[libvirt] [PATCH v2 2/4] rpc: gendispatch: Add a check for zero size client-side buffers

After libvirt switched to GLib, we also started to use glib allocation primitives as of commit e85e34f3. Unlike malloc which is ambiguous with regards to size == 0 (which in our case returned a unique pointer safe to be passed to free), g_malloc0 strictly returns NULL on size == 0. This change broke our legacy APIs which rely on the caller to pre-allocate the target buffer to hold the results and pass the buffer size as an argument. Since it makes very little sense to call an API with nowhere to store the results, fix this by returning 0 directly in such case in the RPC dispatch code - there are modern API equivalents allocating the target buffer automatically anyway. https://bugzilla.redhat.com/show_bug.cgi?id=1772842 Signed-off-by: Erik Skultety <eskultet(a)redhat.com&gt; --- src/rpc/gendispatch.pl | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/src/rpc/gendispatch.pl b/src/rpc/gendispatch.pl index 8656c8f205..524d31f741 100755 --- a/src/rpc/gendispatch.pl +++ b/src/rpc/gendispatch.pl @@ -1073,6 +1073,14 @@ elsif ($mode eq "server") { print " goto cleanup;\n"; print " }\n"; print "\n"; + + + print " if (args->$single_ret_list_max_var == 0) {\n"; + print " ret->$single_ret_list_name.${single_ret_list_name}_len = 0;\n"; + print " rv = 0;\n"; + print " goto cleanup;\n"; + print " }\n"; + print "\n"; } print join("\n", @getters_list); -- 2.23.0