From 45ccef87b3cc0ab09ec5fd1186aa0b33298ee8d4 Mon Sep 17 00:00:00 2001
From: =?utf8?q?Ren=C3=A9=20Scharfe?= <l.s.r@web.de>
Date: Sun, 25 Sep 2016 09:24:03 +0200
Subject: [PATCH] use COPY_ARRAY

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 <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 builtin/mv.c                   |  2 +-
 commit.c                       |  2 +-
 contrib/coccinelle/array.cocci | 26 ++++++++++++++++++++++++++
 pack-revindex.c                |  2 +-
 pathspec.c                     |  3 +--
 split-index.c                  |  6 ++----
 6 files changed, 32 insertions(+), 9 deletions(-)
 create mode 100644 contrib/coccinelle/array.cocci

diff --git a/builtin/mv.c b/builtin/mv.c
index a2014266b..c13e49bf4 100644
--- 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
index 2a90e3751..9d3d7119e 100644
--- 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
new file mode 100644
index 000000000..2d7f25d99
--- /dev/null
+++ 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
index 96d51c346..6bc7c9403 100644
--- 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
index 24e0dd523..49a53607b 100644
--- 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
index 3c75d4b9c..35da55365 100644
--- 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;
-- 
2.11.0