coccinelle

[Tobin C. Harding]

On Tue, Mar 14, 2017 at 08:26:08AM +0000, Nicholas Mc Guire wrote:
> On Tue, Mar 14, 2017 at 06:21:06PM +1100, Tobin C. Harding wrote:
> > Attempting to do transform using Coccinelle
> > 
> > if (foo != 0) {
> >    ...
> > 
> > ->
> > 
> > if (foo) {
> >    ...
> > 
> > Coccinelle script attempt does not work
> > 
> > @@ expression x; @@
> > (
> > - x != 0
> > + x
> > )
> 
> I think you do not need the () here as you only are providing one semanntic patch
> the only thing that was missing is the virtual rule - so using this simple spatch
> file works for me 
> 
> <snip>
> virtual patch
> 
> @tonull@
> expression x;
> @@
> 
> - x != 0
> + x
> <snip>
> 
> hofrat at debian01:~/git/linux-next$ spatch --sp-file x.cocci --dir kernel/ | more
> init_defs_builtins: /usr/local/lib/coccinelle/standard.h
> no inferred keywords
> HANDLING: kernel/sched/cpudeadline.c
> diff = 
> HANDLING: kernel/sched/swait.c
> diff -u -p a/sched/cpudeadline.c b/sched/cpudeadline.c
> --- a/sched/cpudeadline.c
> +++ b/sched/cpudeadline.c
> @@ -80,7 +80,7 @@ static void cpudl_heapify_up(struct cpud
>         int orig_cpu = cp->elements[idx].cpu;
>         u64 orig_dl = cp->elements[idx].dl;
>  
> -       if (idx == 0)
> +       if (!idx)
>                 return;
> ....
> 
> 
> > 
> > `spatch --parse-cocci script.cocci` appears to pass. A similar script
> > worked correctly
> > 
> > @@ expression x; @@
> > (
> > - x == 0
> > + !x
> > )
> 
> likewise
> 
> <snip>
> virtual patch
> 
> @tontnull@
> expression x;
> @@
> 
> - x == 0
> + !x
> <snip>
> 
> Using: spatch --version
> spatch version 1.0.6-00033-g23cca0a compiled with OCaml version 4.0
> .0
> Flags passed to the configure script: [none]
> Python scripting support: yes
> Syntax of regular expresssions: PCRE
> 
> 
> > 
> > I have read various papers and tutorials to no avail. I have tried
> > various other versions also with no success.
> > 
> > Any pointers most appreciated.
> >
> first you might want to read through the myriads of examples that
> come with coccinelle in the kernel:
> scripts/coccinelle/*
> Documentation/dev-tools/coccinelle.rst
> 
> as well as the documentation in coccinelle repository:
> URL: https://github.com/coccinelle/coccinelle 
> 
> And for specific technologies like semantic patches it is best to signeup
> to the coccinelle mailing list and send such questions to
>  Cocci at systeme.lip6.fr
> archive at: https://systeme.lip6.fr/mailman/listinfo/cocci
> 
> thx!
> hofrat

thanks Hofrat, awesome.