Two root causes, confirmed by direct code reading (previously misattributed
to an overlayfs sandbox fdatasync artifact):
conf_trim_old_versions() sorted config-version files by st_mtime (second
resolution). The test writes 3 versions 15ms apart -- well within one
second, so ties are the expected outcome, not a rare edge case. qsort()
isn't stable, so a tied ordering could push the protected current-pointer
file (skipped on deletion, never compensated) past keep_n, leaving one
extra file on disk ("Expected 2 Was 3"). Fixed by sorting on st_mtim
(nanosecond-resolution struct timespec) instead of st_mtime.
cr_setup() keyed its tmpdir on getpid()+time(NULL) (second resolution),
risking collision with a stale directory left by an earlier interrupted
run (ASAN abort, timeout, SIGKILL -- none reach cr_teardown()'s rm -rf)
reusing the same PID within the same second -- test_conf_get_saved_tag_
no_config then observed that directory as "not actually empty" and read
a leftover tag instead of the expected 0. Fixed with a monotonic counter
guaranteeing a unique directory per cr_setup() call.
TDD: RED reproduced on the first attempt (both tests failed with the
exact historical signature). GREEN confirmed across 16+ repeat runs
after the fix, zero other regressions.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019QxaSzHRB7pmYFp4cVnwkA
Rongsong Shen
a02d47772b