[Qemu-devel] [PATCH RFC v4 21/29] qapi: Test failure in middle of array parse

[Eric Blake <eblake@redhat.com>]

Our generated list visitors have the same problem as has been
mentioned elsewhere (see commit 2f52e20): they allocate data
even on failure. An upcoming patch will correct things to
provide saner guarantees, but first we need to expose the
behavior in the testsuite to ensure we aren't introducing any
memory usage bugs.

Signed-off-by: Eric Blake <eblake@redhat.com>
---
 scripts/qapi-visit.py          |  4 ++++
 tests/test-qmp-input-visitor.c | 13 +++++++++++++
 2 files changed, 17 insertions(+)

diff --git a/scripts/qapi-visit.py b/scripts/qapi-visit.py
index 81527ce..ac19d9d 100644
--- a/scripts/qapi-visit.py
+++ b/scripts/qapi-visit.py
@@ -161,6 +161,10 @@ void visit_type_%(c_name)s(Visitor *m, %(c_name)s **obj, const char *name, Error


 def gen_visit_list(name, element_type):
+    # FIXME: if *obj is NULL on entry, and the first visit_next_list()
+    # assigns to *obj, while a later one fails, we should clean up *obj
+    # rather than leaving it non-NULL. As currently written, the caller must
+    # call qapi_free_FOOList() to avoid a memory leak of the partial FOOList.
     return mcgen('''

 void visit_type_%(c_name)s(Visitor *m, %(c_name)s **obj, const char *name, Error **errp)
diff --git a/tests/test-qmp-input-visitor.c b/tests/test-qmp-input-visitor.c
index 67e4d17..03cad64 100644
--- a/tests/test-qmp-input-visitor.c
+++ b/tests/test-qmp-input-visitor.c
@@ -819,6 +819,7 @@ static void test_visitor_in_errors(TestInputVisitorData *data,
     TestStruct *p = NULL;
     Error *err = NULL;
     Visitor *v;
+    strList *q = NULL;

     v = visitor_input_test_init(data, "{ 'integer': false, 'boolean': 'foo', 'string': -42 }");

@@ -829,9 +830,21 @@ static void test_visitor_in_errors(TestInputVisitorData *data,
     g_assert(p->string == NULL);

     error_free(err);
+    err = NULL;
     g_free(p->string);
     g_free(p);
     visitor_input_teardown(data, NULL);
+
+    v = visitor_input_test_init(data, "[ '1', '2', false, '3' ]");
+    /* FIXME - a failed parse should not leave a partially-allocated
+     * array for us to clean up; this could cause callers to leak
+     * memory. */
+    visit_type_strList(v, &q, NULL, &err);
+    assert(q);
+    assert(err);
+    qapi_free_strList(q);
+    error_free(err);
+    visitor_input_teardown(data, NULL);
 }

 int main(int argc, char **argv)
-- 
2.4.3