timefmt.nx

timefmt.nx -- RFC 3339 + RFC 822 timestamp format/parse. Used by: - TLS 1.3 / X.509 cert validity (notBefore / notAfter). X.509 uses UTCTime (YYMMDDhhmmssZ) for dates before 2050 and GeneralizedTime (YYYYMMDDhhmmssZ) after. We support both formats for parse. - HTTP Date header (RFC 7231 §7.1.1.1) -- RFC 822 format. - Structured logs in Nishi services. - JSON responses (RFC 3339 via ISO 8601 subset). NO time zone handling today. All conversion is against UTC only; local time zones require a tz database we haven't built. TLS cert dates are always UTC, HTTP Date must be UTC-in-practice ("GMT"), so this covers the load-bearing cases. Format reference (RFC 3339): date-time = full-date "T" full-time full-date = date-fullyear "-" date-month "-" date-mday full-time = partial-time time-offset partial-time = hour ":" minute ":" second [ "." secfrac ] time-offset = "Z" / ( ("+" / "-") hour ":" minute ) We emit the "Z" form exclusively: "YYYY-MM-DDTHH:MM:SSZ" (20 chars). Invariants: T1 format_rfc3339 writes exactly 20 ASCII bytes plus NUL-free (caller adds terminator if needed) T2 Dates before year 1 are out of scope; years > 9999 are clamped to 9999 so the output stays 20 chars T3 No Y2K / 2038-bugginess. i64 epoch seconds handle every human-relevant date from ~292 BC to ~292 billion AD.