInformation (info);
-		}
-
 		public ImageDebugHeader GetDebugHeader ()
 		{
 			if (IsEmbedded)
 				return new ImageDebugHeader ();
 
-			WritePdbFile ();
-
-			if (final_stream.value != null) {
-				writer.BaseStream.Seek (0, SeekOrigin.Begin);
-				var buffer = new byte [8192];
-				CryptoService.CopyStreamChunk (writer.BaseStream, final_stream.value, buffer, (int)writer.BaseStream.Length);
-			}
+			var directory = new ImageDebugDirectory () {
+				MajorVersion = 256,
+				MinorVersion = 20557,
+				Type = ImageDebugType.CodeView,
+				TimeDateStamp = (int) module.timestamp,
+			};
 
-			ImageDebugHeaderEntry codeViewEntry;
-			{
-				var codeViewDirectory = new ImageDebugDirectory () {
-					MajorVersion = 256,
-					MinorVersion = 20557,
-					Type = ImageDebugType.CodeView,
-					TimeDateStamp = (int)module.timestamp,
-				};
-
-				var buffer = new ByteBuffer ();
-				// RSDS
-				buffer.WriteUInt32 (0x53445352);
-				// Module ID
-				buffer.WriteBytes (pdb_id_guid.ToByteArray ());
-				// PDB Age
-				buffer.WriteUInt32 (pdb_id_age);
-				// PDB Path
-				var fileName = writer.BaseStream.GetFileName ();
-				if (string.IsNullOrEmpty (fileName)) {
-					fileName = module.Assembly.Name.Name + ".pdb";
-				}
-				buffer.WriteBytes (System.Text.Encoding.UTF8.GetBytes (fileName));
-				buffer.WriteByte (0);
-
-				var data = new byte [buffer.length];
-				Buffer.BlockCopy (buffer.buffer, 0, data, 0, buffer.length);
-				codeViewDirectory.SizeOfData = data.Length;
-
-				codeViewEntry = new ImageDebugHeaderEntry (codeViewDirectory, data);
+			var buffer = new ByteBuffer ();
+			// RSDS
+			buffer.WriteUInt32 (0x53445352);
+			// Module ID
+			buffer.WriteBytes (module.Mvid.ToByteArray ());
+			// PDB Age
+			buffer.WriteUInt32 (1);
+			// PDB Path
+			var fileName = writer.BaseStream.GetFileName ();
+			if (string.IsNullOrEmpty (fileName)) {
+				fileName = module.Assembly.Name.Name + ".pdb";
 			}
+			buffer.WriteBytes (System.Text.Encoding.UTF8.GetBytes (fileName));
+			buffer.WriteByte (0);
 
-			ImageDebugHeaderEntry pdbChecksumEntry;
-			{
-				var pdbChecksumDirectory = new ImageDebugDirectory () {
-					MajorVersion = 1,
-					MinorVersion = 0,
-					Type = ImageDebugType.PdbChecksum,
-					TimeDateStamp = 0
-				};
-
-				var buffer = new ByteBuffer ();
-				// SHA256 - Algorithm name
-				buffer.WriteBytes (System.Text.Encoding.UTF8.GetBytes ("SHA256"));
-				buffer.WriteByte (0);
-
-				// Checksum - 32 bytes
-				buffer.WriteBytes (pdb_checksum);
+			var data = new byte [buffer.length];
+			Buffer.BlockCopy (buffer.buffer, 0, data, 0, buffer.length);
+			directory.SizeOfData = data.Length;
 
-				var data = new byte [buffer.length];
-				Buffer.BlockCopy (buffer.buffer, 0, data, 0, buffer.length);
-				pdbChecksumDirectory.SizeOfData = data.Length;
+			return new ImageDebugHeader (new ImageDebugHeaderEntry (directory, data));
+		}
 
-				pdbChecksumEntry = new ImageDebugHeaderEntry (pdbChecksumDirectory, data);
-			}
+		public void Write (MethodDebugInformation info)
+		{
+			CheckMethodDebugInformationTable ();
 
-			return new ImageDebugHeader (new ImageDebugHeaderEntry [] { codeViewEntry, pdbChecksumEntry });
+			pdb_metadata.AddMethodDebugInformation (info);
 		}
 
 		void CheckMethodDebugInformationTable ()
@@ -389,8 +343,10 @@ namespace Mono.Cecil.Cil {
 
 		public void Dispose ()
 		{
-			writer.stream.Dispose ();
-			final_stream.Dispose ();
+			if (IsEmbedded)
+				return;
+
+			WritePdbFile ();
 		}
 
 		void WritePdbFile ()
@@ -404,18 +360,15 @@ namespace Mono.Cecil.Cil {
 			writer.WriteMetadata ();
 
 			writer.Flush ();
-
-			ComputeChecksumAndPdbId ();
-
-			WritePdbId ();
+			writer.stream.Dispose ();
 		}
 
 		void WritePdbHeap ()
 		{
 			var pdb_heap = pdb_metadata.pdb_heap;
 
