如何获取符号链接的文件描述符？

Question

I know that I can read a symbolic link with readlink , and operate upon it with llistxattr etc, but I'm looking to get the file descriptor of it so that I can use it with flistxattr etc.

I've also checked manual of open and I know O_NO_FOLLOW won't open a symbolic link (but will fail so that some applications can be safer).

So is there any way to get the file descriptor of a symbolic link?

Answer 1

is there any way to get the file descriptor of a symbolic link?

From the symlink(7) man page:

Obtaining a file descriptor that refers to a symbolic link

Using the combination of the O_PATH and O_NOFOLLOW flags to open(2) yields a file descriptor that can be passed as the dirfd argument in system calls such as fstatat(2), fchownat(2), fchmodat(2), linkat(2), and readlinkat(2), in order to operate on the symbolic link itself (rather than the file to which it refers).

By default (ie, if the AT_SYMLINK_FOLLOW flag is not specified), if name_to_handle_at(2) is applied to a symbolic link, it yields a handle for the symbolic link (rather than the file to which it refers). One can then obtain a file descriptor for the symbolic link (rather than the file to which it refers) by specifying the O_PATH flag in a subsequent call to open_by_handle_at(2). Again, that file descriptor can be used in the aforementioned system calls to operate on the symbolic link itself.