cocci: Add script to enforce the malloc usage as per cairo/CODING_STYLE

cairo CODING_STYLE guidelines require checking the argument of malloc
for overflow and provide some utilities for common usage patterns such
as (a*b), (a*b*c) and (a*b+c).

Automatically replace malloc invocation of these expressions with the
overflow-safe version.

1 files changed, 27 insertions, 0 deletions

diff --git a/malloc-coding-style.cocci b/malloc-coding-style.cocci
new file mode 100644
index 0000000..90cd4da
--- /dev/null
+++ b/malloc-coding-style.cocci
@@ -0,0 +1,27 @@
+// Apply the malloc replacements suggested in CODING_STYLE
+//
+// Cairo has some utility macros to check that the expressions used to
+// compute the argument of a malloc() call do not overflow.
+// CODING_STYLE indicates the replacements that should be done in
+// order to use these functions correctly.
+
+// malloc (n * size + k) => _cairo_malloc_ab_plus_c (n, size, k)
+@@
+expression n,size,k;
+@@
+-malloc ((n) * (size) + (k))
++_cairo_malloc_ab_plus_c (n, size, k)
+
+// malloc (a * b * size) => _cairo_malloc_abc (a, b, size)
+@@
+expression a,b,size;
+@@
+-malloc ((a) * (b) * (size))
++_cairo_malloc3 (a, b, size)
+
+// malloc (n * size) => _cairo_malloc_ab (n, size)
+@@
+expression n,size;
+@@
+-malloc ((n) * (size))
++_cairo_malloc_ab (n, size)