-			// PDB ID ( GUID + TimeStamp ) are left zeroed out for now. Will be filled at the end with a hash.
-			pdb_heap.WriteBytes (20);
+			pdb_heap.WriteBytes (module.Mvid.ToByteArray ());
+			pdb_heap.WriteUInt32 (module_metadata.timestamp);
 
 			pdb_heap.WriteUInt32 (module_metadata.entry_point.ToUInt32 ());
 
@@ -446,32 +399,6 @@ namespace Mono.Cecil.Cil {
 			pdb_metadata.table_heap.ComputeTableInformations ();
 			pdb_metadata.table_heap.WriteTableHeap ();
 		}
-
-		void ComputeChecksumAndPdbId ()
-		{
-			var buffer = new byte [8192];
-
-			// Compute the has of the entire file - PDB ID is zeroes still
-			writer.BaseStream.Seek (0, SeekOrigin.Begin);
-			var sha256 = SHA256.Create ();
-			using (var crypto_stream = new CryptoStream (Stream.Null, sha256, CryptoStreamMode.Write)) {
-				CryptoService.CopyStreamChunk (writer.BaseStream, crypto_stream, buffer, (int)writer.BaseStream.Length);
-			}
-
-			pdb_checksum = sha256.Hash;
-
-			var hashBytes = new ByteBuffer (pdb_checksum);
-			pdb_id_guid = new Guid (hashBytes.ReadBytes (16));
-			pdb_id_age = hashBytes.ReadUInt32 ();
-		}
-
-		void WritePdbId ()
-		{
-			// PDB ID is the first 20 bytes of the PdbHeap
-			writer.MoveToRVA (TextSegment.PdbHeap);
-			writer.WriteBytes (pdb_id_guid.ToByteArray ());
-			writer.WriteUInt32 (pdb_id_age);
-		}
 	}
 
 	public sealed class EmbeddedPortablePdbWriterProvider : ISymbolWriterProvider {
@@ -508,14 +435,9 @@ namespace Mono.Cecil.Cil {
 			return new EmbeddedPortablePdbReaderProvider ();
 		}
 
-		public void Write (MethodDebugInformation info)
-		{
-			writer.Write (info);
-		}
-
 		public ImageDebugHeader GetDebugHeader ()
 		{
-			ImageDebugHeader pdbDebugHeader = writer.GetDebugHeader ();
+			writer.Dispose ();
 
 			var directory = new ImageDebugDirectory {
 				Type = ImageDebugType.EmbeddedPortablePdb,
@@ -540,12 +462,15 @@ namespace Mono.Cecil.Cil {
 
 			directory.SizeOfData = (int) data.Length;
 
-			var debugHeaderEntries = new ImageDebugHeaderEntry [pdbDebugHeader.Entries.Length + 1];
-			for (int i = 0; i < pdbDebugHeader.Entries.Length; i++)
-				debugHeaderEntries [i] = pdbDebugHeader.Entries [i];
-			debugHeaderEntries [debugHeaderEntries.Length - 1] = new ImageDebugHeaderEntry (directory, data.ToArray ());
+			return new ImageDebugHeader (new [] {
+				writer.GetDebugHeader ().Entries [0],
+				new ImageDebugHeaderEntry (directory, data.ToArray ())
+			});
+		}
 
-			return new ImageDebugHeader (debugHeaderEntries);
+		public void Write (MethodDebugInformation info)
+		{
+			writer.Write (info);
 		}
 
 		public void Dispose ()
diff --git a/Mono.Cecil.Cil/Symbols.cs b/Mono.Cecil.Cil/Symbols.cs
index a669067..5e92b67 100644
--- a/Mono.Cecil.Cil/Symbols.cs
+++ b/Mono.Cecil.Cil/Symbols.cs
@@ -39,7 +39,6 @@ namespace Mono.Cecil.Cil {
 		CodeView = 2,
 		Deterministic = 16,
 		EmbeddedPortablePdb = 17,
-		PdbChecksum = 19,
 	}
 
 	public sealed class ImageDebugHeader {
@@ -1175,11 +1174,6 @@ namespace Mono.Cecil {
 			return GetEntry (header, ImageDebugType.EmbeddedPortablePdb);
 		}
 
-		public static ImageDebugHeaderEntry GetPdbChecksumEntry (this ImageDebugHeader header)
-		{
-			return GetEntry (header, ImageDebugType.PdbChecksum);
-		}
-
 		private static ImageDebugHeaderEntry GetEntry (this ImageDebugHeader header, ImageDebugType type)
 		{
 			if (!header.HasEntries)
diff --git a/Mono.Cecil.PE/ImageReader.cs b/Mono.Cecil.PE/ImageReader.cs
index a34e64d..5358129 100644
--- a/Mono.Cecil.PE/ImageReader.cs
+++ b/Mono.Cecil.PE/ImageReader.cs
@@ -27,7 +27,6 @@ namespace Mono.Cecil.PE {
 		DataDirectory metadata;
 
 		uint table_heap_offset;
-		uint pdb_heap_offset;
 
 		public ImageReader (Disposable<Stream> stream, string file_name)
 			: base (stream.value)
@@ -401,7 +400,6 @@ namespace Mono.Cecil.PE {
 				break;
 			case "#Pdb":
 				image.PdbHeap = new PdbHeap (data);
-				pdb_heap_offset = offset;
 				break;
 			}
 		}
@@ -770,7 +768,7 @@ namespace Mono.Cecil.PE {
 			}
 		}
 
