访问违规将文件从 zip 存档内部复制到剪贴板并处理其数据后的异常
本文关键字：处理 剪贴板 数据 异常 复制 内部 文件 zip 访问 | 更新日期: 2023-09-27 18:32:11
我有一个问题，希望这里有人可以提供帮助。
我们使用这个 OutlookDataObject 项目中经过一些修改的代码来处理从各种邮件客户端（如 outlook）删除的文件，以及通过剪贴板对文件进行常规复制粘贴以处理它们并将它们保存到文件系统。
在大多数情况下，它工作正常，但是如果用户使用Windows资源管理器打开ZIP文件，从那里复制文件并尝试添加它，我们会在FileContentDataObject的GetData方法的以下部分获得AccessViolationException：
//marshal the unmanaged memory to to FILEGROUPDESCRIPTORW struct
object fileGroupDescriptorObject = Marshal.PtrToStructure(fileGroupDescriptorWPointer, typeof(NativeMethods.FILEGROUPDESCRIPTORW));
以下是有问题的整个代码的简化版本，您应该能够重现此问题：
// Starting Method
public void InsertFromClipboard()
{
FileContentDataObjectBase dataObject = GetDataObject();
if(dataObject!= null)
{
dataObject.SaveToFileSystem("C:/temp");
}
}
private FileContentDataObjectBase GetDataObject()
{
var dataObject = System.Windows.Forms.Clipboard.GetDataObject();
return new FileContentDataObject(System.Windows.Forms.Clipboard.GetDataObject());
}
public class FileContentDataObject : FileContentDataObjectBase
{
/// <summary>
/// Initializes a new instance of the <see cref="OutlookDataObject"/> class.
/// </summary>
/// <param name="underlyingDataObject">The underlying data object to wrap.</param>
public FileContentDataObject(System.Windows.Forms.IDataObject underlyingDataObject)
: base(underlyingDataObject) { }
public override void SaveToFileSystem(string path)
{
string[] filenames;
//get the names and data streams of the files dropped
if (this.GetFormats().Contains("FileGroupDescriptor"))
filenames = (string[])this.GetData("FileGroupDescriptor", true);
else if (this.GetFormats().Contains("FileGroupDescriptorW"))
filenames = (string[])this.GetData("FileGroupDescriptorW", true);
else
return;
MemoryStream[] filestreams = (MemoryStream[])this.GetData("FileContents");
SaveToFileSystem(filenames, filestreams, path);
}
public new object GetData(string format, bool autoConvert)
{
switch (format)
{
case "FileGroupDescriptorW":
//override the default handling of FileGroupDescriptorW which returns a
//MemoryStream and instead return a string array of file names
IntPtr fileGroupDescriptorWPointer = IntPtr.Zero;
try
{
//use the underlying IDataObject to get the FileGroupDescriptorW as a MemoryStream
MemoryStream fileGroupDescriptorStream = (MemoryStream)this.underlyingDataObject.GetData("FileGroupDescriptorW");
byte[] fileGroupDescriptorBytes = new byte[fileGroupDescriptorStream.Length];
fileGroupDescriptorStream.Read(fileGroupDescriptorBytes, 0, fileGroupDescriptorBytes.Length);
fileGroupDescriptorStream.Close();
//copy the file group descriptor into unmanaged memory
fileGroupDescriptorWPointer = Marshal.AllocHGlobal(fileGroupDescriptorBytes.Length);
Marshal.Copy(fileGroupDescriptorBytes, 0, fileGroupDescriptorWPointer, fileGroupDescriptorBytes.Length);
//marshal the unmanaged memory to to FILEGROUPDESCRIPTORW struct
object fileGroupDescriptorObject = Marshal.PtrToStructure(fileGroupDescriptorWPointer, typeof(NativeMethods.FILEGROUPDESCRIPTORW));
NativeMethods.FILEGROUPDESCRIPTORW fileGroupDescriptor = (NativeMethods.FILEGROUPDESCRIPTORW)fileGroupDescriptorObject;
//create a new array to store file names in of the number of items in the file group descriptor
string[] fileNames = new string[fileGroupDescriptor.cItems];
//get the pointer to the first file descriptor
