utmp.c to chowntty.c. checkutmp() now only uses an existing utmp
entry if the pid matches and ut_line matches with the current tty.
This fixes a possible DOS when entries can be forged in the utmp
file.
* libmisc/chowntty.c, src/login.c, lib/prototypes.h: Remove the
tty argument from chown_tty. chown_tty always changes stdin and
does not need this argument anymore.
booleans.
* libmisc/utmp.c: Add brackets and parenthesis.
* libmisc/utmp.c: Exit with the EXIT_FAILURE status code in case
of failure.
* libmisc/utmp.c: Avoid assignments in comparisons.
* lib/prototypes.h, libmisc/utmp.c: Change setutmp()'s prototype
to return an int because pututline() and pututxline() may fail.
Files with no license use the default 3-clauses BSD license. The copyright
were mostly not recorded; they were updated according to the Changelog.
"Julianne Frances Haugh and contributors" changed to "copyright holders
and contributors".