-		public static Image ReadPortablePdb (Disposable<Stream> stream, string file_name, out uint pdb_heap_offset)
+		public static Image ReadPortablePdb (Disposable<Stream> stream, string file_name)
 		{
 			try {
 				var reader = new ImageReader (stream, file_name);
@@ -787,7 +785,6 @@ namespace Mono.Cecil.PE {
 
 				reader.metadata = new DataDirectory (0, length);
 				reader.ReadMetadata ();
-				pdb_heap_offset = reader.pdb_heap_offset;
 				return reader.image;
 			} catch (EndOfStreamException e) {
 				throw new BadImageFormatException (stream.value.GetFileName (), e);
diff --git a/Mono.Cecil.PE/ImageWriter.cs b/Mono.Cecil.PE/ImageWriter.cs
index 0648f59..a8a3fa8 100644
--- a/Mono.Cecil.PE/ImageWriter.cs
+++ b/Mono.Cecil.PE/ImageWriter.cs
@@ -48,9 +48,7 @@ namespace Mono.Cecil.PE {
 
 		ushort sections;
 
-		internal long debug_header_entries_position;
-
-		ImageWriter (ModuleDefinition module, string runtime_version, MetadataBuilder metadata, Disposable<Stream> stream, bool metadataOnly = false, ImageDebugHeader debugHeader = null)
+		ImageWriter (ModuleDefinition module, string runtime_version, MetadataBuilder metadata, Disposable<Stream> stream, bool metadataOnly = false)
 			: base (stream.value)
 		{
 			this.module = module;
@@ -63,18 +61,26 @@ namespace Mono.Cecil.PE {
 
 			this.pe64 = module.Architecture == TargetArchitecture.AMD64 || module.Architecture == TargetArchitecture.IA64 || module.Architecture == TargetArchitecture.ARM64;
 			this.has_reloc = module.Architecture == TargetArchitecture.I386;
+			this.GetDebugHeader ();
 			this.GetWin32Resources ();
+			this.BuildTextMap ();
+			this.sections = (ushort) (has_reloc ? 2 : 1); // text + reloc?
+		}
+
+		void GetDebugHeader ()
+		{
+			var symbol_writer = metadata.symbol_writer;
+			if (symbol_writer != null)
+				debug_header = symbol_writer.GetDebugHeader ();
 
-			debug_header = debugHeader;
 			if (module.HasDebugHeader) {
 				var header = module.GetDebugHeader ();
 				var deterministic = header.GetDeterministicEntry ();
-				if (deterministic != null)
-					debug_header = debug_header.AddDeterministicEntry ();
-			}
+				if (deterministic == null)
+					return;
 
-			this.BuildTextMap ();
-			this.sections = (ushort)(has_reloc ? 2 : 1); // text + reloc?
+				debug_header = debug_header.AddDeterministicEntry ();
+			}
 		}
 
 		void GetWin32Resources ()
@@ -90,9 +96,9 @@ namespace Mono.Cecil.PE {
 			}
 		}
 
-		public static ImageWriter CreateWriter (ModuleDefinition module, MetadataBuilder metadata, Disposable<Stream> stream, ImageDebugHeader debugHeader)
+		public static ImageWriter CreateWriter (ModuleDefinition module, MetadataBuilder metadata, Disposable<Stream> stream)
 		{
-			var writer = new ImageWriter (module, module.runtime_version, metadata, stream, metadataOnly: false, debugHeader: debugHeader);
+			var writer = new ImageWriter (module, module.runtime_version, metadata, stream);
 			writer.BuildSections ();
 			return writer;
 		}
@@ -373,7 +379,7 @@ namespace Mono.Cecil.PE {
 			BaseStream.Seek (GetRVAFileOffset (section, rva), SeekOrigin.Begin);
 		}
 
-		internal void MoveToRVA (TextSegment segment)
+		void MoveToRVA (TextSegment segment)
 		{
 			MoveToRVA (text, text_map.GetRVA (segment));
 		}
@@ -594,9 +600,7 @@ namespace Mono.Cecil.PE {
 
 				data_start += entry.Data.Length;
 			}
-
-			debug_header_entries_position = BaseStream.Position;
-
+			
 			for (var i = 0; i < debug_header.Entries.Length; i++) {
 				var entry = debug_header.Entries [i];
 				WriteBytes (entry.Data);
diff --git a/Mono.Cecil/AssemblyWriter.cs b/Mono.Cecil/AssemblyWriter.cs
index e60ab1d..c83f997 100644
--- a/Mono.Cecil/AssemblyWriter.cs
+++ b/Mono.Cecil/AssemblyWriter.cs
@@ -118,17 +118,13 @@ namespace Mono.Cecil {
 					metadata.SetSymbolWriter (symbol_writer);
 					BuildMetadata (module, metadata);
 
