From 12850182ff8a0e6cf26e045057a3d60b3ccd5b0b Mon Sep 17 00:00:00 2001
From: Wizou <11647984+wiz0u@users.noreply.github.com>
Date: Wed, 26 Jan 2022 11:08:33 +0100
Subject: [PATCH] fix #25: possible NullReferenceException with
 Document.LargestThumbSize fix undisposed FileStream on broken session file.

---
 src/Session.cs    | 15 ++++++++-------
 src/TL.Helpers.cs |  2 +-
 2 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/src/Session.cs b/src/Session.cs
index d6736f5..abba80f 100644
--- a/src/Session.cs
+++ b/src/Session.cs
@@ -47,13 +47,13 @@ namespace WTelegram
 		{
 			var header = new byte[8];
 			var fileStream = new FileStream(pathname, FileMode.OpenOrCreate, FileAccess.ReadWrite, FileShare.None, 1); // no buffering
-			if (fileStream.Read(header, 0, 8) == 8)
+			try
 			{
-				try
+				if (fileStream.Read(header, 0, 8) == 8)
 				{
 					var position = BinaryPrimitives.ReadInt32LittleEndian(header);
 					var length = BinaryPrimitives.ReadInt32LittleEndian(header.AsSpan(4));
-					if (position < 0 || length < 0 || position >= 65536 || length >= 32768){ position = 0; length = (int)fileStream.Length; }
+					if (position < 0 || length < 0 || position >= 65536 || length >= 32768) { position = 0; length = (int)fileStream.Length; }
 					var input = new byte[length];
 					fileStream.Position = position;
 					if (fileStream.Read(input, 0, length) != length)
@@ -65,10 +65,11 @@ namespace WTelegram
 					Helpers.Log(2, "Loaded previous session");
 					return session;
 				}
-				catch (Exception ex)
-				{
-					throw new ApplicationException($"Exception while reading session file: {ex.Message}\nDelete the file to start a new session", ex);
-				}
+			}
+			catch (Exception ex)
+			{
+				fileStream.Dispose();
+				throw new ApplicationException($"Exception while reading session file: {ex.Message}\nDelete the file to start a new session", ex);
 			}
 			return new Session { _fileStream = fileStream, _nextPosition = 8, _rgbKey = rgbKey };
 		}
diff --git a/src/TL.Helpers.cs b/src/TL.Helpers.cs
index c74cee4..c890f6c 100644
--- a/src/TL.Helpers.cs
+++ b/src/TL.Helpers.cs
@@ -357,7 +357,7 @@ namespace TL
 		public override long ID => id;
 		protected override InputDocument ToInputDocument() => new() { id = id, access_hash = access_hash, file_reference = file_reference };
 		public InputDocumentFileLocation ToFileLocation(PhotoSizeBase thumbSize = null) => new() { id = id, access_hash = access_hash, file_reference = file_reference, thumb_size = thumbSize?.Type };
-		public PhotoSizeBase LargestThumbSize => thumbs.Aggregate((agg, next) => (long)next.Width * next.Height > (long)agg.Width * agg.Height ? next : agg);
+		public PhotoSizeBase LargestThumbSize => thumbs?.Aggregate((agg, next) => (long)next.Width * next.Height > (long)agg.Width * agg.Height ? next : agg);
 	}
 
 	partial class SendMessageAction