Imported Upstream version 6.6.0.89

Former-commit-id: b39a328747c2f3414dc52e009fb6f0aa80ca2492

external/cecil/Mono.Security.Cryptography/CryptoService.cs

@@ -102,20 +102,48 @@ namespace Mono.Cecil {
 			if (!File.Exists (file))
 				return Empty<byte>.Array;
 
+			using (var stream = new FileStream (file, FileMode.Open, FileAccess.Read, FileShare.Read))
+				return ComputeHash (stream);
+		}
+
+		public static byte [] ComputeHash (Stream stream)
+		{
 			const int buffer_size = 8192;
 
 			var sha1 = new SHA1Managed ();
+			var buffer = new byte [buffer_size];
 
-			using (var stream = new FileStream (file, FileMode.Open, FileAccess.Read, FileShare.Read)) {
+			using (var crypto_stream = new CryptoStream (Stream.Null, sha1, CryptoStreamMode.Write))
+				CopyStreamChunk (stream, crypto_stream, buffer, (int) stream.Length);
 
-				var buffer = new byte [buffer_size];
+			return sha1.Hash;
+		}
 
-				using (var crypto_stream = new CryptoStream (Stream.Null, sha1, CryptoStreamMode.Write))
-					CopyStreamChunk (stream, crypto_stream, buffer, (int) stream.Length);
+		public static byte [] ComputeHash (params ByteBuffer [] buffers)
+		{
+			var sha1 = new SHA1Managed ();
+
+			using (var crypto_stream = new CryptoStream (Stream.Null, sha1, CryptoStreamMode.Write)) {
+				for (int i = 0; i < buffers.Length; i++) {
+					crypto_stream.Write (buffers [0].buffer, 0, buffers [0].length);
+				}
 			}
 
 			return sha1.Hash;
 		}
+
+		public static Guid ComputeGuid (byte [] hash)
+		{
+			// From corefx/src/System.Reflection.Metadata/src/System/Reflection/Metadata/BlobContentId.cs
+			var guid = new byte [16];
+			Buffer.BlockCopy (hash, 0, guid, 0, 16);
+
+			// modify the guid data so it decodes to the form of a "random" guid ala rfc4122
+			guid [7] = (byte) ((guid [7] & 0x0f) | (4 << 4));
+			guid [8] = (byte) ((guid [8] & 0x3f) | (2 << 6));
+
+			return new Guid (guid);
+		}
 	}
 
 	static partial class Mixin {