[Cocci] Finding and replacing a struct inside another struct

Julia Lawall julia.lawall at lip6.fr
Wed Aug 22 12:52:24 CEST 2018



On Wed, 22 Aug 2018, Luca Coelho wrote:

> Hi,
>
> I need some help again. :)
>
> I have a struct (cfg80211_crypto_settings) that contains a new element
> that I want to substitute for a function call
> (cfg_control_port_over_nl80211).  But this struct appears inside
> another struct.
>
> So I tried this:
>
> First I try to find a struct that contains the struct I want (with the
> @parent_child@ rule):
>
> @parent_child@
> identifier child;
> identifier parent_type;
> @@
> struct parent_type
> {
> ...
> struct cfg80211_crypto_settings child;
> ...
> }
>
> And then I try to match usage of the parent struct that I found:
>
> @@
> identifier parent_child.child;
> identifier parent_child.parent_type;
> identifier p;
> @@
> struct parent_type *p;
> <...
> -p.child.control_over_nl80211F
> +cfg_control_port_over_nl80211(&p.child)
> ...>
>
>
> But I'm getting some cryptic errors:
>
> struct parent_type*
> warning: line 715: req, previously declared as a metavariable, is used as an identifier
> warning: line 732: req, previously declared as a metavariable, is used as an identifier
> warning: line 740: req, previously declared as a metavariable, is used as an identifier
> warning: line 912: should name_assign_type be a metavariable?
> warning: line 918: params, previously declared as a metavariable, is used as an identifier
> warning: line 933: params, previously declared as a metavariable, is used as an identifier
> warning: line 941: should reqid be a metavariable?
> line 1175: non-structure type in field ref
> struct parent_type*
> warning: line 715: req, previously declared as a metavariable, is used as an identifier
> warning: line 732: req, previously declared as a metavariable, is used as an identifier
> warning: line 740: req, previously declared as a metavariable, is used as an identifier
> warning: line 912: should name_assign_type be a metavariable?
> warning: line 918: params, previously declared as a metavariable, is used as an identifier
> warning: line 933: params, previously declared as a metavariable, is used as an identifier
> warning: line 941: should reqid be a metavariable?
> line 1175: non-structure type in field ref
>
>
> Does anyone know if there is a proper way to do is?

You already found the solution for the actual errors.  But it is good to
pay attention to the warnings too.  For "should name_assign_type be a
metavariable?" is it concerned because an explicit identifier name is used
as something other than the name of a function or the name of a field.  If
you really want to only match assign_type, then you can make a
metavariable-like declaration symbol assign_type; that basically means
that you know what you are doing and don't want to see the warning any
more.

julia


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