jdanekrh commented on a change in pull request #684: WIP: (Work In Progress)
DISPATCH-1568: using doctest
URL: https://github.com/apache/qpid-dispatch/pull/684#discussion_r380620641
##########
File path: src/router_core/terminus.c
##########
@@ -75,25 +76,47 @@ void qdr_terminus_free(qdr_terminus_t *term)
free_qdr_terminus_t(term);
}
+#ifdef TESTING
+__attribute__((weak))
+int mocked_vsnprintf(char *str, size_t size, const char *format, ...){return
-1;}
+#endif
// DISPATCH-1461: snprintf() is evil - it returns >= size on overflow. This
// wrapper will never return >= size, even if truncated. This makes it safe to
// do pointer & length arithmetic without overflowing the destination buffer in
// qdr_terminus_format()
-//
-static inline int safe_snprintf(char *str, size_t size, const char *format,
...)
-{
+// not static to be used unit-tested
+size_t safe_snprintf(char *str, size_t size, const char *format, ...) {
+ // max size allowed must be INT_MAX (since vsnprintf reutrns an int)
+ if (size == 0 || size > INT_MAX) {
+ //TODO log a warning somewhere?
+ return 0;
+ }
+ int max_possible_return_value = (int)(size - 1);
va_list ap;
va_start(ap, format);
+#ifdef TESTING
+ int rc = mocked_vsnprintf(str, size, format, ap);
Review comment:
I was thinking about this and I don't like this much. I understand that in
C, there isn't many options to replace vsnprintf calls in tests, but this
"pollutes" the production code a lot.
In the C++ world, they seem to call these techniques "seams", [1] [2] [3].
Dispatch already uses the linker seam in two places, to mock
`qd_server_timeout` and `qd_timer_now`.
I generally like using the linker better, it seems cleaner to me.
[1] http://www.informit.com/articles/article.aspx?p=359417&seqNum=3
[2] https://accu.org/index.php/journals/1927 Refactoring Towards Seams in C++
[3] https://cute-test.com/guides/mocking-with-cute/
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