Fix SFTP file UTC time handling

src/Renci.SshNet.Tests/Classes/BaseClientTest_Disconnected_KeepAliveInterval_NotNegativeOne.cs

@@ -14,7 +14,6 @@ public class BaseClientTest_Disconnected_KeepAliveInterval_NotNegativeOne
         private BaseClient _client;
         private ConnectionInfo _connectionInfo;
         private TimeSpan _keepAliveInterval;
-        private int _keepAliveCount;
 
         [TestInitialize]
         public void Setup()
@@ -38,7 +37,6 @@ private void SetupData()
         {
             _connectionInfo = new ConnectionInfo("host", "user", new PasswordAuthenticationMethod("user", "pwd"));
             _keepAliveInterval = TimeSpan.FromMilliseconds(50d);
-            _keepAliveCount = 0;
         }
 
         private void CreateMocks()

src/Renci.SshNet.Tests/Classes/ClientAuthenticationTest_Success_MultiList_PartialSuccessLimitReachedFollowedBySuccessInAlternateBranch.cs

@@ -35,7 +35,6 @@ public class ClientAuthenticationTest_Success_MultiList_PartialSuccessLimitReach
     {
         private int _partialSuccessLimit;
         private ClientAuthentication _clientAuthentication;
-        private SshAuthenticationException _actualException;
 
         protected override void SetupData()
         {
@@ -182,4 +181,4 @@ public void AuthenticateOnPublicKeyAuthenticationMethodShouldHaveBeenInvokedTwic
             PublicKeyAuthenticationMethodMock.Verify(p => p.Authenticate(SessionMock.Object), Times.Exactly(2));
         }
     }
-}
+}

src/Renci.SshNet.Tests/Classes/Common/BigIntegerTest.cs

@@ -1506,10 +1506,12 @@ public void DefaultCtorWorks()
             Assert.AreEqual("0", a.ToString(), "#4");
 
             a = new BigInteger();
+#pragma warning disable CS1718 // Comparison made to same variable
             Assert.AreEqual(true, a == a, "#5");
 
             a = new BigInteger();
             Assert.AreEqual(false, a < a, "#6");
+#pragma warning restore CS1718 // Comparison made to same variable
 
             a = new BigInteger();
             Assert.AreEqual(true, a < 10L, "#7");

src/Renci.SshNet.Tests/Classes/Messages/Connection/ChannelExtendedDataMessageTest.cs

@@ -30,7 +30,7 @@ public void ChannelExtendedDataMessageConstructorTest()
         [Ignore] // placeholder
         public void ChannelExtendedDataMessageConstructorTest1()
         {
-            uint localChannelNumber = 0; // TODO: Initialize to an appropriate value
+            //uint localChannelNumber = 0; // TODO: Initialize to an appropriate value
             //ChannelExtendedDataMessage target = new ChannelExtendedDataMessage(localChannelNumber, null, null);
             Assert.Inconclusive("TODO: Implement code to verify target");
         }

src/Renci.SshNet.Tests/Classes/SftpClientTest.cs

@@ -942,7 +942,9 @@ public void SetLastAccessTimeTest()
             SftpClient target = new SftpClient(connectionInfo); // TODO: Initialize to an appropriate value
             string path = string.Empty; // TODO: Initialize to an appropriate value
             DateTime lastAccessTime = new DateTime(); // TODO: Initialize to an appropriate value
+#pragma warning disable CS0618 // Type or member is obsolete
             target.SetLastAccessTime(path, lastAccessTime);
+#pragma warning restore CS0618 // Type or member is obsolete
             Assert.Inconclusive("A method that does not return a value cannot be verified.");
         }
 
@@ -957,7 +959,9 @@ public void SetLastAccessTimeUtcTest()
             SftpClient target = new SftpClient(connectionInfo); // TODO: Initialize to an appropriate value
             string path = string.Empty; // TODO: Initialize to an appropriate value
             DateTime lastAccessTimeUtc = new DateTime(); // TODO: Initialize to an appropriate value
+#pragma warning disable CS0618 // Type or member is obsolete
             target.SetLastAccessTimeUtc(path, lastAccessTimeUtc);
+#pragma warning restore CS0618 // Type or member is obsolete
             Assert.Inconclusive("A method that does not return a value cannot be verified.");
         }
 
