roundup
(3)round up in steps
#include <sys/param.h> roundup(x, step);
LIBRARY
DESCRIPTION
This macro rounds x to the nearest multiple of step that is not less than x.
It is typically used for rounding up a pointer to align it or increasing a buffer to be allocated.
This API is not designed to be generic, and doesn't work in some cases that are not important for the typical use cases described above. See CAVEATS.