IntPtr fileDescriptorPointer = (IntPtr)((int)fileGroupDescriptorWPointer + Marshal.SizeOf(fileGroupDescriptor.cItems));
//loop for the number of files acording to the file group descriptor
for (int fileDescriptorIndex = 0; fileDescriptorIndex < fileGroupDescriptor.cItems; fileDescriptorIndex++)
{
//marshal the pointer top the file descriptor as a FILEDESCRIPTORW struct and get the file name
NativeMethods.FILEDESCRIPTORW fileDescriptor = (NativeMethods.FILEDESCRIPTORW)Marshal.PtrToStructure(fileDescriptorPointer, typeof(NativeMethods.FILEDESCRIPTORW));
fileNames[fileDescriptorIndex] = fileDescriptor.cFileName;
//move the file descriptor pointer to the next file descriptor
fileDescriptorPointer = (IntPtr)((int)fileDescriptorPointer + Marshal.SizeOf(fileDescriptor));
}
//return the array of filenames
return fileNames;
}
finally
{
//free unmanaged memory pointer
Marshal.FreeHGlobal(fileGroupDescriptorWPointer);
}
}
//use underlying IDataObject to handle getting of data
return this.underlyingDataObject.GetData(format, autoConvert);
}
}
public abstract class FileContentDataObjectBase : System.Windows.Forms.IDataObject
{
#region NativeMethods
protected class NativeMethods
{
[DllImport("kernel32.dll")]
static extern IntPtr GlobalLock(IntPtr hMem);
[DllImport("ole32.dll", PreserveSig = false)]
internal static extern ILockBytes CreateILockBytesOnHGlobal(IntPtr hGlobal, bool fDeleteOnRelease);
[DllImport("OLE32.DLL", CharSet = CharSet.Auto, PreserveSig = false)]
internal static extern IntPtr GetHGlobalFromILockBytes(ILockBytes pLockBytes);
[DllImport("OLE32.DLL", CharSet = CharSet.Unicode, PreserveSig = false)]
internal static extern IStorage StgCreateDocfileOnILockBytes(ILockBytes plkbyt, uint grfMode, uint reserved);
[ComImport, InterfaceType(ComInterfaceType.InterfaceIsIUnknown), Guid("0000000B-0000-0000-C000-000000000046")]
internal interface IStorage
{
[return: MarshalAs(UnmanagedType.Interface)]
IStream CreateStream([In, MarshalAs(UnmanagedType.BStr)] string pwcsName, [In, MarshalAs(UnmanagedType.U4)] int grfMode, [In, MarshalAs(UnmanagedType.U4)] int reserved1, [In, MarshalAs(UnmanagedType.U4)] int reserved2);
[return: MarshalAs(UnmanagedType.Interface)]
IStream OpenStream([In, MarshalAs(UnmanagedType.BStr)] string pwcsName, IntPtr reserved1, [In, MarshalAs(UnmanagedType.U4)] int grfMode, [In, MarshalAs(UnmanagedType.U4)] int reserved2);
[return: MarshalAs(UnmanagedType.Interface)]
IStorage CreateStorage([In, MarshalAs(UnmanagedType.BStr)] string pwcsName, [In, MarshalAs(UnmanagedType.U4)] int grfMode, [In, MarshalAs(UnmanagedType.U4)] int reserved1, [In, MarshalAs(UnmanagedType.U4)] int reserved2);
[return: MarshalAs(UnmanagedType.Interface)]
IStorage OpenStorage([In, MarshalAs(UnmanagedType.BStr)] string pwcsName, IntPtr pstgPriority, [In, MarshalAs(UnmanagedType.U4)] int grfMode, IntPtr snbExclude, [In, MarshalAs(UnmanagedType.U4)] int reserved);
void CopyTo(int ciidExclude, [In, MarshalAs(UnmanagedType.LPArray)] Guid[] pIIDExclude, IntPtr snbExclude, [In, MarshalAs(UnmanagedType.Interface)] IStorage stgDest);
void MoveElementTo([In, MarshalAs(UnmanagedType.BStr)] string pwcsName, [In, MarshalAs(UnmanagedType.Interface)] IStorage stgDest, [In, MarshalAs(UnmanagedType.BStr)] string pwcsNewName, [In, MarshalAs(UnmanagedType.U4)] int grfFlags);
void Commit(int grfCommitFlags);
void Revert();
