Hi John, On Thu, Aug 01, 2024 at 11:16:30AM GMT, John Rinehart wrote: > `util-linux` seems to fail to handle a use case that users like me seem to > be hitting with some frequency. The issue is around > https://github.com/util-linux/util-linux/blob/86b6684e7a215a0608bd130371bd7b3faae67aca/libmount/src/context.c#L2115-L2121 > and seems rooted in the fact that `util-linux` operates on `type` where > type is always of the form <a>.<b> but where <b> is apparently assumed to > not contain Unicode U+002E (ASCII 2E): '.' ("dotless"). I say it "appears > to assume" this since the logic which appears to remove the subtype does so > by using `strrchr`, which addresses only the last period in the `helper` > string. If the `subtype`, itself, has a U+002E character then this won't > remove the subtype. > > As an example, if `helper` looks like > `path/name.type./subtype/path/with/a.period` then the modified `helper` > after `strrchr` will look like `path/name.type./subtype/path/with/a` > instead of the apparently-intended `path/name.type`. the convention for filesystem names is (was): <type>[.<subtype>] For example, for the "mount" helper, it is: /path/mount.<type>[.<subtype>] I believe it is acceptable for the "path" to contain dots (or any other characters). The important thing is the last segment of the path (e.g. /mount.<type>[.<subtype>]). We should not be concerned with anything else besides the last segment. It is strange to assume that <subtype> can also contain path-like segments and dots. It seems like someone may want to use <subtype> to encode additional information ... Miklos (CC:), what is your opinion? Is it correct to assume that <subtype> is whatever? Karel > This crops up for users like me because I use NixOS which is a store-based > Linux operating system using paths like: > ``` > $ readlink -f $(which s3fs) > > /nix/store/xwbx0fbg65ml2qjl86p9p2w58kghqn8r-s3fs-fuse-1.94/bin/s3fs > ``` > (So, paths like `/nix/store/<hash>-<name>-<version>/bin/<cmd>`). `version` > is usually a dot-delimited string like `1.23`. > > I've generated a patch which seems to ameliorate this behavior. It's > attached (sorry if attachments are not the way to go with this mailing > list, specifically, or mailing lists, generally - this is my first time > submitting a patch to a mailing list). The logic is simple, but it > basically iterates through all possible substrings according to the number > of U+002E characters in the `type` string. It's a more generic form of the > logic already present, but it's a little heavy-handed. Happy with any and > all changes which preserve the apparently-corrected behavior. > > Please let me know if I should make any changes or if a change like this > won't be accepted for some reason or if I'm misunderstanding the > problem/solution. > > Thank you! > > Cf. > 1. https://discourse.nixos.org/t/how-to-setup-s3fs-mount/6283/5 > 2. https://github.com/NixOS/nixpkgs/issues/46529#issuecomment-655536831 > > -- John Rinehart -- Karel Zak <kzak@xxxxxxxxxx> http://karelzak.blogspot.com
