util: add a global setup option to our munit wrapper

This allows us to handle/manipulate argv and/or pass a userdata to the
tests. Same ELF section approach as we already have with the MUNIT_TEST
macro but this time it's for a global setup.

Note that for the generated __start and __stop section variables we have
to have at least one entry in that section which we do with one
hardcoded (and ignored) one.

src/util-munit.c

@@ -35,6 +35,14 @@
  * __attribute__(section) documentation.
  */
 DECLARE_TEST_SECTION();
+DECLARE_GLOBAL_SETUP_SECTION();
+
+/* If the tests don't use MUNIT_GLOBAL_SETUP the the above has no linkage, so
+ * let's always define a noop internal one.
+ */
+MUNIT_GLOBAL_SETUP(__internal)
+{
+}
 
 int
 munit_tests_run(int argc, char **argv)
@@ -55,6 +63,20 @@ munit_tests_run(int argc, char **argv)
 		tests[idx++] = test;
 	}
 
+	struct munit_setup setup = {
+		.argc = argc,
+		.argv = argv,
+		.userdata = NULL,
+	};
+	size_t setup_count = 0;
+	foreach_setup(s) {
+		if (!streq(s->name, "__internal")) {
+			assert(setup_count == 0); /* Only one setup func per suite */
+			s->func(&setup);
+			++setup_count;
+		}
+	}
+
 	MunitSuite suite = {
 		"",
 		tests,
@@ -67,7 +89,7 @@ munit_tests_run(int argc, char **argv)
 	const struct rlimit corelimit = { 0, 0 };
 	setrlimit(RLIMIT_CORE, &corelimit);
 
-	int rc = munit_suite_main(&suite, NULL, argc, argv);
+	int rc = munit_suite_main(&suite, setup.userdata, setup.argc, setup.argv);
 
 	for (idx = 0; idx < count; idx++)
 		free(tests[idx].name);

src/util-munit.h

@@ -63,6 +63,34 @@ struct test_function {
 	munit_test_func_t func;	/* test function */
 } __attribute__((aligned(16)));
 
+/**
+ * Put at the top of the file somewhere, declares the start/stop for the setup section we need.
+ */
+#define DECLARE_GLOBAL_SETUP_SECTION() \
+	extern const struct global_setup_function __start_setup_functions_section, __stop_setup_functions_section
+
+/**
+ * Helper to loop through each setup function.
+ */
+#define foreach_setup(s_) \
+	for (const struct global_setup_function *s_ = &__start_setup_functions_section; \
+	     s_ < &__stop_setup_functions_section; \
+	     s_++)
+
+struct munit_setup {
+	int argc;
+	char **argv;
+	void *userdata;
+};
+
+typedef void (*munit_setup_func_t)(struct munit_setup *setup);
+
+struct global_setup_function {
+	const char *name; 	 /* function name */
+	munit_setup_func_t func; /* setup function */
+} __attribute__((aligned(16)));
+
+
 /**
  * Defines a struct test_function in a custom ELF section that we can then
  * loop over in munit_tests_run() to extract the tests. This removes the
@@ -79,5 +107,25 @@ __attribute__((section("test_functions_section"))) = {				\
 };										\
 static MunitResult _func(const MunitParameter params[], void *user_data)
 
+/**
+ * Defines a struct global_setup_function in a custom ELF section that we can
+ * then find in munit_tests_run() to do setup based on argv and/or pass userdata
+ * to the tests.
+ *
+ * Note that there can only be one of those per process.
+ *
+ * The argument to this function is a pointer to a struct munit_setup that has
+ * argc/argv and a (initially NULL) userdata pointer.
+ */
+#define MUNIT_GLOBAL_SETUP(_func) \
+static void _func(struct munit_setup *setup); 					\
+static const struct global_setup_function _setup_##_func			\
+__attribute__((used))								\
+__attribute__((section("setup_functions_section"))) = {				\
+	.name = #_func,								\
+	.func = _func,								\
+};										\
+static void _func(struct munit_setup *setup) 					\
+
 int
 munit_tests_run(int argc, char **argv);