@@ -972,7 +976,9 @@ public void SetLastWriteTimeTest()
             SftpClient target = new SftpClient(connectionInfo); // TODO: Initialize to an appropriate value
             string path = string.Empty; // TODO: Initialize to an appropriate value
             DateTime lastWriteTime = new DateTime(); // TODO: Initialize to an appropriate value
+#pragma warning disable CS0618 // Type or member is obsolete
             target.SetLastWriteTime(path, lastWriteTime);
+#pragma warning restore CS0618 // Type or member is obsolete
             Assert.Inconclusive("A method that does not return a value cannot be verified.");
         }
 
@@ -987,7 +993,9 @@ public void SetLastWriteTimeUtcTest()
             SftpClient target = new SftpClient(connectionInfo); // TODO: Initialize to an appropriate value
             string path = string.Empty; // TODO: Initialize to an appropriate value
             DateTime lastWriteTimeUtc = new DateTime(); // TODO: Initialize to an appropriate value
+#pragma warning disable CS0618 // Type or member is obsolete
             target.SetLastWriteTimeUtc(path, lastWriteTimeUtc);
+#pragma warning restore CS0618 // Type or member is obsolete
             Assert.Inconclusive("A method that does not return a value cannot be verified.");
         }
 
@@ -1269,4 +1277,4 @@ private class TestInfo
             public SftpDownloadAsyncResult DownloadResult { get; set; }
         }
     }
-}
+}

src/Renci.SshNet/Sftp/SftpFile.cs

@@ -99,11 +99,11 @@ public DateTime LastAccessTimeUtc
         {
             get
             {
-                return Attributes.LastAccessTime.ToUniversalTime();
+                return Attributes.LastAccessTimeUtc;
             }
             set
             {
-                Attributes.LastAccessTime = value.ToLocalTime();
+                Attributes.LastAccessTimeUtc = value;
             }
         }
 
@@ -117,11 +117,11 @@ public DateTime LastWriteTimeUtc
         {
             get
             {
-                return Attributes.LastWriteTime.ToUniversalTime();
+                return Attributes.LastWriteTimeUtc;
             }
             set
             {
-                Attributes.LastWriteTime = value.ToLocalTime();
+                Attributes.LastWriteTimeUtc = value;
             }
         }
 

src/Renci.SshNet/Sftp/SftpFileAttributes.cs

@@ -11,7 +11,7 @@ namespace Renci.SshNet.Sftp
     /// </summary>
     public class SftpFileAttributes
     {
-        #region Bitmask constats
+        #region Bitmask constants
 
         private const uint S_IFMT = 0xF000; //  bitmask for the file type bitfields
 
@@ -60,8 +60,8 @@ public class SftpFileAttributes
         private bool _isGroupIDBitSet;
         private bool _isStickyBitSet;
 
-        private readonly DateTime _originalLastAccessTime;
-        private readonly DateTime _originalLastWriteTime;
+        private readonly DateTime _originalLastAccessTimeUtc;
+        private readonly DateTime _originalLastWriteTimeUtc;
         private readonly long _originalSize;
         private readonly int _originalUserId;
         private readonly int _originalGroupId;
@@ -70,12 +70,12 @@ public class SftpFileAttributes
 
         internal bool IsLastAccessTimeChanged
         {
-            get { return _originalLastAccessTime != LastAccessTime; }
+            get { return _originalLastAccessTimeUtc != LastAccessTimeUtc; }
         }
 
         internal bool IsLastWriteTimeChanged
         {
-            get { return _originalLastWriteTime != LastWriteTime; }
+            get { return _originalLastWriteTimeUtc != LastWriteTimeUtc; }
         }
 
         internal bool IsSizeChanged
@@ -104,20 +104,58 @@ internal bool IsExtensionsChanged
         }
 
         /// <summary>
-        /// Gets or sets the time the current file or directory was last accessed.
+        /// Gets or sets the local time the current file or directory was last accessed.
         /// </summary>
         /// <value>
-        /// The time that the current file or directory was last accessed.
+        /// The local time that the current file or directory was last accessed.
         /// </value>
-        public DateTime LastAccessTime { get; set; }
+        public DateTime LastAccessTime
+        {
+            get
+            {
+                return ToLocalTime(this.LastAccessTimeUtc);
+            }
+
+            set
+            {
+                this.LastAccessTimeUtc = ToUniversalTime(value);
+            }
+        }
+
+        /// <summary>
+        /// Gets or sets the local time when the current file or directory was last written to.
+        /// </summary>
+        /// <value>
+        /// The local time the current file was last written.
+        /// </value>
+        public DateTime LastWriteTime
+        {
+            get
+            {
+                return ToLocalTime(this.LastWriteTimeUtc);
+            }
+
+            set
+            {
+                this.LastWriteTimeUtc = ToUniversalTime(value);
+            }
+        }
+
+        /// <summary>
+        /// Gets or sets the UTC time the current file or directory was last accessed.
+        /// </summary>
+        /// <value>
+        /// The UTC time that the current file or directory was last accessed.
+        /// </value>
+        public DateTime LastAccessTimeUtc { get; set; }
 
