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add MOVE_ARRAY 

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>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
René Scharfe 2017-07-15 21:36:20 +02:00 committed by Junio C Hamano
parent f3da2b79be
commit 578398071e
2 changed files with 25 additions and 0 deletions
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17
contrib/coccinelle/array.cocci
View File

@ -25,6 +25,23 @@ expression n;
- memcpy(dst, src, n * sizeof(T));
+ COPY_ARRAY(dst, src, 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;

8
git-compat-util.h
View File

@ -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: