c# - Registry.CreateSubKey 什么时候返回 null？

Question

根据我在文档中的理解，如果失败，它会返回 null，但在我看来，每个失败场景都有一个异常。

在什么标准场景下这个函数实际上会返回一个空值？

Answer 1

如果您通过 Reflector 查看代码，您会发现如果本地方法 Win32Native.RegCreateKeyEx() 的返回值不是错误代码 0，或者如果操作是null，然后它会返回null给你。

此处可能的失败是如果使用了不正确的权限，导致返回拒绝访问错误代码。

该方法背后的代码如下:

[ComVisible(false)]
public unsafe RegistryKey CreateSubKey(string subkey, RegistryKeyPermissionCheck permissionCheck, RegistrySecurity registrySecurity)
{
    ValidateKeyName(subkey);
    ValidateKeyMode(permissionCheck);
    this.EnsureWriteable();
    subkey = FixupName(subkey);
    if (!this.remoteKey)
    {
        RegistryKey key = this.InternalOpenSubKey(subkey, permissionCheck != RegistryKeyPermissionCheck.ReadSubTree);
        if (key != null)
        {
            this.CheckSubKeyWritePermission(subkey);
            this.CheckSubTreePermission(subkey, permissionCheck);
            key.checkMode = permissionCheck;
            return key;
        }
    }
    this.CheckSubKeyCreatePermission(subkey);
    Win32Native.SECURITY_ATTRIBUTES structure = null;
    if (registrySecurity != null)
    {
        structure = new Win32Native.SECURITY_ATTRIBUTES();
        structure.nLength = Marshal.SizeOf(structure);
        byte[] securityDescriptorBinaryForm = registrySecurity.GetSecurityDescriptorBinaryForm();
        byte* pDest = stackalloc byte[1 * securityDescriptorBinaryForm.Length];
        Buffer.memcpy(securityDescriptorBinaryForm, 0, pDest, 0, securityDescriptorBinaryForm.Length);
        structure.pSecurityDescriptor = pDest;
    }
    int lpdwDisposition = 0;
    SafeRegistryHandle hkResult = null;
    int errorCode = Win32Native.RegCreateKeyEx(this.hkey, subkey, 0, null, 0, GetRegistryKeyAccess(permissionCheck != RegistryKeyPermissionCheck.ReadSubTree), structure, out hkResult, out lpdwDisposition);
    if ((errorCode == 0) && !hkResult.IsInvalid)
    {
        RegistryKey key2 = new RegistryKey(hkResult, permissionCheck != RegistryKeyPermissionCheck.ReadSubTree, false, this.remoteKey, false);
        this.CheckSubTreePermission(subkey, permissionCheck);
        key2.checkMode = permissionCheck;
        if (subkey.Length == 0)
        {
            key2.keyName = this.keyName;
            return key2;
        }
        key2.keyName = this.keyName + @"\" + subkey;
        return key2;
    }
    if (errorCode != 0)
    {
        this.Win32Error(errorCode, this.keyName + @"\" + subkey);
    }
    return null;
}