From: Lennart Poettering <lennart@amutable.com>
Date: Thu, 25 Jun 2026 15:18:55 +0000 (+0200)
Subject: unit-name: introduce "strict" mode for unit name mangling (#42638)
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=4162b65338c5a59cabb8d141e8d1e0ed8d50b0a5;p=thirdparty%2Fsystemd.git

unit-name: introduce "strict" mode for unit name mangling (#42638)

unit_name_mangle_with_suffix() is quite benevolent by default and allows
the unit to "transition" into a different unit type than what's
requested via its suffix argument. For example, calling
unit_name_mangle_with_suffix() with "/foo/bar" as a unit name and
".service" as a suffix would give you "foo-bar.mount", without any
warning or error.

This could then lead to a quite confusing errors in certain situations:
```
~# systemd-run --remain-after-exit --unit /foo/bar true
Failed to start transient service unit: Cannot set property RemainAfterExit, or unknown property.
```
Given we can't change the default behaviour of
unit_name_mangle_with_suffix() as some parts of systemd already depend
on its "benevolence" (like systemctl), let's introduce a new flag -
UNIT_NAME_MANGLE_STRICT - that checks if the mangled/resolved unit
name's suffix matches the requested one and errors out if not.

With the flag used throughout systemd-run's code, the error in the above
case is now a bit more clear:
```
~# build/systemd-run --remain-after-exit --unit /foo/bar true
Path "/foo/bar" resolves to unit type "mount", but "service" is expected as unit.
Failed to mangle unit name: Invalid argument
```
Resolves: #39996
---

4162b65338c5a59cabb8d141e8d1e0ed8d50b0a5