Chain-Load: verify building blocks of lazy-init

2023-11-24 23:26:41 +01:00 · 2023-11-24 23:26:41 +01:00 · c658512d7b
commit c658512d7b
parent b00f4501a3
3 changed files with 190 additions and 57 deletions
--- a/src/lib/lazy-init.hpp
+++ b/src/lib/lazy-init.hpp
@ -117,7 +117,7 @@ namespace lib {
      char* anchorAddr = reinterpret_cast<char*> (unConst(anchor));
      char* adjusted   = anchorAddr + offset;
      void* rawTarget  = reinterpret_cast<void*> (adjusted);
-      return static_cast<TAR*> (adjusted);
+      return static_cast<TAR*> (rawTarget);
    }
    
    
@ -129,7 +129,7 @@ namespace lib {
     *          exploited as a trick to allow for automatic late initialisation
     *          in a situation, were a functor needs to capture references.
     */
-    const ptrdiff_t PAYLOAD_OFFSET =
+    const ptrdiff_t FUNCTOR_PAYLOAD_OFFSET =
      []{
          size_t slot{42};
          std::function<RawAddr(void)> probe = [slot]{ return RawAddr(&slot); };
@ -272,6 +272,14 @@ namespace lib {
        }
      
      
+      template<class SIG>
+      void
+      installEmptyInitialiser()
+        {
+          pendingInit_.reset (new HeapStorage{emptyInitialiser<SIG>()});
+        }
+      
+    private:
      template<class SIG>
      DelegateType<SIG>
      emptyInitialiser()
@ -283,40 +291,6 @@ namespace lib {
                                       return disabledFunctor;
                                     });
        }
-      template<class SIG>
-      void
-      installEmptyInitialiser()
-        {
-          pendingInit_.reset (new HeapStorage{emptyInitialiser<SIG>()});
-        }
-      
-      
-    private:
-      template<class SIG, class INI>
-      DelegateType<SIG>
-      buildInitialiserDelegate (std::function<SIG>& targetFunctor, INI&& initialiser)
-        {
-          using TargetFun = std::function<SIG>;
-          return DelegateType<SIG>{
-                     [performInit = forward<INI> (initialiser)
-                     ,targetOffset = captureRawAddrOffset (this, &targetFunctor)]
-                     (RawAddr location) -> TargetFun&
-                        {// apply known offset backwards to find current location of the host object
-                          TargetFun* target = relocate<TargetFun> (location, -PAYLOAD_OFFSET);
-                          LazyInit* self = relocate<LazyInit> (target, -targetOffset);
-                          REQUIRE (self);
-                          performInit (self);
-                          self->pendingInit_.reset();
-                          return *target;
-                        }};
-        }
-      
-      template<class SIG>
-      DelegateType<SIG>*
-      getPointerToDelegate(HeapStorage& buffer)
-        {
-          return reinterpret_cast<DelegateType<SIG>*> (&buffer);
-        }
      
      template<class SIG, class INI>
      PendingInit
@ -329,6 +303,32 @@ namespace lib {
          targetFunctor = TrojanFun<SIG>::generateTrap (getPointerToDelegate<SIG> (*storageHandle));
          return storageHandle;
        }
+      
+      template<class SIG>
+      DelegateType<SIG>*
+      getPointerToDelegate(HeapStorage& buffer)
+        {
+          return reinterpret_cast<DelegateType<SIG>*> (&buffer);
+        }
+      
+      template<class SIG, class INI>
+      DelegateType<SIG>
+      buildInitialiserDelegate (std::function<SIG>& targetFunctor, INI&& initialiser)
+        {
+          using TargetFun = std::function<SIG>;
+          return DelegateType<SIG>{
+                     [performInit = forward<INI> (initialiser)
+                     ,targetOffset = captureRawAddrOffset (this, &targetFunctor)]
+                     (RawAddr location) -> TargetFun&
+                        {// apply known offset backwards to find current location of the host object
+                          TargetFun* target = relocate<TargetFun> (location, -FUNCTOR_PAYLOAD_OFFSET);
+                          LazyInit* self = relocate<LazyInit> (target, -targetOffset);
+                          REQUIRE (self);
+                          performInit (self);
+                          self->pendingInit_.reset();
+                          return *target;
+                        }};
+        }
    };
  
