Escape NUL byte as '\0'. Fixes #1121

Author: bgrainger

src/MySqlConnector/MySqlParameter.cs

@@ -226,16 +226,16 @@ internal void AppendSqlString(ByteBufferWriter writer, StatementPreparerOptions
 			writer.Write((byte) '\'');
 			switch (charValue)
 			{
-			case '\'':
-				writer.Write((byte) '\'');
-				writer.Write((byte) charValue);
+			case '\0' when !noBackslashEscapes:
+				writer.Write((ushort) 0x305C); // \0
 				break;
 
-			case '\\':
-				if (!noBackslashEscapes)
-					writer.Write((byte) '\\');
+			case '\'':
+				writer.Write((ushort) 0x2727); // ''
+				break;
 
-				writer.Write((byte) charValue);
+			case '\\' when !noBackslashEscapes:
+				writer.Write((ushort) 0x5C5C); // \\
 				break;
 
 			default:
@@ -288,7 +288,7 @@ internal void AppendSqlString(ByteBufferWriter writer, StatementPreparerOptions
 			var length = inputSpan.Length + BinaryBytes.Length + 1;
 			foreach (var by in inputSpan)
 			{
-				if (by is 0x27 || by is 0x5C && !noBackslashEscapes)
+				if (by is 0x27 || by is 0x00 or 0x5C && !noBackslashEscapes)
 					length++;
 			}
 
@@ -297,9 +297,18 @@ internal void AppendSqlString(ByteBufferWriter writer, StatementPreparerOptions
 			var index = BinaryBytes.Length;
 			foreach (var by in inputSpan)
 			{
-				if (by is 0x27 || by is 0x5C && !noBackslashEscapes)
+				if (by == 0x00 && !noBackslashEscapes)
+				{
+					// \0
+					outputSpan[index++] = 0x5C;
+					outputSpan[index++] = 0x30;
+				}
+				else
+				{
+					if (by is 0x27 || by is 0x5C && !noBackslashEscapes)
+						outputSpan[index++] = by;
 					outputSpan[index++] = by;
-				outputSpan[index++] = by;
+				}
 			}
 			outputSpan[index++] = 0x27;
 			Debug.Assert(index == length, "index == length");
@@ -394,9 +403,9 @@ internal void AppendSqlString(ByteBufferWriter writer, StatementPreparerOptions
 				writer.Write(BinaryBytes);
 				foreach (var by in bytes)
 				{
-					if (by is 0x27 or 0x5C)
+					if (by is 0x00 or 0x27 or 0x5C)
 						writer.Write((byte) 0x5C);
-					writer.Write(by);
+					writer.Write(by == 0 ? (byte) 0x30 : by);
 				}
 				writer.Write((byte) '\'');
 			}
@@ -471,7 +480,7 @@ static void WriteString(ByteBufferWriter writer, bool noBackslashEscapes, string
 			if (noBackslashEscapes)
 				writer.Write(value.Replace("'", "''"));
 			else
-				writer.Write(value.Replace("\\", "\\\\").Replace("'", "''"));
+				writer.Write(value.Replace("\\", "\\\\").Replace("'", "''").Replace("\0", "\\0"));
 
 			writer.Write((byte) '\'');
 		}
@@ -485,7 +494,7 @@ static void WriteString(ByteBufferWriter writer, bool noBackslashEscapes, bool w
 			while (charsWritten < value.Length)
 			{
 				var remainingValue = value.Slice(charsWritten);
-				var nextDelimiterIndex = remainingValue.IndexOfAny('\'', '\\');
+				var nextDelimiterIndex = remainingValue.IndexOfAny('\0', '\'', '\\');
 				if (nextDelimiterIndex == -1)
 				{
 					// write the rest of the string
@@ -495,11 +504,17 @@ static void WriteString(ByteBufferWriter writer, bool noBackslashEscapes, bool w
 				else
 				{
 					// write up to (and including) the delimiter, then double it
-					writer.Write(remainingValue.Slice(0, nextDelimiterIndex + 1), flush: true);
+					writer.Write(remainingValue.Slice(0, nextDelimiterIndex), flush: true);
 					if (remainingValue[nextDelimiterIndex] == '\\' && !noBackslashEscapes)
-						writer.Write((byte) '\\');
+						writer.Write((ushort) 0x5C5C); // \\
+					else if (remainingValue[nextDelimiterIndex] == '\\' && noBackslashEscapes)
+						writer.Write((byte) 0x5C); // \
 					else if (remainingValue[nextDelimiterIndex] == '\'')
-						writer.Write((byte) '\'');
+						writer.Write((ushort) 0x2727); // ''
+					else if (remainingValue[nextDelimiterIndex] == '\0' && !noBackslashEscapes)
+						writer.Write((ushort) 0x305C); // \0
+					else if (remainingValue[nextDelimiterIndex] == '\0' && noBackslashEscapes)
+						writer.Write((byte) 0x00); // (nul)
 					charsWritten += nextDelimiterIndex + 1;
 				}
 			}

tests/SideBySide/InsertTests.cs

@@ -680,6 +680,32 @@ value set('one', 'two', 'four', 'eight') null
 		Assert.Equal(new[] { "one", "one,two", "one,four", "one,two,four" }, m_database.Connection.Query<string>(@"select value from insert_mysql_set where find_in_set('one', value) order by rowid"));
 	}
 
+	[Theory]
+	[MemberData(nameof(GetChars))]
+	public void InsertChar(char ch, bool prepare)
+	{
+		using var connection = new MySqlConnection(AppConfig.ConnectionString);
+		connection.Open();
+		connection.Execute(@"drop table if exists insert_char;
+create table insert_char(
+rowid integer not null primary key auto_increment,
+value tinytext null
+);");
+
+		using (var cmd = new MySqlCommand("insert into insert_char(value) values(@data);", connection))
+		{
+			cmd.Parameters.AddWithValue("@data", ch);
+			if (prepare)
+				cmd.Prepare();
+			cmd.ExecuteNonQuery();
+		}
+		Assert.Equal(ch, connection.Query<char>(@"select value from insert_char;").Single());
+	}
+
+	public static IEnumerable<object[]> GetChars() =>
+		new[] { '\0', 'a', '\'', '\"', '\\', 'A', '\b', '\n', '\r', '\t', '\x1A' }
+			.SelectMany(x => new[] { false, true }.Select(y => new object[] { x, y }));
+
 
 #if !BASELINE
 	[Theory]