Re: [help-gnubatch] gbch-xq

[Jan Schampera]

John Collins (home) wrote:

> I suppose it could wrap UID switches round every message queue 
> operation. Originally I had it use semaphores as well which would make 
> it even worse.

Yes, that was the basic idea of my statement. More formal:
- program operates with the RUID from the beginning and most of the time 
(process creator user ID/real user ID)
- for GNUBatch API access it uses the SUID (saved UID, at the beginning 
it's the UID of the file owner)

The POSIX rationale for setuid() [1] holds an interesting discussion by 
the way, covering some historical quirks and stuff. Since I'm mostly 
"generation Linux", I can't help much with the portability.

> The messages about the .gnubatch file are probably because you've got a 
> 700 permission home directory and it can't be read with the setuid 
> gnubatch process.

This also can be "solved" using the RUID the same way as for the DISPLAY 
access.


Regards,
Jan


[1] http://www.opengroup.org/onlinepubs/9699919799/functions/setuid.html