Zbigniew Jędrzejewski-Szmek
d6c9411072
This is a fairly noticable change, but I think it needs to be done. So far we'd create an absolute symlink to the target unit file: .wants/foo.service → /usr/lib/systemd/system/foo.service or alias.service → /etc/systemd/system/aliased.service. This works reasonably well, except in one case: where the unit file is linked. When we look at a file link, the name of the physical file isn't used, and we only take the account the symlink source name. (In fact, the destination filename may not even be a well-formed unit name, so we couldn't use it, even if we wanted to.) But this means that if a file is linked, and specifies aliases, we'd create absolute links for those aliases, and systemd would consider each "alias" to be a separate unit. This isn't checked by the tests here, because we don't have a running systemd instance, but it is easy enough to check manually. The most reasonable way to fix this is to create relative links to the unit file: .wants/foo.service → ../foo.service alias.service → aliased.service. I opted to use no prefix for aliases, both normal and 'default.target', and to add "../" for .wants/ and .requires/. Note that the link that is created doesn't necessarily point to the file. E.g. if we're enabling a file under /usr/lib/systemd/system, and create a symlink in /etc/systemd/system, it'll still be "../foo.service", not "../../usr/lib/systemd/system/foo.service". For our unit loading logic this doesn't matter, and figuring out a path that actually leads somewhere would be more work. Since the user is allowed to move the unit file, or add a new unit file in a different location, and we don't actually follow the symlink, I think it's OK to create a dangling symlink. The prefix of "../" is useful to give a hint that the link points to files that are conceptually "one level up" in the directory hierarchy. With the relative symlinks, systemd knows that those are aliases. The tests are adjusted to use the new forms. There were a few tests that weren't really testing something useful: 'test -e x' fails if 'x' is a a dangling symlink. Absolute links in the chroot would be dangling, even though the target existed in the expected path, but become non-dangling when made relative and the test fails. This should be described in NEWS, but I'm not adding that here, because it'd likely result in conflicts.
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