-					ImageDebugHeader debugHeader = null;
-					if (symbol_writer != null)
-						debugHeader = symbol_writer.GetDebugHeader ();
+					if (parameters.DeterministicMvid)
+						metadata.ComputeDeterministicMvid ();
 
-					var writer = ImageWriter.CreateWriter (module, metadata, stream, debugHeader);
+					var writer = ImageWriter.CreateWriter (module, metadata, stream);
 					stream.value.SetLength (0);
 					writer.WriteImage ();
 
-					if (parameters.DeterministicMvid)
-						ComputeDeterministicMvid (writer, module);
-
 					if (parameters.HasStrongNameKey)
 						CryptoService.StrongName (stream.value, writer, parameters);
 				}
@@ -160,26 +156,6 @@ namespace Mono.Cecil {
 
 			return symbol_writer_provider.GetSymbolWriter (module, fq_name);
 		}
-
-		static void ComputeDeterministicMvid (ImageWriter writer, ModuleDefinition module)
-		{
-			long previousPosition = writer.BaseStream.Position;
-			writer.BaseStream.Seek(0, SeekOrigin.Begin);
-
-			// The hash should be computed with the MVID set to all zeroes
-			// which it is - we explicitly write all zeroes GUID into the heap
-			// as the MVID.
-			// Same goes for strong name signature, which also already in the image but all zeroes right now.
-			Guid guid = CryptoService.ComputeGuid (CryptoService.ComputeHash (writer.BaseStream));
-
-			// The MVID GUID is always the first GUID in the GUID heap
-			writer.MoveToRVA (TextSegment.GuidHeap);
-			writer.WriteBytes (guid.ToByteArray ());
-			writer.Flush ();
-			module.Mvid = guid;
-
-			writer.BaseStream.Seek(previousPosition, SeekOrigin.Begin);
-		}
 	}
 
 	abstract class MetadataTable {
@@ -2666,6 +2642,25 @@ namespace Mono.Cecil {
 
 			method_debug_information_table.rows [rid - 1].Col2 = GetBlobIndex (signature);
 		}
+
+		public void ComputeDeterministicMvid ()
+		{
+			var guid = CryptoService.ComputeGuid (CryptoService.ComputeHash (
+				data,
+				resources,
+				string_heap,
+				user_string_heap,
+				blob_heap,
+				table_heap,
+				code));
+
+			var position = guid_heap.position;
+			guid_heap.position = 0;
+			guid_heap.WriteBytes (guid.ToByteArray ());
+			guid_heap.position = position;
+
+			module.Mvid = guid;
+		}
 	}
 
 	sealed class SignatureWriter : ByteBuffer {
diff --git a/Mono.Security.Cryptography/CryptoService.cs b/Mono.Security.Cryptography/CryptoService.cs
index 3877deb..dd9613f 100644
--- a/Mono.Security.Cryptography/CryptoService.cs
+++ b/Mono.Security.Cryptography/CryptoService.cs
@@ -109,7 +109,7 @@ namespace Mono.Cecil {
 			return sha1.Hash;
 		}
 
-		public static void CopyStreamChunk (Stream stream, Stream dest_stream, byte [] buffer, int length)
+		static void CopyStreamChunk (Stream stream, Stream dest_stream, byte [] buffer, int length)
 		{
 			while (length > 0) {
 				int read = stream.Read (buffer, 0, System.Math.Min (buffer.Length, length));
diff --git a/Test/Mono.Cecil.Tests/ImageReadTests.cs b/Test/Mono.Cecil.Tests/ImageReadTests.cs
index f663b60..ef6ab06 100644
--- a/Test/Mono.Cecil.Tests/ImageReadTests.cs
+++ b/Test/Mono.Cecil.Tests/ImageReadTests.cs
@@ -237,16 +237,9 @@ namespace Mono.Cecil.Tests {
 
 				var header = module.GetDebugHeader ();
 
-				Assert.IsTrue (header.Entries.Length >= 2);
+				Assert.AreEqual (2, header.Entries.Length);
 				Assert.IsTrue (header.Entries.Any (e => e.Directory.Type == ImageDebugType.CodeView));
 				Assert.IsTrue (header.Entries.Any (e => e.Directory.Type == ImageDebugType.Deterministic));
-
-				// If read directly from a file the PdbChecksum may not be persent (in this test case it isn't)
-				// but when written through Cecil it will always be there.
-				if (header.Entries.Length > 2) {
-					Assert.AreEqual (3, header.Entries.Length);
-					Assert.IsTrue (header.Entries.Any (e => e.Directory.Type == ImageDebugType.PdbChecksum));
-				}
 			}, symbolReaderProvider: typeof (PortablePdbReaderProvider), symbolWriterProvider: typeof (PortablePdbWriterProvider));
 		}
 
