Currently, opening a symlink with O_NOFOLLOW fails with ELOOP. Following Linux, the first patch in this series allows the call to succeed if O_PATH is also specified.
According to the Linux man page for open(2), "the call returns a file descriptor referring to the symbolic link. This file descriptor can be used as the dirfd argument in calls to fchownat(2), fstatat(2), linkat(2), and readlinkat(2) with an empty pathname to have the calls operate on the symbolic link." The second patch achieves this for readlinkat. The third patch does this for fstatat and fchownat by adding support for the AT_EMPTY_PATH flag. Nothing needs to be done for linkat, which already supports the AT_EMPTY_PATH flag. Ken Brown (4): Cygwin: allow opening a symlink with O_PATH | O_NOFOLLOW Cygwin: readlinkat: allow pathname to be empty Cygwin: fstatat, fchownat: support the AT_EMPTY_PATH flag Cygwin: document recent changes winsup/cygwin/release/3.1.3 | 19 +++++++++-- winsup/cygwin/syscalls.cc | 68 ++++++++++++++++++++++++++++++++----- winsup/doc/new-features.xml | 19 +++++++++++ 3 files changed, 94 insertions(+), 12 deletions(-) -- 2.21.0
