use COPY_ARRAY

rscharfe · gitster · commit 45ccef87b3cc · 2016-09-25T16:44:13.000-07:00
Add a semantic patch for converting certain calls of memcpy(3) to
COPY_ARRAY() and apply that transformation to the code base.  The result
is
 shorter and safer code.  For now only consider calls where source and
destination have the same type, or in other words: easy cases.

Signed-off-by: Rene Scharfe &lt;l.s.r@web.de&gt;
Signed-off-by: Junio C Hamano &lt;gitster@pobox.com&gt;
diff --git a/builtin/mv.c b/builtin/mv.c
@@ -26,7 +26,7 @@ static const char **internal_copy_pathspec(const char *prefix,
 	int i;
 	const char **result;
 	ALLOC_ARRAY(result, count + 1);
-	memcpy(result, pathspec, count * sizeof(const char *));
+	COPY_ARRAY(result, pathspec, count);
 	result[count] = NULL;
 	for (i = 0; i < count; i++) {
 		int length = strlen(result[i]);
diff --git a/commit.c b/commit.c
@@ -931,7 +931,7 @@ static int remove_redundant(struct commit **array, int cnt)
 	}
 
 	/* Now collect the result */
-	memcpy(work, array, sizeof(*array) * cnt);
+	COPY_ARRAY(work, array, cnt);
 	for (i = filled = 0; i < cnt; i++)
 		if (!redundant[i])
 			array[filled++] = work[i];
diff --git a/contrib/coccinelle/array.cocci b/contrib/coccinelle/array.cocci
@@ -0,0 +1,26 @@
+@@
+type T;
+T *dst;
+T *src;
+expression n;
+@@
+- memcpy(dst, src, n * sizeof(*dst));
++ COPY_ARRAY(dst, src, n);
+
+@@
+type T;
+T *dst;
+T *src;
+expression n;
+@@
+- memcpy(dst, src, n * sizeof(*src));
++ COPY_ARRAY(dst, src, n);
+
+@@
+type T;
+T *dst;
+T *src;
+expression n;
+@@
+- memcpy(dst, src, n * sizeof(T));
++ COPY_ARRAY(dst, src, n);
diff --git a/pack-revindex.c b/pack-revindex.c
@@ -107,7 +107,7 @@ static void sort_revindex(struct revindex_entry *entries, unsigned n, off_t max)
 	 * we have to move it back from the temporary storage.
 	 */
 	if (from != entries)
-		memcpy(entries, tmp, n * sizeof(*entries));
+		COPY_ARRAY(entries, tmp, n);
 	free(tmp);
 	free(pos);
 
diff --git a/pathspec.c b/pathspec.c
@@ -485,8 +485,7 @@ void copy_pathspec(struct pathspec *dst, const struct pathspec *src)
 {
 	*dst = *src;
 	ALLOC_ARRAY(dst->items, dst->nr);
-	memcpy(dst->items, src->items,
-	       sizeof(struct pathspec_item) * dst->nr);
+	COPY_ARRAY(dst->items, src->items, dst->nr);
 }
 
 void clear_pathspec(struct pathspec *pathspec)
diff --git a/split-index.c b/split-index.c
@@ -83,8 +83,7 @@ void move_cache_to_base_index(struct index_state *istate)
 	si->base->timestamp = istate->timestamp;
 	ALLOC_GROW(si->base->cache, istate->cache_nr, si->base->cache_alloc);
 	si->base->cache_nr = istate->cache_nr;
-	memcpy(si->base->cache, istate->cache,
-	       sizeof(*istate->cache) * istate->cache_nr);
+	COPY_ARRAY(si->base->cache, istate->cache, istate->cache_nr);
 	mark_base_index_entries(si->base);
 	for (i = 0; i < si->base->cache_nr; i++)
 		si->base->cache[i]->ce_flags &= ~CE_UPDATE_IN_BASE;
@@ -141,8 +140,7 @@ void merge_base_index(struct index_state *istate)
 	istate->cache	    = NULL;
 	istate->cache_alloc = 0;
 	ALLOC_GROW(istate->cache, istate->cache_nr, istate->cache_alloc);
-	memcpy(istate->cache, si->base->cache,
-	       sizeof(*istate->cache) * istate->cache_nr);
+	COPY_ARRAY(istate->cache, si->base->cache, istate->cache_nr);
 
 	si->nr_deletions = 0;
 	si->nr_replacements = 0;

Original file line number	Diff line number	Diff line change
`@@ -931,7 +931,7 @@ static int remove_redundant(struct commit **array, int cnt)`
`931`	`931`	`}`
`932`	`932`
`933`	`933`	`/* Now collect the result */`
`934`		`- memcpy(work, array, sizeof(array) cnt);`
	`934`	`+ COPY_ARRAY(work, array, cnt);`
`935`	`935`	`for (i = filled = 0; i < cnt; i++)`
`936`	`936`	`if (!redundant[i])`
`937`	`937`	`array[filled++] = work[i];`
Original file line number	Diff line number	Diff line change
`@@ -485,8 +485,7 @@ void copy_pathspec(struct pathspec dst, const struct pathspec src)`
`485`	`485`	`{`
`486`	`486`	`dst = src;`
`487`	`487`	`ALLOC_ARRAY(dst->items, dst->nr);`
`488`		`- memcpy(dst->items, src->items,`
`489`		`- sizeof(struct pathspec_item) * dst->nr);`
	`488`	`+ COPY_ARRAY(dst->items, src->items, dst->nr);`
`490`	`489`	`}`
`491`	`490`
`492`	`491`	`void clear_pathspec(struct pathspec *pathspec)`