@@ -258,17 +251,10 @@ namespace Mono.Cecil.Tests {
 
 				var header = module.GetDebugHeader ();
 
-				Assert.IsTrue (header.Entries.Length >= 3);
+				Assert.AreEqual (3, header.Entries.Length);
 				Assert.IsTrue (header.Entries.Any (e => e.Directory.Type == ImageDebugType.CodeView));
 				Assert.IsTrue (header.Entries.Any (e => e.Directory.Type == ImageDebugType.Deterministic));
 				Assert.IsTrue (header.Entries.Any (e => e.Directory.Type == ImageDebugType.EmbeddedPortablePdb));
-
-				// If read directly from a file the PdbChecksum may not be persent (in this test case it isn't)
-				// but when written through Cecil it will always be there.
-				if (header.Entries.Length > 3) {
-					Assert.AreEqual (4, header.Entries.Length);
-					Assert.IsTrue (header.Entries.Any (e => e.Directory.Type == ImageDebugType.PdbChecksum));
-				}
 			}, symbolReaderProvider: typeof (EmbeddedPortablePdbReaderProvider), symbolWriterProvider: typeof (EmbeddedPortablePdbWriterProvider));
 		}
 	}
diff --git a/Test/Mono.Cecil.Tests/PortablePdbTests.cs b/Test/Mono.Cecil.Tests/PortablePdbTests.cs
index 1401f63..d9786cb 100644
--- a/Test/Mono.Cecil.Tests/PortablePdbTests.cs
+++ b/Test/Mono.Cecil.Tests/PortablePdbTests.cs
@@ -1,8 +1,6 @@
 using System;
 using System.IO;
-using System.IO.Compression;
 using System.Linq;
-using System.Security.Cryptography;
 using System.Text;
 using NUnit.Framework;
 
@@ -359,23 +357,15 @@ namespace Mono.Cecil.Tests {
 				var header = module.GetDebugHeader ();
 
 				Assert.IsNotNull (header);
-				Assert.IsTrue (header.Entries.Length >= 2);
+				Assert.AreEqual (2, header.Entries.Length);
 
-				int i = 0;
-				var cv = header.Entries [i++];
+				var cv = header.Entries [0];
 				Assert.AreEqual (ImageDebugType.CodeView, cv.Directory.Type);
 
-				if (header.Entries.Length > 2) {
-					Assert.AreEqual (3, header.Entries.Length);
-					var pdbChecksum = header.Entries [i++];
-					Assert.AreEqual (ImageDebugType.PdbChecksum, pdbChecksum.Directory.Type);
-				}
-
-				var eppdb = header.Entries [i++];
+				var eppdb = header.Entries [1];
 				Assert.AreEqual (ImageDebugType.EmbeddedPortablePdb, eppdb.Directory.Type);
 				Assert.AreEqual (0x0100, eppdb.Directory.MajorVersion);
 				Assert.AreEqual (0x0100, eppdb.Directory.MinorVersion);
-
 			}, symbolReaderProvider: typeof (EmbeddedPortablePdbReaderProvider), symbolWriterProvider: typeof (EmbeddedPortablePdbWriterProvider));
 		}
 
@@ -410,7 +400,7 @@ namespace Mono.Cecil.Tests {
 		{
 			TestModule ("PdbTarget.exe", test, symbolReaderProvider: typeof (PortablePdbReaderProvider), symbolWriterProvider: typeof (PortablePdbWriterProvider));
 			TestModule ("EmbeddedPdbTarget.exe", test, verify: !Platform.OnMono);
-			TestModule ("EmbeddedCompressedPdbTarget.exe", test, symbolReaderProvider: typeof(EmbeddedPortablePdbReaderProvider), symbolWriterProvider: typeof (EmbeddedPortablePdbWriterProvider));
+			TestModule ("EmbeddedCompressedPdbTarget.exe", test, symbolReaderProvider: typeof(EmbeddedPortablePdbReaderProvider), symbolWriterProvider: typeof(EmbeddedPortablePdbWriterProvider));
 		}
 
