MFC r288963:

Now that we own the code, use arc4random(3) unconditionally
and remove the corresponding HAVE_ARC4RANDOM conditions.

MFC r274898:

Fix the following -Werror warnings from clang 3.5.0, while building
usr.sbin/rtadvd:

usr.sbin/rtadvd/rtadvd.c:1291:7: error: taking the absolute value of unsigned type 'unsigned int' has no effect [-Werror,-Wabsolute-value]
abs(preferred_time - pfx->pfx_pltimeexpire) > rai->rai_clockskew) {
^
usr.sbin/rtadvd/rtadvd.c:1291:7: note: remove the call to 'abs' since unsigned values cannot be negative
abs(preferred_time - pfx->pfx_pltimeexpire) > rai->rai_clockskew) {
^~~
usr.sbin/rtadvd/rtadvd.c:1324:7: error: taking the absolute value of unsigned type 'unsigned int' has no effect [-Werror,-Wabsolute-value]
abs(valid_time - pfx->pfx_vltimeexpire) > rai->rai_clockskew) {
^
usr.sbin/rtadvd/rtadvd.c:1324:7: note: remove the call to 'abs' since unsigned values cannot be negative
abs(valid_time - pfx->pfx_vltimeexpire) > rai->rai_clockskew) {
^~~
2 errors generated.

These warnings occur because both preferred_time and pfx_pltimeexpire
are uint32_t's, so the subtraction expression is also unsigned, and
calling abs() is a no-op.

However, the intention was to look at the absolute difference between
the two unsigned quantities. Introduce a small static function to
clarify what we're doing, and call that instead.

Reviewed by: hrs
Differential Revision: https://reviews.freebsd.org/D1197

MFC r274898:

Fix the following -Werror warnings from clang 3.5.0, while building
usr.sbin/rtadvd:

usr.sbin/rtadvd/rtadvd.c:1291:7: error: taking the absolute value of unsigned type 'unsigned int' has no effect [-Werror,-Wabsolute-value]
abs(preferred_time - pfx->pfx_pltimeexpire) > rai->rai_clockskew) {
^
usr.sbin/rtadvd/rtadvd.c:1291:7: note: remove the call to 'abs' since unsigned values cannot be negative
abs(preferred_time - pfx->pfx_pltimeexpire) > rai->rai_clockskew) {
^~~
usr.sbin/rtadvd/rtadvd.c:1324:7: error: taking the absolute value of unsigned type 'unsigned int' has no effect [-Werror,-Wabsolute-value]
abs(valid_time - pfx->pfx_vltimeexpire) > rai->rai_clockskew) {
^
usr.sbin/rtadvd/rtadvd.c:1324:7: note: remove the call to 'abs' since unsigned values cannot be negative
abs(valid_time - pfx->pfx_vltimeexpire) > rai->rai_clockskew) {
^~~
2 errors generated.

These warnings occur because both preferred_time and pfx_pltimeexpire
are uint32_t's, so the subtraction expression is also unsigned, and
calling abs() is a no-op.

However, the intention was to look at the absolute difference between
the two unsigned quantities. Introduce a small static function to
clarify what we're doing, and call that instead.

Reviewed by: hrs
Differential Revision: https://reviews.freebsd.org/D1197