Improve extracting Unix and NT timestamps from ZipExtraData

Author: bastianeicher

ICSharpCode.SharpZipLib/Zip/ZipEntry.cs

@@ -1033,57 +1033,41 @@ internal void ProcessExtraData(bool localHeader)
 				}
 			}
 
-			if (extraData.Find(10)) {
-				// No room for any tags.
-				if (extraData.ValueLength < 4) {
-					throw new ZipException("NTFS Extra data invalid");
-				}
-
-				extraData.ReadInt(); // Reserved
-
-				while (extraData.UnreadCount >= 4) {
-					int ntfsTag = extraData.ReadShort();
-					int ntfsLength = extraData.ReadShort();
-					if (ntfsTag == 1) {
-						if (ntfsLength >= 24) {
-							long lastModification = extraData.ReadLong();
-							long lastAccess = extraData.ReadLong();
-							long createTime = extraData.ReadLong();
-
-							dateTime = System.DateTime.FromFileTimeUtc(lastModification);
-						}
-						break;
-					} else {
-						// An unknown NTFS tag so simply skip it.
-						extraData.Skip(ntfsLength);
-					}
-				}
-			} else if (extraData.Find(0x5455)) {
-				int length = extraData.ValueLength;
-				int flags = extraData.ReadByte();
-
-				// Can include other times but these are ignored.  Length of data should
-				// actually be 1 + 4 * no of bits in flags.
-				if (((flags & 1) != 0) && (length >= 5)) {
-					int iTime = extraData.ReadInt();
-
-					dateTime = (new System.DateTime ( 1970, 1, 1, 0, 0, 0, DateTimeKind.Utc ) +
-						new TimeSpan ( 0, 0, 0, iTime, 0 ));
-				}
-			} else {
-				uint sec = Math.Min(59, 2 * (dosTime & 0x1f));
-				uint min = Math.Min(59, (dosTime >> 5) & 0x3f);
-				uint hrs = Math.Min(23, (dosTime >> 11) & 0x1f);
-				uint mon = Math.Max(1, Math.Min(12, ((dosTime >> 21) & 0xf)));
-				uint year = ((dosTime >> 25) & 0x7f) + 1980;
-				int day = Math.Max(1, Math.Min(DateTime.DaysInMonth((int)year, (int)mon), (int)((dosTime >> 16) & 0x1f)));
-				dateTime = new DateTime((int)year, (int)mon, day, (int)hrs, (int)min, (int)sec, DateTimeKind.Utc);
-			}
+			dateTime = GetDateTime(extraData);
 			if (method == CompressionMethod.WinZipAES) {
 				ProcessAESExtraData(extraData);
 			}
 		}
 
+		private DateTime GetDateTime(ZipExtraData extraData) {
+			// Check for NT timestamp
+            // NOTE: Disable by default to match behavior of InfoZIP
+#if RESPECT_NT_TIMESTAMP
+			NTTaggedData ntData = extraData.GetData<NTTaggedData>();
+			if (ntData != null)
+				return ntData.LastModificationTime;
+#endif
+
+			// Check for Unix timestamp
+			ExtendedUnixData unixData = extraData.GetData<ExtendedUnixData>();
+			if (unixData != null &&
+				// Only apply modification time, but require all other values to be present
+				// This is done to match InfoZIP's behaviour
+				((unixData.Include & ExtendedUnixData.Flags.ModificationTime) != 0) &&
+				((unixData.Include & ExtendedUnixData.Flags.AccessTime) != 0) &&
+				((unixData.Include & ExtendedUnixData.Flags.CreateTime) != 0))
+				return unixData.ModificationTime;
+
+			// Fall back to DOS time
+			uint sec = Math.Min(59, 2 * (dosTime & 0x1f));
+			uint min = Math.Min(59, (dosTime >> 5) & 0x3f);
+			uint hrs = Math.Min(23, (dosTime >> 11) & 0x1f);
+			uint mon = Math.Max(1, Math.Min(12, ((dosTime >> 21) & 0xf)));
+			uint year = ((dosTime >> 25) & 0x7f) + 1980;
+			int day = Math.Max(1, Math.Min(DateTime.DaysInMonth((int)year, (int)mon), (int)((dosTime >> 16) & 0x1f)));
+			return new DateTime((int)year, (int)mon, day, (int)hrs, (int)min, (int)sec, DateTimeKind.Utc);
+		}
+
 		// For AES the method in the entry is 99, and the real compression method is in the extradata
 		//
 		private void ProcessAESExtraData(ZipExtraData extraData)

ICSharpCode.SharpZipLib/Zip/ZipExtraData.cs

@@ -190,11 +190,15 @@ public void SetData(byte[] data, int index, int count)
 				// bit 2           if set, creation time is present
 
 				_flags = (Flags)helperStream.ReadByte();
-				if (((_flags & Flags.ModificationTime) != 0) && (count >= 5)) {
+				if (((_flags & Flags.ModificationTime) != 0))
+				{
 					int iTime = helperStream.ReadLEInt();
 
 					_modificationTime = new DateTime(1970, 1, 1, 0, 0, 0, 0, DateTimeKind.Utc) +
 						new TimeSpan(0, 0, 0, iTime, 0);
+
+					// Central-header version is truncated after modification time
+					if (count <= 5) return;
 				}
 
 				if ((_flags & Flags.AccessTime) != 0) {
@@ -321,7 +325,7 @@ public DateTime CreateTime
 		/// <summary>
 		/// Get/set the <see cref="Flags">values</see> to include.
 		/// </summary>
-		Flags Include
+		public Flags Include
 		{
 			get { return _flags; }
 			set { _flags = value; }
@@ -575,33 +579,18 @@ public Stream GetStreamForTag(int tag)
 		/// <summary>
 		/// Get the <see cref="ITaggedData">tagged data</see> for a tag.
 		/// </summary>
-		/// <param name="tag">The tag to search for.</param>
+		/// <typeparam name="T">The tag to search for.</typeparam>
 		/// <returns>Returns a <see cref="ITaggedData">tagged value</see> or null if none found.</returns>
-		private ITaggedData GetData(short tag)
+		public T GetData<T>()
+			where T : class, ITaggedData, new()
 		{
-			ITaggedData result = null;
-			if (Find(tag)) {
-				result = Create(tag, _data, _readValueStart, _readValueLength);
-			}
-			return result;
-		}
-
-		static ITaggedData Create(short tag, byte[] data, int offset, int count)
-		{
-			ITaggedData result = null;
-			switch (tag) {
-			case 0x000A:
-				result = new NTTaggedData();
-				break;
-			case 0x5455:
-				result = new ExtendedUnixData();
-				break;
-			default:
-				result = new RawTaggedData(tag);
-				break;
+			T result = new T();
+			if (Find(result.TagID))
+			{
+				result.SetData(_data, _readValueStart, _readValueLength);
+				return result;
 			}
-			result.SetData(data, offset, count);
-			return result;
+			else return null;
 		}
 
 		/// <summary>