 		[Test]
@@ -614,7 +604,7 @@ class Program
 		}
 
 		[Test]
-		public void PortablePdbLineInfo()
+		public void PortablePdbLineInfo  ()
 		{
 			TestModule ("line.exe", module => {
 				var type = module.GetType ("Tests");
@@ -819,288 +809,5 @@ class Program
 				}
 			});
 		}
-
-		[Test]
-		public void DoubleWriteAndReadWithDeterministicMvidAndVariousChanges ()
-		{
-			Guid mvidIn, mvidARM64Out, mvidX64Out;
-
-			const string resource = "mylib.dll";
-			{
-				string destination = Path.GetTempFileName ();
-
-				using (var module = GetResourceModule (resource, new ReaderParameters { ReadSymbols = true })) {
-					mvidIn = module.Mvid;
-					module.Architecture = TargetArchitecture.ARM64; // Can't use I386 as it writes different import table size -> differnt MVID
-					module.Write (destination, new WriterParameters { DeterministicMvid = true, WriteSymbols = true });
-				}
-
-				using (var module = ModuleDefinition.ReadModule (destination, new ReaderParameters { ReadSymbols = true })) {
-					mvidARM64Out = module.Mvid;
-				}
-
-				Assert.AreNotEqual (mvidIn, mvidARM64Out);
-			}
-
-			{
-				string destination = Path.GetTempFileName ();
-
-				using (var module = GetResourceModule (resource, new ReaderParameters { ReadSymbols = true })) {
-					Assert.AreEqual (mvidIn, module.Mvid);
-					module.Architecture = TargetArchitecture.AMD64;
-					module.Write (destination, new WriterParameters { DeterministicMvid = true, WriteSymbols = true });
-				}
-
-				using (var module = ModuleDefinition.ReadModule (destination, new ReaderParameters { ReadSymbols = true })) {
-					mvidX64Out = module.Mvid;
-				}
-
-				Assert.AreNotEqual (mvidARM64Out, mvidX64Out);
-			}
-
-			{
-				string destination = Path.GetTempFileName ();
-
-				using (var module = GetResourceModule (resource, new ReaderParameters { ReadSymbols = true })) {
-					Assert.AreEqual (mvidIn, module.Mvid);
-					module.Architecture = TargetArchitecture.AMD64;
-					module.timestamp = 42;
-					module.Write (destination, new WriterParameters { DeterministicMvid = true, WriteSymbols = true });
-				}
-
-				Guid mvidDifferentTimeStamp;
-				using (var module = ModuleDefinition.ReadModule (destination, new ReaderParameters { ReadSymbols = true })) {
-					mvidDifferentTimeStamp = module.Mvid;
-				}
-
-				Assert.AreNotEqual (mvidX64Out, mvidDifferentTimeStamp);
-			}
-		}
-
-		[Test]
-		public void ReadPortablePdbChecksum ()
-		{
-			const string resource = "PdbChecksumLib.dll";
-
-			using (var module = GetResourceModule (resource, new ReaderParameters { ReadSymbols = true })) {
-				GetPdbChecksumData (module.GetDebugHeader (), out string algorithmName, out byte [] checksum);
-				Assert.AreEqual ("SHA256", algorithmName);
-
-				string pdbPath = GetDebugHeaderPdbPath (module);
-				CalculatePdbChecksumAndId (pdbPath, out byte [] expectedChecksum, out byte [] pdbId);
-
-				CollectionAssert.AreEqual (expectedChecksum, checksum);
-			}
-		}
-
-		[Test]
-		public void ReadEmbeddedPortablePdbChecksum ()
-		{
-			const string resource = "EmbeddedPdbChecksumLib.dll";
-
-			using (var module = GetResourceModule (resource, new ReaderParameters { ReadSymbols = true })) {
-				var debugHeader = module.GetDebugHeader ();
-				GetPdbChecksumData (debugHeader, out string algorithmName, out byte [] checksum);
-				Assert.AreEqual ("SHA256", algorithmName);
-
-				GetEmbeddedPdb (debugHeader, out byte [] embeddedPdb);
-				CalculatePdbChecksumAndId (embeddedPdb, out byte [] expectedChecksum, out byte [] pdbId);
-
-				CollectionAssert.AreEqual (expectedChecksum, checksum);
-			}
-		}
-
-		[Test]
-		public void WritePortablePdbChecksum ()
-		{
-			const string resource = "PdbChecksumLib.dll";
-			string destination = Path.GetTempFileName ();
-
-			using (var module = GetResourceModule (resource, new ReaderParameters { ReadSymbols = true })) {
-				module.Write (destination, new WriterParameters { DeterministicMvid = true, WriteSymbols = true });
-			}
-
-			using (var module = ModuleDefinition.ReadModule (destination, new ReaderParameters { ReadSymbols = true })) {
-				GetPdbChecksumData (module.GetDebugHeader (), out string algorithmName, out byte [] checksum);
-				Assert.AreEqual ("SHA256", algorithmName);
-
-				string pdbPath = GetDebugHeaderPdbPath (module);
-				CalculatePdbChecksumAndId (pdbPath, out byte [] expectedChecksum, out byte [] pdbId);
-
