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CSHARP-5614: Fix deserialization of primitive arrays on Big Endian systems #1683

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Merged
merged 3 commits into from
Jun 12, 2025
Merged

CSHARP-5614: Fix deserialization of primitive arrays on Big Endian systems #1683

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89a8e71
fix(bson): correct deserialization of primitive arrays using BinaryPr…
medhatiwari May 6, 2025
9180338
CSHARP-5614: Fix deserialization of primitive arrays on Big Endian sy…
medhatiwari Jun 11, 2025
31d88d5
CSHARP-5614: added BinaryPrimitivesCompat.ReadDoubleLittleEndian for …
medhatiwari Jun 11, 2025
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36 changes: 16 additions & 20 deletions src/MongoDB.Bson/Serialization/Serializers/PrimitivesArrayReader.cs
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Original file line number Diff line number Diff line change
@@ -1,4 +1,5 @@
using System;
using System.Buffers.Binary;
using System.Collections.Generic;
using System.Runtime.CompilerServices;
using MongoDB.Bson.IO;
Expand Down Expand Up @@ -77,6 +78,7 @@ private static T[] ReadBsonArray<T>(

var result = new List<T>();


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No need for empty lines changes (extra line here, and removed lines below)

var index = 4; // 4 first bytes are array object size in bytes
var maxIndex = array.Length - 1;

Expand All @@ -85,7 +87,7 @@ private static T[] ReadBsonArray<T>(
ValidateBsonType(bsonDataType);

// Skip name
while (bytes[index] != 0) { index++; };
while (bytes[index] != 0) { index++; }
index++; // Skip string terminating 0

T value = default;
Expand All @@ -95,85 +97,81 @@ private static T[] ReadBsonArray<T>(
{
case ConversionType.DoubleToSingle:
{
var v = (float)BitConverter.ToDouble(bytes, index);

var v = (float)BitConverter.Int64BitsToDouble(BinaryPrimitives.ReadInt64LittleEndian(bytes.AsSpan(index)));
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Probably could just use BinaryPrimitivesCompat.ReadDoubleLittleEndian ?

value = Unsafe.As<float, T>(ref v);
break;
}
case ConversionType.DoubleToDouble:
{
var v = BitConverter.ToDouble(bytes, index);
var v = BitConverter.Int64BitsToDouble(BinaryPrimitives.ReadInt64LittleEndian(bytes.AsSpan(index)));
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Looks like we can just work with span instead of bytes in all cases.

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I’ve updated the code to work directly with Span<byte> instead of using byte[] where applicable, as you suggested. Please verify and let me know if any further changes are needed.

value = Unsafe.As<double, T>(ref v);
break;
}
case ConversionType.Decimal128ToDecimal128:
{
var lowBits = (ulong)BitConverter.ToInt64(bytes, index);
var highBits = (ulong)BitConverter.ToInt64(bytes, index + 8);
var lowBits = BinaryPrimitives.ReadUInt64LittleEndian(bytes.AsSpan(index));
var highBits = BinaryPrimitives.ReadUInt64LittleEndian(bytes.AsSpan(index + 8));
var v = Decimal128.ToDecimal(Decimal128.FromIEEEBits(highBits, lowBits));

value = Unsafe.As<decimal, T>(ref v);
break;
}
case ConversionType.BoolToBool:
{
var v = bytes[index] != 0;

value = Unsafe.As<bool, T>(ref v);
break;
}
case ConversionType.Int32ToInt8:
{
var v = (sbyte)BitConverter.ToInt32(bytes, index);
var v = (sbyte)BinaryPrimitives.ReadInt32LittleEndian(bytes.AsSpan(index));
value = Unsafe.As<sbyte, T>(ref v);

break;
}
case ConversionType.Int32ToUInt8:
{
var v = (byte)BitConverter.ToInt32(bytes, index);
var v = (byte)BinaryPrimitives.ReadInt32LittleEndian(bytes.AsSpan(index));
value = Unsafe.As<byte, T>(ref v);
break;
}
case ConversionType.Int32ToInt16:
{
var v = (short)BitConverter.ToInt32(bytes, index);
var v = (short)BinaryPrimitives.ReadInt32LittleEndian(bytes.AsSpan(index));
value = Unsafe.As<short, T>(ref v);
break;
}
case ConversionType.Int32ToUInt16:
{
var v = (ushort)BitConverter.ToInt32(bytes, index);
var v = (ushort)BinaryPrimitives.ReadInt32LittleEndian(bytes.AsSpan(index));
value = Unsafe.As<ushort, T>(ref v);
break;
}
case ConversionType.Int32ToChar:
{
var v = BitConverter.ToChar(bytes, index);
var v = (char)(ushort)BinaryPrimitives.ReadInt32LittleEndian(bytes.AsSpan(index));
value = Unsafe.As<char, T>(ref v);
break;
}
case ConversionType.Int32ToInt32:
{
var v = BitConverter.ToInt32(bytes, index);
var v = BinaryPrimitives.ReadInt32LittleEndian(bytes.AsSpan(index));
value = Unsafe.As<int, T>(ref v);
break;
}
case ConversionType.Int32ToUInt32:
{
var v = BitConverter.ToUInt32(bytes, index);
var v = BinaryPrimitives.ReadUInt32LittleEndian(bytes.AsSpan(index));
value = Unsafe.As<uint, T>(ref v);
break;
}
case ConversionType.Int64ToInt64:
{
var v = BitConverter.ToInt64(bytes, index);
var v = BinaryPrimitives.ReadInt64LittleEndian(bytes.AsSpan(index));
value = Unsafe.As<long, T>(ref v);
break;
}
case ConversionType.Int64ToUInt64:
{
var v = BitConverter.ToUInt64(bytes, index);
var v = BinaryPrimitives.ReadUInt64LittleEndian(bytes.AsSpan(index));
value = Unsafe.As<ulong, T>(ref v);
break;
}
Expand All @@ -182,12 +180,10 @@ private static T[] ReadBsonArray<T>(
}

result.Add(value);

index += bsonDataSize;
}

ValidateBsonType(BsonType.EndOfDocument);

return result.ToArray();

void ValidateBsonType(BsonType bsonType)
Expand Down
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