read-cache: check range before dereferencing an array element

Before accessing an array element at a given index, we should make sure
that the index is within the desired bounds, not afterwards, otherwise
it may not make sense to even access the array element in the first
place.

Pointed out by CodeQL's `cpp/offset-use-before-range-check` rule.

Signed-off-by: Johannes Schindelin <[email protected]>

Author: dscho

read-cache.c

@@ -2686,8 +2686,8 @@ static int ce_write_entry(struct hashfile *f, struct cache_entry *ce,
 		int common, to_remove, prefix_size;
 		unsigned char to_remove_vi[16];
 		for (common = 0;
-		     (ce->name[common] &&
-		      common < previous_name->len &&
+		     (common < previous_name->len &&
+		      ce->name[common] &&
 		      ce->name[common] == previous_name->buf[common]);
 		     common++)
 			; /* still matching */