hex: make wraparound of the index into ring-buffer explicit

diff --git a/git-compat-util.h b/git-compat-util.h
index 2c949983dc8313d78b6b45e635f7efb5d61e9dec..aec8cc98909237a17afde7809372389000a35a7e 100644 (file)
--- a/git-compat-util.h
+++ b/git-compat-util.h
@@ -798,6 +798,14 @@ extern FILE *fopen_for_writing(const char *path);
 #define ALLOC_ARRAY(x, alloc) (x) = xmalloc(st_mult(sizeof(*(x)), (alloc)))
 #define REALLOC_ARRAY(x, alloc) (x) = xrealloc((x), st_mult(sizeof(*(x)), (alloc)))
 
+#define COPY_ARRAY(dst, src, n) copy_array((dst), (src), (n), sizeof(*(dst)) + \
+       BUILD_ASSERT_OR_ZERO(sizeof(*(dst)) == sizeof(*(src))))
+static inline void copy_array(void *dst, const void *src, size_t n, size_t size)
+{
+       if (n)
+               memcpy(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: