Merge pull request #3543 from kinke/dynamic_cast

Fix Issue 22218 - Dynamic casts across binary boundaries can easily fail

Author: RazvanN7

src/rt/cast_.d

@@ -19,6 +19,16 @@ extern (C):
 nothrow:
 pure:
 
+// Needed because ClassInfo.opEquals(Object) does a dynamic cast,
+// but we are trying to implement dynamic cast.
+extern (D) private bool areClassInfosEqual(scope const ClassInfo a, scope const ClassInfo b) @safe
+{
+    if (a is b)
+        return true;
+    // take care of potential duplicates across binaries
+    return a.name == b.name;
+}
+
 /******************************************
  * Given a pointer:
  *      If it is an Object, return that Object.
@@ -80,19 +90,19 @@ void* _d_dynamic_cast(Object o, ClassInfo c)
 
 int _d_isbaseof2(scope ClassInfo oc, scope const ClassInfo c, scope ref size_t offset) @safe
 {
-    if (oc is c)
+    if (areClassInfosEqual(oc, c))
         return true;
 
     do
     {
-        if (oc.base is c)
+        if (oc.base && areClassInfosEqual(oc.base, c))
             return true;
 
         // Bugzilla 2013: Use depth-first search to calculate offset
         // from the derived (oc) to the base (c).
         foreach (iface; oc.interfaces)
         {
-            if (iface.classinfo is c || _d_isbaseof2(iface.classinfo, c, offset))
+            if (areClassInfosEqual(iface.classinfo, c) || _d_isbaseof2(iface.classinfo, c, offset))
             {
                 offset += iface.offset;
                 return true;
@@ -107,17 +117,17 @@ int _d_isbaseof2(scope ClassInfo oc, scope const ClassInfo c, scope ref size_t o
 
 int _d_isbaseof(scope ClassInfo oc, scope const ClassInfo c) @safe
 {
-    if (oc is c)
+    if (areClassInfosEqual(oc, c))
         return true;
 
     do
     {
-        if (oc.base is c)
+        if (oc.base && areClassInfosEqual(oc.base, c))
             return true;
 
         foreach (iface; oc.interfaces)
         {
-            if (iface.classinfo is c || _d_isbaseof(iface.classinfo, c))
+            if (areClassInfosEqual(iface.classinfo, c) || _d_isbaseof(iface.classinfo, c))
                 return true;
         }
 

test/shared/Makefile

@@ -2,7 +2,7 @@ LINK_SHARED:=1
 
 include ../common.mak
 
-TESTS:=link load linkD linkDR loadDR host finalize
+TESTS:=link load linkD linkDR loadDR host finalize dynamiccast
 TESTS+=link_linkdep load_linkdep link_loaddep load_loaddep load_13414
 
 EXPORT_DYNAMIC=$(if $(findstring $(OS),linux freebsd dragonflybsd),-L--export-dynamic,)
@@ -13,9 +13,12 @@ all: $(addprefix $(ROOT)/,$(addsuffix .done,$(TESTS)))
 
 $(ROOT)/loadDR.done $(ROOT)/host.done: RUN_ARGS:=$(DRUNTIMESO)
 
+$(ROOT)/dynamiccast.done: CLEANUP:=rm dynamiccast_endmain dynamiccast_endbar
+
 $(ROOT)/%.done: $(ROOT)/%
 	@echo Testing $*
 	$(QUIET)$(TIMELIMIT)$< $(RUN_ARGS)
+	$(CLEANUP)
 	@touch $@
 
 $(ROOT)/link: $(SRC)/link.d $(ROOT)/lib.so $(DRUNTIMESO)
@@ -39,6 +42,12 @@ $(ROOT)/load $(ROOT)/finalize: $(ROOT)/%: $(SRC)/%.d $(ROOT)/lib.so $(DRUNTIMESO
 $(ROOT)/load_13414: $(ROOT)/%: $(SRC)/%.d $(ROOT)/lib_13414.so $(DRUNTIMESO)
 	$(QUIET)$(DMD) $(DFLAGS) -of$@ $< $(LINKDL)
 
