Fix crash when no entry point found for LVSA

Author: NathanJPhillips

src/driver/sec_driver_parse_options.cpp

@@ -109,10 +109,13 @@ void sec_driver_parse_optionst::get_command_line_options(optionst &options)
 
 static irep_idt get_cprover_start_main_callee(const goto_modelt &goto_model)
 {
-  const goto_programt &start_body =
-    goto_model.get_goto_functions().function_map.at(
-      goto_functionst::entry_point()).body;
+  const goto_functionst::function_mapt &function_map =
+    goto_model.get_goto_functions().function_map;
+  auto entry_it = function_map.find(goto_functionst::entry_point());
+  if(entry_it == function_map.end())
+    return {};
 
+  const goto_programt &start_body = entry_it->second.body;
   auto last_call_it =
     std::find_if(
       start_body.instructions.rbegin(),
@@ -242,12 +245,15 @@ int sec_driver_parse_optionst::doit()
     local_value_set_analysist::dbt summarydb(serializer, 30);
     namespacet ns(goto_model.symbol_table);
 
-    const std::string function_name = cmdline.get_value("function");
     const bool print_function_summary = cmdline.isset("show-value-sets");
     const bool print_all_summaries = cmdline.isset("show-value-sets-all");
 
-    irep_idt fully_qualified_name =
-      get_cprover_start_main_callee(goto_model);
+    irep_idt fully_qualified_name = get_cprover_start_main_callee(goto_model);
+    if(fully_qualified_name.empty())
+    {
+      error() << "You must specify an entry point with --function" << eom;
+      return CPROVER_EXIT_USAGE_ERROR;
+    }
 
     call_grapht const call_graph(goto_model.goto_functions);
     std::vector<irep_idt> process_order =