r249685, r249686:

r249668:

Use procstat_getprocs(3) for retrieving thread information instead of
direct sysctl calls.

r249669:

Use more generic procstat_getvmmap(3) for retrieving VM layout of a process.

r249671:

Use procstat_getgroups(3) for retrieving groups information instead of
direct sysctl.

r249673:

Use procstat_getumask(3) for retrieving umaks information instead of
direct sysctl.

r249675:

Use procstat_getrlimit(3) for retrieving rlimit information instead of
direct sysctl calls.

r249678:

Use libprocstat(3) when retrieving binary information for a process.

r249680:

Use libprocstat(3) to retrieve process command line arguments and
environment variables.

r249683:

Use libprocstat(3) to retrieve ELF auxiliary vector.

r249685:

Use procstat_getkstack(3) for retrieving process kernel stacks
instead of direct sysctl calls.

r249686:

Make use of newly added libprocstat(3) ability to extract procstat
info from a process core file.

So now one can run procstat(1) on a process core e.g. to get a list of
files opened by a process when it crashed:

root@lisa:/ # procstat -f /root/vi.core
  PID COMM               FD T V FLAGS     REF  OFFSET PRO NAME
  658 vi               text v r r--------   -       - -   /usr/bin/vi
  658 vi               ctty v c rw-------   -       - -   /dev/pts/0
  658 vi                cwd v d r--------   -       - -   /root
  658 vi               root v d r--------   -       - -   /
  658 vi                  0 v c rw-------  11    3208 -   /dev/pts/0
  658 vi                  1 v c rw-------  11    3208 -   /dev/pts/0
  658 vi                  2 v c rw-------  11    3208 -   /dev/pts/0
  658 vi                  3 v r r----n-l-   1       0 -   /tmp/vi.0AYKz3Lps7
  658 vi                  4 v r rw-------   1       0 -   /var/tmp/vi.recover/vi.GaGYsz
  658 vi                  5 v r rw-------   1       0 -   -

PR:		kern/173723
Suggested by:	jhb

  file and processes information retrieval from the running kernel via sysctl
  in the form of new library, libprocstat.  The library also supports KVM backend
  for analyzing memory crash dumps.  Both procstat(1) and fstat(1) utilities have
  been modified to take advantage of the library (as the bonus point the fstat(1)
  utility no longer need superuser privileges to operate), and the procstat(1)
  utility is now able to display information from memory dumps as well.

  The newly introduced fuser(1) utility also uses this library and able to operate
  via sysctl and kvm backends.

  The library is by no means complete (e.g. KVM backend is missing vnode name
  resolution routines, and there're no manpages for the library itself) so I
  plan to improve it further.  I'm commiting it so it will get wider exposure
  and review.

  We won't be able to MFC this work as it relies on changes in HEAD, which
  was introduced some time ago, that break kernel ABI.  OTOH we may be able
  to merge the library with KVM backend if we really need it there.

Discussed with:	rwatson