Coccinelle: Add api/memdup.cocci

Use kmemdup rather than duplicating its implementation
Signed-off-by: Nicolas Palix <npalix@diku.dk>
Signed-off-by: Julia Lawall <julia@diku.dk>
Signed-off-by: Michal Marek <mmarek@suse.cz>

scripts/coccinelle/api/memdup.cocci

+/// Use kmemdup rather than duplicating its implementation
+///
+// Confidence: High
+// Copyright: (C) 2010 Nicolas Palix, DIKU.  GPLv2.
+// Copyright: (C) 2010 Julia Lawall, DIKU.  GPLv2.
+// Copyright: (C) 2010 Gilles Muller, INRIA/LiP6.  GPLv2.
+// URL: http://coccinelle.lip6.fr/
+// Comments:
+// Options: -no_includes -include_headers
+
+virtual patch
+
+@r1@
+expression from,to;
+expression flag;
+position p;
+@@
+
+   to = \(kmalloc@p\|kzalloc@p\)(strlen(from) + 1,flag);
+
+@r2@
+expression x,from,to;
+expression flag,E1;
+position p;
+@@
+
+    x = strlen(from) + 1;
+    ... when != \( x = E1 \| from = E1 \)
+    to = \(kmalloc@p\|kzalloc@p\)(x,flag);
+
+@@
+expression from,to,size,flag;
+position p != {r1.p,r2.p};
+statement S;
+@@
+
+-  to = \(kmalloc@p\|kzalloc@p\)(size,flag);
++  to = kmemdup(from,size,flag);
+   if (to==NULL || ...) S
+-  memcpy(to, from, size);