[Qemu-devel] [PATCH v2 3/3] tests: Enhance qobject output to cover partial visit

[Eric Blake]

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 <address@hidden>

---
v2: rebase (and hence retitle), add list & alternate coverage
---
 tests/test-qobject-output-visitor.c | 39 +++++++++++++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)

diff --git a/tests/test-qobject-output-visitor.c 
b/tests/test-qobject-output-visitor.c
index c2e0f43..fdae0d5 100644
--- a/tests/test-qobject-output-visitor.c
+++ b/tests/test-qobject-output-visitor.c
@@ -254,6 +254,43 @@ 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 } };
+    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. Alternates can't be
+     * virtually visited, so we get to inline the first half of
+     * visit_type_UserDefAlternate(). */
+    visit_start_alternate(data->ov, NULL, (GenericAlternate **)&obj,
+                          sizeof(uda), false, &error_abort);
+    visit_start_struct(data->ov, NULL, NULL, 0, &error_abort);
+    visit_type_UserDefUnionBase_members(data->ov,
+                                        (UserDefUnionBase *)&uda.u.udfu,
+                                        &err);
+    error_free_or_abort(&err);
+    visitor_reset(data);
+}
+
+
 static void test_visitor_out_list(TestOutputVisitorData *data,
                                   const void *unused)
 {
@@ -817,6 +854,8 @@ 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",
-- 
2.7.4