问题描述
C定义
typedef struct {
const uint8_t* buf;
int bufLen;
} Info;
int Foo(Info* info);
C#定义
[StructLayout(LayoutKind.Sequential)]
public struct Info
{
// [MarshalAs( ??? )]
public byte[] buf;
int bufLen
}
[DllImport(...)]
public static extern int Foo(ref Info info);
我在弄清楚在C#结构定义中为byte[] buf
上的MarshalAs
属性指定的内容时遇到了麻烦.缓冲区是在.NET端分配的,其长度在调用时是已知的.
I'm having trouble figuring out what to specify for the MarshalAs
attribute on byte[] buf
in the C# struct definition. The buffer is allocated on the .NET side, and its length is known at call time.
在一个简单的小测试中:
In a simple little test:
var info = new Info {
buf = new byte[] {0x40, 0x50, 0x60, 0x70},
bufLen = 4,
};
Foo(ref info);
一切似乎都正常运行,但是实际上我缓冲区中的数据不正确.从DLL中打印出来,我看到01 00 80 00
-不确定是什么.
Everything seems to be working correctly, but in fact the data in my buffer is incorrect. Printing it out from the DLL I see 01 00 80 00
- not sure what that is.
我尝试过:
- 否
MarshalAs
-
[MarshalAs(UnmanagedType.SafeArray)]
- No
MarshalAs
[MarshalAs(UnmanagedType.SafeArray)]
没有任何作用.
总的来说,我真的也不知道调试这类问题的最佳方法.
In general, I really don't know the best way to debug these kinds of problems either.
推荐答案
根据汉斯·帕桑特(Hans Passant)的建议,我实现了以下内容:
Per Hans Passant's suggestion, I implemented the following:
[StructLayout(LayoutKind.Sequential)]
public struct Info : IDisposable
{
private IntPtr buf;
private int bufLen;
public Info(byte[] buf) : this() {
this.buf = Marshal.AllocHGlobal(buf.Length);
Marshal.Copy(buf, 0, this.buf, buf.Length);
this.bufLen = buf.Length;
}
public void Dispose() {
if (buf != IntPtr.Zero) {
Marshal.FreeHGlobal(buf);
buf= IntPtr.Zero;
}
}
}
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