Split the single directory fd that chaseat() used to take into two separate
fds: a root_fd that sets the chroot boundary (symlinks may not escape it,
absolute symlinks resolve relative to it), and a dir_fd that path resolution
starts from. This makes the chroot semantics of chaseat() explicit at every
call site instead of encoding them in the CHASE_AT_RESOLVE_IN_ROOT flag,
which is removed. It also decouples the starting directory from the root
boundary, so callers can descend from any inode inside the tree without
having to reopen the root separately.
XAT_FDROOT passed as root_fd means "no containment" (host root); as dir_fd
it means "start at root_fd". For a smoother transition, AT_FDCWD is also
accepted as root_fd and treated as XAT_FDROOT. When root_fd points to a
directory that is actually the host root, it is normalized to XAT_FDROOT
up front so the existing shortcut path can kick in.
Absolute paths returned by chaseat() are now relative to root_fd, and
relative paths are relative to dir_fd. The result is absolute only when
there is no chroot boundary (root_fd is XAT_FDROOT), or when an absolute
symlink made resolution jump out of the dir_fd subtree; otherwise callers
get a relative path they can feed straight back into an openat()-style
call against dir_fd. Specifically, when dir_fd == root_fd and we're not
operating on the host's root directory, we return a relative path even if
we received an absolute path or resolved an absolute symlink to allow
passing the path directly to openat() style functions. We do this to not
have to go modify every caller of chaseat() to make sure they deal properly
with any absolute paths they might receive. Only when root_fd != dir_fd do
we have to return an absolute path to indicate that the path is relative to
root_fd and not dir_fd.
The shortcut that skips the per-component walk is reworked around a new
chase_xopenat() helper that funnels CHASE_NOFOLLOW, CHASE_MUST_BE_* and
CHASE_TRIGGER_AUTOFS through xopenat_full()'s O_NOFOLLOW, O_DIRECTORY,
XO_REGULAR, XO_SOCKET and XO_TRIGGER_AUTOMOUNT flags. As a result these
flags no longer force us off the shortcut and can be dropped from
CHASE_NO_SHORTCUT_MASK, and the old openat_opath_with_automount() helper
goes away. A CHASE_MUST_BE_ANY alias is introduced for shortcut callers
(stat/access paths) that don't go through xopenat_full() and still need
to bail on those flags locally.
All *_and_* helpers built on top of chaseat() (chase_and_openat,
chase_and_opendirat, chase_and_statat, chase_and_accessat,
chase_and_fopenat_unlocked, chase_and_unlinkat, chase_and_open_parent_at)
gain the same root_fd parameter, and every call site in the tree is
ported to the new signature.
chase_and_open() is also fixed to correctly handle CHASE_EXTRACT_FILENAME
without CHASE_PARENT.
As mentioned in the grandfather commit, I want to use the _many
suffix for freeing of the contents of an array, so the functions
to free the array to get the suffix _array.
This is useful in tools such as system-repart where we show the
definition file paths a lot in our output, but if prefixed with the root
path we'd show a temporary mount dir when operating on a image file.
Hence, let's drop the prefix here, and show only the path within the
image.
Let's make sure we can safely load configuration files based on a root
fd, including XAT_FDROOT.
(While we are at it, always pass path to root fs before fd to root fs,
following our recently updated CODING_STYLE)
With the previous commit, now CHASE_MUST_BE_DIRECTORY can be set with
CHASE_NONEXISTENT. Let's unconditionally set the flag to chase the
directory part of the conf file.
Before 50c81130b6, the function used
chase(), hence if root is an empty string, each config directory made
prefixed with the current working directory if it is relative. See
implementation of chase().
With 50c81130b6, conf_files_list_strv()
internally uses chaseat(), hence each config directory is not prefixed
anymore even if it is relative.
To restore the previous behavior, this makes
- if root is an empty string, prefix each config directories with the
current working directory if relative.
- if root is relative, make it absolute to make the prefixed results also
absolute, and debugging logs show absolute paths.
- use chaseat_prefix_root() to prefix the results, for safety.