  
--- a/tests/library/lazy-init-test.cpp
+++ b/tests/library/lazy-init-test.cpp
@ -73,22 +73,11 @@ namespace test{
      void
      run (Arg)
        {
-          simpleUse();
-          
          verify_trojanLambda();
          verify_inlineStorage();
-//          verify_numerics();
-//          verify_adaptMapping();
-//          verify_dynamicChange();
-        }
-      
-      
-      
-      /** @test demonstrate a basic usage scenario
-       */
-      void
-      simpleUse()
-        {
+          verify_TargetRelocation();
+          verify_triggerMechanism();
+          verify_lazyInitialisation();
        }
      
      
@ -203,6 +192,112 @@ namespace test{
      
      
      
+      /** @test verify navigating an object structure
+       *        by applying known offsets consecutively
+       *        from a starting point within an remote instance
+       * @remark in the real usage scenario, we know _only_ the offset
+       *        and and attempt to find home without knowing the layout.
+       */
+      void
+      verify_TargetRelocation()
+        {
+          struct Nested
+            {
+              int unrelated{rand()};
+              int anchor{rand()};
+            };
+          struct Demo
+            {
+              Nested nested;
+              virtual ~Demo(){ };
+              virtual RawAddr peek()
+                {
+                  return &nested.anchor;
+                }
+            };
+          
+          // find out generic offset...
+          const ptrdiff_t offNested = []{
+                                         Nested probe;
+                                         return captureRawAddrOffset(&probe, &probe.anchor);
+                                        }();
+          Demo here;
+          // find out actual offset in existing object
+          const ptrdiff_t offBase = captureRawAddrOffset(&here, &here.nested);
+          
+          CHECK (offBase > 0);
+          CHECK (offNested > 0);
+          
+          // create a copy far far away...
+          auto farAway = std::make_unique<Demo> (here);
+          
+          // reconstruct base address from starting point
+          RawAddr startPoint = farAway->peek();
+          Nested* farNested = relocate<Nested>(startPoint, -offNested);
+          CHECK (here.nested.unrelated == farNested->unrelated);
+
+          Demo* farSelf = relocate<Demo> (farNested, -offBase);
+          CHECK (here.nested.anchor == farSelf->nested.anchor);
+          CHECK (isSameObject (*farSelf, *farAway));
+        }
+      
+      
+      
+      /** @test demonstrate the trigger mechanism in isolation
+       */
+      void
+      verify_triggerMechanism()
+        {
+          using Fun = std::function<float(int)>;
+          Fun theFun;
+          CHECK (not theFun);
+          
+          int report{0};
+          auto delegate = [&report](RawAddr insideFun) -> Fun&
+                              {
+                                auto realFun = [&report](int num)
+                                                          {
+                                                            report += num;
+                                                            return num + 23.55f;
+                                                          };
+                                Fun& target = *relocate<Fun>(insideFun, -FUNCTOR_PAYLOAD_OFFSET);
+                                report = -42; // as proof that the init-delegate was invoked
+                                target = realFun;
+                                return target;
+                              };
+          CHECK (not theFun);
+          // install the init-»trap«
+          theFun = TrojanFun<float(int)>::generateTrap (&delegate);
+          CHECK (theFun);
+          CHECK (0 == report);
+          
+          // invoke function
+          int feed{1+rand()%100};
+          float res = theFun (feed);
+          
+          // delegate *and* realFun were invoked
+          CHECK (feed == report + 42);
+          CHECK (res = feed -42 +23.55f);
+          
+          // again...
+          report = 0;
+          feed = -1-rand()%20;
+          res = theFun (feed);
+          
+          // this time the delegate was *not* invoked,
+          // only the installed realFun
+          CHECK (feed == report);
+          CHECK (res = feed + 23.55f);
+        }
+      
+      
+      
+      /** @test demonstrate a basic usage scenario
+       */
+      void
+      verify_lazyInitialisation()
+        {
+        }
    };
  
