[systemd-devel] [PATCH] path-util: Fix path_is_mount_point for files

[Martin Pitt]

Martin Pitt [2015-05-25 21:06 +0200]:
> in 220, path_is_mount_point() now always fails with "-20 ENOTDIR" when
> calling it on files. This is problematic as it's perfectly valid to
> have bind-mounted files; in fact, systemd's machine_id_setup() itself
> creates a /run/machine-id → /etc/machine-id bind mount if /etc is
> read-only at that time (and systemd-machine-id-commit will write it
> once root fs becomes writable).
> 
> This was first introduced here:
> 
>   http://cgit.freedesktop.org/systemd/systemd/commit/?id=27cc6f166
>       path-util: fix path_is_mount_point() for symlinks
> 
> which added O_DIRECTORY, so that openat() fails with the above error.
> It also replaced path_get_parent() (which works fine for files) with
> name_to_handle_at(fd, "..", ...) which only works for directories.
> 
> In fd_is_mount_point() we obviously don't have access to the file name
> any more, and presumably we do want to keep it for efficiently
> implementing the "rm-rf: never cross mount points" commit f25afeb.

This patch fixes this. When writing the new tests I also noticed that
allow_symlink==false was broken, this also gets fixed.

Martin
-- 
Martin Pitt                        | http://www.piware.de
Ubuntu Developer (www.ubuntu.com)  | Debian Developer  (www.debian.org)
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