我正在尝试按下function来收到一些WCHAR <paramName>[1]个参数。
从我在多个地方读过的内容来看，在C / C ++中你实际上无法将数组传递给函数，而是将它们转换为包含数组第一个元素的指针，这意味着数组长度变得无关紧要因此WCHAR <paramName>[1]与WCHAR* <paramName>相同。
通常我会在C＃中将其声明为StringBuilder并将其编组为LPWStr，但在这种特殊情况下会抛出各种错误。
基本上，上面的函数接收GET_VIRTUAL_DISK_INFO，而Accessor又包含一些结构和其他松散字段的并集。并且联盟中的一些结构会收到WCHAR <paramName>[1]。
当我尝试将其整理为LPWStr并将我的字段声明为StringBuilder或string时，我收到错误[...] contains an object field at offset 0 that is incorrectly aligned or overlapped by a non-object field.
我也尝试将其声明为IntPtr，然后使用Marshal.PtrToStringAuto(<IntPtr>)，但我得到一个空字符串。
我的C＃代码包含所有结构，枚举等：
using System;
using System.ComponentModel;
using System.Runtime.InteropServices;
using System.Security.Permissions;
namespace ConsoleApplication1
{
class Program
{
public static Guid VirtualStorageTypeVendorMicrosoft = new Guid("EC984AEC-A0F9-47e9-901F-71415A66345B");
static void Main(string[] args)
{
var handle = new VirtualDiskSafeHandle();
var storageType = new VirtualStorageType
{
DeviceId = VirtualStorageDeviceType.Vhdx,
VendorId = VirtualStorageTypeVendorMicrosoft
};
var parameters = new OpenVirtualDiskParameters
{
Version = OpenVirtualDiskVersion.Version2
};
var result = OpenVirtualDisk(ref storageType, "D:\\Test2.vhdx", VirtualDiskAccessMask.None, OpenVirtualDiskFlag.None,
ref parameters, ref handle);
if (result != 0)
{
throw new Win32Exception((int) result);
}
var info = new GetVirtualDiskInfo {Version = GetVirtualDiskInfoVersion.PhysicalDisk};
var infoSize = (uint) Marshal.SizeOf(info);
uint sizeUsed = 0;
result = GetVirtualDiskInformation(handle, ref infoSize, ref info, ref sizeUsed);
if (result != 0)
{
throw new Win32Exception((int) result);
}
Console.WriteLine($"LogicalSizeSector = {info.Union.PhysicalDisk.LogicalSectorSize}");
Console.WriteLine($"PhysicalSizeSector = {info.Union.PhysicalDisk.PhysicalSectorSize}");
Console.ReadLine();
}
[DllImport("virtdisk.dll", CharSet = CharSet.Unicode)]
public static extern uint OpenVirtualDisk(
[In] ref VirtualStorageType virtualStorageType,
[In] string path,
[In] VirtualDiskAccessMask virtualDiskAccessMask,
[In] OpenVirtualDiskFlag flags,
[In] ref OpenVirtualDiskParameters parameters,
[In, Out] ref VirtualDiskSafeHandle handle);
[DllImport("kernel32.dll", SetLastError = true)]
public static extern bool CloseHandle(
[In] IntPtr hObject);
[DllImport("virtdisk.dll", CharSet = CharSet.Unicode)]
public static extern uint GetVirtualDiskInformation(
[In] VirtualDiskSafeHandle virtualDiskHandle,
[In, Out] ref uint virtualDiskInfoSize,
[In, Out] ref GetVirtualDiskInfo virtualDiskInfo,
[In, Out] ref uint sizeUsed);
[SecurityPermission(SecurityAction.Demand)]
public class VirtualDiskSafeHandle : SafeHandle
{
public VirtualDiskSafeHandle() : base(IntPtr.Zero, true) { }
public override bool IsInvalid => IsClosed || (handle == IntPtr.Zero);
public bool IsOpen => !IsInvalid;
protected override bool ReleaseHandle()
{
return CloseHandle(handle);
}
public override string ToString()
{
return handle.ToString();
}
}
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
public struct OpenVirtualDiskParameters
{
public OpenVirtualDiskVersion Version; //OPEN_VIRTUAL_DISK_VERSION
public OpenVirtualDiskParametersUnion Union;
}
[StructLayout(LayoutKind.Explicit, CharSet = CharSet.Unicode)]
public struct OpenVirtualDiskParametersUnion
{
[FieldOffset(0)]
public OpenVirtualDiskParametersVersion1 Version1;
[FieldOffset(0)]
public OpenVirtualDiskParametersVersion2 Version2;
[FieldOffset(0)]
public OpenVirtualDiskParametersVersion3 Version3;
}
/// <summary>
/// </summary>
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
public struct OpenVirtualDiskParametersVersion1
{
public uint RWDepth; //ULONG
}
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
public struct OpenVirtualDiskParametersVersion2
{
public bool GetInfoOnly; //BOOL
public bool ReadOnly; //BOOL
public Guid ResiliencyGuid; //GUID
}
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
public struct OpenVirtualDiskParametersVersion3
{
public bool GetInfoOnly; //BOOL
public bool ReadOnly; //BOOL
public Guid ResiliencyGuid; //GUID
public Guid SnapshotId; //GUID
}
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
public struct GetVirtualDiskInfo
{
public GetVirtualDiskInfoVersion Version; //GET_VIRTUAL_DISK_INFO_VERSION
public GetVirtualDiskInfoUnion Union;
}
[StructLayout(LayoutKind.Explicit, CharSet = CharSet.Unicode)]
