- parse_ull_arg() rejects a leading '-'/'+' (strtoull would silently wrap
-1 to ULLONG_MAX) and --chunk-size/--delta-max enforce their upper bounds.
- Escape local untrusted paths before logging (client_send, scanner,
--filter rule, pattern-file reads) with output_escape(..., 8-bit mode).
- Read --exclude-from/--include-from through the bounded line reader.
- Open --log-file with O_NOFOLLOW|O_CLOEXEC, mode 0600, via open+fdopen;
create --write-batch with O_NOFOLLOW|O_CLOEXEC, mode 0600.
- Reject --dry-run together with --write-batch (dry-run must not write the
batch file), alongside the existing --read-batch/--only-write-batch rules.
Tests: signed/oversized numeric rejection, over-long pattern file, dry-run +
write-batch unit and integration coverage.