From: Behan Webster <behanw@xxxxxxxxxxxxxxxxxx>
Add a macro which replaces the use of a Variable Length Array In Struct (VLAIS)
with a C99 compliant equivalent. This macro instead allocates the appropriate
amount of memory using an char array.
The new code can be compiled with both gcc and clang.
struct shash_desc contains a flexible array member member ctx declared with
CRYPTO_MINALIGN_ATTR, so sizeof(struct shash_desc) aligns the beginning
of the array declared after struct shash_desc with long long.
No trailing padding is required because it is not a struct type that can
be used in an array.
The CRYPTO_MINALIGN_ATTR is required so that desc is aligned with long long
as would be the case for a struct containing a member with
CRYPTO_MINALIGN_ATTR.
If you want to get to the ctx at the end of the shash_desc as before you can do
so using shash_desc_ctx(shash)
Signed-off-by: Behan Webster <behanw@xxxxxxxxxxxxxxxxxx>
Reviewed-by: Mark Charlebois <charlebm@xxxxxxxxx>
Acked-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Cc: Michał Mirosław <mirqus@xxxxxxxxx>
---
include/crypto/hash.h | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/include/crypto/hash.h b/include/crypto/hash.h
index a391955..74b13ec 100644
--- a/include/crypto/hash.h
+++ b/include/crypto/hash.h
@@ -58,6 +58,11 @@ struct shash_desc {
void *__ctx[] CRYPTO_MINALIGN_ATTR;
};
+#define SHASH_DESC_ON_STACK(shash, ctx) \
+ char __##shash##_desc[sizeof(struct shash_desc) + \
+ crypto_shash_descsize(ctx)] CRYPTO_MINALIGN_ATTR; \
+ struct shash_desc *shash = (struct shash_desc *)__##shash##_desc
+
struct shash_alg {
int (*init)(struct shash_desc *desc);
int (*update)(struct shash_desc *desc, const u8 *data,
--
1.9.1
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