void EnumElements([In, MarshalAs(UnmanagedType.U4)] int reserved1, IntPtr reserved2, [In, MarshalAs(UnmanagedType.U4)] int reserved3, [MarshalAs(UnmanagedType.Interface)] out object ppVal);
void DestroyElement([In, MarshalAs(UnmanagedType.BStr)] string pwcsName);
void RenameElement([In, MarshalAs(UnmanagedType.BStr)] string pwcsOldName, [In, MarshalAs(UnmanagedType.BStr)] string pwcsNewName);
void SetElementTimes([In, MarshalAs(UnmanagedType.BStr)] string pwcsName, [In] System.Runtime.InteropServices.ComTypes.FILETIME pctime, [In] System.Runtime.InteropServices.ComTypes.FILETIME patime, [In] System.Runtime.InteropServices.ComTypes.FILETIME pmtime);
void SetClass([In] ref Guid clsid);
void SetStateBits(int grfStateBits, int grfMask);
void Stat([Out]out System.Runtime.InteropServices.ComTypes.STATSTG pStatStg, int grfStatFlag);
}
[ComImport, Guid("0000000A-0000-0000-C000-000000000046"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
internal interface ILockBytes
{
void ReadAt([In, MarshalAs(UnmanagedType.U8)] long ulOffset, [Out, MarshalAs(UnmanagedType.LPArray, SizeParamIndex = 1)] byte[] pv, [In, MarshalAs(UnmanagedType.U4)] int cb, [Out, MarshalAs(UnmanagedType.LPArray)] int[] pcbRead);
void WriteAt([In, MarshalAs(UnmanagedType.U8)] long ulOffset, IntPtr pv, [In, MarshalAs(UnmanagedType.U4)] int cb, [Out, MarshalAs(UnmanagedType.LPArray)] int[] pcbWritten);
void Flush();
void SetSize([In, MarshalAs(UnmanagedType.U8)] long cb);
void LockRegion([In, MarshalAs(UnmanagedType.U8)] long libOffset, [In, MarshalAs(UnmanagedType.U8)] long cb, [In, MarshalAs(UnmanagedType.U4)] int dwLockType);
void UnlockRegion([In, MarshalAs(UnmanagedType.U8)] long libOffset, [In, MarshalAs(UnmanagedType.U8)] long cb, [In, MarshalAs(UnmanagedType.U4)] int dwLockType);
void Stat([Out]out System.Runtime.InteropServices.ComTypes.STATSTG pstatstg, [In, MarshalAs(UnmanagedType.U4)] int grfStatFlag);
}
[StructLayout(LayoutKind.Sequential)]
internal sealed class POINTL
{
public int x;
public int y;
}
[StructLayout(LayoutKind.Sequential)]
internal sealed class SIZEL
{
public int cx;
public int cy;
}
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]
internal sealed class FILEGROUPDESCRIPTORA
{
public uint cItems;
public FILEDESCRIPTORA[] fgd;
}
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]
internal 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;
}
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
internal sealed class FILEGROUPDESCRIPTORW
{
public uint cItems;
public FILEDESCRIPTORW[] fgd;
}
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
internal sealed class FILEDESCRIPTORW
{
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;
}
}
#endregion
#region Property(s)
/// <summary>
/// Holds the <see cref="System.Windows.Forms.IDataObject"/> that this class is wrapping
/// </summary>
protected System.Windows.Forms.IDataObject underlyingDataObject;
/// <summary>
/// Holds the <see cref="System.Runtime.InteropServices.ComTypes.IDataObject"/> interface to the <see cref="System.Windows.Forms.IDataObject"/> that this class is wrapping.
/// </summary>
protected System.Runtime.InteropServices.ComTypes.IDataObject comUnderlyingDataObject;
/// <summary>
/// Holds the internal ole <see cref="System.Windows.Forms.IDataObject"/> to the <see cref="System.Windows.Forms.IDataObject"/> that this class is wrapping.
