我正在尝试使用C#中的VHD API创建一些vhd/vhdx文件.
有一个C++联合看起来像这样:
typedef struct _CREATE_VIRTUAL_DISK_PARAMETERS
{
CREATE_VIRTUAL_DISK_VERSION Version;
union
{
struct
{
GUID UniqueId;
ULONGLONG MaximumSize;
ULONG BlockSizeInBytes;
ULONG SectorSizeInBytes;
PCWSTR ParentPath;
PCWSTR SourcePath;
} Version1;
struct
{
GUID UniqueId;
ULONGLONG MaximumSize;
ULONG BlockSizeInBytes;
ULONG SectorSizeInBytes;
ULONG PhysicalSectorSizeInBytes;
PCWSTR ParentPath;
PCWSTR SourcePath;
OPEN_VIRTUAL_DISK_FLAG OpenFlags;
VIRTUAL_STORAGE_TYPE ParentVirtualStorageType;
VIRTUAL_STORAGE_TYPE SourceVirtualStorageType;
GUID ResiliencyGuid;
} Version2;
struct
{
GUID UniqueId;
ULONGLONG MaximumSize;
ULONG BlockSizeInBytes;
ULONG SectorSizeInBytes;
ULONG PhysicalSectorSizeInBytes;
PCWSTR ParentPath;
PCWSTR SourcePath;
OPEN_VIRTUAL_DISK_FLAG OpenFlags;
VIRTUAL_STORAGE_TYPE ParentVirtualStorageType;
VIRTUAL_STORAGE_TYPE SourceVirtualStorageType;
GUID ResiliencyGuid;
PCWSTR SourceLimitPath;
VIRTUAL_STORAGE_TYPE BackingStorageType;
} Version3;
};
} CREATE_VIRTUAL_DISK_PARAMETERS, *PCREATE_VIRTUAL_DISK_PARAMETERS;
我正在尝试将其转换为C#,但没有太多运气.我根本不对Version3感兴趣,所以我就把它排除在外.
我已经尝试过很多东西,而且我能做的最好的就是让Version2工作(通过做一些非常奇怪的事情),但我从来没有设法让Version1和Version2同时工作.
到目前为止已经取得了最好结果的解决方案就是这样,但是那里有一些错误,因为Version1根本不起作用,而SectorSizeInBytes在Version1中是一个ulong而不是uint(如果我把它改成uint它应该是,我打破版本2和版本1仍然无效!)
[StructLayout(LayoutKind.Explicit, CharSet = CharSet.Unicode)]
public struct CreateVirtualDiskParameters
{
[FieldOffset(0)] public CreateVirtualDiskParametersVersion1 Version1;
[FieldOffset(0)] public CreateVirtualDiskParametersVersion2 Version2;
}
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
public struct CreateVirtualDiskParametersVersion1
{
public CreateVirtualDiskVersion Version;
public Guid UniqueId;
public ulong MaximumSize;
public uint BlockSizeInBytes;
public ulong SectorSizeInBytes;
public string ParentPath;
public string SourcePath;
}
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
public struct CreateVirtualDiskParametersVersion2
{
public CreateVirtualDiskVersion Version;
public Guid UniqueId;
public ulong MaximumSize;
public uint BlockSizeInBytes;
public uint SectorSizeInBytes;
public uint PhysicalSectorSizeInBytes;
public string ParentPath;
public string SourcePath;
public OpenVirtualDiskFlags OpenFlags;
public VirtualStorageType ParentVirtualStorageType;
public VirtualStorageType SourceVirtualStorageType;
public Guid ResiliencyGuid;
}
我从理论上知道该Version字段应该在Version结构之外设置,我也尝试过,但它只是让事情更加有趣......
