C未签名`char ** out`到C#`byte []`

时间:2013-05-20 15:56:59

标签: c# c openssl marshalling dllimport

这是来自libeay32.dll(openssl project)的函数:

int i2o_ECPublicKey (EC_KEY * key, unsigned char ** out)

如何在C#中描述它(如果我想得到一个字节[])?

代码:

[DllImport(DLLNAME, CallingConvention = CallingConvention.Cdecl)]
public extern static int i2o_ECPublicKey (IntPtr encKey, StringBuilder outPar);

我不喜欢这个,因为我认为结果是unicode。

答案

        [DllImport(DLLNAME, CallingConvention = CallingConvention.Cdecl)]
        public extern static int i2o_ECPublicKey(IntPtr encKey, ref IntPtr outPar);

        [DllImport(DLLNAME, CallingConvention = CallingConvention.Cdecl)]
        public static extern int i2o_ECPublicKey(IntPtr encKey, int outPar);


        //Pass *out as null for required buffer length.
        int reqLen = i2o_ECPublicKey(k, 0);

        Byte[] outBuf = new Byte[reqLen];
        IntPtr unmanagedOut = Marshal.AllocCoTaskMem(outBuf.Length);
        int res = i2o_ECPublicKey(k, ref unmanagedOut);
        if (res == reqLen)
        {
            unmanagedOut -= reqLen; // because i2o_ECPublicKey add size to unmanagedOut
            Marshal.Copy(unmanagedOut, outBuf, 0, outBuf.Length);
        }
        Marshal.FreeCoTaskMem(unmanagedOut);

2 个答案:

答案 0 :(得分:2)

我相信手动完成,你需要使用Marshal.Copy将数组从非托管内存复制到托管字节[]。 (注意,代码未经测试)。

public extern static int i2o_ECPublicKey (IntPtr encKey, ref IntPtr outPar);

...
//Pass *out as null for required buffer length.
int reqLen = i2o_ECPublicKey(key, null);

Byte[] outBuf = new Byte[reqLen];
IntPtr unmanagedOut = Marshal.AllocCoTaskMem(outBuf.Length);
int res = i2o_ECPublicKey(key, ref unmanagedOut);
if (res == 1) {
    Marshal.Copy(unmanaged, outBuf, 0, outBuf.Length);
}
Marshal.FeeCoTaskMem(unmanagedOut);

答案 1 :(得分:0)

您可以使用GetBytes

获取包含正确编码的字符串
StringBuilder outPar;
string result = "";
byte[] parbytes = System.Text.Encoding.Unicode.GetBytes(outPar.ToString());
foreach(byte parbyte in parbytes)
{
    result+= Convert.ToChar(parbyte);
}
return result;