[Cocci] how to use Coccinelle

[Cocci] how to use Coccinelle

[藤本太希]

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Hello.

I am a student of Kochi University of Technology in Japan.

I have asked a question before.

Thank you for all your help on that occasion.

This time I have two questions about how to use Coccinelle.



This is the first question.

Identifiers can be declared in scripts.

Can you declare the type in same way?

For example, there are the following programs.

———————————————————

@script:python pre@

alloc;

@@

coccinelle.alloc = “malloc”


@ rule1 @

type T={int, double};

identifier v, pre.alloc;

@@

T v;

…

alloc(...)


@ rule2 @

type T={int, double};

identifier v, pre.alloc;

@@

T v;

… when != alloc(…)

———————————————————

In these two rules there is T of type with the same restriction.

Can you declare this like alloc?

Do you have to declare in each rule?



Next is the second question.

In the previous answer you said

“Coccinelle rather focuses on the case where variables are all defined at
the top of a function”.

Do you mean that we can not distinguish between the same name variables?

For example, there are the following programs.

———————————————————

—c-program—

void foo() {

  int a;

  {

    int a;

    hoge(a);

  }

}


—cocci—

@rule@

identifier v;

type T;

@@

T v;

…

hoge(v);

———————————————————

matched first a and second a．

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Re: [Cocci] how to use Coccinelle

[Julia Lawall]

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On Fri, 14 Dec 2018, 藤本太希 wrote:

>
> Hello. 
>
> I am a student of Kochi University of Technology in Japan.
>
> I have asked a question before.
>
> Thank you for all your help on that occasion.
>
> This time I have two questions about how to use Coccinelle.
>
>
>
> This is the first question.
>
> Identifiers can be declared in scripts.
>
> Can you declare the type in same way?
>
> For example, there are the following programs.
>
> ———————————————————
>
> @script:python pre@
>
> alloc;
>
> @@
>
> coccinelle.alloc = “malloc”
>
>
> @ rule1 @
>
> type T={int, double};
>
> identifier v, pre.alloc;
>
> @@
>
> T v;
>
> …
>
> alloc(...)
>
>
> @ rule2 @
>
> type T={int, double};
>
> identifier v, pre.alloc;
>
> @@
>
> T v;
>
> … when != alloc(…)
>
> ———————————————————
>
> In these two rules there is T of type with the same restriction.
>
> Can you declare this like alloc?
>
> Do you have to declare in each rule?

I think that you can say

type T = {r1.type1, r1.type2};

In your python rule, though, you should say eg

coccinelle.type1 = make_type("int")

It is necessary to make the list of possible types in each rule.  If you
said type rule1.T; in rule2, that would only be the specific binding of T
chosen in rule1.


>
>
>
> Next is the second question.
>
> In the previous answer you said
>
> “Coccinelle rather focuses on the case where variables are all defined at the top of a function”.
>
> Do you mean that we can not distinguish between the same name variables?
>
> For example, there are the following programs.
>
> ———————————————————
>
> —c-program—
>
> void foo() {
>
>   int a;
>
>   {
>
>     int a;
>
>     hoge(a);
>
>   }
>
> }
>
>
> —cocci—
>
> @rule@
>
> identifier v;
>
> type T;
>
> @@
>
> T v;
>
> …
>
> hoge(v);
>
> ———————————————————
>
> matched first a and second a．

An identifier is just a name.  It has no notion of scope.  If you want to
be sure that the second one is not matched, then you should put

T v;
... when != T1 v;
hoge(v);

julia

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