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>
René Scharfe committed
Jul 15, 2017 at 21:36 UTC
578398071e45d296c3dc1de10acdbc15365e763f
2 files changed
+25
contrib/coccinelle/array.cocci
+17
@@ -25,6 +25,23 @@ expression n;
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- memcpy(dst, src, n * sizeof(T));
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+ COPY_ARRAY(dst, src, n);
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+@@
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+type T;
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+T *dst;
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+T *src;
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+expression n;
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+@@
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+(
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+- memmove(dst, src, (n) * sizeof(*dst));
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++ MOVE_ARRAY(dst, src, n);
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+|
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+- memmove(dst, src, (n) * sizeof(*src));
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++ MOVE_ARRAY(dst, src, n);
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+|
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+- memmove(dst, src, (n) * sizeof(T));
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++ MOVE_ARRAY(dst, src, n);
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+)
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+
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@@
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type T;
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T *ptr;
git-compat-util.h
+8
@@ -825,6 +825,14 @@ static inline void copy_array(void *dst, const void *src, size_t n, size_t size)
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memcpy(dst, src, st_mult(size, n));
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}
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+#define MOVE_ARRAY(dst, src, n) move_array((dst), (src), (n), sizeof(*(dst)) + \
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+ BUILD_ASSERT_OR_ZERO(sizeof(*(dst)) == sizeof(*(src))))
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+static inline void move_array(void *dst, const void *src, size_t n, size_t size)
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+{
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+ if (n)
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+ memmove(dst, src, st_mult(size, n));
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+}
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+
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/*
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* These functions help you allocate structs with flex arrays, and copy
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* the data directly into the array. For example, if you had: