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[PATCH 2/2] use MOVE_ARRAY




Simplify the code for moving members inside of an array and make it more
robust by using the helper macro MOVE_ARRAY.  It calculates the size
based on the specified number of elements for us and supports NULL
pointers when that number is zero.  Raw memmove(3) calls with NULL can
cause the compiler to (over-eagerly) optimize out later NULL checks.

This patch was generated with contrib/coccinelle/array.cocci and spatch
(Coccinelle).

Signed-off-by: Rene Scharfe <l.s.r@xxxxxx>
---
Downside: The one in builtin/ls-files.c papers over a report by UBSan
for the case of istate->cache being NULL.  Technically we still try to
add pos to NULL if pruning an empty index, but we won't see it anymore.
Will send a separate patch.

 builtin/ls-files.c     | 3 +--
 builtin/merge.c        | 2 +-
 builtin/pack-objects.c | 5 ++---
 cache-tree.c           | 5 ++---
 commit.c               | 5 ++---
 notes-merge.c          | 3 +--
 read-cache.c           | 5 ++---
 reflog-walk.c          | 7 +++----
 string-list.c          | 8 +++-----
 9 files changed, 17 insertions(+), 26 deletions(-)

diff --git a/builtin/ls-files.c b/builtin/ls-files.c
index b8514a0029..dc4a6aa3d9 100644
--- a/builtin/ls-files.c
+++ b/builtin/ls-files.c
@@ -378,8 +378,7 @@ static void prune_index(struct index_state *istate,
 		}
 		last = next;
 	}
-	memmove(istate->cache, istate->cache + pos,
-		(last - pos) * sizeof(struct cache_entry *));
+	MOVE_ARRAY(istate->cache, istate->cache + pos, last - pos);
 	istate->cache_nr = last - pos;
 }
 
diff --git a/builtin/merge.c b/builtin/merge.c
index 900bafdb45..d5797b8fe7 100644
--- a/builtin/merge.c
+++ b/builtin/merge.c
@@ -537,7 +537,7 @@ static void parse_branch_merge_options(char *bmo)
 		die(_("Bad branch.%s.mergeoptions string: %s"), branch,
 		    split_cmdline_strerror(argc));
 	REALLOC_ARRAY(argv, argc + 2);
-	memmove(argv + 1, argv, sizeof(*argv) * (argc + 1));
+	MOVE_ARRAY(argv + 1, argv, argc + 1);
 	argc++;
 	argv[0] = "branch.*.mergeoptions";
 	parse_options(argc, argv, NULL, builtin_merge_options,
diff --git a/builtin/pack-objects.c b/builtin/pack-objects.c
index f4a8441fe9..e730b415bf 100644
--- a/builtin/pack-objects.c
+++ b/builtin/pack-objects.c
@@ -1298,9 +1298,8 @@ static int check_pbase_path(unsigned hash)
 		   done_pbase_paths_alloc);
 	done_pbase_paths_num++;
 	if (pos < done_pbase_paths_num)
-		memmove(done_pbase_paths + pos + 1,
-			done_pbase_paths + pos,
-			(done_pbase_paths_num - pos - 1) * sizeof(unsigned));
+		MOVE_ARRAY(done_pbase_paths + pos + 1, done_pbase_paths + pos,
+			   done_pbase_paths_num - pos - 1);
 	done_pbase_paths[pos] = hash;
 	return 0;
 }
diff --git a/cache-tree.c b/cache-tree.c
index ec23d8c03d..2440d1dc89 100644
--- a/cache-tree.c
+++ b/cache-tree.c
@@ -131,9 +131,8 @@ static int do_invalidate_path(struct cache_tree *it, const char *path)
 			 * move 4 and 5 up one place (2 entries)
 			 * 2 = 6 - 3 - 1 = subtree_nr - pos - 1
 			 */
-			memmove(it->down+pos, it->down+pos+1,
-				sizeof(struct cache_tree_sub *) *
-				(it->subtree_nr - pos - 1));
+			MOVE_ARRAY(it->down + pos, it->down + pos + 1,
+				   it->subtree_nr - pos - 1);
 			it->subtree_nr--;
 		}
 		return 1;
diff --git a/commit.c b/commit.c
index cbfd689939..d3150d6270 100644
--- a/commit.c
+++ b/commit.c
@@ -223,9 +223,8 @@ int unregister_shallow(const struct object_id *oid)
 	if (pos < 0)
 		return -1;
 	if (pos + 1 < commit_graft_nr)
-		memmove(commit_graft + pos, commit_graft + pos + 1,
-				sizeof(struct commit_graft *)
-				* (commit_graft_nr - pos - 1));
+		MOVE_ARRAY(commit_graft + pos, commit_graft + pos + 1,
+			   commit_graft_nr - pos - 1);
 	commit_graft_nr--;
 	return 0;
 }
diff --git a/notes-merge.c b/notes-merge.c
index 70e3fbeefb..c12b354f10 100644
--- a/notes-merge.c
+++ b/notes-merge.c
@@ -99,8 +99,7 @@ static struct notes_merge_pair *find_notes_merge_pair_pos(
 	else {
 		*occupied = 0;
 		if (insert_new && i < len) {
-			memmove(list + i + 1, list + i,
-				(len - i) * sizeof(struct notes_merge_pair));
+			MOVE_ARRAY(list + i + 1, list + i, len - i);
 			memset(list + i, 0, sizeof(struct notes_merge_pair));
 		}
 	}
diff --git a/read-cache.c b/read-cache.c
index 2121b6e7bb..acfb028f48 100644
--- a/read-cache.c
+++ b/read-cache.c
@@ -515,9 +515,8 @@ int remove_index_entry_at(struct index_state *istate, int pos)
 	istate->cache_nr--;
 	if (pos >= istate->cache_nr)
 		return 0;
-	memmove(istate->cache + pos,
-		istate->cache + pos + 1,
-		(istate->cache_nr - pos) * sizeof(struct cache_entry *));
+	MOVE_ARRAY(istate->cache + pos, istate->cache + pos + 1,
+		   istate->cache_nr - pos);
 	return 1;
 }
 