+$(ROOT)/dynamiccast: $(SRC)/dynamiccast.d $(ROOT)/dynamiccast.so $(DRUNTIMESO)
+	$(QUIET)$(DMD) $(DFLAGS) -of$@ $(SRC)/dynamiccast.d $(LINKDL)
+
+$(ROOT)/dynamiccast.so: $(SRC)/dynamiccast.d $(DRUNTIMESO)
+	$(QUIET)$(DMD) $(DFLAGS) -of$@ $< -version=DLL -fPIC -shared $(LINKDL)
+
 $(ROOT)/linkD: $(SRC)/linkD.c $(ROOT)/lib.so $(DRUNTIMESO)
 	$(QUIET)$(CC) $(CFLAGS) -o $@ $< $(ROOT)/lib.so $(LDL) -pthread
 

test/shared/src/dynamiccast.d

@@ -0,0 +1,98 @@
+class C : Exception
+{
+    this() { super(""); }
+}
+
+version (DLL)
+{
+    version (Windows)
+    {
+        import core.sys.windows.dll;
+        mixin SimpleDllMain;
+    }
+
+    pragma(mangle, "foo")
+    export Object foo(Object o)
+    {
+        assert(cast(C) o);
+        return new C;
+    }
+
+    pragma(mangle, "bar")
+    export void bar(void function() f)
+    {
+        import core.stdc.stdio : fopen, fclose;
+        bool caught;
+        try
+            f();
+        catch (C e)
+            caught = true;
+        assert(caught);
+
+        // verify we've actually got to the end, because for some reason we can
+        // end up exiting with code 0 when throwing an exception
+        fclose(fopen("dynamiccast_endbar", "w"));
+        throw new C;
+    }
+}
+else
+{
+    T getFunc(T)(const(char)* sym, string thisExePath)
+    {
+        import core.runtime : Runtime;
+
+        version (Windows)
+        {
+            import core.sys.windows.winbase : GetProcAddress;
+            return cast(T) Runtime.loadLibrary("dynamiccast.dll")
+                .GetProcAddress(sym);
+        }
+        else version (Posix)
+        {
+            import core.sys.posix.dlfcn : dlsym;
+            import core.stdc.string : strrchr;
+
+            auto name = thisExePath ~ '\0';
+            const pathlen = strrchr(name.ptr, '/') - name.ptr + 1;
+            name = name[0 .. pathlen] ~ "dynamiccast.so";
+            return cast(T) Runtime.loadLibrary(name)
+                .dlsym(sym);
+        }
+        else static assert(0);
+    }
+
+    version (DigitalMars) version (Win64) version = DMD_Win64;
+
+    void main(string[] args)
+    {
+        import core.stdc.stdio : fopen, fclose, remove;
+
+        remove("dynamiccast_endmain");
+        remove("dynamiccast_endbar");
+
+        C c = new C;
+
+        auto o = getFunc!(Object function(Object))("foo", args[0])(c);
+        assert(cast(C) o);
+
+        version (DMD_Win64)
+        {
+            // FIXME: apparent crash & needs more work, see https://github.com/dlang/druntime/pull/2874
+            fclose(fopen("dynamiccast_endbar", "w"));
+        }
+        else
+        {
+            bool caught;
+            try
+                getFunc!(void function(void function()))("bar", args[0])(
+                    { throw new C; });
+            catch (C e)
+                caught = true;
+            assert(caught);
+        }
+
+        // verify we've actually got to the end, because for some reason we can
+        // end up exiting with code 0 when throwing an exception
+        fclose(fopen("dynamiccast_endmain", "w"));
+    }
+}

test/shared/win64.mak

@@ -4,7 +4,7 @@ DMD=dmd
 MODEL=64
 DRUNTIMELIB=druntime64.lib
 
-test: loadlibwin dllrefcount dllgc
+test: loadlibwin dllrefcount dllgc dynamiccast
 
 dllrefcount:
 	$(DMD) -g -m$(MODEL) -conf= -Isrc -defaultlib=$(DRUNTIMELIB) test\shared\src\dllrefcount.d
@@ -21,3 +21,11 @@ dllgc:
 	$(DMD) -g -m$(MODEL) -conf= -Isrc -defaultlib=$(DRUNTIMELIB) -ofloaddllgc.exe test\shared\src\dllgc.d
 	loaddllgc.exe
 	del loaddllgc.exe loaddllgc.obj dllgc.dll dllgc.obj
+
+dynamiccast:
+	$(DMD) -g -m$(MODEL) -conf= -Isrc -defaultlib=$(DRUNTIMELIB) -version=DLL -shared -ofdynamiccast.dll test\shared\src\dynamiccast.d
+	$(DMD) -g -m$(MODEL) -conf= -Isrc -defaultlib=$(DRUNTIMELIB) -ofdynamiccast.exe test\shared\src\dynamiccast.d
+	dynamiccast.exe
+	cmd /c "if not exist dynamiccast_endbar exit 1"
+	cmd /c "if not exist dynamiccast_endmain exit 1"
+	del dynamiccast.exe dynamiccast.dll dynamiccast.obj dynamiccast_endbar dynamiccast_endmain