build-gnu.sh: Enable test/df/no-mtab-status.sh (#9759)

* build-gnu.sh: Enable test/df/no-mtab-status.sh

* Document why no-mtab-status.sh fails

.github/workflows/GnuTests.yml

@@ -6,6 +6,7 @@ name: GnuTests
 # spell-checker:ignore (options) Ccodegen Coverflow Cpanic Zpanic
 # spell-checker:ignore (people) Dawid Dziurla * dawidd dtolnay
 # spell-checker:ignore (vars) FILESET SUBDIRS XPASS
+# spell-checker:ignore userns
 
 # * note: to run a single test => `REPO/util/run-gnu-test.sh PATH/TO/TEST/SCRIPT`
 
@@ -116,6 +117,9 @@ jobs:
     - name: Run GNU tests
       shell: bash
       run: |
+        ## Use unshare
+        sudo sysctl -w kernel.unprivileged_userns_clone=1
+        sudo sysctl -w kernel.apparmor_restrict_unprivileged_userns=0
         ## Run GNU tests
         path_GNU='gnu'
         path_UUTILS='uutils'

util/build-gnu.sh

@@ -4,7 +4,7 @@
 
 # spell-checker:ignore (paths) abmon deref discrim eacces getlimits getopt ginstall inacc infloop inotify reflink ; (misc) INT_OFLOW OFLOW
 # spell-checker:ignore baddecode submodules xstrtol distros ; (vars/env) SRCDIR vdir rcexp xpart dired OSTYPE ; (utils) greadlink gsed multihardlink texinfo CARGOFLAGS
-# spell-checker:ignore openat TOCTOU CFLAGS
+# spell-checker:ignore openat TOCTOU CFLAGS tmpfs
 
 set -e
 
@@ -171,6 +171,8 @@ grep -rl '\$abs_path_dir_' tests/*/*.sh | xargs -r "${SED}" -i "s|\$abs_path_dir
 "${SED}" -i 's/^print_ver_.*/require_selinux_/' tests/runcon/runcon-no-reorder.sh
 "${SED}" -i 's/^print_ver_.*/require_selinux_/' tests/chcon/chcon-fail.sh
 
+# Mask mtab by unshare instead of LD_PRELOAD (able to merge this to GNU?)
+"${SED}" -i -e 's|^export LD_PRELOAD=.*||' -e "s|.*maybe LD_PRELOAD.*|df() { unshare -rm bash -c \"mount -t tmpfs tmpfs /proc \&\& command df \\\\\"\\\\\$@\\\\\"\" -- \"\$@\"; }|" tests/df/no-mtab-status.sh
 # We use coreutils yes
 "${SED}" -i "s|--coreutils-prog=||g" tests/misc/coreutils.sh
 # Different message

util/why-error.md

@@ -7,6 +7,7 @@ This file documents why some GNU tests are failing:
 * dd/nocache_eof.sh
 * dd/skip-seek-past-file.sh - https://github.com/uutils/coreutils/issues/7216
 * dd/stderr.sh
+* tests/df/no-mtab-status.sh - https://github.com/uutils/coreutils/issues/9760
 * fmt/non-space.sh
 * help/help-version-getopt.sh
 * help/help-version.sh

util/why-skip.md

@@ -7,7 +7,6 @@
 * tests/rm/rm-readdir-fail.sh
 * tests/rm/r-root.sh
 * tests/df/skip-duplicates.sh
-* tests/df/no-mtab-status.sh
 
 = LD_PRELOAD was ineffective? =
 * tests/cp/nfs-removal-race.sh