/// </summary>
protected System.Windows.Forms.IDataObject oleUnderlyingDataObject;
/// <summary>
/// Holds the <see cref="MethodInfo"/> of the "GetDataFromHGLOBLAL" method of the internal ole <see cref="System.Windows.Forms.IDataObject"/>.
/// </summary>
protected MethodInfo getDataFromHGLOBLALMethod;
#endregion
#region Constructor(s)
/// <summary>
/// Initializes a new instance of the <see cref="OutlookDataObject"/> class.
/// </summary>
/// <param name="underlyingDataObject">The underlying data object to wrap.</param>
public FileContentDataObjectBase(System.Windows.Forms.IDataObject underlyingDataObject)
{
//get the underlying dataobject and its ComType IDataObject interface to it
this.underlyingDataObject = underlyingDataObject;
this.comUnderlyingDataObject = (System.Runtime.InteropServices.ComTypes.IDataObject)this.underlyingDataObject;
//get the internal ole dataobject and its GetDataFromHGLOBLAL so it can be called later
FieldInfo innerDataField = this.underlyingDataObject.GetType().GetField("innerData", BindingFlags.NonPublic | BindingFlags.Instance);
this.oleUnderlyingDataObject = (System.Windows.Forms.IDataObject)innerDataField.GetValue(this.underlyingDataObject);
this.getDataFromHGLOBLALMethod = this.oleUnderlyingDataObject.GetType().GetMethod("GetDataFromHGLOBLAL", BindingFlags.NonPublic | BindingFlags.Instance);
}
#endregion
#region IDataObject Members
/// <summary>
/// Retrieves the data associated with the specified class type format.
/// </summary>
/// <param name="format">A <see cref="T:System.Type"></see> representing the format of the data to retrieve. See <see cref="T:System.Windows.Forms.DataFormats"></see> for predefined formats.</param>
/// <returns>
/// The data associated with the specified format, or null.
/// </returns>
public object GetData(Type format)
{
return this.GetData(format.FullName);
}
/// <summary>
/// Retrieves the data associated with the specified data format.
/// </summary>
/// <param name="format">The format of the data to retrieve. See <see cref="T:System.Windows.Forms.DataFormats"></see> for predefined formats.</param>
/// <returns>
/// The data associated with the specified format, or null.
/// </returns>
public object GetData(string format)
{
return this.GetData(format, true);
}
/// <summary>
/// Retrieves the data associated with the specified data format, using a Boolean to determine whether to convert the data to the format.
/// </summary>
/// <param name="format">The format of the data to retrieve. See <see cref="T:System.Windows.Forms.DataFormats"></see> for predefined formats.</param>
/// <param name="autoConvert">true to convert the data to the specified format; otherwise, false.</param>
/// <returns>
/// The data associated with the specified format, or null.
/// </returns>
public object GetData(string format, bool autoConvert)
{
return this.underlyingDataObject.GetData(format, autoConvert);
}
/// <summary>
/// Retrieves the data associated with the specified data format at the specified index.
/// </summary>
/// <param name="format">The format of the data to retrieve. See <see cref="T:System.Windows.Forms.DataFormats"></see> for predefined formats.</param>
/// <param name="index">The index of the data to retrieve.</param>
/// <returns>
/// A <see cref="MemoryStream"/> containing the raw data for the specified data format at the specified index.
