CVS commit: src/sys/kern

["Taylor R Campbell" <riastradh%netbsd.org@localhost>]

Module Name:    src
Committed By:   riastradh
Date:           Sun May 15 16:20:10 UTC 2022

Modified Files:
        src/sys/kern: kern_time.c

Log Message:
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...


To generate a diff of this commit:
cvs rdiff -u -r1.213 -r1.214 src/sys/kern/kern_time.c

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.