[Qemu-devel] [PATCH 01/19] qapi-commands.py: Don't call the output marshal on error

[Luiz Capitulino <lcapitulino@redhat.com>]

Today we generate something like this:

    int qmp_marshal_input_query_foo(...)

        ...

        retval = qmp_query_foo(errp);
        qmp_marshal_output_query_foo(retval, ret, errp);

        ...

However, if qmp_query_foo() fails 'retval' will probably be NULL,
which can cause a segfault as not all visitors check if 'retval'
is valid.

This commit fixes that by changing the code generator to only
call the output marshal if qmp_query_foo() succeeds, like this:

    retval = qmp_query_foo(errp);
    if (!error_is_set(errp)) {
        qmp_marshal_output_query_foo(retval, ret, errp);
    }

Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
---
 scripts/qapi-commands.py |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)

diff --git a/scripts/qapi-commands.py b/scripts/qapi-commands.py
index c947ba4..f7def16 100644
--- a/scripts/qapi-commands.py
+++ b/scripts/qapi-commands.py
@@ -62,7 +62,9 @@ def gen_sync_call(name, args, ret_type, indent=0):
                 name=c_var(name), args=arglist, retval=retval).rstrip()
     if ret_type:
         ret += "\n" + mcgen(''''
-%(marshal_output_call)s
+if (!error_is_set(errp)) {
+    %(marshal_output_call)s
+}
 ''',
                             marshal_output_call=gen_marshal_output_call(name, ret_type)).rstrip()
     pop_indent(indent)
-- 
1.7.7.1.475.g997a1