/// </returns>
public MemoryStream GetData(string format, int index)
{
//create a FORMATETC struct to request the data with
FORMATETC formatetc = new FORMATETC();
formatetc.cfFormat = (short)DataFormats.GetFormat(format).Id;
formatetc.dwAspect = DVASPECT.DVASPECT_CONTENT;
formatetc.lindex = index;
formatetc.ptd = new IntPtr(0);
formatetc.tymed = TYMED.TYMED_ISTREAM | TYMED.TYMED_ISTORAGE | TYMED.TYMED_HGLOBAL;
//create STGMEDIUM to output request results into
STGMEDIUM medium = new STGMEDIUM();
//using the Com IDataObject interface get the data using the defined FORMATETC
this.comUnderlyingDataObject.GetData(ref formatetc, out medium);
//retrieve the data depending on the returned store type
switch (medium.tymed)
{
case TYMED.TYMED_ISTORAGE:
//to handle a IStorage it needs to be written into a second unmanaged
//memory mapped storage and then the data can be read from memory into
//a managed byte and returned as a MemoryStream
NativeMethods.IStorage iStorage = null;
NativeMethods.IStorage iStorage2 = null;
NativeMethods.ILockBytes iLockBytes = null;
System.Runtime.InteropServices.ComTypes.STATSTG iLockBytesStat;
try
{
//marshal the returned pointer to a IStorage object
iStorage = (NativeMethods.IStorage)Marshal.GetObjectForIUnknown(medium.unionmember);
Marshal.Release(medium.unionmember);
//create a ILockBytes (unmanaged byte array) and then create a IStorage using the byte array as a backing store
iLockBytes = NativeMethods.CreateILockBytesOnHGlobal(IntPtr.Zero, true);
iStorage2 = NativeMethods.StgCreateDocfileOnILockBytes(iLockBytes, 0x00001012, 0);
//copy the returned IStorage into the new IStorage
iStorage.CopyTo(0, null, IntPtr.Zero, iStorage2);
iLockBytes.Flush();
iStorage2.Commit(0);
//get the STATSTG of the ILockBytes to determine how many bytes were written to it
iLockBytesStat = new System.Runtime.InteropServices.ComTypes.STATSTG();
iLockBytes.Stat(out iLockBytesStat, 1);
int iLockBytesSize = (int)iLockBytesStat.cbSize;
//read the data from the ILockBytes (unmanaged byte array) into a managed byte array
byte[] iLockBytesContent = new byte[iLockBytesSize];
iLockBytes.ReadAt(0, iLockBytesContent, iLockBytesContent.Length, null);
//wrapped the managed byte array into a memory stream and return it
return new MemoryStream(iLockBytesContent);
}
finally
{
//release all unmanaged objects
Marshal.ReleaseComObject(iStorage2);
Marshal.ReleaseComObject(iLockBytes);
Marshal.ReleaseComObject(iStorage);
}
case TYMED.TYMED_ISTREAM:
//to handle a IStream it needs to be read into a managed byte and
//returned as a MemoryStream
IStream iStream = null;
System.Runtime.InteropServices.ComTypes.STATSTG iStreamStat;
try
{
//marshal the returned pointer to a IStream object
iStream = (IStream)Marshal.GetObjectForIUnknown(medium.unionmember);
Marshal.Release(medium.unionmember);
//get the STATSTG of the IStream to determine how many bytes are in it
iStreamStat = new System.Runtime.InteropServices.ComTypes.STATSTG();
iStream.Stat(out iStreamStat, 0);
int iStreamSize = (int)iStreamStat.cbSize;
//read the data from the IStream into a managed byte array
byte[] iStreamContent = new byte[iStreamSize];
iStream.Read(iStreamContent, iStreamContent.Length, IntPtr.Zero);
//wrapped the managed byte array into a memory stream and return it
return new MemoryStream(iStreamContent);
}
finally
{
//release all unmanaged objects
Marshal.ReleaseComObject(iStream);
}
case TYMED.TYMED_HGLOBAL:
//to handle a HGlobal the exisitng "GetDataFromHGLOBLAL" method is invoked via
//reflection
return (MemoryStream)this.getDataFromHGLOBLALMethod.Invoke(this.oleUnderlyingDataObject, new object[] { DataFormats.GetFormat((short)formatetc.cfFormat).Name, medium.unionmember });
}
return null;
}
/// <summary>
/// Returns a list of all formats that data stored in this instance is associated with or can be converted to.
/// </summary>
/// <returns>
/// An array of the names that represents a list of all formats that are supported by the data stored in this object.
/// </returns>
public string[] GetFormats()
{
return this.underlyingDataObject.GetFormats();
}
/// <summary>
/// Gets a list of all formats that data stored in this instance is associated with or can be converted to, using a Boolean value to determine whether to retrieve all formats that the data can be converted to or only native data formats.
