Support floating point infinity. Fixes #1185

Author: bgrainger

src/MySqlConnector/Core/TextRow.cs

@@ -96,10 +96,24 @@ protected override object GetValueCore(ReadOnlySpan<byte> data, ColumnDefinition
 			return ParseInt32(data);
 
 		case ColumnType.Float:
-			return !Utf8Parser.TryParse(data, out float floatValue, out var floatBytesConsumed) || floatBytesConsumed != data.Length ? throw new FormatException() : floatValue;
+			if (Utf8Parser.TryParse(data, out float floatValue, out var floatBytesConsumed) && floatBytesConsumed == data.Length)
+				return floatValue;
+			ReadOnlySpan<byte> floatInfinity = new byte[] { 0x2D, 0x69, 0x6E, 0x66 }; // "-inf"
+			if (data.SequenceEqual(floatInfinity))
+				return float.NegativeInfinity;
+			if (data.SequenceEqual(floatInfinity.Slice(1)))
+				return float.PositiveInfinity;
+			throw new FormatException("Couldn't parse '{0}' as float".FormatInvariant(Encoding.UTF8.GetString(data)));
 
 		case ColumnType.Double:
-			return !Utf8Parser.TryParse(data, out double doubleValue, out var doubleBytesConsumed) || doubleBytesConsumed != data.Length ? throw new FormatException() : doubleValue;
+			if (Utf8Parser.TryParse(data, out double doubleValue, out var doubleBytesConsumed) && doubleBytesConsumed == data.Length)
+				return doubleValue;
+			ReadOnlySpan<byte> doubleInfinity = new byte[] { 0x2D, 0x69, 0x6E, 0x66 }; // "-inf"
+			if (data.SequenceEqual(doubleInfinity))
+				return double.NegativeInfinity;
+			if (data.SequenceEqual(doubleInfinity.Slice(1)))
+				return double.PositiveInfinity;
+			throw new FormatException("Couldn't parse '{0}' as double".FormatInvariant(Encoding.UTF8.GetString(data)));
 
 		case ColumnType.Decimal:
 		case ColumnType.NewDecimal:

tests/MySqlConnector.Tests/ConnectionTests.cs

@@ -203,6 +203,25 @@ public void ConnectionTimeout()
 		}
 	}
 
+	[Fact]
+	public void ReadInfinity()
+	{
+		using var connection = new MySqlConnection(m_csb.ConnectionString);
+		connection.Open();
+		using var command = new MySqlCommand("select infinity", connection);
+		using var reader = command.ExecuteReader();
+		Assert.True(reader.Read());
+		Assert.Equal(float.NaN, reader.GetValue(0));
+		Assert.Equal(double.NaN, reader.GetValue(1));
+		Assert.True(reader.Read());
+		Assert.Equal(float.PositiveInfinity, reader.GetValue(0));
+		Assert.Equal(double.PositiveInfinity, reader.GetValue(1));
+		Assert.True(reader.Read());
+		Assert.Equal(float.NegativeInfinity, reader.GetValue(0));
+		Assert.Equal(double.NegativeInfinity, reader.GetValue(1));
+		Assert.False(reader.Read());
+	}
+
 	private static async Task WaitForConditionAsync<T>(T expected, Func<T> getValue)
 	{
 		var sw = Stopwatch.StartNew();

tests/MySqlConnector.Tests/FakeMySqlServerConnection.cs

@@ -162,6 +162,22 @@ public async Task RunAsync(TcpClient client, CancellationToken token)
 							var wasSet = CancelQueryEvent.Wait(0, token);
 							await SendAsync(stream, 1, WriteOk);
 						}
+						else if (query == "select infinity")
+						{
+							var packets = new[]
+							{
+								new byte[] { 2 }, // two columns
+								new byte[] { 3, 0x64, 0x65, 0x66, 0, 0, 0, 1, 0x46, 0, 0x0c, 0x3f, 0, 1, 0, 0, 0, 4, 0x01, 0, 0x1F, 0, 0 }, // column definition (float)
+								new byte[] { 3, 0x64, 0x65, 0x66, 0, 0, 0, 1, 0x44, 0, 0x0c, 0x3f, 0, 1, 0, 0, 0, 5, 0x01, 0, 0x1F, 0, 0 }, // column definition (double)
+								new byte[] { 0xFE, 0, 0, 2, 0 }, // EOF
+								new byte[] { 3, 0x6e, 0x61, 0x6e, 3, 0x6e, 0x61, 0x6e }, // nan
+								new byte[] { 3, 0x69, 0x6e, 0x66, 3, 0x69, 0x6e, 0x66 }, // inf
+								new byte[] { 4, 0x2d, 0x69, 0x6e, 0x66, 4, 0x2d, 0x69, 0x6e, 0x66 }, // -inf
+								new byte[] { 0xFE, 0, 0, 2, 0 }, // EOF
+							};
+							for (var packetIndex = 0; packetIndex < packets.Length; packetIndex++)
+								await SendAsync(stream, packetIndex + 1, x => x.Write(packets[packetIndex]));
+						}
 						else
 						{
 							await SendAsync(stream, 1, x => WriteError(x, "Unhandled query: " + query));