c# - "Attempted to read or write protected memory"由 urlmon.dll 引起

Question

我知道这个问题已经被问过很多次了，但遗憾的是我还没有找到解决问题的方法，我正在使用 urlmon.dll 从字节数组中查找 MIME 类型，但我收到了IIS 进程 w3wp.exe

崩溃

Attempted to read or write protected memory. This is often an indication that other memory is corrupt.

代码:

public static int MimeSampleSize = 256;

public static string DefaultMimeType = "application/octet-stream";

[DllImport(@"urlmon.dll", CharSet = CharSet.Auto)]
private extern static uint FindMimeFromData(
    uint pBC,
    [MarshalAs(UnmanagedType.LPStr)] string pwzUrl,
    [MarshalAs(UnmanagedType.LPArray)] byte[] pBuffer,
    uint cbSize,
    [MarshalAs(UnmanagedType.LPStr)] string pwzMimeProposed,
    uint dwMimeFlags,
    out uint ppwzMimeOut,
    uint dwReserverd
);

public static string GetMimeFromBytes(byte[] data)
{
    try
    {
        uint mimeType;
        FindMimeFromData(0, null, data, (uint)MimeSampleSize, null, 0, out mimeType, 0);

        var mimePointer = new IntPtr(mimeType);
        var mime = Marshal.PtrToStringUni(mimePointer); // <-- Crash happens here
        Marshal.FreeCoTaskMem(mimePointer);

        return mime ?? DefaultMimeType;
    }
    catch
    {
        return DefaultMimeType;
    }
}

崩溃发生在以下行:

var mime = Marshal.PtrToStringUni(mimePointer);

我曾尝试取消选中“Suppress JIT optimization on module load”选项，但没有成功。还尝试将构建更改为 x86 而不是任何 CPU，但没有任何运气。

注意:我使用的是 4.5 框架，IIS 8

Answer 1

我认为问题出在 FindMimeFromData() 的签名上。在 PInvoke.net 上查看函数的正确签名:

http://www.pinvoke.net/default.aspx/urlmon/findmimefromdata.html

..因此，对于 pBC 和 ppwzMimeOut，您将需要 IntPtr 而不是 uint!

另见:

urlmon.dll FindMimeFromData() works perfectly on 64bit desktop/console but generates errors on ASP.NET