Previously fts_build() called _dup(_dirfd(dirp)) for every child
entry, holding N simultaneous fds for a directory with N children.
Redefine fts_dirfd: instead of a fd for the entry's parent
directory, it is now a fd for the entry itself, set only for
directory entries. One dup per directory in fts_build() instead
of one per child. Close fts_dirfd during the directory post-order
visit, before advancing to its sibling.
To access a file using fd-relative operations, callers should use
openat(ent->fts_parent->fts_dirfd, ent->fts_name, ...) instead of
openat(ent->fts_dirfd, ent->fts_name, ...). The fd is valid until the
directory's post-order visit (FTS_DP).
Reported by: Mark Johnston <[email protected]>
Fixes: 4bd01d6ae0 (fts: refactor to use fd-relative operations)
Sponsored by: Google LLC (GSoC 2026)
Reviewed by: asomers
Pull Request: https://github.com/freebsd/freebsd-src/pull/2360
Jitendra Bhati
dd532ad133