Question

我正在使用找到的代码here直接从outlook拖放.msg文件。 FileDescriptorA类的实现方式如下：

[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]
public sealed class FILEDESCRIPTORA
{
    public uint dwFlags;
    public Guid clsid;
    public SIZEL sizel;
    public POINTL pointl;
    public uint dwFileAttributes;
    public System.Runtime.InteropServices.ComTypes.FILETIME ftCreationTime;
    public System.Runtime.InteropServices.ComTypes.FILETIME ftLastAccessTime;
    public System.Runtime.InteropServices.ComTypes.FILETIME ftLastWriteTime;
    public uint nFileSizeHigh;
    public uint nFileSizeLow;
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 260)]
    public string cFileName;
}

获取文件名的代码是：

MemoryStream fgdStream = 
  (MemoryStream)e.Data.GetData("FileGroupDescriptor");
byte[] fgdBytes = new byte[fgdStream.Length];
fgdStream.Read(fgdBytes, 0, fgdBytes.Length);
fgdStream.Close();

//copy the file group descriptor into unmanaged memory
IntPtr fgdaPtr = Marshal.AllocHGlobal(fgdBytes.Length);
Marshal.Copy(fgdBytes, 0, fgdaPtr, fgdBytes.Length);

int numFiles = Marshal.ReadInt32(fgdaPtr);

string[] fileNames = new string[numFiles];

//get the pointer to the first file descriptor
IntPtr fdPtr = (IntPtr)((int)fgdaPointer + Marshal.SizeOf(fgdaPointer));

//loop for the number of files acording to the file group descriptor
for(int fdIndex = 0;fdIndex < numfiles;fdIndex++)
{
    //marshal the pointer to the file descriptor as a FILEDESCRIPTORA struct
    object fdObj = Marshal.PtrToStructure(fdPtr, 
                          typeof(NativeMethods.FILEDESCRIPTORA));
    NativeMethods.FILEDESCRIPTORA fd = (NativeMethods.FILEDESCRIPTORA)fdObj;

    //get file name of file descriptor and put in array
    fileNames[fdIndex] = fd.cFileName;

    //move the file descriptor pointer to the next file descriptor
    fdPtr = (IntPtr)((int)fdPtr + Marshal.SizeOf(fd));
}

这一切都很有效，除了返回的文件名总是缺少前几个字符。有谁知道会导致什么和/或如何修复它？

Answer 1

在the codeproject page的评论中，另一个人提到了同样的问题 - 在这种情况下，数组项的偏移量是从结构的开头计算出来的，没有考虑到包含的第一个32/64位。数组中的项目数：

[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]
public sealed class FILEGROUPDESCRIPTORA
{
    public uint cItems;
    public FILEDESCRIPTORA[] fgd;
}

FileDescriptora缺少字符

1 个答案: