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From: lyndon@cs.athabascau.ca (Lyndon Nerenberg)
Newsgroups: comp.unix.questions
Subject: Re: long userids
Message-ID: <612@aupair.cs.athabascau.ca>
Date: 17 Jan 91 22:25:21 GMT
References: <70DsV1w163w@wvus.wciu.edu> <epeterso.663955198@houligan>
Organization: Athabasca University
Lines: 26

>| Are there any deadly implications to using long (>8 chars) userid names
>| in /etc/passwd?

Yes. A lot of Unix implementations have the following line in <stdio.h>:

	#define L_cuserid       9

This constant defines the size of a char array large enough to hold
a login name plus the terminating NULL. Some (not a lot, but some)
software uses this constant to size buffers. If the code doesn't check
for (strlen(pw->pw_name) < L_cuserid) you're going to have problems.

Not all Unix releases document this constant. Under SunOS it's mentioned
in the cuserid(3) man page.

I would strongly advise that you limit login names to a maximum of
eight characters. There are better ways to achieve what you're setting
out to do than by overloading the semantics of login names.



-- 
    Lyndon Nerenberg  VE6BBM / Computing Services / Athabasca University
        {alberta,cbmvax,mips}!atha!lyndon || lyndon@cs.athabascau.ca
                    Packet: ve6bbm@ve6mc [.ab.can.na]
      The only thing open about OSF is their mouth.  --Chuck Musciano