Check for NULL APIs returned by sai_api_query() before calling. (open…

…computeproject#1558)

Signed-off-by: Chris Sommers <chrispsommers@gmail.com>

Co-authored-by: Chris Sommers <chrispsommers@gmail.com>

meta/templates/sai_rpc_server_functions.tt

@@ -28,6 +28,16 @@
 [% END -%]
 [%- END -%]
 
+[%- BLOCK check_sai_function -%]
+[% name = function.name; UNLESS methods.$name %]
+[% END -%]
+if ([% api %]_api->[% name = function.name; GET methods.$name %] == (void *)0) {
+        std::cerr << "NULL ptr: [% api %]_api->[% name = function.name; GET methods.$name %]" << std::endl;
+        [%- PROCESS throw_null_api_exception %]
+    }
+
+[%- END -%]
+
 [%- ######################################################################## -%]
 
 [%- ######################################################################## -%]
@@ -133,6 +143,14 @@
 [% indent %]throw e;
 [%- END -%]
 
+[%- BLOCK throw_null_api_exception -%]
+    [%- indentation = indentation || 2; tab = 2; indent = ' '; indent = indent.repeat(tab*indentation) %]
+
+[% indent %]sai_thrift_exception e;
+[% indent %]e.status = SAI_STATUS_NOT_IMPLEMENTED;
+[% indent %]throw e;
+[%- END -%]
+
 [%- ######################################################################## -%]
 
 [%- ######################################################################## -%]
@@ -351,6 +369,9 @@
 
         [%- PROCESS preprocess_arguments %]
 
+        [%- # Ensure function ptr not NULL -%]
+    [% name = function.name; UNLESS methods.$name %]//[% END %][% PROCESS check_sai_function -%]
+
         [%- # Now just call the function -%]
     [% name = function.name; UNLESS methods.$name %]//[% END %]status = [% PROCESS call_sai_function -%]