pacman intermittently freezes at its FIRST PreTransaction hook - 5 abandoned
transactions since 2026-07-29, stalls of 4 minutes to overnight, always fine on
retry. This investigates it and repairs the real defects found on the way.
The stall is NOT fixed, and deliberately so: no verified defect was found, so
nothing pacman-side was changed.
- Not guard-lib. /etc/guard-lib/targets was empty, so that hook script
provably exits in milliseconds. The failures share POSITION (first hook of
the transaction), not identity: one stall hit the hosts hook back when that
one ran first.
- Not reproducible on demand. 65 real transactions (40 idle, 25 under 2.6 GB
of memory pressure) produced zero stalls. Against the historical 4-in-56
rate that is ~0.9% likely, so the trigger is conditional on something a
synthetic load does not recreate. Memory pressure is untested at the load
that actually occurred - not refuted.
So diagnose_pacman_hook_stall.sh drives real transactions with a watchdog, and
its --watch mode passively captures /proc/<pid>/{stack,wchan,syscall}, the
process tree, meminfo and PSI from the next REAL stall. No pacman-side fix
should ship before that dump exists.
Three real defects were found and fixed:
1. The deployed pacman wrapper was 19916 B against a 27510 B source, never
sourcing the shared pacman_lock_lib.sh that makepkg_wrapper already used.
It hid because check_pacman_wrapper() only tested that files EXIST. Both
installers now write a drift manifest covering source AND installed hashes;
the checker replays it with sha256sum -c and fails closed when it cannot
verify. Manifest paths are absolute - relative ones resolve to nothing under
systemd's cwd=/ and would have looped reinstalling forever.
2. The guard-lib migration (66c4698) was never finished here: guard-lib was
installed with zero registered targets while the legacy hosts-guard layer did
all the work, so every transaction ran two PreTransaction hooks and the first
one did nothing. migrate_hosts_guard_to_guard_lib.sh registers hosts,
nsswitch and resolved, retires the legacy hooks and units, and has a
--rollback that was actually exercised. Plugins install to a stable path
because guardctl records absolute plugin paths. Side effect: one hook pair
instead of two, transactions ~5-6s -> ~2-3s.
3. "One heavy job at a time" was a rule a human had to remember. heavy_job_lock.sh
makes the overlap impossible: one system-wide flock shared between root and
the user (a per-user lock would give root's pacman and the user's builds
separate locks and no exclusion at all). Wired into pacman TRANSACTIONS only
- read-only queries stay instant - plus makepkg_capped and the coverage hook.
Always fails open.
Two bugs surfaced only by running --rollback, both of which briefly left
/etc/hosts with no immutable flag: fg_uninstall clears +i on its way out while
legacy watchers only fire on PathModified, and `((i > 20)) && break` left the
loop body's status at 1, which under set -e aborted the rollback silently - but
only when the loop actually ran, so --dry-run looked healthy.
Not migrated: the shutdown-schedule guard (/etc/shutdown-schedule.conf does not
exist here). Not wired: Flutter/Gradle builds, which have no single entry point.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
`git commit`/`git push` export GIT_DIR to every hook they run, and the
flutter tool shells out to git to identify its own SDK. `git -C
"$FLUTTER_ROOT" rev-parse HEAD` in bin/internal/shared.sh does not beat an
inherited GIT_DIR -- `-C` only changes directory, GIT_DIR overrides
repository discovery outright:
$ git -C /opt/flutter rev-parse HEAD
058e0af2c2... <- Flutter's HEAD
$ GIT_DIR=~/diet-guard/.git git -C /opt/flutter rev-parse HEAD
84bd550331... <- diet-guard's HEAD
So inside a hook, flutter reports the project as the SDK:
Flutter 3.47.0-0.1.pre • channel main • https://github.com/kuhyx/diet-guard
pub then resolves the SDK as 0.0.0-unknown and every version constraint
becomes unsatisfiable. flutter also writes that into its own version cache,
so the wrong answer outlives the hook and follows the next caller into an
unrelated repository -- which is why the identical command passes when you
re-run it by hand and fails again on the next push.
diet-guard's pre-push gate hit this today. Clearing the variables per call in
each hook works, and screen-locker and diet-guard now do, but only for as
long as every future hook author remembers -- deployment hygiene, not a fix.
This installs a wrapper ahead of /usr/bin on PATH that strips them for every
caller in every repo, covering both flutter and dart. It removes its own
directory from PATH before exec so the Flutter entry point's internal `which
flutter` cannot loop back into it, and it verifies itself by running flutter
against a throwaway poisoned GIT_DIR and failing unless the real SDK comes
back.
Not patching bin/internal/shared.sh: that file belongs to the flutter-bin
package, so the next update would silently restore the bug. Upstream already
unsets these variables in content_aware_hash.sh and update_engine_version.sh,
just not in the version path.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
- Move all linux_configuration scripts into two semantic categories:
- single_use/: scripts run once manually (fresh install, fixes, setup)
- periodic_background/: scripts run by systemd timers or daemons
- Preserve existing subdirectory structure within each category
- Fix lib/common.sh source paths for new directory depths
- Fix CONFIG_DIR depth in setup_periodic_system.sh and check_and_enable_services.sh
- Update all references in tests, fresh-install/main.sh, nix modules, and docs
- Fix check_polling_antipatterns.sh false positives (||, regex |, case patterns, jq strings)
- Fix pre-existing mypy exclusion path and type annotations for moved tools/ directory
- Rewrite check_polling_antipatterns.sh using awk (no bash regex loops); add require_serial: true
