There is the non-standard O_NOFOLLOW.

DblPlusUngood · on July 22, 2016

Why do you say "non-standard"? O_NOFOLLOW is specified by POSIX.

loeg · on July 23, 2016

The Linux manual page is a little misleading, and I didn't dig further into POSIX. Mea culpa.

       O_NOFOLLOW
              If pathname is a symbolic link, then the open fails.  This is a FreeBSD extension, which was added  to  Linux  in  version
              2.1.126.  Symbolic links in earlier components of the pathname will still be followed.  See also O_PATH below.

...

       The O_CLOEXEC, O_DIRECTORY, and O_NOFOLLOW flags are not specified in POSIX.1-2001, but are  specified  in  POSIX.1-2008.

adrianratnapala · on July 22, 2016

Can you not do an ordinary open without O_NOFOLLOW and then lstat the filename?

cyphar · on July 22, 2016

Race condition again. The file could be unlinked. fstat is the only safe way of getting stat information for an open file.

loeg · on July 23, 2016

Right. The right thing to do is open() with NOFOLLOW, then fstat the resulting fd. Then check for S_ISLNK(st_mode).