Re: weird utmp/perl problem

[Roderick Schertler <roderick@argon.org>]

On 23 Apr 1998 04:56:12 -0700, Guy Maor <maor@ece.utexas.edu> said:
> Roderick Schertler <roderick@argon.org> writes:
>> 
>> getlogin() is supposed to work even if isatty(0) is false.  It is bug
>> #17528.
> 
> How can it?  If isatty() is false, then ttyname(3) is null, so
> getlogin() can't look up the entry in utmp.

It's supposed to open /dev/tty instead of using stdin.  This is the way
it works on all the systems I could get people to check for me, which
are Linux with libc5, AIX 4.2, Solaris 2.4, Solaris 2.5, DG/UX 4.11 and
FreeBSD 2.2.2-R.

Here's an example (from dgux):

    # who | grep 'pts/[45] '
    roderick   pts/4        Apr 23 02:01
    ccost      pts/5        Apr 23 09:11
    # tty
    /dev/pts/4
    # cat getlogin
    #!/usr/bin/perl -lw
    $l = getlogin;
    print defined($l) ? $l : 'undef';
    # ./getlogin
    roderick
    # ./getlogin < /dev/pts/5
    roderick
    # ./getlogin < /dev/null
    roderick
    # setsid ./getlogin
    undef
    # 

-- 
Roderick Schertler
roderick@argon.org


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