是否可以使用std :: filesystem获得根名称列表？

Question

我知道如何获取某些路径的root name，并且有std::filesystem::directory_iterator用于遍历目录。

但是如何获取具有根名的列表，如果不可能，那为什么呢？

Answer 1

看看最近开放的Microsoft实现的std::filesystem，更具体地说是helper function _Find_root_name_end：

_Find_root_name_end

这突出了许多问题：

• Windows中的驱动器字母可以来回移动，因此“有效根目录列表”在一个调用之间会有所不同

•         // This is the place in the generic grammar where library implementations have the most freedom.
          // Below are example Windows paths, and what we've decided to do with them:
          // * X:DriveRelative, X:\DosAbsolute
          //   We parse X: as root-name, if and only if \ is present we consider that root-directory
          // * \RootRelative
          //   We parse no root-name, and \ as root-directory
          // * \\server\share
          //   We parse \\server as root-name, \ as root-directory, and share as the first element in relative-path.
          //   Technically, Windows considers all of \\server\share the logical "root", but for purposes
          //   of decomposition we want those split, so that path(R"(\\server\share)").replace_filename("other_share")
          //   is \\server\other_share
          // * \\?\device
          // * \??\device
          // * \\.\device
          //   CreateFile appears to treat these as the same thing; we will set the first three characters as root-name
          //   and the first \ as root-directory. Support for these prefixes varies by particular Windows version, but
          //   for the purposes of path decomposition we don't need to worry about that.
          // * \\?\UNC\server\share
          //   MSDN explicitly documents the \\?\UNC syntax as a special case. What actually happens is that the device
          //   Mup, or "Multiple UNC provider", owns the path \\?\UNC in the NT namespace, and is responsible for the
          //   network file access. When the user says \\server\share, CreateFile translates that into
          //   \\?\UNC\server\share to get the remote server access behavior. Because NT treats this like any other
          //   device, we have chosen to treat this as the \\?\ case above.

  情况将需要“有效根目录”来基本上枚举整个Internet，因为\\server\share是有效的主机。