xref: /kernel/linux/linux-6.6/scripts/coccinelle/null/badzero.cocci

// SPDX-License-Identifier: GPL-2.0-only
/// Compare pointer-typed values to NULL rather than 0
///
//# This makes an effort to choose between !x and x == NULL.  !x is used
//# if it has previously been used with the function used to initialize x.
//# This relies on type information.  More type information can be obtained
//# using the option -all_includes and the option -I to specify an
//# include path.
//
// Confidence: High
// Copyright: (C) 2012 Julia Lawall, INRIA/LIP6.
// Copyright: (C) 2012 Gilles Muller, INRIA/LiP6.
// URL: https://coccinelle.gitlabpages.inria.fr/website
// Requires: 1.0.0
// Options:

virtual patch
virtual context
virtual org
virtual report

@initialize:ocaml@
@@
let negtable = Hashtbl.create 101

@depends on patch@
expression *E;
identifier f;
@@

(
  (E = f(...)) ==
- 0
+ NULL
|
  (E = f(...)) !=
- 0
+ NULL
|
- 0
+ NULL
  == (E = f(...))
|
- 0
+ NULL
  != (E = f(...))
)


@t1 depends on !patch@
expression *E;
identifier f;
position p;
@@

(
  (E = f(...)) ==
* 0@p
|
  (E = f(...)) !=
* 0@p
|
* 0@p
  == (E = f(...))
|
* 0@p
  != (E = f(...))
)

@script:python depends on org@
p << t1.p;
@@

coccilib.org.print_todo(p[0], "WARNING comparing pointer to 0")

@script:python depends on report@
p << t1.p;
@@

coccilib.report.print_report(p[0], "WARNING comparing pointer to 0")

// Tests of returned values

@s@
identifier f;
expression E,E1;
@@

 E = f(...)
 ... when != E = E1
 !E

@script:ocaml depends on s@
f << s.f;
@@

try let _ = Hashtbl.find negtable f in ()
with Not_found -> Hashtbl.add negtable f ()

@ r disable is_zero,isnt_zero exists @
expression *E;
identifier f;
@@

E = f(...)
...
(E == 0
|E != 0
|0 == E
|0 != E
)

@script:ocaml@
f << r.f;
@@

try let _ = Hashtbl.find negtable f in ()
with Not_found -> include_match false

// This rule may lead to inconsistent path problems, if E is defined in two
// places
@ depends on patch disable is_zero,isnt_zero @
expression *E;
expression E1;
identifier r.f;
@@

E = f(...)
<...
(
- E == 0
+ !E
|
- E != 0
+ E
|
- 0 == E
+ !E
|
- 0 != E
+ E
)
...>
?E = E1

@t2 depends on !patch disable is_zero,isnt_zero @
expression *E;
expression E1;
identifier r.f;
position p1;
position p2;
@@

E = f(...)
<...
(
* E == 0@p1
|
* E != 0@p2
|
* 0@p1 == E
|
* 0@p1 != E
)
...>
?E = E1

@script:python depends on org@
p << t2.p1;
@@

coccilib.org.print_todo(p[0], "WARNING comparing pointer to 0, suggest !E")

@script:python depends on org@
p << t2.p2;
@@

coccilib.org.print_todo(p[0], "WARNING comparing pointer to 0")

@script:python depends on report@
p << t2.p1;
@@

coccilib.report.print_report(p[0], "WARNING comparing pointer to 0, suggest !E")

@script:python depends on report@
p << t2.p2;
@@

coccilib.report.print_report(p[0], "WARNING comparing pointer to 0")

@ depends on patch disable is_zero,isnt_zero @
expression *E;
@@

(
  E ==
- 0
+ NULL
|
  E !=
- 0
+ NULL
|
- 0
+ NULL
  == E
|
- 0
+ NULL
  != E
)

@ t3 depends on !patch disable is_zero,isnt_zero @
expression *E;
position p;
@@

(
* E == 0@p
|
* E != 0@p
|
* 0@p == E
|
* 0@p != E
)

@script:python depends on org@
p << t3.p;
@@

coccilib.org.print_todo(p[0], "WARNING comparing pointer to 0")

@script:python depends on report@
p << t3.p;
@@

coccilib.report.print_report(p[0], "WARNING comparing pointer to 0")