Merge pull request #803 from DannyBoyk/802_Add_UnixTimeExtraField_Support_Zips

Add support for the UnixTimeExtraField in Zip files

Author: adamhathcock

src/SharpCompress/Common/Zip/Headers/DirectoryEntryHeader.cs

@@ -85,6 +85,36 @@ internal override void Read(BinaryReader reader)
                 RelativeOffsetOfEntryHeader = zip64ExtraData.RelativeOffsetOfEntryHeader;
             }
         }
+
+        var unixTimeExtra = Extra.FirstOrDefault(u => u.Type == ExtraDataType.UnixTimeExtraField);
+
+        if (unixTimeExtra is not null)
+        {
+            // Tuple order is last modified time, last access time, and creation time.
+            var unixTimeTuple = ((UnixTimeExtraField)unixTimeExtra).UnicodeTimes;
+
+            if (unixTimeTuple.Item1.HasValue)
+            {
+                var dosTime = Utility.DateTimeToDosTime(unixTimeTuple.Item1.Value);
+
+                LastModifiedDate = (ushort)(dosTime >> 16);
+                LastModifiedTime = (ushort)(dosTime & 0x0FFFF);
+            }
+            else if (unixTimeTuple.Item2.HasValue)
+            {
+                var dosTime = Utility.DateTimeToDosTime(unixTimeTuple.Item2.Value);
+
+                LastModifiedDate = (ushort)(dosTime >> 16);
+                LastModifiedTime = (ushort)(dosTime & 0x0FFFF);
+            }
+            else if (unixTimeTuple.Item3.HasValue)
+            {
+                var dosTime = Utility.DateTimeToDosTime(unixTimeTuple.Item3.Value);
+
+                LastModifiedDate = (ushort)(dosTime >> 16);
+                LastModifiedTime = (ushort)(dosTime & 0x0FFFF);
+            }
+        }
     }
 
     internal ushort Version { get; private set; }

src/SharpCompress/Common/Zip/Headers/LocalEntryHeader.cs

@@ -64,6 +64,36 @@ internal override void Read(BinaryReader reader)
                 UncompressedSize = zip64ExtraData.UncompressedSize;
             }
         }
+
+        var unixTimeExtra = Extra.FirstOrDefault(u => u.Type == ExtraDataType.UnixTimeExtraField);
+
+        if (unixTimeExtra is not null)
+        {
+            // Tuple order is last modified time, last access time, and creation time.
+            var unixTimeTuple = ((UnixTimeExtraField)unixTimeExtra).UnicodeTimes;
+
+            if (unixTimeTuple.Item1.HasValue)
+            {
+                var dosTime = Utility.DateTimeToDosTime(unixTimeTuple.Item1.Value);
+
+                LastModifiedDate = (ushort)(dosTime >> 16);
+                LastModifiedTime = (ushort)(dosTime & 0x0FFFF);
+            }
+            else if (unixTimeTuple.Item2.HasValue)
+            {
+                var dosTime = Utility.DateTimeToDosTime(unixTimeTuple.Item2.Value);
+
+                LastModifiedDate = (ushort)(dosTime >> 16);
+                LastModifiedTime = (ushort)(dosTime & 0x0FFFF);
+            }
+            else if (unixTimeTuple.Item3.HasValue)
+            {
+                var dosTime = Utility.DateTimeToDosTime(unixTimeTuple.Item3.Value);
+
+                LastModifiedDate = (ushort)(dosTime >> 16);
+                LastModifiedTime = (ushort)(dosTime & 0x0FFFF);
+            }
+        }
     }
 
     internal ushort Version { get; private set; }

src/SharpCompress/Common/Zip/Headers/LocalEntryHeaderExtraFactory.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Buffers.Binary;
 using System.Text;
 
