通过IntPtr循环构建struct数组出错

本文关键字:数组 出错 struct 构建 IntPtr 循环 通过 | 更新日期: 2023-09-27 18:07:32

我在另一个struct中从IntPtr构建struct s数组时遇到了问题。

这个结构是由我使用的Windows API返回的:

public struct DFS_INFO_9 {
    [MarshalAs(UnmanagedType.LPWStr)]
    public string EntryPath;
    [MarshalAs(UnmanagedType.LPWStr)]
    public string Comment;
    public DFS_VOLUME_STATE State;
    public UInt32 Timeout;
    public Guid Guid;
    public UInt32 PropertyFlags;
    public UInt32 MetadataSize;
    public UInt32 SdLengthReserved;
    public IntPtr pSecurityDescriptor;
    public UInt32 NumberOfStorages;
    public IntPtr Storage;
}
[DllImport("netapi32", CharSet = CharSet.Auto, SetLastError = true)]
public static extern int NetDfsEnum([MarshalAs(UnmanagedType.LPWStr)]string DfsName, int Level, int PrefMaxLen, out IntPtr Buffer, [MarshalAs(UnmanagedType.I4)]out int EntriesRead, [MarshalAs(UnmanagedType.I4)]ref int ResumeHandle);

我正试图获得IntPtr Storage引用的DFS_STORAGE_INFO_1 s数组。

结构是这样的(如果重要的话):

public struct DFS_STORAGE_INFO_1 {
    public DFS_STORAGE_STATE State;
    [MarshalAs(UnmanagedType.LPWStr)]
    public string ServerName;
    [MarshalAs(UnmanagedType.LPWStr)]
    public string ShareName;
    public IntPtr TargetPriority;
}

到目前为止,这段代码一直在努力获得只有一个存储的DFS_INFO_9,但是当试图封送数组中的第二个项时失败了。

DFS_INFO_9 info = GetInfoFromWinApi();
List<DFS_STORAGE_INFO_1> Storages = new List<DFS_STORAGE_INFO_1>();
for (int i = 0; i < info.NumberOfStorages; i++) {
    IntPtr pStorage = new IntPtr(info.Storage.ToInt64() + i * Marshal.SizeOf(typeof(DFS_STORAGE_INFO_1)));
    DFS_STORAGE_INFO_1 storage = (DFS_STORAGE_INFO_1)Marshal.PtrToStructure(pStorage, typeof(DFS_STORAGE_INFO_1));
    Storages.Add(storage);
}

我得到一个FatalExecutionEngineError,吐出错误代码0x0000005(访问被拒绝)。我假设DFS_STORAGE_INFO_1的大小被错误地计算,导致marshal试图访问为数组分配的内存之外的内存。但这发生在i = 1上,当时可能有7个存储需要通过。也许是我的想法有问题,但我不知道如何改正。

通过IntPtr循环构建struct数组出错

DFS_STORAGE_INFO_1的实际定义是:

public struct DFS_STORAGE_INFO_1 {
    public DFS_STORAGE_STATE State;
    [MarshalAs(UnmanagedType.LPWStr)]
    public string ServerName;
    [MarshalAs(UnmanagedType.LPWStr)]
    public string ShareName;
    DFS_TARGET_PRIORITY TargetPriority;
}

TargetPriority是一个结构,定义如下:

public struct DFS_TARGET_PRIORITY {
    public DFS_TARGET_PRIORITY_CLASS TargetPriorityClass;
    public UInt16 TargetPriorityRank;
    public UInt16 Reserved;
}
public enum DFS_TARGET_PRIORITY_CLASS {
    DfsInvalidPriorityClass = -1,
    DfsSiteCostNormalPriorityClass = 0,
    DfsGlobalHighPriorityClass = 1,
    DfsSiteCostHighPriorityClass = 2,
    DfsSiteCostLowPriorityClass = 3,
    DfsGlobalLowPriorityClass = 4
}

对于FatalExecutionEngineError,我认为DFS_STORAGE_INFO_1的大小被错误地计算了,因为它被错误地定义了。当试图将指针转换为它们引用的结构时,下一个索引是错误的,因为大小关闭了。当转换内存块时,它可能引用了一个不应该被访问的块,抛出"Access Denied (0x0000005)"错误。