lib: rework how we "override" assert()

The previous method, using zassert.h and hoping nothing includes
assert.h (which, on glibc at least, just does "#undef assert" and puts
its own definition in...) was fragile - and actually broke undetected.

Just provide our own assert.h and control overriding by putting it in a
separate directory to add to the include path (or not.)

Signed-off-by: David Lamparter <equinox@opensourcerouting.org>

1 files changed, 64 insertions, 0 deletions

diff --git a/tests/lib/test_assert.c b/tests/lib/test_assert.c
new file mode 100644
index 0000000000..8f1f4f2bad
--- /dev/null
+++ b/tests/lib/test_assert.c
@@ -0,0 +1,64 @@
+/*
+ * Quick test for assert()
+ * Copyright (C) 2021  David Lamparter for NetDEF, Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; see the file COPYING; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+/* make sure this works with assert.h & nothing else.  also check the include
+ * shadowing, we don't want to pick up system assert.h
+ */
+#include <assert.h>
+
+__attribute__((noinline))
+void func_for_bt(int number)
+{
+	assert(number > 2);
+	assertf(number > 3, "(A) the number was %d", number);
+}
+
+#include <zebra.h>
+#include "lib/zlog.h"
+#include "lib/thread.h"
+#include "lib/sigevent.h"
+
+int main(int argc, char **argv)
+{
+	int number = 10;
+	struct thread_master *master;
+
+	zlog_aux_init("NONE: ", LOG_DEBUG);
+
+	if (argc > 1)
+		number = atoi(argv[1]);
+
+	assert(number > 0);
+	assertf(number > 1, "(B) the number was %d", number);
+
+	/* set up SIGABRT handler */
+	master = thread_master_create("test");
+	signal_init(master, 0, NULL);
+
+	func_for_bt(number);
+	assert(number > 4);
+	assertf(number > 5, "(C) the number was %d", number);
+
+	assertf(number > 10, "(D) the number was %d", number);
+	return 0;
+}