Print ACSL Annotations with Frama-C script - annotations

Question

I am learning how to develop a Frama-C plugin. After reading the Frama-C Developer manual and doing the CFG plugin example, I tried to do a basic script that prints all annotations in a C file. I came up with this:
open Cil_types
class print_annot out = object
inherit Visitor.frama_c_inplace
method vstmt_aux s =
let annots = Annotations.code_annot s in
let anleng = List.length annots in
if anleng <= 0 then Format.fprintf out "Empty List\n"
else
Format.fprintf out "Number of Annotations: %d\n" anleng;
List.iter (fun annot -> Format.fprintf out " -> s%d\n" annot.annot_id) annots;
Cil.DoChildren
end
let run () =
let chan = open_out "annots.out" in
let fmt = Format.formatter_of_out_channel chan in
Visitor.visitFramacFileSameGlobals (new print_annot fmt) (Ast.get());
close_out chan
let () = Db.Main.extend run
It always says the list is empty even when the input file has ACSL annotations and never prints the annotations id. What am I doing wrong?
Edit:
An example with the following code:
/*# requires y >= 0;
# ensures \result >= 0;
*/
int g(int y){
int x=0;
if(y>0){
x=100;
x=x+50;
x=x-100;
}else{
x = x - 150;
x=x-100;
x=x+100;
}
return x;
}
void main(){
int a = g(0);
}
And invoking frama-c with:
$ frama-c -load-script annot_script.ml condi.c
Gives the following output:
Empty List
Empty List
Empty List
Empty List
Empty List
Empty List
Empty List
Empty List
Empty List
Empty List
Empty List

Answer 1

In your example, none of the annotations are attached to a statement. The requires and the ensures are part of a function contract and are attached to the function g, not to any statement of g.
An annotation that would be attached to a statement would for instance be /*# assert x == 150; */ after the line x=x+50;.
If I modify condi.c to insert this assertion, then with the same commandline, I get:
Empty List
Empty List
Empty List
Empty List
Number of Annotations: 1
-> s1
Empty List
Empty List
Empty List
Empty List
Empty List
Empty List
Empty List
It seems that your script is working as expected, for a value of “expected” that corresponds to printing annotations attached to statements.