使用 Protobuf-net 恢复损坏的文件序列化

Question

The machine power was cut while, I assume, my application was updating a file. When turned back on and my application started it attempted to deserialize the file. The call to Serializer.Deserialize did not fail, but the resulting object has default values for every property.

My file updating/saving:

using (FileStream theStream = File.Open(fileName + "_tmp", FileMode.Create)) {
    ProtoBuf.Serializer.Serialize<MyObject>(theStream, inObjectToSerialize);
}
File.Copy(fileName + "_tmp", fileName, true);

There is no _tmp file, just the main file. The size of the file is non-zero which makes me believe the information is intact. Is there a way to recover this data?

Update:

I've tried the Marc's suggestion with ProtoReader and the file in questions causes an exception the be thrown at reader.ReadFieldHeader() . The ProtoException reads: "Invalid field in source data:0"

Answer 1

There isn't much for me to go on there... I guess the short version would be: it depends what is left in the file .

One thing you could do would be to walk the file to see what is there:

using (var input = File.OpenRead(path))
using (var reader = new ProtoReader(input, RuntimeTypeModel.Default, null))
{
    while (reader.ReadFieldHeader() > 0)
    {
        Console.WriteLine("offset {0}, field {1}, type {2}",
            reader.Position, reader.FieldNumber, reader.WireType);
        reader.SkipField();
    }
}

That would at least allow you to see how much data is currently processing.

If you know the layout of some fields (ie "field 3 is a string, field 7 is a sub-object, etc"), then you could make the output more detailed.