@@ -13,7 +13,8 @@ internal enum ExtraDataType : ushort
     // Third Party Mappings
     // -Info-ZIP Unicode Path Extra Field
     UnicodePathExtraField = 0x7075,
-    Zip64ExtendedInformationExtraField = 0x0001
+    Zip64ExtendedInformationExtraField = 0x0001,
+    UnixTimeExtraField = 0x5455
 }
 
 internal class ExtraData
@@ -145,6 +146,84 @@ ushort diskNumber
     public uint VolumeNumber { get; private set; }
 }
 
+internal sealed class UnixTimeExtraField : ExtraData
+{
+    public UnixTimeExtraField(ExtraDataType type, ushort length, byte[] dataBytes)
+        : base(type, length, dataBytes) { }
+
+    /// <summary>
+    /// The unix modified time, last access time, and creation time, if set.
+    /// </summary>
+    /// <remarks>Must return Tuple explicitly due to net462 support.</remarks>
+    internal Tuple<DateTime?, DateTime?, DateTime?> UnicodeTimes
+    {
+        get
+        {
+            // There has to be at least 5 byte for there to be a timestamp.
+            // 1 byte for flags and 4 bytes for a timestamp.
+            if (DataBytes is null || DataBytes.Length < 5)
+            {
+                return Tuple.Create<DateTime?, DateTime?, DateTime?>(null, null, null);
+            }
+
+            var flags = DataBytes[0];
+            var isModifiedTimeSpecified = (flags & 0x01) == 1;
+            var isLastAccessTimeSpecified = (flags & 0x02) == 1;
+            var isCreationTimeSpecified = (flags & 0x04) == 1;
+            var currentIndex = 1;
+            DateTime? modifiedTime = null;
+            DateTime? lastAccessTime = null;
+            DateTime? creationTime = null;
+
+            if (isModifiedTimeSpecified)
+            {
+                var modifiedEpochTime = BinaryPrimitives.ReadInt32LittleEndian(
+                    DataBytes.AsSpan(currentIndex, 4)
+                );
+
+                currentIndex += 4;
+                modifiedTime = DateTimeOffset.FromUnixTimeSeconds(modifiedEpochTime).UtcDateTime;
+            }
+
+            if (isLastAccessTimeSpecified)
+            {
+                if (currentIndex + 4 > DataBytes.Length)
+                {
+                    throw new ArchiveException("Invalid UnicodeExtraTime field");
+                }
+
+                var lastAccessEpochTime = BinaryPrimitives.ReadInt32LittleEndian(
+                    DataBytes.AsSpan(currentIndex, 4)
+                );
+
+                currentIndex += 4;
+                lastAccessTime = DateTimeOffset
+                    .FromUnixTimeSeconds(lastAccessEpochTime)
+                    .UtcDateTime;
+            }
+
+            if (isCreationTimeSpecified)
+            {
+                if (currentIndex + 4 > DataBytes.Length)
+                {
+                    throw new ArchiveException("Invalid UnicodeExtraTime field");
+                }
+
+                var creationTimeEpochTime = BinaryPrimitives.ReadInt32LittleEndian(
+                    DataBytes.AsSpan(currentIndex, 4)
+                );
+
+                currentIndex += 4;
+                creationTime = DateTimeOffset
+                    .FromUnixTimeSeconds(creationTimeEpochTime)
+                    .UtcDateTime;
+            }
+
+            return Tuple.Create(modifiedTime, lastAccessTime, creationTime);
+        }
+    }
+}
+
 internal static class LocalEntryHeaderExtraFactory
 {
     internal static ExtraData Create(ExtraDataType type, ushort length, byte[] extraData) =>
@@ -154,6 +233,7 @@ internal static ExtraData Create(ExtraDataType type, ushort length, byte[] extra
                 => new ExtraUnicodePathExtraField(type, length, extraData),
             ExtraDataType.Zip64ExtendedInformationExtraField
                 => new Zip64ExtendedInformationExtraField(type, length, extraData),
+            ExtraDataType.UnixTimeExtraField => new UnixTimeExtraField(type, length, extraData),
             _ => new ExtraData(type, length, extraData)
         };
 }