Re: file handling with fopen() and fclose()

[John Breen <locutus borg apana org au>]

On Wed, 2002-02-27 at 13:04, Valdis Kletnieks vt edu wrote:
> On Wed, 27 Feb 2002 12:53:53 +0800, John Breen <locutus borg apana org au>  said:
> 
> > fp=fopen("/etc/shadow");
> 
> SYNOPSIS
>        #include <stdio.h>
> 
>        FILE *fopen(const char *path, const char *mode);

sorry, the code is actually 

fp = fopen("/etc/shadow", "r");

> 
> 
> Might want to pass a mode there, it would SIGSEGV pretty quickly otherwise.
> 
> Also, note that /etc/shadow is probably only readable by root - which means
> that you're in for *LOADS* of security fun (you get to run set-UID, or
> run as root, or figure out how to use PAM on systems that support it).

the code's been compiled, and then

chgrp shadow executable
chmod g+s executable

which means that the app will be run if by a member of the shadow group,
which is the group on /etc/shadow, and has read-access to /etc/shadow.  

> 
> Personally, I think PAM is your best bet if you can use it.

I hadn't thought of PAM (and don't know how to use it in the context of
this app. anyway :( )

the thing is, it works ok for me in a console version, just won't work
in GTK+ - it seems to get to the first line using the file after fopen()
and close the app down totally.

oh well, time to climb the ol' learning curve again.  shame, 'cause i
wanted to get this bit out of the way quickly - the rest of the app
should be pretty easy after that...

cheers,

John Breen