那么,有人可以建议如何正确地将上述内容转换为C#,而不需要那样的Version3结构吗？
小智 1
使用Pack = 1toStructLayout属性可以消除成员之间的任何填充struct。在 TCP 连接中，结构体通常在不进行填充的情况下传递，以便使用该结构体的所有程序都可以就其在内存中的布局达成一致。
然而，正如 @David Heffernan 指出的那样，将结构传递给 Windows DLL 时情况可能并非如此。我没有测试实际的调用，CreateVirtualDisk因为它看起来有点冒险，因为我以前没有使用过这个调用，并且不想在犯错误时破坏我的磁盘。根据以下引用，看起来 8 字节的默认打包（Pack = 0对于 default 或）可能是正确的设置。Pack = 8
请参阅64 位 Windows API 结构对齐导致命名管道上的访问被拒绝错误
Windows SDK 期望打包为 8 个字节。来自使用 Windows 标头
项目应编译为使用默认的结构打包，当前为 8 字节，因为最大的整型类型为 8 字节。这样做可以确保头文件中的所有结构类型都按照 Windows API 期望的相同对齐方式编译到应用程序中。它还确保具有 8 字节值的结构正确对齐，并且不会在强制数据对齐的处理器上导致对齐错误。
Version被移动到 的顶部CreateVirtualDiskParameters。两个工会随后跟进。两者具有相同的偏移量sizeof(CREATE_VIRTUAL_DISK_VERSION)。
亦SectorSizeInBytes是uint而非ulong。
string您可以让编组器使用属性来完成填充成员的工作，例如
[MarshalAs(UnmanagedType.LPWStr)] public string ParentPath;
或者，您可以将其表示为内存中出现的形式，即指向 Unicode 字符串的指针：
public IntPtr ParentPath;
然后自己提取字符串
Marshal.PtrToStringAuto(vdp.Version1.ParentPath)
如果要将 C# 结构传递给外部 DLL，请使用非托管字符串填充它
vdp.Version1.ParentPath = (IntPtr)Marshal.StringToHGlobalAuto("I am a managed string");
然后在完成后释放非托管字符串
Marshal.FreeHGlobal(vdp.Version1.ParentPath);
尝试这个。
public enum CREATE_VIRTUAL_DISK_VERSION
{
CREATE_VIRTUAL_DISK_VERSION_UNSPECIFIED = 0,
CREATE_VIRTUAL_DISK_VERSION_1 = 1,
CREATE_VIRTUAL_DISK_VERSION_2 = 2
};
public enum OPEN_VIRTUAL_DISK_FLAG
{
OPEN_VIRTUAL_DISK_FLAG_NONE = 0x00000000,
OPEN_VIRTUAL_DISK_FLAG_NO_PARENTS = 0x00000001,
OPEN_VIRTUAL_DISK_FLAG_BLANK_FILE = 0x00000002,
OPEN_VIRTUAL_DISK_FLAG_BOOT_DRIVE = 0x00000004,
OPEN_VIRTUAL_DISK_FLAG_CACHED_IO = 0x00000008,
OPEN_VIRTUAL_DISK_FLAG_CUSTOM_DIFF_CHAIN = 0x00000010
};
[StructLayout(LayoutKind.Sequential, Pack = 8, CharSet = CharSet.Unicode)]
public struct VIRTUAL_STORAGE_TYPE
{
uint DeviceId;
Guid VendorId;
};
[StructLayout(LayoutKind.Explicit, Pack = 8, CharSet = CharSet.Unicode)]
public struct CreateVirtualDiskParameters
{
[FieldOffset(0)]
public CREATE_VIRTUAL_DISK_VERSION Version;
[FieldOffset(8))]
public CreateVirtualDiskParametersVersion1 Version1;
[FieldOffset(8))]
public CreateVirtualDiskParametersVersion2 Version2;
}
[StructLayout(LayoutKind.Sequential, Pack = 8, CharSet = CharSet.Unicode)]
public struct CreateVirtualDiskParametersVersion1
{
public Guid UniqueId;
public ulong MaximumSize;
public uint BlockSizeInBytes;
public uint SectorSizeInBytes;
//public IntPtr ParentPath; // PCWSTR in C++ which is a pointer to a Unicode string
//public IntPtr SourcePath; //string
[MarshalAs(UnmanagedType.LPWStr)] public string ParentPath;
[MarshalAs(UnmanagedType.LPWStr)] public string SourcePath;
}
[StructLayout(LayoutKind.Sequential, Pack = 8, CharSet = CharSet.Unicode)]
public struct CreateVirtualDiskParametersVersion2
{
public Guid UniqueId;
public ulong MaximumSize;
public uint BlockSizeInBytes;
public uint SectorSizeInBytes;
public uint PhysicalSectorSizeInBytes;
//public IntPtr ParentPath; //string
//public IntPtr SourcePath; //string
[MarshalAs(UnmanagedType.LPWStr)] public string ParentPath;
[MarshalAs(UnmanagedType.LPWStr)] public string SourcePath;
public OPEN_VIRTUAL_DISK_FLAG OpenFlags;
public VIRTUAL_STORAGE_TYPE ParentVirtualStorageType;
public VIRTUAL_STORAGE_TYPE SourceVirtualStorageType;
public Guid ResiliencyGuid;
}