Improve SHA1 speed and checksum exception

src/Squirrel/Compression/ChecksumFailedException.cs

@@ -10,6 +10,19 @@ public class ChecksumFailedException : Exception
         /// <summary>
         /// The filename of the package which failed validation
         /// </summary>
-        public string Filename { get; set; }
+        public string FilePath { get; }
+
+        /// <inheritdoc cref="ChecksumFailedException"/>
+        public ChecksumFailedException(string filePath)
+            : this(filePath, "Checksum failed")
+        {
+        }
+
+        /// <inheritdoc cref="ChecksumFailedException"/>
+        public ChecksumFailedException(string filePath, string message)
+            : base(message + $" ({filePath})")
+        {
+            FilePath = filePath;
+        }
     }
 }

src/Squirrel/Compression/DeltaPackage.cs

@@ -202,12 +202,12 @@ void verifyPatchedFile(string relativeFilePath, string inputFile, string tempTar
 
             if (expectedReleaseEntry.Filesize != actualReleaseEntry.Filesize) {
                 _log.Warn($"Patched file {relativeFilePath} has incorrect size, expected {expectedReleaseEntry.Filesize}, got {actualReleaseEntry.Filesize}");
-                throw new ChecksumFailedException() { Filename = relativeFilePath };
+                throw new ChecksumFailedException(relativeFilePath);
             }
 
             if (expectedReleaseEntry.SHA1 != actualReleaseEntry.SHA1) {
                 _log.Warn($"Patched file {relativeFilePath} has incorrect SHA1, expected {expectedReleaseEntry.SHA1}, got {actualReleaseEntry.SHA1}");
-                throw new ChecksumFailedException() { Filename = relativeFilePath };
+                throw new ChecksumFailedException(relativeFilePath);
             }
         }
     }

src/Squirrel/Internal/Utility.cs

@@ -154,8 +154,8 @@ public static IEnumerable<string> GetAllFilePathsRecursively(string rootPath)
         public static string CalculateFileSHA1(string filePath)
         {
             Contract.Requires(filePath != null);
-
-            using (var stream = File.OpenRead(filePath)) {
+            var bufferSize = 1000000; // 1mb
+            using (var stream = new FileStream(filePath, FileMode.Open, FileAccess.Read, FileShare.Read, bufferSize)) {
                 return CalculateStreamSHA1(stream);
             }
         }