         /// <summary>
-        /// Gets or sets the time when the current file or directory was last written to.
+        /// Gets or sets the UTC time when the current file or directory was last written to.
         /// </summary>
         /// <value>
-        /// The time the current file was last written.
+        /// The UTC time the current file was last written.
         /// </value>
-        public DateTime LastWriteTime { get; set; }
+        public DateTime LastWriteTimeUtc { get; set; }
 
         /// <summary>
         /// Gets or sets the size, in bytes, of the current file.
@@ -397,8 +435,8 @@ private SftpFileAttributes()
 
         internal SftpFileAttributes(DateTime lastAccessTime, DateTime lastWriteTime, long size, int userId, int groupId, uint permissions, IDictionary<string, string> extensions)
         {
-            LastAccessTime = _originalLastAccessTime = lastAccessTime;
-            LastWriteTime = _originalLastWriteTime = lastWriteTime;
+            LastAccessTimeUtc = _originalLastAccessTimeUtc = ToUniversalTime(lastAccessTime);
+            LastWriteTimeUtc = _originalLastWriteTimeUtc = ToUniversalTime(lastWriteTime);
             Size = _originalSize = size;
             UserId = _originalUserId = userId;
             GroupId = _originalGroupId = groupId;
@@ -491,9 +529,9 @@ public byte[] GetBytes()
 
             if (IsLastAccessTimeChanged || IsLastWriteTimeChanged)
             {
-                var time = (uint)(LastAccessTime.ToFileTime() / 10000000 - 11644473600);
+                var time = (uint)(LastAccessTimeUtc.ToFileTimeUtc() / 10000000 - 11644473600);
                 stream.Write(time);
-                time = (uint)(LastWriteTime.ToFileTime() / 10000000 - 11644473600);
+                time = (uint)(LastWriteTimeUtc.ToFileTimeUtc() / 10000000 - 11644473600);
                 stream.Write(time);
             }
 
@@ -544,10 +582,12 @@ internal static SftpFileAttributes FromBytes(SshDataStream stream)
 
             if ((flag & 0x00000008) == 0x00000008)   //  SSH_FILEXFER_ATTR_ACMODTIME
             {
+                // The incoming times are "Unix times", so they're already in UTC.  We need to preserve that
+                // to avoid losing information in a local time conversion during the "fall back" hour in DST.
                 var time = stream.ReadUInt32();
-                accessTime = DateTime.FromFileTime((time + 11644473600) * 10000000);
+                accessTime = DateTime.FromFileTimeUtc((time + 11644473600) * 10000000);
                 time = stream.ReadUInt32();
-                modifyTime = DateTime.FromFileTime((time + 11644473600) * 10000000);
+                modifyTime = DateTime.FromFileTimeUtc((time + 11644473600) * 10000000);
             }
 
             if ((flag & 0x80000000) == 0x80000000)   //  SSH_FILEXFER_ATTR_EXTENDED
@@ -572,5 +612,37 @@ internal static SftpFileAttributes FromBytes(byte[] buffer)
                 return FromBytes(stream);
             }
         }
+
+        internal static DateTime ToLocalTime(DateTime value)
+        {
+            DateTime result;
+
+            if (value == DateTime.MinValue)
+            {
+                result = DateTime.SpecifyKind(DateTime.MinValue, DateTimeKind.Local);
+            }
+            else
+            {
+                result = value.ToLocalTime();
+            }
+
+            return result;
+        }
+
+        internal static DateTime ToUniversalTime(DateTime value)
+        {
+            DateTime result;
+
+            if (value == DateTime.MinValue)
+            {
+                result = DateTime.SpecifyKind(DateTime.MinValue, DateTimeKind.Utc);
+            }
+            else
+            {
+                result = value.ToUniversalTime();
+            }
+
+            return result;
+        }
     }
 }