public struct GetVirtualDiskInfoUnion
{
[FieldOffset(0)] public GetVirtualDiskInfoSize Size;
[FieldOffset(0)] public Guid Identifier; //GUID
[FieldOffset(0)] public GetVirtualDiskInfoParentLocation ParentLocation;
[FieldOffset(0)] public Guid ParentIdentifier; //GUID
[FieldOffset(0)] public uint ParentTimestamp; //ULONG
[FieldOffset(0)] public VirtualStorageType VirtualStorageType; //VIRTUAL_STORAGE_TYPE
[FieldOffset(0)] public uint ProviderSubtype; //ULONG
[FieldOffset(0)] public bool Is4kAligned; //BOOL
[FieldOffset(0)] public bool IsLoaded; //BOOL
[FieldOffset(0)] public GetVirtualDiskInfoPhysicalDisk PhysicalDisk;
[FieldOffset(0)] public uint VhdPhysicalSectorSize; //ULONG
[FieldOffset(0)] public ulong SmallestSafeVirtualSize; //ULONGLONG
[FieldOffset(0)] public uint FragmentationPercentage; //ULONG
[FieldOffset(0)] public Guid VirtualDiskId; //GUID
[FieldOffset(0)] public GetVirtualDiskInfoChangeTrackingState ChangeTrackingState;
}
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
public struct GetVirtualDiskInfoSize
{
public ulong VirtualSize; //ULONGLONG
public ulong PhysicalSize; //ULONGLONG
public uint BlockSize; //ULONG
public uint SectorSize; //ULONG
}
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
public struct GetVirtualDiskInfoParentLocation
{
public bool ParentResolved; //BOOL
public IntPtr ParentLocationBuffer; //WCHAR[1]
}
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
public struct GetVirtualDiskInfoPhysicalDisk
{
public uint LogicalSectorSize; //ULONG
public uint PhysicalSectorSize; //ULONG
public bool IsRemote; //BOOL
}
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
public struct GetVirtualDiskInfoChangeTrackingState
{
public bool Enabled; //BOOL
public bool NewerChanges; //BOOL
public IntPtr MostRecentId; //WCHAR[1]
}
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
public struct VirtualStorageType
{
public VirtualStorageDeviceType DeviceId; //ULONG
public Guid VendorId; //GUID
}
public enum GetVirtualDiskInfoVersion
{
Unspecified = 0,
Size = 1,
Identifier = 2,
ParentLocation = 3,
ParentIdentifier = 4,
ParentTimestamp = 5,
VirtualStorageType = 6,
ProviderSubtype = 7,
Is4KAligned = 8,
PhysicalDisk = 9,
VhdPhysicalSectorSize = 10,
SmallestSafeVirtualSize = 11,
Fragmentation = 12,
IsLoaded = 13,
VirtualDiskId = 14,
ChangeTrackingState = 15
}
public enum VirtualStorageDeviceType
{
Unknown = 0,
Iso = 1,
Vhd = 2,
Vhdx = 3,
Vhdset = 4
}
public enum VirtualDiskAccessMask
{
None = 0x00000000,
AttachRo = 0x00010000,
AttachRw = 0x00020000,
Detach = 0x00040000,
GetInfo = 0x00080000,
Create = 0x00100000,
Metaops = 0x00200000,
Read = 0x000d0000,
All = 0x003f0000,
Writable = 0x00320000
}
[Flags]
public enum OpenVirtualDiskFlag
{
None = 0x00000000,
NoParents = 0x00000001,
BlankFile = 0x00000002,
BootDrive = 0x00000004,
CachedIo = 0x00000008,
CustomDiffChain = 0x00000010,
ParentCachedIo = 0x00000020,
VhdsetFileOnly = 0x00000040
}
public enum OpenVirtualDiskVersion
{
Unspecified = 0,
Version1 = 1,
Version2 = 2,
Version3 = 3,
}
}
}
请注释掉该行：
[FieldOffset(0)] public GetVirtualDiskInfoChangeTrackingState ChangeTrackingState;
如果不这样，结构结果将完全搞砸，仍然试图找出原因。
答案 0 :(得分：2)
将函数调用中的结构编组为IntPtr。你将需要使用Marshal.AllocHGlobal或其他类似的技术来获得一块非托管内存，因为元帅不会为你做这件事。然后，您可以手动加载尺寸成员，或使用Marshal.StructureToPtr。
从那里使用Marshal.OffsetOf获取Union成员的偏移量。完成后，使用Marshal.Read和Marshal.PtrToStringUni来获取数据。例如，使用父位置信息：
IntPtr raw = Marshal.AllocHGlobal(1024);
// This is the GetVirtualDiskInfo from your provided code.
GetVirtualDiskInfo info = new GetVirtualDiskInfo();
info.Version = GetVirtualDiskInfoVersion.ParentLocation;
Marshal.StructureToPtr(info, raw, true);
Class1.Test(raw); // Replace this with your call to the function,
// This is a call to a C++/CLI method I wrote to stuff data
// into the structure.
IntPtr offsetToUnion = Marshal.OffsetOf(typeof(GetVirtualDiskInfo), "Union");
IntPtr data = raw + offsetToUnion.ToInt32();
bool parentResolved = Marshal.ReadInt32(data) != 0;
string parentLocationBuffer = Marshal.PtrToStringUni(data + 4);
Marshal.FreeHGlobal(raw); // Don't forget this!
这是C ++ / CLI中加载数据以进行测试的方法：
static void Test(IntPtr ptr)
{
GET_VIRTUAL_DISK_INFO* info = (GET_VIRTUAL_DISK_INFO*)ptr.ToPointer();
info->ParentLocation.ParentResolved = TRUE;
memcpy(info->ParentLocation.ParentLocationBuffer, L"123456789", 20);
}