notes: document length of fanout path with a constant

We know that a fanned-out sha1 in a notes tree cannot be
more than "aa/bb/cc/...", and we have an assert() to confirm
that. But let's factor out that length into a constant so we
can be sure it is used consistently. And even though we
assert() earlier, let's replace a strcpy with xsnprintf, so
it is clear to a reader that all cases are covered.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/notes.c b/notes.c
index eacd2a61daf9b4133e81a936340abc63c1078a48..db77922130b4f7df6ab72122206a76d6c580faac 100644 (file)
--- a/notes.c
+++ b/notes.c
@@ -539,6 +539,9 @@ static unsigned char determine_fanout(struct int_node *tree, unsigned char n,
        return fanout + 1;
 }
 
+/* hex SHA1 + 19 * '/' + NUL */
+#define FANOUT_PATH_MAX 40 + 19 + 1
+
 static void construct_path_with_fanout(const unsigned char *sha1,
                unsigned char fanout, char *path)
 {
@@ -551,7 +554,7 @@ static void construct_path_with_fanout(const unsigned char *sha1,
                path[i++] = '/';
                fanout--;
        }
-       strcpy(path + i, hex_sha1 + j);
+       xsnprintf(path + i, FANOUT_PATH_MAX - i, "%s", hex_sha1 + j);
 }
 
 static int for_each_note_helper(struct notes_tree *t, struct int_node *tree,
@@ -562,7 +565,7 @@ static int for_each_note_helper(struct notes_tree *t, struct int_node *tree,
        void *p;
        int ret = 0;
        struct leaf_node *l;
-       static char path[40 + 19 + 1];  /* hex SHA1 + 19 * '/' + NUL */
+       static char path[FANOUT_PATH_MAX];
 
        fanout = determine_fanout(tree, n, fanout);
        for (i = 0; i < 16; i++) {
@@ -595,7 +598,7 @@ static int for_each_note_helper(struct notes_tree *t, struct int_node *tree,
                                /* invoke callback with subtree */
                                unsigned int path_len =
                                        l->key_sha1[19] * 2 + fanout;
-                               assert(path_len < 40 + 19);
+                               assert(path_len < FANOUT_PATH_MAX - 1);
                                construct_path_with_fanout(l->key_sha1, fanout,
                                                           path);
                                /* Create trailing slash, if needed */