Re: [RFC PATCH] SELinux: Cleanup the secid/secctx conversion functions

[Paul Moore <paul.moore@hp.com>]

On Friday 29 February 2008 9:13:46 am Stephen Smalley wrote:
> On Fri, 2008-02-29 at 08:54 -0500, Stephen Smalley wrote:
> > On Thu, 2008-02-28 at 16:41 -0500, Paul Moore wrote:
> > > While looking at the SELinux secid/secctx conversion functions I
> > > realized they could probably do with a little cleanup to reduce the
> > > amount of code and make better use of existing string processing
> > > functions in the kernel.  Making use of the kernel's existing string
> > > processing functions is a good idea as many architectures have
> > > specialized/optimized routines which should be an improvement over the
> > > generic code in the SELinux security server. ---
> > >
> > >  security/selinux/ss/mls.c      |   61 +++++--------
> > >  security/selinux/ss/mls.h      |    3 -
> > >  security/selinux/ss/services.c |  194
> > > ++++++++++++++++------------------------ 3 files changed, 103
> > > insertions(+), 155 deletions(-)
> >
> > The snippet below looks like a step backward rather than an improvement
> > - single sprintf replaced by series of strcat calls.  That can't be more
> > efficient.
>
> Hmm...well, maybe I'm wrong (after looking at the implementations).

That is exactly why I decided the multiple strcpy()/strcat() calls would be 
faster.  Our formatting needs here are pretty simple and the kernel's 
sprintf() implementation looks very involved versus strcpy()/strcat().

> Pity that Linux doesn't have stpcpy (as in glibc) - that is much nicer
> than a series of strcat's since it returns the end pointer and doesn't
> require finding the end of string each time.

That would be nice here.  However, I think at least moving away from sprintf() 
should yield an advantage.

-- 
paul moore
linux security @ hp

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