[siof] understand that <iostream> initialises streams

Summary:
Inject a marker using a global variable in <iostream>, and whitelist it so that
the frontend translates it.

Use the marker in the SIOF checker to tell whether a file includes <iostream>.
If so, start the analysis of its methods assuming that the standard streams are
initialised.

Reviewed By: sblackshear

Differential Revision: D5941343

fbshipit-source-id: 3388d55

infer/models/cpp/include/infer_model/iostream.h

@@ -0,0 +1,15 @@
+/*
+ * Copyright (c) 2017 - present Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+#pragma once
+
+#include_next <iostream>
+
+// this is a marker so that infer can tell whether iostream has been included by
+// a give source file
+std::ios_base::Init __infer_translation_unit_init_streams;

infer/models/cpp/include/iostream

@@ -0,0 +1,7 @@
+#include <infer_model/portability.h>
+
+#ifdef INFER_CPP11_ON
+# include <infer_model/iostream.h>
+#else
+# include_next <iostream>
+#endif

infer/src/checkers/Siof.ml

@@ -28,17 +28,17 @@ type siof_model =
 
 let parse_siof_model (qual_name, initialized_globals) = {qual_name; initialized_globals}
 
-let models =
-  List.map ~f:parse_siof_model
-    [ ( "std::ios_base::Init::Init"
-      , [ "std::cerr"
-        ; "std::wcerr"
-        ; "std::cin"
-        ; "std::wcin"
-        ; "std::clog"
-        ; "std::wclog"
-        ; "std::cout"
-        ; "std::wcout" ] ) ]
+let standard_streams =
+  [ "std::cerr"
+  ; "std::wcerr"
+  ; "std::cin"
+  ; "std::wcin"
+  ; "std::clog"
+  ; "std::wclog"
+  ; "std::cout"
+  ; "std::wcout" ]
+
+let models = List.map ~f:parse_siof_model [("std::ios_base::Init::Init", standard_streams)]
 
 let is_modelled =
   let models_matcher =
@@ -223,9 +223,30 @@ let siof_check pdesc gname (summary: Specs.summary) =
   | Some (Bottom, _) | None
    -> ()
 
-let checker {Callbacks.proc_desc; tenv; summary} : Specs.summary =
+let checker {Callbacks.proc_desc; tenv; summary; get_procs_in_file} : Specs.summary =
+  let standard_streams_initialized_in_tu =
+    let includes_iostream tu =
+      let magic_iostream_marker =
+        (* always [Some _] because we create a global variable with [mk_global] *)
+        Option.value_exn
+          ( Pvar.mk_global
+              (Mangled.from_string
+                 (* infer's C++ headers define this global variable in <iostream> *)
+                 "__infer_translation_unit_init_streams") (TUFile tu)
+          |> Pvar.get_initializer_pname )
+      in
+      get_procs_in_file (Procdesc.get_proc_name proc_desc)
+      |> List.exists ~f:(Typ.Procname.equal magic_iostream_marker)
+    in
+    Option.value_map ~default:false ~f:includes_iostream
+      (Procdesc.get_attributes proc_desc).ProcAttributes.translation_unit
+  in
   let proc_data = ProcData.make_default proc_desc tenv in
-  let initial = (Bottom, SiofDomain.VarNames.empty) in
+  let initial =
+    ( Bottom
+    , if standard_streams_initialized_in_tu then SiofDomain.VarNames.of_list standard_streams
+      else SiofDomain.VarNames.empty )
+  in
   let updated_summary =
     match Analyzer.compute_post proc_data ~initial with
     | Some post

infer/src/clang/cFrontend_decl.ml

@@ -197,33 +197,41 @@ module CFrontend_decl_funct (T : CModule_type.CTranslation) : CModule_type.CFron
       | None
        -> false
 
