It's a familiar pattern: some code uses ARRAY_SIZE, then refactoring changes the argument from an array to a pointer to a dynamically allocated buffer. Code keeps compiling but any ARRAY_SIZE calls now return the size of the pointer divided by element size.
Let's add build time checks to ARRAY_SIZE before we allow more of these in the code-base. Signed-off-by: Michael S. Tsirkin <m...@redhat.com> Reviewed-by: Markus Armbruster <arm...@redhat.com> Reviewed-by: Eric Blake <ebl...@redhat.com> --- include/qemu/osdep.h | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/include/qemu/osdep.h b/include/qemu/osdep.h index 689f253..56c9e22 100644 --- a/include/qemu/osdep.h +++ b/include/qemu/osdep.h @@ -198,8 +198,15 @@ extern int daemon(int, int); #define DIV_ROUND_UP(n,d) (((n) + (d) - 1) / (d)) #endif +/* + * &(x)[0] is always a pointer - if it's same type as x then the argument is a + * pointer, not an array. + */ +#define QEMU_IS_ARRAY(x) (!__builtin_types_compatible_p(typeof(x), \ + typeof(&(x)[0]))) #ifndef ARRAY_SIZE -#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0])) +#define ARRAY_SIZE(x) ((sizeof(x) / sizeof((x)[0])) + \ + QEMU_BUILD_BUG_ON_ZERO(!QEMU_IS_ARRAY(x))) #endif int qemu_daemon(int nochdir, int noclose); -- MST
