Fix bugs escaping characters in MySqlBulkCopy.

Author: bgrainger

src/MySqlConnector/MySql.Data.MySqlClient/MySqlBulkCopy.cs

@@ -356,7 +356,7 @@ static bool WriteString(string value, Span<byte> output, out int bytesWritten)
 				bytesWritten = 0;
 				while (index < value.Length)
 				{
-					if (value[index] == '\t' || value[index] == '\\')
+					if (Array.IndexOf(s_specialCharacters, value[index]) != -1)
 					{
 						if (output.Length < 2)
 						{
@@ -365,13 +365,14 @@ static bool WriteString(string value, Span<byte> output, out int bytesWritten)
 						}
 
 						output[0] = (byte) '\\';
-						output[1] = value[index] == '\t' ? (byte) 't' : (byte) '\\';
+						output[1] = (byte) value[index];
 						output = output.Slice(2);
 						bytesWritten += 2;
+						index++;
 					}
 					else
 					{
-						var nextIndex = value.IndexOfAny(new char[] { '\t', '\\' }, index);
+						var nextIndex = value.IndexOfAny(s_specialCharacters, index);
 						if (nextIndex == -1)
 							nextIndex = value.Length;
 						var encodedBytesWritten = Encoding.UTF8.GetBytes(value.AsSpan(index, nextIndex - index), output);
@@ -414,6 +415,7 @@ static bool WriteBytes(ReadOnlySpan<byte> value, Span<byte> output, out int byte
 		}
 
 		private static ReadOnlySpan<byte> EscapedNull => new byte[] { 0x5C, 0x4E };
+		private static readonly char[] s_specialCharacters = new char[] { '\t', '\\', '\n' };
 
 		readonly MySqlConnection m_connection;
 		readonly MySqlTransaction? m_transaction;

tests/SideBySide/BulkLoaderSync.cs

@@ -525,6 +525,49 @@ public void BulkLoadDataTableWithLongData()
 			bulkCopy.WriteToServer(dataTable);
 		}
 
+		[Fact]
+		public void BulkLoadDataTableWithSpecialCharacters()
+		{
+			var dataTable = new DataTable()
+			{
+				Columns =
+				{
+					new DataColumn("id", typeof(int)),
+					new DataColumn("data", typeof(string)),
+				},
+			};
+
+			var strings = new[] { " ", "\t", ",", "\n", "\r", "\\", "ab\t", "\tcd", "ab\tcd", "\tab\ncd\t" };
+			for (var i = 0; i < strings.Length; i++)
+				dataTable.Rows.Add(i, strings[i]);
+
+			using var connection = new MySqlConnection(GetLocalConnectionString());
+			connection.Open();
+			using (var cmd = new MySqlCommand(@"drop table if exists bulk_load_data_table;
+create table bulk_load_data_table(a int, b text);", connection))
+			{
+				cmd.ExecuteNonQuery();
+			}
+
+			var bulkCopy = new MySqlBulkCopy(connection)
+			{
+				DestinationTableName = "bulk_load_data_table",
+			};
+			bulkCopy.WriteToServer(dataTable);
+
+			using (var cmd = new MySqlCommand("select * from bulk_load_data_table order by a;", connection))
+			using (var reader = cmd.ExecuteReader())
+			{
+				for (int i = 0; i < strings.Length; i++)
+				{
+					Assert.True(reader.Read());
+					Assert.Equal(i, reader.GetInt32(0));
+					Assert.Equal(strings[i], reader.GetString(1));
+				}
+				Assert.False(reader.Read());
+			}
+		}
+
 		[Fact]
 		public void BulkLoadDataTableWithTooLongData()
 		{