CreateFileA 失败并显示 ERROR_ACCESS_DENIED

Question

我需要检索目录句柄才能调用 ReadDirectoryChangesW 就可以了。实际上我需要的不止于此，但让我们先放轻松。我已将问题缩小为:

m_directoryHandle = CreateFileA(
    "C:\\Users\\victor\\Documents\\Projets\\libxnotify\\unittests", // __in      LPCTSTR lpFileName,
    FILE_LIST_DIRECTORY,    // __in      DWORD dwDesiredAccess,
    0,                      // __in      DWORD dwShareMode,
    0,                      // __in_opt  LPSECURITY_ATTRIBUTES lpSecurityAttributes,
    OPEN_EXISTING,          // __in      DWORD dwCreationDisposition,
    0,                      // __in      DWORD dwFlagsAndAttributes,
    0                       // __in_opt  HANDLE hTemplateFile
);

这将返回一个 INVALID_HANDLE_VALUE，最后一个错误代码为 ERROR_ACCESS_DENIED。不用说，我尝试了很多不同的参数，但没有一个起作用。我以 victor 身份运行我的程序，并确保我确实拥有该 unittests 目录的权限，我打开了一个命令 shell 并键入:

C:\Users\victor>echo bla >> "C:\Users\victor\Documents\Projets\libxnotify\unittests\test"

它奏效了。

Answer 1

ReadDirectoryChangesW 的文档有一句话说:

To obtain a handle to a directory, use the CreateFile function with the FILE_FLAG_BACKUP_SEMANTICS flag.

CreateFile 的文档然后对此还有更详细的评论:

Directories

An application cannot create a directory by using CreateFile, therefore only the OPEN_EXISTING value is valid for dwCreationDisposition for this use case. To create a directory, the application must call CreateDirectory or CreateDirectoryEx.

To open a directory using CreateFile, specify the FILE_FLAG_BACKUP_SEMANTICS flag as part of dwFlagsAndAttributes. Appropriate security checks still apply when this flag is used without SE_BACKUP_NAME and SE_RESTORE_NAME privileges.

您错过了 dwFlagsAndAttributes 的这个重要的 FILE_FLAG_BACKUP_SEMANTICS 标志。