-				CollectionAssert.AreEqual (expectedChecksum, checksum);
-			}
-		}
-
-		[Test]
-		public void WritePortablePdbToWriteOnlyStream ()
-		{
-			const string resource = "PdbChecksumLib.dll";
-			string destination = Path.GetTempFileName ();
-
-			// Note that the module stream already requires read access even on writing to be able to compute strong name
-			using (var module = GetResourceModule (resource, new ReaderParameters { ReadSymbols = true }))
-			using (var pdbStream = new FileStream (destination + ".pdb", FileMode.Create, FileAccess.Write)) {
-				module.Write (destination, new WriterParameters {
-					DeterministicMvid = true,
-					WriteSymbols = true,
-					SymbolWriterProvider = new PortablePdbWriterProvider (),
-					SymbolStream = pdbStream
-				});
-			}
-		}
-
-		[Test]
-		public void DoubleWritePortablePdbDeterministicPdbId ()
-		{
-			const string resource = "PdbChecksumLib.dll";
-			string destination = Path.GetTempFileName ();
-
-			using (var module = GetResourceModule (resource, new ReaderParameters { ReadSymbols = true })) {
-				module.Write (destination, new WriterParameters { DeterministicMvid = true, WriteSymbols = true });
-			}
-
-			byte [] pdbIdOne;
-			using (var module = ModuleDefinition.ReadModule (destination, new ReaderParameters { ReadSymbols = true })) {
-				string pdbPath = GetDebugHeaderPdbPath (module);
-				CalculatePdbChecksumAndId (pdbPath, out byte [] expectedChecksum, out pdbIdOne);
-			}
-
-			using (var module = GetResourceModule (resource, new ReaderParameters { ReadSymbols = true })) {
-				module.Write (destination, new WriterParameters { DeterministicMvid = true, WriteSymbols = true });
-			}
-
-			byte [] pdbIdTwo;
-			using (var module = ModuleDefinition.ReadModule (destination, new ReaderParameters { ReadSymbols = true })) {
-				string pdbPath = GetDebugHeaderPdbPath (module);
-				CalculatePdbChecksumAndId (pdbPath, out byte [] expectedChecksum, out pdbIdTwo);
-			}
-
-			CollectionAssert.AreEqual (pdbIdOne, pdbIdTwo);
-		}
-
-		[Test]
-		public void WriteEmbeddedPortablePdbChecksum ()
-		{
-			const string resource = "EmbeddedPdbChecksumLib.dll";
-			string destination = Path.GetTempFileName ();
-
-			using (var module = GetResourceModule (resource, new ReaderParameters { ReadSymbols = true })) {
-				module.Write (destination, new WriterParameters { DeterministicMvid = true, WriteSymbols = true });
-			}
-
-			using (var module = ModuleDefinition.ReadModule (destination, new ReaderParameters { ReadSymbols = true })) {
-				var debugHeader = module.GetDebugHeader ();
-				GetPdbChecksumData (debugHeader, out string algorithmName, out byte [] checksum);
-				Assert.AreEqual ("SHA256", algorithmName);
-
-				GetEmbeddedPdb (debugHeader, out byte [] embeddedPdb);
-				CalculatePdbChecksumAndId (embeddedPdb, out byte [] expectedChecksum, out byte [] pdbId);
-
-				CollectionAssert.AreEqual (expectedChecksum, checksum);
-			}
-		}
-
-		[Test]
-		public void DoubleWriteEmbeddedPortablePdbChecksum ()
-		{
-			const string resource = "EmbeddedPdbChecksumLib.dll";
-			string destination = Path.GetTempFileName ();
-
-			using (var module = GetResourceModule (resource, new ReaderParameters { ReadSymbols = true })) {
-				module.Write (destination, new WriterParameters { DeterministicMvid = true, WriteSymbols = true });
-			}
-
-			byte [] pdbIdOne;
-			using (var module = ModuleDefinition.ReadModule (destination, new ReaderParameters { ReadSymbols = true })) {
-				var debugHeader = module.GetDebugHeader ();
-				GetEmbeddedPdb (debugHeader, out byte [] embeddedPdb);
-				CalculatePdbChecksumAndId (embeddedPdb, out byte [] expectedChecksum, out pdbIdOne);
-			}
-
-			using (var module = GetResourceModule (resource, new ReaderParameters { ReadSymbols = true })) {
-				module.Write (destination, new WriterParameters { DeterministicMvid = true, WriteSymbols = true });
-			}
-
-			byte [] pdbIdTwo;
-			using (var module = ModuleDefinition.ReadModule (destination, new ReaderParameters { ReadSymbols = true })) {
-				var debugHeader = module.GetDebugHeader ();
-				GetEmbeddedPdb (debugHeader, out byte [] embeddedPdb);
-				CalculatePdbChecksumAndId (embeddedPdb, out byte [] expectedChecksum, out pdbIdTwo);
-			}
-
-			CollectionAssert.AreEqual (pdbIdOne, pdbIdTwo);
-		}
-
-		private void GetEmbeddedPdb (ImageDebugHeader debugHeader, out byte [] embeddedPdb)
-		{
