---
- branch: MAIN
  date: Sun May 15 16:20:10 UTC 2022
  files:
  - new: '1.214'
    old: '1.213'
    path: src/sys/kern/kern_time.c
    pathrev: src/sys/kern/kern_time.c@1.214
    type: modified
  id: 20220515T162010Z.4ae92cfecf5fab414dfb590e175eb75d5bfec79f
  log: |
    adjtime(2): Handle negative tv_sec and tv_usec.

    Previously I clamped these to avoid dangerous arithmetic overflow.
    But I assumed sensible values should be nonnegative.

    For tv_sec, this assumption was just wrong -- the adjustment may be
    negative.

    For tv_usec, this assumption is...not wrong, but also not right.
    tv_usec is not _supposed_ to be negative (by POSIX, the type need
    only represent values in [-1, 1000000]; semantically the member is
    supposed to be a nonnegative number of microseconds below 1000000),
    but ntp abuses it to hold negative values, for reasons unclear -- the
    same effect could be had by subtracting one from tv_sec, and adding
    1000000 to the negative tv_usec.  However, let's not break existing
    ntp userlands...
  module: src
  subject: 'CVS commit: src/sys/kern'
  unixtime: '1652631610'
  user: riastradh