diff --git a/reflog-walk.c b/reflog-walk.c
index 081f89b70d..81bca2ed23 100644
--- a/reflog-walk.c
+++ b/reflog-walk.c
@@ -111,10 +111,9 @@ static struct commit_info *get_commit_info(struct commit *commit,
 			struct commit_info *result = &lifo->items[i];
 			if (pop) {
 				if (i + 1 < lifo->nr)
-					memmove(lifo->items + i,
-						lifo->items + i + 1,
-						(lifo->nr - i) *
-						sizeof(struct commit_info));
+					MOVE_ARRAY(lifo->items + i,
+						   lifo->items + i + 1,
+						   lifo->nr - i);
 				lifo->nr--;
 			}
 			return result;
diff --git a/string-list.c b/string-list.c
index c650500c6e..806b4c8723 100644
--- a/string-list.c
+++ b/string-list.c
@@ -43,9 +43,8 @@ static int add_entry(int insert_at, struct string_list *list, const char *string
 
 	ALLOC_GROW(list->items, list->nr+1, list->alloc);
 	if (index < list->nr)
-		memmove(list->items + index + 1, list->items + index,
-				(list->nr - index)
-				* sizeof(struct string_list_item));
+		MOVE_ARRAY(list->items + index + 1, list->items + index,
+			   list->nr - index);
 	list->items[index].string = list->strdup_strings ?
 		xstrdup(string) : (char *)string;
 	list->items[index].util = NULL;
@@ -77,8 +76,7 @@ void string_list_remove(struct string_list *list, const char *string,
 			free(list->items[i].util);
 
 		list->nr--;
-		memmove(list->items + i, list->items + i + 1,
-			(list->nr - i) * sizeof(struct string_list_item));
+		MOVE_ARRAY(list->items + i, list->items + i + 1, list->nr - i);
 	}
 }
 
-- 
2.13.3