  
--- a/wiki/thinkPad.ichthyo.mm
+++ b/wiki/thinkPad.ichthyo.mm
@ -97283,8 +97283,8 @@ Date:&#160;&#160;&#160;Thu Apr 20 18:53:17 2023 +0200<br/>
 <icon BUILTIN="pencil"/>
 </node>
 </node>
-<node BACKGROUND_COLOR="#eef0c5" COLOR="#990000" CREATED="1700786308827" ID="ID_627670298" MODIFIED="1700792001666" TEXT="der Trojanische-Funktor">
-<icon BUILTIN="pencil"/>
+<node COLOR="#338800" CREATED="1700786308827" ID="ID_627670298" MODIFIED="1700865645701" TEXT="der Trojanische-Funktor">
+<icon BUILTIN="button_ok"/>
 <node COLOR="#5b280f" CREATED="1700786329960" ID="ID_579721558" MODIFIED="1700829943723" TEXT="bettet einen shared_ptr ein">
 <linktarget COLOR="#e64156" DESTINATION="ID_579721558" ENDARROW="Default" ENDINCLINATION="581;-41;" ID="Arrow_ID_1803799256" SOURCE="ID_1318522029" STARTARROW="None" STARTINCLINATION="-98;-231;"/>
 <icon BUILTIN="button_cancel"/>
@ -97304,11 +97304,11 @@ Date:&#160;&#160;&#160;Thu Apr 20 18:53:17 2023 +0200<br/>
 </node>
 <node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1700786402490" ID="ID_846455233" MODIFIED="1700786418812" TEXT="Trick-Mechanismus zur this-Ermittlung">
 <icon BUILTIN="flag-yellow"/>
-<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1700786427859" ID="ID_569731992" MODIFIED="1700795340778" TEXT="mu&#xdf; zu Beginn &#xbb;proben&#xab;">
-<icon BUILTIN="flag-yellow"/>
+<node COLOR="#338800" CREATED="1700786427859" ID="ID_569731992" MODIFIED="1700865640264" TEXT="mu&#xdf; zu Beginn &#xbb;proben&#xab;">
+<icon BUILTIN="button_ok"/>
 </node>
-<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1700786446976" ID="ID_646471757" MODIFIED="1700795338010" TEXT="Zusatz-Problem: das &#x3bb; sieht nur seine capture">
-<icon BUILTIN="flag-yellow"/>
+<node COLOR="#338800" CREATED="1700786446976" ID="ID_646471757" MODIFIED="1700865636679" TEXT="Zusatz-Problem: das &#x3bb; sieht nur seine capture">
+<icon BUILTIN="button_ok"/>
 <node CREATED="1700786476589" ID="ID_1376774629" MODIFIED="1700786490117" TEXT="&#x27f6; also mehrstufig vorgehen"/>
 <node CREATED="1700786494226" ID="ID_990128277" MODIFIED="1700786508492" TEXT="generisch das Verh&#xe4;ltnis zur std::function ermitteln"/>
 <node CREATED="1700786514967" ID="ID_1504854205" MODIFIED="1700786531452" TEXT="ebenso das Verh&#xe4;ltnis von der std::function zu *this"/>
@ -97393,7 +97393,7 @@ Date:&#160;&#160;&#160;Thu Apr 20 18:53:17 2023 +0200<br/>
 </node>
 <node CREATED="1700846290266" ID="ID_1685278359" MODIFIED="1700846318281" TEXT="Also bleibt nur: LazyInit packt den eigentlichen Initialiser in einen opaque container"/>
 </node>
-<node BACKGROUND_COLOR="#f8f1cb" COLOR="#a50125" CREATED="1700856150252" ID="ID_1283688015" MODIFIED="1700856166026" TEXT="Address-Relocation">
