In user_dirs() in path-lookup.c, I want to replace this:
symlink("../../../.config/systemd/user", data_home);
with
symlink(config_home, data_home);
to avoid hardcoding .config when XDG_CONFIG_HOME is set.
The problem is that config_home is an absolute path, and it's better
to make the symlink relative. path_make_relative() is an utility
function that converts an absolute path into a relative one.
Running systemctl enable/disable/set-default/... with the --root
option under strace reveals that it accessed various files and
directories in the main fs, and not underneath the specified root.
This can lead to correct results only when the layout and
configuration in the container are identical, which often is not the
case. Fix this by adding the specified root to all file access
operations.
This patch does not handle some corner cases: symlinks which point
outside of the specified root might be interpreted differently than
they would be by the kernel if the specified root was the real root.
But systemctl does not create such symlinks by itself, and I think
this is enough of a corner case not to be worth the additional
complexity of reimplementing link chasing in systemd.
Also, simplify the code in a few places and remove an hypothetical
memory leak on error.
In contrast to a filename-only argument, find_binary() did not
actually check if an path exists, allowing the code to fail later on.
This was OK, but it seems nicer to treat both paths identically.
Also take advantage of path_make_absolute_cwd doing strdup() by itself
if necessary to simplify.
The conf_files_list family accepts an alternate root path to prefix all
directories in the list but path_strv_canonicalize_uniq doesn't use it.
This results in the suspicious behavior of resolving directory symlinks
based on the contents of / instead of the alternate root.
This adds a prefix argument to path_strv_canonicalize which will now
prepend the prefix, if given, to every path in the list. To avoid
answering what a relative path means when called with a root prefix
path_strv_canonicalize is now path_strv_canonicalize_absolute and only
considers absolute paths. Fortunately all users of already call
path_strv_canonicalize with a list of absolute paths.
The only problem is that libgen.h #defines basename to point to it's
own broken implementation instead of the GNU one. This can be fixed
by #undefining basename.
This unifies much of the logic behind them:
- All four will now ofllow the rule that the earlier file and earlier
assignment in the .d/ directories wins. Before, sysctl was the only
outlier, where the later setting always won.
- All four now support getopt() and --help on the command line.
- All four can now handle specification of configuration file names on
the command line to apply. The tools will automatically find them, and
apply them. Previously only tmpfiles could do that. This is useful for
%post scripts in RPMs and suchlike.
- This fixes various error path issues in conf_files_list()
The ability to start a new unit with 'systemctl start ...' should not
depend on whether there are other units in the directory. Previously,
an additional 'systemctl daemon-reload' would be necessary to tell
systemd to update the list of unit lookup paths.
In cases where path_strv_canonicalize() returns NULL, strv_free() is
called afterwards and it will call free() on pointers which were freed
already in path_strv_canonicalize()
- Make writing/reading of /etc/timezone dependendent of HAVE_SYSV_COMPAT
- Introduce symlink_atomic() after all, and use it
- Use relative symlink for /etc/localtime
