[PATCH] scripts/coccinelle: semantic patch converting 0 test to null test

From: Julia Lawall <Julia.Lawall@lip6.fr>

Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>



diff --git a/scripts/coccinelle/null/badzero.cocci b/scripts/coccinelle/null/badzero.cocci
new file mode 100644
index 0000000..5cb7e96
/dev/null
+++ b/scripts/coccinelle/null/badzero.cocci
@@ -0,0 +1,237 @@
+/// 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. GPLv2.
+// Copyright: (C) 2012 Gilles Muller, INRIA/LiP6. GPLv2.
+// URL: http://coccinelle.lip6.fr/
+// Comments:
+// 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")

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