-			var entry = Mixin.GetEmbeddedPortablePdbEntry (debugHeader);
-			Assert.IsNotNull (entry);
-
-			var compressed_stream = new MemoryStream (entry.Data);
-			var reader = new BinaryStreamReader (compressed_stream);
-			Assert.AreEqual (0x4244504D, reader.ReadInt32 ());
-			var length = reader.ReadInt32 ();
-			var decompressed_stream = new MemoryStream (length);
-
-			using (var deflate = new DeflateStream (compressed_stream, CompressionMode.Decompress, leaveOpen: true))
-				deflate.CopyTo (decompressed_stream);
-
-			embeddedPdb = decompressed_stream.ToArray ();
-		}
-
-		private void GetPdbChecksumData (ImageDebugHeader debugHeader, out string algorithmName, out byte [] checksum)
-		{
-			var entry = Mixin.GetPdbChecksumEntry (debugHeader);
-			Assert.IsNotNull (entry);
-
-			var length = Array.IndexOf (entry.Data, (byte)0, 0);
-			var bytes = new byte [length];
-			Buffer.BlockCopy (entry.Data, 0, bytes, 0, length);
-			algorithmName = Encoding.UTF8.GetString (bytes);
-			int checksumSize = 0;
-			switch (algorithmName) {
-			case "SHA256": checksumSize = 32; break;
-			case "SHA384": checksumSize = 48; break;
-			case "SHA512": checksumSize = 64; break;
-			}
-			checksum = new byte [checksumSize];
-			Buffer.BlockCopy (entry.Data, length + 1, checksum, 0, checksumSize);
-		}
-
-		private void CalculatePdbChecksumAndId (string filePath, out byte [] pdbChecksum, out byte [] pdbId)
-		{
-			using (var fs = File.OpenRead (filePath))
-				CalculatePdbChecksumAndId (fs, out pdbChecksum, out pdbId);
-		}
-
-		private void CalculatePdbChecksumAndId (byte [] data, out byte [] pdbChecksum, out byte [] pdbId)
-		{
-			using (var pdb = new MemoryStream (data))
-				CalculatePdbChecksumAndId (pdb, out pdbChecksum, out pdbId);
-		}
-
-		private void CalculatePdbChecksumAndId (Stream pdbStream, out byte [] pdbChecksum, out byte [] pdbId)
-		{
-			// Get the offset of the PDB heap (this requires parsing several headers
-			// so it's easier to use the ImageReader directly for this)
-			Image image = ImageReader.ReadPortablePdb (new Disposable<Stream> (pdbStream, false), "test.pdb", out uint pdbHeapOffset);
-			pdbId = new byte [20];
-			Array.Copy (image.PdbHeap.data, 0, pdbId, 0, 20);
-
-			pdbStream.Seek (0, SeekOrigin.Begin);
-			byte [] rawBytes = pdbStream.ReadAll ();
-
-			var bytes = new byte [rawBytes.Length];
-
-			Array.Copy (rawBytes, 0, bytes, 0, pdbHeapOffset);
-
-			// Zero out the PDB ID (20 bytes)
-			for (int i = 0; i < 20; bytes [i + pdbHeapOffset] = 0, i++) ;
-
-			Array.Copy (rawBytes, pdbHeapOffset + 20, bytes, pdbHeapOffset + 20, rawBytes.Length - pdbHeapOffset - 20);
-
-			var sha256 = SHA256.Create ();
-			pdbChecksum = sha256.ComputeHash (bytes);
-		}
 	}
 }
diff --git a/Test/Resources/assemblies/EmbeddedPdbChecksumLib.dll b/Test/Resources/assemblies/EmbeddedPdbChecksumLib.dll
deleted file mode 100644
index 2de939b..0000000
--- a/Test/Resources/assemblies/EmbeddedPdbChecksumLib.dll
+++ /dev/null
diff --git a/Test/Resources/assemblies/PdbChecksumLib.dll b/Test/Resources/assemblies/PdbChecksumLib.dll
deleted file mode 100644
index 9c28db7..0000000
--- a/Test/Resources/assemblies/PdbChecksumLib.dll
+++ /dev/null
diff --git a/Test/Resources/assemblies/PdbChecksumLib.pdb b/Test/Resources/assemblies/PdbChecksumLib.pdb
deleted file mode 100644
index 81975e7..0000000
--- a/Test/Resources/assemblies/PdbChecksumLib.pdb
+++ /dev/null
diff --git a/symbols/pdb/Mono.Cecil.Pdb/NativePdbWriter.cs b/symbols/pdb/Mono.Cecil.Pdb/NativePdbWriter.cs
index 9a9166b..01b6c7a 100644
--- a/symbols/pdb/Mono.Cecil.Pdb/NativePdbWriter.cs
+++ b/symbols/pdb/Mono.Cecil.Pdb/NativePdbWriter.cs
@@ -44,15 +44,9 @@ namespace Mono.Cecil.Pdb {
 
 		public ImageDebugHeader GetDebugHeader ()
 		{
-			var entry_point = module.EntryPoint;
-			if (entry_point != null)
-				writer.SetUserEntryPoint (entry_point.MetadataToken.ToInt32 ());
-
 			ImageDebugDirectory directory;
 			var data = writer.GetDebugInfo (out directory);
 			directory.TimeDateStamp = (int) module.timestamp;
-
-			writer.Close ();
 			return new ImageDebugHeader (new ImageDebugHeaderEntry (directory, data));
 		}
 
@@ -261,6 +255,11 @@ namespace Mono.Cecil.Pdb {
 
 		public void Dispose ()
 		{
+			var entry_point = module.EntryPoint;
+			if (entry_point != null)
+				writer.SetUserEntryPoint (entry_point.MetadataToken.ToInt32 ());
+
+			writer.Close ();
 		}
 	}