Read memory mapped file or knowing its size to read it correctely

问题

In this question,

Read all contents of memory mapped file or Memory Mapped View Accessor without knowing the size of it

there is a problem, the (int)stream.Length is not giving me the correct length, it rather gives the size of the internal buffer used! I need to refresh this question because it is very pressing.

The main question was:

I need something similar to ReadToEnd or ReadAllBytes to read all of the contents of the MemoryMappedFile using the MappedViewAccessor if I don't know the size of it, how can I do it?

I have searched for it, I have seen this question, but it is not the thing I am looking for:

How can I quickly read bytes from a memory mapped file in .NET?

The old answer was:

pub

public static ReadMMFAllBytes(string fileName)
{
    using (var mmf = MemoryMappedFile.OpenExisting(fileName))
    {
        using (var stream = mmf.CreateViewStream())
        {
            using (BinaryReader binReader = new BinaryReader(stream))
            {
                return binReader.ReadBytes((int)stream.Length));
            }
        }
    }
}

In this question:

Memory Mapped File Length

There is no exact answer of the exact question! the question is about something else than the title.

回答1:

The best approach is to send over a fixed-length header of sorts first, rather than just streaming raw bytes. This way the first blob you read is a consistent length and it gives you the info you need to read the variable-length remainder.

In the simplest case, your record could be as simple as having a length field written first, followed by the payload (your bytes). Depending on your needs, you can add data to the header like record type, version, etc.

来源：https://stackoverflow.com/questions/15229166/read-memory-mapped-file-or-knowing-its-size-to-read-it-correctely