/// </summary>
/// <param name="autoConvert">true to retrieve all formats that data stored in this instance is associated with or can be converted to; false to retrieve only native data formats.</param>
/// <returns>
/// An array of the names that represents a list of all formats that are supported by the data stored in this object.
/// </returns>
public string[] GetFormats(bool autoConvert)
{
return this.underlyingDataObject.GetFormats(autoConvert);
}
#endregion
#region methods
public static void SaveToFileSystem(string[] filenames, MemoryStream[] filestreams, string path)
{
for (int fileIndex = 0; fileIndex < filenames.Length; fileIndex++)
{
try
{
//use the fileindex to get the name and data stream
string filename = filenames[fileIndex];
MemoryStream filestream = filestreams[fileIndex];
//save the file stream using its name to the application path
FileStream outputStream = File.Create(Path.Combine(path, GetStrippedFileName(filename)));
filestream.WriteTo(outputStream);
outputStream.Close();
}
catch (IOException ex)
{
throw new Exception(ex.Message, ex);
}
catch (SecurityException ex)
{
throw new Exception(ex.Message, ex);
}
}
}
public static void SaveToFileSystem(FileContentDataObjectBase dataObject, string path)
{
dataObject.SaveToFileSystem(path);
}
public abstract void SaveToFileSystem(string path);
private static string GetStrippedFileName(string input)
{
foreach (var chr in Path.GetInvalidFileNameChars())
input = input.Replace(chr.ToString(), String.Empty);
return input;
}
#endregion
}
我想弄清楚为什么会发生这种情况以及如何解决问题。
欢迎任何帮助或见解。
提前谢谢。
经过一段时间的搜索，我终于找到了这个问题，这要归功于这个有用的评论。
事实证明，我们使用的原始代码中的 FILEGROUPDESCRIPTORA 和 FILEGROUPDESCRIPTORW 声明是错误的，在某些情况下可能会导致 AccessViolation 异常。
所以我确实更改了声明，就像评论员描述的那样......
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]
public sealed class FILEGROUPDESCRIPTORA
{
public uint cItems;
public FILEDESCRIPTORA[] fgd;
}
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
public sealed class FILEGROUPDESCRIPTORW
{
public uint cItems;
public FILEDESCRIPTORW[] fgd;
}
自。。。
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]
public sealed class FILEGROUPDESCRIPTORA
{
public uint cItems;
public FILEDESCRIPTORA fgd;
}
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
public sealed class FILEGROUPDESCRIPTORW
{
public uint cItems;
public FILEDESCRIPTORW fgd;
}
之后，访问违规异常消失了，我只需要修改我在问题中链接的原始代码即可使其工作。
在处理剪贴板文件"FileContent"格式的过程中，我不得不添加一些额外的检查，以确保每次都使用两个 FILEGROUPDESCRIPTOR 的正确性，但现在它再次完美运行。
您的代码中可能仍然存在错误。"FILEGROUPDESCRIPTORW"处理程序中的第一行在 Win8 计算机上可能会/将失败。
取代
object fileGroupDescriptorObject = Marshal.PtrToStructure(fileGroupDescriptorWPointer, typeof(NativeMethods.FILEGROUPDESCRIPTORW));
NativeMethods.FILEGROUPDESCRIPTORW fgd = (NativeMethods.FILEGROUPDESCRIPTORW)fileGroupDescriptorObject;
files = new NativeMethods.FILEDESCRIPTOR[fgd.cItems];
pdata = (IntPtr)((int)pdata + Marshal.SizeOf(pdata));
for (int index = 0; index < fgd.cItems; index++)
跟
int ITEMCOUNT = Marshal.ReadInt32(pdata);
files = new NativeMethods.FILEDESCRIPTOR[ITEMCOUNT];
// Set our pointer offset to the beginning of the FILEDESCRIPTOR* array
pdata = (IntPtr)((long)pdata + Marshal.SizeOf(pdata));
// Walk the array, converting each FILEDESCRIPTOR* to a FILEDESCRIPTOR
for (int index = 0; index < ITEMCOUNT; index++)
有关更多详细信息，请参阅：
将多个附件从 Outlook 拖放到 C# 窗口窗体