Add sample checker to detect reads and writes to globals

Reviewed By: jvillard

Differential Revision: D3392625

fbshipit-source-id: f76e57e

infer/src/checkers/checkers.ml

@@ -566,3 +566,31 @@ let callback_print_c_method_calls { Callbacks.proc_desc; proc_name } =
           description
     | _ -> () in
   Cfg.Procdesc.iter_instrs do_instr proc_desc
+
+(** Print access to globals. *)
+let callback_print_access_to_globals { Callbacks.proc_desc; proc_name } =
+  let do_pvar is_read pvar loc =
+    let description =
+      Printf.sprintf "%s of global %s"
+        (if is_read then "read" else "write")
+        (Pvar.to_string pvar) in
+    ST.report_error
+      proc_name
+      proc_desc
+      "CHECKERS_ACCESS_GLOBAL"
+      loc
+      description in
+  let rec get_global_var = function
+    | Sil.Lvar pvar when Pvar.is_global pvar ->
+        Some pvar
+    | Sil.Lfield (e, _, _) ->
+        get_global_var e
+    | _ ->
+        None in
+  let do_instr _ = function
+    | Sil.Letderef (_, e, _, loc) when get_global_var e <> None ->
+        Option.may (fun pvar -> do_pvar true pvar loc) (get_global_var e)
+    | Sil.Set (e, _, _, loc) when get_global_var e <> None ->
+        Option.may (fun pvar -> do_pvar false pvar loc) (get_global_var e)
+    | _ -> () in
+  Cfg.Procdesc.iter_instrs do_instr proc_desc

infer/src/checkers/checkers.mli

@@ -53,3 +53,4 @@ val callback_check_write_to_parcel : Callbacks.proc_callback_t
 val callback_find_deserialization : Callbacks.proc_callback_t
 val callback_check_field_access : Callbacks.proc_callback_t
 val callback_print_c_method_calls : Callbacks.proc_callback_t
+val callback_print_access_to_globals : Callbacks.proc_callback_t

infer/src/checkers/registerCheckers.ml

@@ -38,6 +38,7 @@ let active_procedure_checkers () =
         RepeatedCallsChecker.callback_check_repeated_calls, checkers_enabled;
         PrintfArgs.callback_printf_args, checkers_enabled;
         AnnotationReachability.Interprocedural.check_and_report, checkers_enabled;
+        Checkers.callback_print_access_to_globals, false;
       ] in
     IList.map (fun (x, y) -> (x, y, Some Config.Java)) l in
   let c_cpp_checkers =
@@ -45,6 +46,7 @@ let active_procedure_checkers () =
       [
         Checkers.callback_print_c_method_calls, false;
         CheckDeadCode.callback_check_dead_code, false;
+        Checkers.callback_print_access_to_globals, false;
       ] in
     IList.map (fun (x, y) -> (x, y, Some Config.Clang)) l in