Behaviour of cp in coreutils-from-uutils/rust-coreutils break test case in util-linux

[frank-heimes]

While preparing a potential update of util-linux (LP#2142862) and doing a test build,
I noticed that one test case started to fail (on all platforms).

"
1 tests of 337 FAILED
setpriv/landlock
make[5]: *** [Makefile:19529: check-local-tests] Error 1
...
dh_auto_test: error: make -j1 check ... returned exit code 2
"
The The failing sub-test is setpriv/landlock → partial-access-fail, and the "failure" is a string mismatch (stonking_s390x.txt:12227):

The test case seems to expect cp output from GNU coreutils, since it works with it.
It looks for:
cp: cannot create regular file '/dev/zero': Permission denied

But the coreutils-from-uutils cp produces in the same test case this:
cp: '/dev/null' -> '/dev/zero': Permission denied

Which leads to a failed test.

The chroot that is used while doing the test buildi (in PPA) for Ubuntu 26.10 has coreutils-from-uutils 0.0.0~ubuntu27 / rust-coreutils 0.8.0-0ubuntu4.

While rebuilding the same in PPA with -proposed disabled, the test is successful (now with rust-coreutils 0.8.0-0ubuntu3).

Since rust-coreutils is supposed to be a drop-in replacement, and esp. since this works on the previous version, I think this is a regression and should be solved in coreutils.

---

I'm cross referencing the Ubuntu Launchpad bug:
https://bugs.launchpad.net/bugs/2157011

[sylvestre]

can we get a reproducer?

[frank-heimes]

Hi, sure.
A simple reproducer is:

$ /usr/lib/cargo/bin/coreutils/cp --version
cp (uutils coreutils) 0.8.0
$ /usr/lib/cargo/bin/coreutils/cp /dev/null /etc/os-release
cp: '/dev/null' -> '/etc/os-release': Permission denied

$ cp --version
cp (GNU coreutils) 9.7
Packaged by Ubuntu (9.7-3ubuntu2)
Copyright (C) 2025 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later https://gnu.org/licenses/gpl.html.
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.

Written by Torbjörn Granlund, David MacKenzie, and Jim Meyering.
$ cp /dev/null /etc/os-release
cp: cannot create regular file '/etc/os-release': Permission denied

---

A more complex one, that is closer to the affected util-linux test case is:

(Rust)
$ for dst in /proc/cpuinfo /proc/version /proc/sys/kernel/ostype /sys/kernel/notes /proc/newfile sys/newfile; do printf '%-32s -> ' "/usr/lib/cargo/bin/coreutils/cp /dev/null $dst"; /usr/lib/cargo/bin/coreutils/cp /dev/null "$dst" 2>&1 || true; done; echo "--- confirm nothing got created/clobbered---"; ls -l /proc/newfile /sys/newfile 2>&1
/usr/lib/cargo/bin/coreutils/cp /dev/null /proc/cpuinfo -> cp: '/dev/null' -> '/proc/cpuinfo': Permission denied
/usr/lib/cargo/bin/coreutils/cp /dev/null /proc/version -> cp: '/dev/null' -> '/proc/version': Permission denied
/usr/lib/cargo/bin/coreutils/cp /dev/null /proc/sys/kernel/ostype -> cp: '/dev/null' -> '/proc/sys/kernel/ostype': Permission denied
/usr/lib/cargo/bin/coreutils/cp /dev/null /sys/kernel/notes -> cp: '/dev/null' -> '/sys/kernel/notes': Permission denied
/usr/lib/cargo/bin/coreutils/cp /dev/null /proc/newfile -> cp: '/dev/null' -> '/proc/newfile': No such file or directory
/usr/lib/cargo/bin/coreutils/cp /dev/null sys/newfile -> cp: '/dev/null' -> 'sys/newfile': No such file or directory
--- confirm nothing got created/clobbered---
ls: cannot access '/proc/newfile': No such file or directory
ls: cannot access '/sys/newfile': No such file or directory

(GNU)
$ for dst in /proc/cpuinfo /proc/version /proc/sys/kernel/ostype /sys/kernel/notes /proc/newfile sys/newfile; do printf '%-32s -> ' "cp /dev/null $dst"; cp /dev/null "$dst" 2>&1 || true; done; echo "--- confirm nothing got created/clobbered---"; ls -l /proc/newfile /sys/newfile 2>&1
cp /dev/null /proc/cpuinfo -> cp: cannot create regular file '/proc/cpuinfo': Permission denied
cp /dev/null /proc/version -> cp: cannot create regular file '/proc/version': Permission denied
cp /dev/null /proc/sys/kernel/ostype -> cp: cannot create regular file '/proc/sys/kernel/ostype': Permission denied
cp /dev/null /sys/kernel/notes -> cp: cannot create regular file '/sys/kernel/notes': Permission denied
cp /dev/null /proc/newfile -> cp: cannot create regular file '/proc/newfile': No such file or directory
cp /dev/null sys/newfile -> cp: cannot create regular file 'sys/newfile': No such file or directory
--- confirm nothing got created/clobbered---
ls: cannot access '/proc/newfile': No such file or directory
ls: cannot access '/sys/newfile': No such file or directory

I just noticed that one of the coreutils packages (coreutils-from-uutils) in Ubuntu 26.10 (devel) got updated, now pointing to GNU cp (which unblocks me for the moment),
with changelog message:

• uutils: Reinstate gnucp (LP: #2158691)
  and the LP: #2158691 bug points to: cp -afL fails with 'cp: -r not specified; omitting directory <dir-name>' #13207