The header comment grew to 39 lines across two audit-driven rounds,
over the 30-line comment-block-lint max. Trimmed to 30: merged the
value-as-argument rationale with its /proc/cmdline justification into
one paragraph, cut the usage example to one call instead of two, and
condensed the args paragraph — no content dropped, just restatement.
persistence.md's first-boot-migration marker paragraph used "it is"
and "there is not" — vale's Microsoft.Contractions rule (this repo's
config) wants the contracted forms, and "is not" also collides with
"is nothing" as a literal substring, which is what actually tripped
the error. Reworded to "it's" / "there's nothing", no meaning change.
Lint-only: no script logic changed, gates re-run below are all lint
checks (no module-eval, no cargo).
Refs #4723
The pipe contract had a gap: if a producer piped into
atomic_write_secret exited non-zero after writing partial output,
cat still saw a clean EOF and wrote that partial content through to
the live target via mv — pipefail only reported the failure
afterward, once the bad write was already committed. The helper now
takes the value as its 4th argument and writes it itself with printf
(a shell builtin, so the value never touches an external process's
own argv/environ, same as a function argument never does), so there
is no pipe left to fail silently.
Callers that compute the value with a command now capture it into a
variable first (`value=$(cmd)`), which fails under `set -e` before
atomic_write_secret is ever called — swarm-bao.nix's pin.env site is
the one that needed this (`pin_env_value="BAO_HSM_PIN=$(cat ...)"`).
All seven call sites converted; output is byte-identical (same
printf '%s\n' framing, now applied inside the helper instead of by
each caller).
Refs #4723
atomic_write_secret's cleanup trap used RETURN, which never fires when
set -e aborts the function mid-body (a failing cat/chmod/chown), so a
secret-bearing temp file was left behind instead of being removed.
The write now runs in a subshell with its own EXIT trap, invoked via a
named handler (so `local rc=$?` is a normal, shellcheck-visible
assignment) that only removes the temp file when the subshell's exit
status is nonzero — the subshell's trap table is private, so a calling
unit's own EXIT trap is untouched. Reproduced the leftover-tmp bug
against the prior commit, confirmed it's gone, and confirmed both the
success path and a caller's own EXIT trap still work as before.
swarm-bao.nix's swarm-bao-forwarder-oidc unit had the identical
write-then-chmod-on-live-path defect as the four sites already fixed
here (fetches an OIDC client secret from swarm-bao, printfs it to the
live host path, chowns/chmods after) and was missed by the original
sweep. Converted it to atomic_write_secret; content and final
owner/mode (root:root, 0400) are unchanged.
Refs #4723
Four host glue units fetched a secret from swarm-bao and rendered it
with `> path; chmod`: a reader racing the write could see a truncated
file, and briefly one at the wrong mode before the chmod landed.
glue-matrix-bao-token.nix, glue-queue-agent-credential.nix (both
files), swarm-grafana.nix and swarm-otel.nix now write to a same-
directory temp file, set its final mode/owner, then `mv -f` it over
the target — a shared `atomic_write_secret` helper
(nix/host-modules/lib/atomic-write-secret.nix) so the five call sites
share one implementation.
The first-boot `/root/.claude` migration in nix/agent-modules/user.nix
wrote its done-marker unconditionally, so a failed `cp` (disk full,
permission error) left the marker behind and no boot ever retried the
copy. The marker is now written only when there was nothing to
migrate or the copy succeeded; `cp -an`'s no-clobber semantics already
make a retry after a partial copy safe.
Refs #4723
