shorten_unambiguous_ref: use xsnprintf

We convert the ref_rev_parse_rules array into scanf formats
on the fly, and use snprintf() to write into each string. We
should have enough memory to hold everything because of the
earlier total_len computation. Let's use xsnprintf() to
give runtime confirmation that this is the case, and to make
it easy for people auditing the code to know there's no
truncation bug.

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

diff --git a/refs.c b/refs.c
index 20ba82b4343ff2ef72cea32deec8a8d7fbd6def7..bd7ac72aa71a933d4232407d4517a6a47aaa3a45 100644 (file)
--- a/refs.c
+++ b/refs.c
@@ -1132,8 +1132,8 @@ char *shorten_unambiguous_ref(const char *refname, int strict)
                for (i = 0; i < nr_rules; i++) {
                        assert(offset < total_len);
                        scanf_fmts[i] = (char *)&scanf_fmts[nr_rules] + offset;
-                       offset += snprintf(scanf_fmts[i], total_len - offset,
-                                          ref_rev_parse_rules[i], 2, "%s") + 1;
+                       offset += xsnprintf(scanf_fmts[i], total_len - offset,
+                                           ref_rev_parse_rules[i], 2, "%s") + 1;
                }
        }