[Cocci] Simple replacement of an expression of given type?

[Cocci] Simple replacement of an expression of given type?

[Rusty Russell]

Hi!

        In my current project, I moved a field from a structure
(struct block) into another network-endian structure.  I used the
following patch.cocci to do the fixups:

        @ rule1 @
        struct block *b;
        @@
        
        - b->blocknum
        + le32_to_cpu(b->hdr->depth)

It got 99%, but it missed the two cases where b was actually in another
structure, ie. "te->block->blocknum".

I *think* this is because I want to substitute any expression of type
struct block *, rather than only identifiers?

But I couldn't understand the documentation enough to do this :(

Clues appreciated!
Rusty.

[Cocci] Simple replacement of an expression of given type?

[Lars-Peter Clausen]

On 06/21/2014 01:38 AM, Rusty Russell wrote:
> Hi!
>
>          In my current project, I moved a field from a structure
> (struct block) into another network-endian structure.  I used the
> following patch.cocci to do the fixups:
>
>          @ rule1 @
>          struct block *b;
>          @@
>
>          - b->blocknum
>          + le32_to_cpu(b->hdr->depth)
>
> It got 99%, but it missed the two cases where b was actually in another
> structure, ie. "te->block->blocknum".
>
> I *think* this is because I want to substitute any expression of type
> struct block *, rather than only identifiers?
>
> But I couldn't understand the documentation enough to do this :(

This should work. But by default coccinelle does not parse global headers, 
so if the struct for te is defined in a global header it won't know that 
te->block is of type 'struct block *'. If that is the case try to run it 
with --all-includes

- Lars

[Cocci] Simple replacement of an expression of given type?

[Julia Lawall]

On Sat, 21 Jun 2014, Rusty Russell wrote:

> Hi!
> 
>         In my current project, I moved a field from a structure
> (struct block) into another network-endian structure.  I used the
> following patch.cocci to do the fixups:
> 
>         @ rule1 @
>         struct block *b;
>         @@
>         
>         - b->blocknum
>         + le32_to_cpu(b->hdr->depth)
> 
> It got 99%, but it missed the two cases where b was actually in another
> structure, ie. "te->block->blocknum".
> 
> I *think* this is because I want to substitute any expression of type
> struct block *, rather than only identifiers?
> 
> But I couldn't understand the documentation enough to do this :(

You are already working on expressions.  The problem is that sometimes 
Coccinelle doesn't know what is the type of te->block.  To give it the 
most possible amount of informations, you can give the options

--recursive-includes --relax-include-path

The first means that it will take into account include files that are 
referenced from other include files rather than just those referenced 
directly in the C file.  The second means that if it doesn't find xyz.h in 
the include path but it does find exactly one xyz.h somewhere else in the 
source tree, then it will use that xyz.h, since it has to be the right 
one.

This will probably take more time than it is taking now, because it has to 
parse more code.  You may want to use the option --use-cache so that it 
will cache already parsed code.

julia

[Cocci] Simple replacement of an expression of given type?

[Rusty Russell]

Julia Lawall <julia.lawall@lip6.fr> writes:
> On Sat, 21 Jun 2014, Rusty Russell wrote:
>
>> Hi!
>> 
>>         In my current project, I moved a field from a structure
>> (struct block) into another network-endian structure.  I used the
>> following patch.cocci to do the fixups:
>> 
>>         @ rule1 @
>>         struct block *b;
>>         @@
>>         
>>         - b->blocknum
>>         + le32_to_cpu(b->hdr->depth)
>> 
>> It got 99%, but it missed the two cases where b was actually in another
>> structure, ie. "te->block->blocknum".
>> 
>> I *think* this is because I want to substitute any expression of type
>> struct block *, rather than only identifiers?
>> 
>> But I couldn't understand the documentation enough to do this :(
>
> You are already working on expressions.  The problem is that sometimes 
> Coccinelle doesn't know what is the type of te->block.  To give it the 
> most possible amount of informations, you can give the options
>
> --recursive-includes --relax-include-path

Ah, thanks for the explanation, and indeed, that worked perfectly.

And thanks Julia and Lars for your quick responses!

Cheers,
Rusty.