[U-Boot] [PATCH] Handle environment variables like commands

[Wolfgang Denk]

Dear Stefano,

In message <48F5DBB7.4070307 at babic.homelinux.org> you wrote:
> Wolfgang Denk wrote:
> 
> > Good catch. Yes, this must be prevented. Any variable named "builtin"
> > must be ignored here - i. e. we should issue  an  erro  when  someone
> > tries  a  "setenv", and ignore this variable explicitly (just in case
> > someone sneaks this into the default environment,  or  uses  un-fixed
> > Linux tools to create such a variable).
> 
> I know, I wanted to know which is the preferred method to avoid that.
> One way is to avoid to set the variable, as you suggest.
> The other way is never execute a variable with the name "builtin" in the
> command interpreter: "setenv builtin <something>" remains possible but
> "builtin <command>" calls always the U-Boot commands.

We should do both: avoid that the variable gets set, and raise  error
messages  (both  in setenv() and in the fw_setenv Linux tool), but we
should also be defensive and never execute  it  if  we  run  into  it
(which  could  for  example  happen  if we're being poresented an old
environment where some user defined such a variable).

Best regards,

Wolfgang Denk

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