More bbsh design notes.

Rob Landley rob at landley.net
Thu Sep 14 18:34:58 UTC 2006


On Thursday 14 September 2006 3:46 am, Ian Oliver wrote:
> > Shells do goto?  (Checks susv3 "Shell command language" page...  Search 
> > for "goto" not found.  Checks bash man page...  Does not include the 
> > word "goto".)  Apparently not.
> 
> Hmmm, OK, probably a good thing. As long as return is implemented for 
functions, which 
> it doesn't seem to be in hush (unless I'm wrong about this too!)

I can make shell functions return in bbsh, sure.  I vaguely suspect it's in 
SUSv3 once I read that far...

> > And the shell returning 0 would mean it wouldn't have to call ifconfig, 
route, 
> > or write resolve.conf.  It could veto it by returning 1 (or do it itself), 
> > and the dhcp client wouldn't do this until _after_ the script returned, so 
if 
> > you wanted to add firewall rules before the interface went up, you could.
> 
> There are also all the other cases where udhcpc calls the external 
script/program to 
> consider. But I guess it's all just using ifconfig/route to set things up 
and rip them 
> down.

What a dhcp client fundamentally _does_ is grab and defend an address from a 
server, and set the address, gateway, and nameserver information related to 
that server.

Currently, udhcpc needs an external script to actually do this.  I don't like 
that.

> > And yeah, it could be a CONFIG option.
> 
> BTW, did I mention that on this here embedded box in front of me, the Korean 
engineers 
> who hacked all the calls to ifconfig, route, etc. into udhcpc also got it to 
directly 
> write the IP address and netmask into known places in memory? So, I'll be 
needing 
> config options for where to write the values, and I'll need them endian 
swapping. :)

A) No, you won't.

B) Can we have the patch?  (Busybox is GPL, doo dah, doo dah...)

Rob
-- 
Never bet against the cheap plastic solution.



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