tests: add fuzzing to visitor tests

Perform input tests on random data.

Improvement to code coverage for qapi/string-input-visitor.c
is about 3 percentage points.

Signed-off-by: Blue Swirl <blauwirbel@gmail.com>

tests/test-string-input-visitor.c

@@ -165,6 +165,53 @@ static void test_visitor_in_enum(TestInputVisitorData *data,
     data->siv = NULL;
 }
 
+/* Try to crash the visitors */
+static void test_visitor_in_fuzz(TestInputVisitorData *data,
+                                 const void *unused)
+{
+    int64_t ires;
+    bool bres;
+    double nres;
+    char *sres;
+    EnumOne eres;
+    Error *errp = NULL;
+    Visitor *v;
+    unsigned int i;
+    char buf[10000];
+
+    for (i = 0; i < 100; i++) {
+        unsigned int j;
+
+        j = g_test_rand_int_range(0, sizeof(buf) - 1);
+
+        buf[j] = '\0';
+
+        if (j != 0) {
+            for (j--; j != 0; j--) {
+                buf[j - 1] = (char)g_test_rand_int_range(0, 256);
+            }
+        }
+
+        v = visitor_input_test_init(data, buf);
+        visit_type_int(v, &ires, NULL, &errp);
+
+        v = visitor_input_test_init(data, buf);
+        visit_type_bool(v, &bres, NULL, &errp);
+        visitor_input_teardown(data, NULL);
+
+        v = visitor_input_test_init(data, buf);
+        visit_type_number(v, &nres, NULL, &errp);
+
+        v = visitor_input_test_init(data, buf);
+        visit_type_str(v, &sres, NULL, &errp);
+        g_free(sres);
+
+        v = visitor_input_test_init(data, buf);
+        visit_type_EnumOne(v, &eres, NULL, &errp);
+        visitor_input_teardown(data, NULL);
+    }
+}
+
 static void input_visitor_test_add(const char *testpath,
                                    TestInputVisitorData *data,
                                    void (*test_func)(TestInputVisitorData *data, const void *user_data))
@@ -189,6 +236,8 @@ int main(int argc, char **argv)
                             &in_visitor_data, test_visitor_in_string);
     input_visitor_test_add("/string-visitor/input/enum",
                             &in_visitor_data, test_visitor_in_enum);
+    input_visitor_test_add("/string-visitor/input/fuzz",
+                            &in_visitor_data, test_visitor_in_fuzz);
 
     g_test_run();