[Qemu-devel] [PATCH v2 1/4] tests: Enhance qobject output to cover partial visit

[Eric Blake <eblake@redhat.com>]

Add a test that proves (at least when run under valgrind) that
we are correctly handling allocated memory even when a visit
is aborted in the middle for whatever other reason.

See commit f24582d "qapi: fix double free in
qmp_output_visitor_cleanup()" for a fix that was lacking
testsuite exposure prior to this patch.

Signed-off-by: Eric Blake <eblake@redhat.com>

---
v2: tweak partial alternate visit
---
 tests/test-qobject-output-visitor.c | 42 ++++++++++++++++++++++++++++++++++++-
 1 file changed, 41 insertions(+), 1 deletion(-)

diff --git a/tests/test-qobject-output-visitor.c b/tests/test-qobject-output-visitor.c
index 749c54065f..ce2fb8f368 100644
--- a/tests/test-qobject-output-visitor.c
+++ b/tests/test-qobject-output-visitor.c
@@ -1,7 +1,7 @@
 /*
  * QObject Output Visitor unit-tests.
  *
- * Copyright (C) 2011-2016 Red Hat Inc.
+ * Copyright (C) 2011-2017 Red Hat Inc.
  *
  * Authors:
  *  Luiz Capitulino <lcapitulino@redhat.com>
@@ -251,6 +251,44 @@ static void test_visitor_out_struct_errors(TestOutputVisitorData *data,
 }


+static void test_visitor_out_partial_visit(TestOutputVisitorData *data,
+                                           const void *unused)
+{
+    /* Various checks that a mid-visit abort doesn't leak or double-free. */
+    const char *str = "hi";
+    Error *err = NULL;
+    UserDefAlternate uda = {
+        .type = QTYPE_QDICT,
+        .u.udfu = { .integer = 1,
+                    .string = (char *) "bye",
+                    .enum1 = -1 } /* intentionally bad */
+    };
+    UserDefAlternate *obj = &uda;
+
+    /* Abort within a nested object with no data members */
+    visit_start_struct(data->ov, NULL, NULL, 0, &error_abort);
+    visit_start_struct(data->ov, "nested", NULL, 0, &error_abort);
+    visitor_reset(data);
+
+    /* Abort in the middle of a list of strings */
+    visit_start_list(data->ov, "list", NULL, 0, &error_abort);
+    visit_type_str(data->ov, NULL, (char **)&str, &error_abort);
+    visit_type_str(data->ov, NULL, (char **)&str, &error_abort);
+    visitor_reset(data);
+
+    /*
+     * Abort in the middle of an alternate, due to bad "enum1"
+     * discriminator value.  Since alternates don't support virtual
+     * visits, we perform a real one, relying on our knowledge that
+     * visit_type_UserDefAlternate() calls visit_start_alternate()
+     * under the hood.
+     */
+    visit_type_UserDefAlternate(data->ov, NULL, &obj, &err);
+    error_free_or_abort(&err);
+    visitor_reset(data);
+}
+
+
 static void test_visitor_out_list(TestOutputVisitorData *data,
                                   const void *unused)
 {
@@ -815,6 +853,8 @@ int main(int argc, char **argv)
                             &out_visitor_data, test_visitor_out_struct_nested);
     output_visitor_test_add("/visitor/output/struct-errors",
                             &out_visitor_data, test_visitor_out_struct_errors);
+    output_visitor_test_add("/visitor/output/partial-visit",
+                            &out_visitor_data, test_visitor_out_partial_visit);
     output_visitor_test_add("/visitor/output/list",
                             &out_visitor_data, test_visitor_out_list);
     output_visitor_test_add("/visitor/output/any",
-- 
2.13.3