-  let should_translate_decl trans_unit_ctx dec decl_trans_context =
+  let should_translate_decl trans_unit_ctx (dec: Clang_ast_t.decl) decl_trans_context =
     let info = Clang_ast_proj.get_decl_tuple dec in
     let source_range = info.Clang_ast_t.di_source_range in
     let translate_when_used =
       match dec with
-      | Clang_ast_t.FunctionDecl (_, name_info, _, _)
-      | Clang_ast_t.CXXMethodDecl (_, name_info, _, _, _)
-      | Clang_ast_t.CXXConstructorDecl (_, name_info, _, _, _)
-      | Clang_ast_t.CXXConversionDecl (_, name_info, _, _, _)
-      | Clang_ast_t.CXXDestructorDecl (_, name_info, _, _, _)
+      | FunctionDecl (_, name_info, _, _)
+      | CXXMethodDecl (_, name_info, _, _, _)
+      | CXXConstructorDecl (_, name_info, _, _, _)
+      | CXXConversionDecl (_, name_info, _, _, _)
+      | CXXDestructorDecl (_, name_info, _, _, _)
        -> is_whitelisted_cpp_method (CAst_utils.get_qualified_name name_info)
       | _
        -> false
     in
+    let always_translate =
+      match dec with
+      | VarDecl (_, {ni_name}, _, _)
+       -> String.is_prefix ni_name ~prefix:"__infer_"
+      | _
+       -> false
+    in
     let translate_location =
-      CLocation.should_translate_lib trans_unit_ctx source_range decl_trans_context
-        ~translate_when_used
+      always_translate
+      || CLocation.should_translate_lib trans_unit_ctx source_range decl_trans_context
+           ~translate_when_used
     in
     let never_translate_decl =
       match dec with
-      | Clang_ast_t.FunctionDecl (_, name_info, _, _)
-      | Clang_ast_t.CXXMethodDecl (_, name_info, _, _, _)
-      | Clang_ast_t.CXXConstructorDecl (_, name_info, _, _, _)
-      | Clang_ast_t.CXXConversionDecl (_, name_info, _, _, _)
-      | Clang_ast_t.CXXDestructorDecl (_, name_info, _, _, _)
+      | FunctionDecl (_, name_info, _, _)
+      | CXXMethodDecl (_, name_info, _, _, _)
+      | CXXConstructorDecl (_, name_info, _, _, _)
+      | CXXConversionDecl (_, name_info, _, _, _)
+      | CXXDestructorDecl (_, name_info, _, _, _)
        -> let fun_name = name_info.Clang_ast_t.ni_name in
-          Str.string_match (Str.regexp "__infer_skip__") fun_name 0
+          String.is_prefix ~prefix:"__infer_skip__" fun_name
       | _
        -> false
     in
@@ -282,7 +290,8 @@ module CFrontend_decl_funct (T : CModule_type.CTranslation) : CModule_type.CFron
             | None
              -> () )
         | VarDecl (decl_info, named_decl_info, qt, ({vdi_is_global; vdi_init_expr} as vdi))
-          when vdi_is_global && Option.is_some vdi_init_expr
+          when String.is_prefix ~prefix:"__infer_" named_decl_info.ni_name
+               || vdi_is_global && Option.is_some vdi_init_expr
          -> (* create a fake procedure that initializes the global variable so that the variable
               initializer can be analyzed by the backend (eg, the SIOF checker) *)
             let procname =

infer/tests/codetoanalyze/cpp/siof/Makefile

@@ -20,6 +20,7 @@ SOURCES = \
   siof/pod_across_translation_units-1.cpp \
   siof/pod_across_translation_units-2.cpp \
   siof/pod_same_translation_unit.cpp \
+  siof/include_iostream.cpp \
   siof/siof.cpp \
   siof/siof_templated.cpp \
   siof/siof_different_tu.cpp \

infer/tests/codetoanalyze/cpp/siof/siof/include_iostream.cpp

@@ -0,0 +1,13 @@
+/*
+ * Copyright (c) 2017 - present Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+#include <iostream>
+
+void safe_streams() {
+  std::cout << "yay I'm safe thanks to having included <iostream>";
+}

infer/tests/codetoanalyze/cpp/siof/siof/siof.cpp

@@ -12,6 +12,7 @@
 extern SomeNonPODObject extern_global_object;
 SomeNonPODObject global_object;
 extern int access_to_non_pod();
+void safe_streams();
 
 struct SomeOtherNonPODObject {
   SomeOtherNonPODObject() {
@@ -21,6 +22,7 @@ struct SomeOtherNonPODObject {
 
   SomeOtherNonPODObject(int i) {
     global_object.some_method(); // OK, same translation unit
+    safe_streams(); // OK, that function is SIOF safe
   };
 };
 

infer/tests/codetoanalyze/cpp/siof/siof/std_ios_base_init.cpp

@@ -6,11 +6,23 @@
  * LICENSE file in the root directory of this source tree. An additional grant
  * of patent rights can be found in the PATENTS file in the same directory.
  */
-#include <iostream>
+#include <istream>
+#include <ostream>
+
+namespace std {
+extern std::istream cin;
+extern std::wistream wcin;
+extern std::ostream cerr;
+extern std::wostream wcerr;
+extern std::ostream clog;
+extern std::wostream wclog;
+extern std::ostream cout;
+extern std::wostream wcout;
+}; // namespace std
 
 void printing_no_SIOF() {
   std::ios_base::Init ioInit;
-  std::cerr << "I haz warning!";
+  std::cerr << "it's ok to print here";
 }
 
 void printing_SIOF() {