+<node COLOR="#435e98" CREATED="1700856150252" ID="ID_1283688015" MODIFIED="1700865608154" TEXT="Address-Relocation">
 <icon BUILTIN="messagebox_warning"/>
 <node BACKGROUND_COLOR="#fafe99" COLOR="#fa002a" CREATED="1700856167326" ID="ID_903304450" MODIFIED="1700856175977" TEXT="der Compiler weint und winselt">
 <icon BUILTIN="broken-line"/>
@ -97412,6 +97412,44 @@ Date:&#160;&#160;&#160;Thu Apr 20 18:53:17 2023 +0200<br/>
 <node BACKGROUND_COLOR="#e0ceaa" COLOR="#690f14" CREATED="1700856538050" ID="ID_30859769" MODIFIED="1700856555062" TEXT="aber die Layout-Annahme selber kann ich leider nicht pr&#xfc;fen">
 <icon BUILTIN="clanbomber"/>
 </node>
+<node COLOR="#338800" CREATED="1700865572986" ID="ID_819138430" MODIFIED="1700865582889" TEXT="zumindest im Test nachgestellt und funktioniert">
+<icon BUILTIN="button_ok"/>
+</node>
+</node>
+<node BACKGROUND_COLOR="#eef0c5" COLOR="#990000" CREATED="1700865668069" ID="ID_96300659" MODIFIED="1700865853252" TEXT="Speicherverwaltung">
+<icon BUILTIN="pencil"/>
+<node COLOR="#435e98" CREATED="1700865679180" ID="ID_3672857" MODIFIED="1700865823343">
+<richcontent TYPE="NODE"><html>
+  <head>
+    
+  </head>
+  <body>
+    <p>
+      OpaqueHolder<i>&#160;mi&#223;braucht</i>
+    </p>
+  </body>
+</html>
+</richcontent>
+<icon BUILTIN="idea"/>
+<node CREATED="1700865718074" ID="ID_46417679" MODIFIED="1700865732256" TEXT="er setzt eigentlich gemeinsame Basisklasse vorraus"/>
+<node CREATED="1700865733257" ID="ID_19147628" MODIFIED="1700865768147" TEXT="InPlaceAnyHolder w&#xfc;rde den Fall unterst&#xfc;tzen, ist aber zu schwergewichtig (VTable)"/>
+<node CREATED="1700865775966" ID="ID_1852703821" MODIFIED="1700865806222" TEXT="ist hier grade noch so machbar, da wir das Objekt nach Erstellung nur noch verwalten"/>
+</node>
+<node COLOR="#338800" CREATED="1700865829132" ID="ID_1420005046" MODIFIED="1700865850429" TEXT="shared_ptr nach Triggern der Initialisierung reset()">
+<icon BUILTIN="button_ok"/>
+</node>
+</node>
+<node COLOR="#338800" CREATED="1700865861639" ID="ID_409549839" MODIFIED="1700865919942" TEXT="gegebenes Init-&#x3bb; adaptieren">
+<icon BUILTIN="button_ok"/>
+<node COLOR="#338800" CREATED="1700865886375" ID="ID_594517704" MODIFIED="1700865897328" TEXT="self-Offset capture">
+<icon BUILTIN="button_ok"/>
+</node>
+<node COLOR="#338800" CREATED="1700865898011" ID="ID_831512370" MODIFIED="1700865904118" TEXT="self-Offset restore">
+<icon BUILTIN="button_ok"/>
+</node>
+<node COLOR="#338800" CREATED="1700865906981" ID="ID_1800834277" MODIFIED="1700865917596" TEXT="am Ende Referenz auf target-Functor liefern">
+<icon BUILTIN="button_ok"/>
+</node>
 </node>
 </node>
 <node COLOR="#c1019e" CREATED="1700856585458" ID="ID_373199802" MODIFIED="1700856611800" TEXT="ich f&#xfc;hl mich schei&#xdf;e">