Follow-ups for 50c81130b6.
This reverts commit 49653adef3.
The commit was merged without review, and has several issues.
Let's revert the change now, and address the issue pointed out by
the commit later in another way.
Previously, symlinks in the replacement was not chased, hence we may
inserted a path to outside of the root directory, or we may have wrong
judgement whether we should insert the replacement or not.
This makes the symlinks in the replacement also resolved.
Also, as the function is only used by tmpfiles and sysusers, this
enables CONF_FILES_REGULAR, CONF_FILES_CHASE_BASENAME, and
CONF_FILES_FILTER_MASKED_BY_SYMLINK flags.
Previously, when a root directory is specified to conf_files_list() and
friends, the last component of each result was not resolved, even though
they internally chases the last component. So the caller needs to chase
the path again when the file is used.
This introduce a new flag that makes the whole path of each result is
resolved, hence caller can use it as is.
Previously, symlinks in paths to conf directories are chased, but
symlink files in conf directories were not.
This also makes symlink files in conf directories chased. And, any
unresolvable symlinks are dropped, even if no verification is requested.
Admittedly, some of our glyphs _are_ special, e.g. "O=" for SPECIAL_GLYPH_TOUCH ;)
But we don't need this in the name. The very long names make some invocations
very wordy, e.g. special_glyph(SPECIAL_GLYPH_SLIGHTLY_UNHAPPY_SMILEY).
Also, I want to add GLYPH_SPACE, which is not special at all.
Also, use the more correct type of 'const char* const*' for the input strv.
This requires adding the cast in a few places, but also allows to remove some
casts in others.
Previously, if given an absolute path, we would open the file, but when given a
relative path, we'd attempt to search the directories. If the user wants to open
a file from the search path, allowing paths is very confusing. E.g. with a path
like 'sysusers/foo.conf', we'd try to open '/etc/sysusers.d/sysusers/foo.conf',
'/run/sysusers.d/sysusers/foo.conf', …, and with '../foo.conf', we'd try to open
'/etc/sysusers.d/../foo.conf', '/run/sysusers.d/../foo.conf', …. This just isn't
useful, and in fact for a scheme like sysusers.d and tmpfiles.d where there we
have a flat directory with config files, only searching for plain names can
result in success. When a user specifies a relative path, it's more likely that
they wanted to open some local file. OTOH, to correctly open a local file, e.g.
one that they're just writing, this interface is also awkward, because something
like '$PWD/file.conf' has to be used to open a file with a relative path.
This patch changes the interface so that any path (i.e. an argument with "/") is
used to open a file directly, and only plain basenames are used for searching.
(Note that tpmfiles and sysusers are somewhat special here: their "config files"
make sense without the other config and users are likely to want to test them
without the other config. I was trying to do just that when writing a spec file
for a package and attempting to convert the existing scripts to sysusers and
tmpfiles. The same logic wouldn't apply for example to units or udev rules,
because they generally can only be interpreted with the whole rest of config
also available.)
I was annoyed that systemd-sysusers doesn't print any info when it opens a
config file. Its read_config_file() started out the same as the one in tmpfiles,
and then they diverged. The one in tmpfiles has that logging, hence the rework
to use it here too and get better logging. The two programs should provide
similar functionality, so using a common helper will make it easier to extend
them in tandem later.
No functional change apart from the log info.
The userdata argument (Context) is moved to the last position as requested in
the review.
Chasing symlinks is a core function that's used in a lot of places
so it deservers a less verbose names so let's rename it to chase()
and chaseat().
We also slightly change the pattern used for the chaseat() helpers
so we get chase_and_openat() and similar.
The name "def.h" originates from before the rule of "no needless abbreviations"
was established. Let's rename the file to clarify that it contains a collection
of various semi-related constants.
Daan De Meyer
Zbigniew Jędrzejewski-Szmek
Lennart Poettering
Yu Watanabe
Alexis-Emmanuel Haeringer
Daan De Meyer
Zbigniew Jędrzejewski-Szmek
Mike Yuan