transport_anonymize_url: use xstrfmt

This function uses xcalloc and two memcpy calls to
concatenate two strings. We can do this as an xstrfmt
one-liner, and then it is more clear that we are allocating
the correct amount of memory.

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

Author: peff

transport.c

@@ -1350,7 +1350,7 @@ int transport_disconnect(struct transport *transport)
  */
 char *transport_anonymize_url(const char *url)
 {
-	char *anon_url, *scheme_prefix, *anon_part;
+	char *scheme_prefix, *anon_part;
 	size_t anon_len, prefix_len = 0;
 
 	anon_part = strchr(url, '@');
@@ -1384,10 +1384,8 @@ char *transport_anonymize_url(const char *url)
 			goto literal_copy;
 		prefix_len = scheme_prefix - url + 3;
 	}
-	anon_url = xcalloc(1, 1 + prefix_len + anon_len);
-	memcpy(anon_url, url, prefix_len);
-	memcpy(anon_url + prefix_len, anon_part, anon_len);
-	return anon_url;
+	return xstrfmt("%.*s%.*s", (int)prefix_len, url,
+		       (int)anon_len, anon_part);
 literal_copy:
 	return xstrdup(url);
 }