Re: Changing argv[0] under Linux.

[jw schultz]

On Tue, Jan 14, 2003 at 11:46:44PM -0500, Mark Mielke wrote:
> On Tue, Jan 14, 2003 at 03:11:41PM -0800, Bob Miller wrote:
> > On Tue, Jan 14, 2003 at 03:04:18PM -0800, Bob Miller wrote:
> > > Or you can copy your all your args and env to a temporary place and
> > > then re-build your args and env with the new argv[0] in it's place.
> > > But you must be carefull that your new argv[0] length plus the 
> > > length of all remaining args, envp and pointers is not greater than
> > > the system defined size for this space.
> > In thinking about this more this will NOT work.  The user stack starts
> > right after your envp.  So, writing more info there would blow away
> > your stack.
> 
> I can smell the next hack... memmove() the stack down to make room... :-)

No need.  You can memcpy the environment.  See setenv(3),
putenv(3) and related library routines.

Once you've parsed your argv who cares if you overwrite it,
put a double NULL at the end, set argc = 1 and argv[1] =
NULL.  If argv[argc] - argv[0] + strlen(argv[argc] is
shorter than what you overwrite it with you won't even need
to relocate the environment block if you wish to preserve
that.  Just don't leave any loose ends to confuse /proc and
the ps utils.

-- 
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	J.W. Schultz            Pegasystems Technologies
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