Add class cycle detection during unmarshaling (#946)

Add support for detection of class cycles during unmarshaling in
languages which do no have garbage collection: C++, Swift, and Objective-C.
A `MarshalException` is thrown when a cycle is detected.

The property `Ice.AcceptClassCycles` can be set to a value greater than `0`
to change this behavior.

4 files changed, 34 insertions, 1 deletions

diff --git a/java/src/Ice/src/main/java/com/zeroc/IceInternal/PropertyNames.java b/java/src/Ice/src/main/java/com/zeroc/IceInternal/PropertyNames.java
index 60078543e6f..3ba05d0bde6 100644
--- a/java/src/Ice/src/main/java/com/zeroc/IceInternal/PropertyNames.java
+++ b/java/src/Ice/src/main/java/com/zeroc/IceInternal/PropertyNames.java
@@ -1,7 +1,7 @@
 //
 // Copyright (c) ZeroC, Inc. All rights reserved.
 //
-// Generated by makeprops.py from file ./config/PropertyNames.xml, Fri Sep  6 18:11:04 2019
+// Generated by makeprops.py from file ./config/PropertyNames.xml, Thu Jul  2 14:55:02 2020
 
 // IMPORTANT: Do not edit this file -- any edits made here will be lost!
 
@@ -11,6 +11,7 @@ public final class PropertyNames
 {
     public static final Property IceProps[] =
     {
+        new Property("Ice\\.AcceptClassCycles", false, null),
         new Property("Ice\\.ACM\\.Client", true, null),
         new Property("Ice\\.ACM\\.Server", true, null),
         new Property("Ice\\.ACM\\.Timeout", false, null),
diff --git a/java/test/src/main/java/test/Ice/objects/AllTests.java b/java/test/src/main/java/test/Ice/objects/AllTests.java
index aa11250a6fa..d161292e807 100644
--- a/java/test/src/main/java/test/Ice/objects/AllTests.java
+++ b/java/test/src/main/java/test/Ice/objects/AllTests.java
@@ -435,6 +435,24 @@ public class AllTests
         }
         out.println("ok");
 
+        out.print("testing sending class cycle... ");
+        out.flush();
+        {
+            Recursive rec = new Recursive();
+            rec.v = rec;
+            boolean acceptsCycles = initial.acceptsClassCycles();
+            try
+            {
+                initial.setCycle(rec);
+                test(acceptsCycles);
+            }
+            catch(com.zeroc.Ice.UnknownLocalException ex)
+            {
+                test(!acceptsCycles);
+            }
+        }
+        out.println("ok");
+
         return initial;
     }
 }
diff --git a/java/test/src/main/java/test/Ice/objects/InitialI.java b/java/test/src/main/java/test/Ice/objects/InitialI.java
index 7760480f1e9..125427eb06a 100644
--- a/java/test/src/main/java/test/Ice/objects/InitialI.java
+++ b/java/test/src/main/java/test/Ice/objects/InitialI.java
@@ -112,6 +112,17 @@ public final class InitialI implements Initial
     }
 
     @Override
+    public void setCycle(Recursive r, com.zeroc.Ice.Current current)
+    {
+    }
+
+    @Override
+    public boolean acceptsClassCycles(com.zeroc.Ice.Current current)
+    {
+        return true;
+    }
+
+    @Override
     public com.zeroc.Ice.Value getI(com.zeroc.Ice.Current current)
     {
         return new II();
diff --git a/java/test/src/main/java/test/Ice/objects/Test.ice b/java/test/src/main/java/test/Ice/objects/Test.ice
index 50e6248fd4a..a0862f9f4f4 100644
--- a/java/test/src/main/java/test/Ice/objects/Test.ice
+++ b/java/test/src/main/java/test/Ice/objects/Test.ice
@@ -216,6 +216,9 @@ interface Initial
     void setRecursive(Recursive p);
     bool supportsClassGraphDepthMax();
 
+    void setCycle(Recursive r);
+    bool acceptsClassCycles();
+
     ["marshaled-result"] B getMB();
     ["amd", "marshaled-result"] B getAMDMB();