求仅具有引用指针的对象数组的总大小？

Question

总而言之，我正在使用 Wlanapi，而且我对它相当陌生（一般来说是原生 api）。我在将结构从 C++ 转换为 C# 时遇到问题。现在我有：

Original:

typedef struct _WLAN_BSS_LIST {
    DWORD          dwTotalSize;
    DWORD          dwNumberOfItems;
    WLAN_BSS_ENTRY wlanBssEntries[1];
} WLAN_BSS_LIST, *PWLAN_BSS_LIST;

Conversion:

[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
struct WLAN_BSS_LIST 
{
    internal uint             dwTotalSize;
    internal uint             dwNumberOfItems;
    internal WLAN_BSS_ENTRY[] wlanBssEntries;

    internal WLAN_BSS_LIST(IntPtr ppBssList)
    {
        dwNumberOfItems = (uint)Marshal.ReadInt32(ppBssList);
        //I need to set the value of dwTotalSize but I dunno how
        wlanBssEntries = new WLAN_BSS_ENTRY[dwNumberOfItems];

        for (int i = 0; i < dwNumberOfItems; i++)
        {
            IntPtr pWlanBssEntry = new IntPtr(ppBssList.ToInt32() + i * 
                Marshal.SizeOf(typeof(WLAN_BSS_ENTRY)) + 8);
            wlanBssEntries[i] = (WLAN_BSS_ENTRY)Marshal.
                                    PtrToStructure(pWlanBssEntry, 
                                        typeof(WLAN_BSS_ENTRY));
        }
    }
}

我只是不知道如何获取 ppBssList 引用的数组的总大小:(

仅供参考，如果有人指出我，我会非常失望一个现有的库。

编辑以添加原始结构

Answer 1

我不确定你的 twTotalSize 是否反映了为 wlanBssEntries 中的条目分配的内存量，如果是这样，一个简单的计算就足够了，

 sizeof(typeof(WLAN_BSS_ENTRY)) * dwNumberOfItems + 8

否则，我建议你发布原始的本机数据结构，也许，有更好的从内存块编组它的替代方法。

Answer 2

所以我明白了，我不知道我在想什么......

[StructLayout(LayoutKind.Sequential, Pack=1)]
struct WLAN_BSS_LIST
{
    internal uint dwTotalSize;
    internal uint dwNumberOfItems;
    internal WLAN_BSS_ENTRY[] wlanBssEntries;

    internal WLAN_BSS_LIST(IntPtr ppBssList)
    {
        dwTotalSize = (uint)Marshal.ReadInt32(ppBssList);
        dwNumberOfItems = (uint)Marshal.ReadInt32(ppBssList, 4);
        wlanBssEntries = new WLAN_BSS_ENTRY[dwNumberOfItems];
        for (int i = 0; i < dwNumberOfItems; i++)
        {
            IntPtr pWlanBssEntry = new IntPtr(ppBssList.ToInt32() + i * 
                Marshal.SizeOf(typeof(WLAN_BSS_ENTRY)) + 8);
            wlanBssEntries[i] = (WLAN_BSS_ENTRY)Marshal.
                PtrToStructure(pWlanBssEntry, typeof(WLAN_BSS_ENTRY));
        }
    }
}

然后

[StructLayout(LayoutKind.Sequential)]
public struct WLAN_BSS_ENTRY
{
    public DOT11_SSID dot11Ssid;
    public uint uPhyId;
    [MarshalAs(UnmanagedType.ByValArray, SizeConst = 6)]
    public byte[] dot11Bssid;
    public DOT11_BSS_TYPE dot11BssType;
    public DOT11_PHY_TYPE dot11BssPhyType;
    public int lRssi;
    public uint uLinkQuality;
    public bool bInRegDomain;
    public UInt16 usBeaconPeriod;
    public UInt64 ullTimestamp;
    public UInt64 ullHostTimestamp;
    public UInt16 usCapabilityInformation;
    public uint ulChCenterFrequency;
    public WLAN_RATE_SET wlanRateSet;
    public uint ulIeOffset;
    public uint ulIeSize;
}