MFC 198411:

MFC 198411:
- Fix several off-by-one errors when using MAXCOMLEN.  The p_comm[] and
  td_name[] arrays are actually MAXCOMLEN + 1 in size and a few places that
  created shadow copies of these arrays were just using MAXCOMLEN.
- Prefer using sizeof() of an array type to explicit constants for the
  array length in a few places.
- Ensure that all of p_comm[] and td_name[] is always zero'd during
  execve() to guard against any possible information leaks.  Previously
  trailing garbage in p_comm[] could be leaked to userland in ktrace
  record headers via td_name[].

git-svn-id: svn://svn.freebsd.org/base/stable/8@202764 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f