free ref string returned by dwim_ref

A call to "dwim_ref(name, len, flags, &ref)" will allocate a
new string in "ref" to return the exact ref we found. We do
not consistently free it in all code paths, leading to small
leaks. The worst is in get_sha1_basic, which may be called
many times (e.g., by "cat-file --batch"), though it is
relatively unlikely, as it only triggers on a bogus reflog
specification.

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

builtin/rev-parse.c

@@ -150,6 +150,7 @@ static void show_rev(int type, const unsigned char *sha1, const char *name)
 				error("refname '%s' is ambiguous", name);
 				break;
 			}
+			free(full);
 		} else {
 			show_with_type(type, name);
 		}

builtin/show-branch.c

@@ -779,6 +779,7 @@ int cmd_show_branch(int ac, const char **av, const char *prefix)
 			sprintf(nth_desc, "%s@{%d}", *av, base+i);
 			append_ref(nth_desc, sha1, 1);
 		}
+		free(ref);
 	}
 	else if (all_heads + all_remotes)
 		snarf_refs(all_heads, all_remotes);

sha1_name.c

@@ -540,8 +540,10 @@ static int get_sha1_basic(const char *str, int len, unsigned char *sha1)
 			char *tmp = xstrndup(str + at + 2, reflog_len);
 			at_time = approxidate_careful(tmp, &errors);
 			free(tmp);
-			if (errors)
+			if (errors) {
+				free(real_ref);
 				return -1;
+			}
 		}
 		if (read_ref_at(real_ref, at_time, nth, sha1, NULL,
 				&co_time, &co_tz, &co_cnt)) {