diff options
| author | Rusty Russell | 2007-05-06 14:51:05 -0700 |
|---|---|---|
| committer | Linus Torvalds | 2007-05-07 12:13:00 -0700 |
| commit | c5e631cf65f4d6875efcd571275436f2964a8b48 (patch) | |
| tree | 1aee9d61560ee369b4a2f077a79e37ab868a4b2d /arch | |
| parent | f34d9d2dcb7f17b64124841345b23adc0843e7a5 (diff) | |
ARRAY_SIZE: check for type
We can use a gcc extension to ensure that ARRAY_SIZE() is handed an array,
not a pointer. This is especially important when code is changed from a
fixed array to a pointer. I assume the Intel compiler doesn't support
__builtin_types_compatible_p.
[jdike@addtoit.com: uml: update UML definition of ARRAY_SIZE]
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/um/include/user_util.h | 15 |
1 files changed, 13 insertions, 2 deletions
diff --git a/arch/um/include/user_util.h b/arch/um/include/user_util.h index 73ffea1829fc..b52bc4084830 100644 --- a/arch/um/include/user_util.h +++ b/arch/um/include/user_util.h @@ -8,8 +8,19 @@ #include "sysdep/ptrace.h" -/* Copied from kernel.h */ -#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0])) +/* Copied from kernel.h and compiler-gcc.h */ + +/* Force a compilation error if condition is true, but also produce a + result (of value 0 and type size_t), so the expression can be used + e.g. in a structure initializer (or where-ever else comma expressions + aren't permitted). */ +#define BUILD_BUG_ON_ZERO(e) (sizeof(char[1 - 2 * !!(e)]) - 1) + +/* &a[0] degrades to a pointer: a different type from an array */ +#define __must_be_array(a) \ + BUILD_BUG_ON_ZERO(__builtin_types_compatible_p(typeof(a), typeof(&a[0]))) + +#define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]) + __must_be_array(arr)) #define CATCH_EINTR(expr) while ((errno = 0, ((expr) < 0)) && (errno == EINTR)) |