[PATCH 1/2] add MOVE_ARRAY
- From
René Scharfe <l.s.r@web.de>
- Date
- Jul 15, 2017, 19:36 UTC
- Message-ID
- <ec78a849-36e4-4b1d-1ad6-46dcc39a1396@web.de>
Similar to COPY_ARRAY (introduced in 60566cbb58), add a safe and convenient helper for moving potentially overlapping ranges of array entries. It infers the element size, multiplies automatically and safely to get the size in bytes, does a basic type safety check by comparing element sizes and unlike memmove(3) it supports NULL pointers iff 0 elements are to be moved.
Also add a semantic patch to demonstrate the helper's intended usage.
Signed-off-by: Rene Scharfe <l.s.r@web.de> --- contrib/coccinelle/array.cocci | 17 +++++++++++++++++ git-compat-util.h | 8 ++++++++ 2 files changed, 25 insertions(+)
diff --git a/contrib/coccinelle/array.cocci b/contrib/coccinelle/array.cocci index 4ba98b7eaf..c61d1ca8dc 100644 --- a/contrib/coccinelle/array.cocci +++ b/contrib/coccinelle/array.cocci @@ -27,6 +27,23 @@ expression n; @@ type T; +T *dst; +T *src; +expression n; +@@ +( +- memmove(dst, src, (n) * sizeof(*dst)); ++ MOVE_ARRAY(dst, src, n); +| +- memmove(dst, src, (n) * sizeof(*src)); ++ MOVE_ARRAY(dst, src, n); +| +- memmove(dst, src, (n) * sizeof(T)); ++ MOVE_ARRAY(dst, src, n); +) + +@@ +type T; T *ptr; expression n; @@ diff --git a/git-compat-util.h b/git-compat-util.h index 047172d173..159f82154a 100644 --- a/git-compat-util.h +++ b/git-compat-util.h @@ -825,6 +825,14 @@ static inline void copy_array(void *dst, const void *src, size_t n, size_t size) memcpy(dst, src, st_mult(size, n)); } +#define MOVE_ARRAY(dst, src, n) move_array((dst), (src), (n), sizeof(*(dst)) + \ + BUILD_ASSERT_OR_ZERO(sizeof(*(dst)) == sizeof(*(src)))) +static inline void move_array(void *dst, const void *src, size_t n, size_t size) +{ + if (n) + memmove(dst, src, st_mult(size, n)); +} + /* * These functions help you allocate structs with flex arrays, and copy * the data directly into the array. For example, if you had:
-- 2.13.3