This allows an application to only update a password entry if it is
in the state it expects.  Additionally, if the old passwd struct
is specified the new one may have a different pw_name field since
matching is done on the original.  Adapted from FreeBSD.

instead of 16.  E.g. it is now /dev/{p,t}typ[0-9a-zA-z] instead of just
/dev/{p,t}typ[0-9a-f].  This requires that you update MAKEDEV and run:
# cd /dev && ./MAKEDEV pty0 && rm -f [pt]ty[rq]*

ioctl(2), an unprivileged process may allocate a pty and have its owner
and mode set appropriately.  This means that programs such as xterm and
screen no longer need to be setuid.  Programs using the openpty()
function require zero changes and will "just work".
Designed by beck@ and deraadt@; changes by beck@ with cleanup (and
a rewrite of the vnode bits) by art@ and tweaks/bugfixes by me.
Tested by many.

o Round negative numbers correctly
o Do not print fractional valus for byte values
ok ian@ henning@

millert ok

where applicable.

rescinded 22 July 1999.  Proofed by myself and Theo.

- clean up .Xr's

- new sentence, new line

or scaled numbers. fmt_scaled, and the format, based on Ken Stailey's
code for "df -h"; scan_scaled is new. Significantly commented on
and reworked by pjanzen@; other comments from millert@.  OK pjanzen@.

ok deraadt@

now build libraries with propolice enabled.  Without this, existing
binaries (such as ports/packages) that link with any system library
other than libc will fail with an undefined symbol of "___guard"
(__guard on ELF).
Pointed out by markus@ and discussed with deraadt@

that the first char in the line is not NUL after killing comments.

field separators as empty field.  This is not what we want for
whitespace-delimited fields.

o make first arg const since we don't modify it
o use strsep() instead of strtok() as strtok() changes internal state
o add some bounds checking and use strlcat() instead of pointer arithmetic
o ANSI function headers
Originally based on a patch from Lars J. Buitinck but much modified.

some brave soul should look at it.

XXX libraries should not use atexit(3) from within, as program can terminate
with _exit.

o) always close .Bl tags;
o) fix usage of .Xr;
millert@ ok

o) remove extra space in the end of line;
o) remove extra blank lines in the end of file;
o) remove .Pp before .Ss;
o) CAVEAT -> CAVEATS;
o) fix usage of .Fa;
o) <blank-line> -> .Pp;
o) wrap long lines;
millert@ ok

millert@ ok
deraadt@ ok to commit

will be overwritten by subsequent calls; suggested by pjanzen, ok millert

millert@ ok

clobbered by longjmp / vfork instead of the gcc "(void)&foo;" hack.