Merge pull request libgit2#3984 from pks-t/pks/pack-find-offset-race

pack: fix race in pack_entry_find_offset

Author: carlosmn

src/pack.c

@@ -1268,8 +1268,8 @@ static int pack_entry_find_offset(
 	const git_oid *short_oid,
 	size_t len)
 {
-	const uint32_t *level1_ofs = p->index_map.data;
-	const unsigned char *index = p->index_map.data;
+	const uint32_t *level1_ofs;
+	const unsigned char *index;
 	unsigned hi, lo, stride;
 	int pos, found = 0;
 	git_off_t offset;
@@ -1283,11 +1283,11 @@ static int pack_entry_find_offset(
 		if ((error = pack_index_open(p)) < 0)
 			return error;
 		assert(p->index_map.data);
-
-		index = p->index_map.data;
-		level1_ofs = p->index_map.data;
 	}
 
+	index = p->index_map.data;
+	level1_ofs = p->index_map.data;
+
 	if (p->index_version > 1) {
 		level1_ofs += 2;
 		index += 8;