lib: test-base64 - Make sure base64_decode() won't allocate any extra space

I was just considering an optimization where it would, until I realized it
could break some existing code.

diff --git a/src/lib/test-base64.c b/src/lib/test-base64.c
index ce51c39b9a967fea7c5fa86e68f046adabe720cc..3c4abb8926baa6c8c254c95351598b0550ed15a4 100644 (file)
--- a/src/lib/test-base64.c
+++ b/src/lib/test-base64.c
@@ -55,21 +55,31 @@ static void test_base64_decode(void)
                  "hel", -1, 4 },
        };
        string_t *str;
+       buffer_t buf;
        unsigned int i;
        size_t src_pos;
        int ret;
 
        test_begin("base64_decode()");
-       str = t_str_new(256);
        for (i = 0; i < N_ELEMENTS(tests); i++) {
-               str_truncate(str, 0);
+               /* Some of the base64_decode() callers use fixed size buffers.
+                  Use a fixed size buffer here as well to test that
+                  base64_decode() can't allocate any extra space even
+                  temporarily. */
+               size_t max_decoded_size =
+                       MAX_BASE64_DECODED_SIZE(strlen(tests[i].input));
 
+               buffer_create_from_data(&buf, t_malloc0(max_decoded_size),
+                                       max_decoded_size);
+               str = &buf;
                src_pos = 0;
                ret = base64_decode(tests[i].input, strlen(tests[i].input),
                                    &src_pos, str);
 
                test_assert_idx(tests[i].ret == ret, i);
-               test_assert_idx(strcmp(tests[i].output, str_c(str)) == 0, i);
+               test_assert_idx(strlen(tests[i].output) == str_len(str) &&
+                               memcmp(tests[i].output, str_data(str),
+                                      str_len(str)) == 0, i);
                test_assert_idx(src_pos == tests[i].src_pos ||
                                (tests[i].src_pos == UINT_MAX &&
                                 src_pos == strlen(tests[i].input)), i);