illumos gate

All of these man pages try to be helpful and list the two members of struct iovec. E.g., from read(2):

       The iovec structure contains the following members:

         caddr_t   iov_base;
         int       iov_len;

iov_len used to be int a really long time ago. You can still see it in libbc:

usr/src/lib/libbc/inc/include/sys/uio.h:        int     iov_len;

All other definitions in the gate use some type which is the same size as a pointer (i.e., size_t or long).