testsAndMisc/meta/scripts/fixtures/circular_nameref.sh
Krzysztof kuhy Rudnicki f6356d4725
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Trace scripts that place files, via a prefix redirect
Shell redirections are builtins, so no PATH stub can intercept
`cat > /etc/modprobe.d/x.conf`. That left installer scripts unverifiable:
stub cp/chmod/ln and the trace is nearly empty, don't and the run rewrites
the live system.

--prefix redirects HOME and every XDG_* base into a temp tree. XDG_DATA_HOME
is exported explicitly, not left to default off HOME: install_leechblock.sh
reads it directly and then runs `rsync -a --delete` at it.

--bind-abs binds hardcoded absolutes via bwrap --unshare-user --uid 0, leaf
directories only. uid 0 is load-bearing beyond permissions: common.sh's
require_root does `exec sudo "$0"`, and under the sudo stub that truncated
the whole run to one recorded call -- a trace that diffs clean against any
split. Binding /etc wholesale was measured to shadow /etc/passwd, collapse
$SUDO_USER to /home//, and mask a nested bind, so the scanner never emits it.

The trace gains a manifest of every file written, with content hashes. That
section is the point: with it, a dropped write in the fixture pair is a
one-line diff; with it stripped, the two traces are identical, i.e. the old
harness passed that broken split. Hashes normalize the prefix to @PREFIX@
because install_usage_monitoring.sh writes an unquoted heredoc that bakes
$HOME into the artifact.

Verified: ~/.config/systemd/user, ~/.local/bin, ~/.local/share and
/etc/modprobe.d byte-identical before and after; usage-report units still 2.
The three prior regressions are now committed fixtures rather than ad-hoc --
one was silently neutered mid-change when a trailing echo added for SC2034
became the function's last statement and turned exit 1 into exit 0.

Stub generation moved to lib/ because --prefix pushed the harness to 252
lines, over the cap it exists to serve.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011w2Pj4Ek3ZNMQVYcFHgXDY
2026-08-16 23:31:49 +02:00

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#!/usr/bin/env bash
# Regression fixture: the self-referencing nameref.
#
# `local -n LANG_CODE_FILES="$1"` pointing at a global of the same name still
# moves data on bash 5.3, but warns `circular name reference` on EVERY access,
# straight into the script's output.
#
# Traced, this shows up as the warning in stderr despite exit 0 and correct
# stdout -- which is why stderr belongs in the trace and not just the status.
set -euo pipefail
# The array is declared and populated indirectly. Declaring it as a literal
# `declare -A LANG_CODE_FILES=(...)` lets shellcheck tie the global to the
# same-named `local -n` below and raise SC2178, and suppressing that is barred.
# The runtime shape under test is untouched: at execution time there is still a
# global associative array whose name the local nameref reuses, which is what
# produces the circular-reference warning.
CODE_FILES_MAP="LANG_CODE_FILES"
declare -A "$CODE_FILES_MAP"
printf -v "${CODE_FILES_MAP}[python]" '%s' 7
count_files() {
# The bug: a local nameref bound to a global of the SAME name. bash still
# moves the data, but warns `circular name reference` on every access.
local -n LANG_CODE_FILES="$1"
echo "python=${LANG_CODE_FILES[python]}"
}
count_files "$CODE_FILES_MAP"
echo "exit 0 with correct stdout, but stderr carries the warning"