传递非空值终止字符串非托管code [英] Passing NON null-terminated strings to unmanaged code

问题描述

考虑下面的结构要通过TCP发送到一个非托管的DLL

Consider the following struct to be sent over TCP to an unmanaged dll

[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi, Pack = 1)]
public struct FooMessage
{
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 42)]
    public string foo;

    //More fields...
}

使用下面的函数（信贷<一个href="http://stackoverflow.com/questions/1929540/c-send-structure-objects-through-socket/1929763#1929763">Cheeso):

Using the following function (credit to Cheeso):

public byte[] RawSerialize( T item )
{
    int rawSize = Marshal.SizeOf( typeof(T) );
    IntPtr buffer = Marshal.AllocHGlobal( rawSize );
    Marshal.StructureToPtr( item, buffer, false );
    byte[] rawData = new byte[ rawSize ];
    Marshal.Copy( buffer, rawData, 0, rawSize );
    Marshal.FreeHGlobal( buffer );
    return rawData;
}

问题：编组假设foo是一个空结尾的字符串，而不受管理的DLL不 - 和实际使用的最后一个字符（这永远是空的编组）

Problem: The marshaller assumes foo is a null terminated string, whereas the unmanaged dll does not - and actually uses the last char (which always comes out null from the marshaller).

任何想法？

澄清：我不能只是改变SizeConst到43，因为我需要保持消息的总规模，以及下一个字段在结构中的位置（按现有的ICD）

Clarification: I can't just change the SizeConst to 43, because I need to maintain the total size of the message, as well as the position of the next fields in the struct (according to an existing ICD)

推荐答案

由于没有其他的答案已经发布，这里是<一个href="http://bytes.com/topic/c-sharp/answers/250805-sharing-structure-containing-char-array-using-memory-mapped-file"相对=nofollow>解决方法我发现

Since no other answer has been posted, here is the workaround I've found

[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi, Pack = 1)]
public struct FooMessage
{
    // use this for non-null-terminated strings
    // use default encoder to convert to and from string
    [MarshalAs(UnmanagedType.ByValArray, SizeConst=42)]
    public char[] foo;

    //More fields...
}

此外href="http://nitoprograms.blogspot.com/2010/02/interop-multidimensional-arrays-of.html" rel="nofollow">通过TCP专家斯蒂芬类似解决方案

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