From 777c9215350e4ff1118fded7ecc27fa51f21bf24 Mon Sep 17 00:00:00 2001
From: Michael Davidsaver <mdavidsaver@gmail.com>
Date: Thu, 2 Jul 2026 18:40:52 -0700
Subject: [PATCH] Check for match of complex element types

eg. Array of Structure must have Structure elements.
---
 src/factory/FieldCreateFactory.cpp |  8 ++++++--
 testApp/misc/testSerialization.cpp | 31 +++++++++++++++++++++++++++++-
 2 files changed, 36 insertions(+), 3 deletions(-)

diff --git a/src/factory/FieldCreateFactory.cpp b/src/factory/FieldCreateFactory.cpp
index 561e8ee..b584ad9 100644
--- a/src/factory/FieldCreateFactory.cpp
+++ b/src/factory/FieldCreateFactory.cpp
@@ -1564,7 +1564,9 @@ FieldConstPtr FieldCreate::deserialize(ByteBuffer* buffer, DeserializableControl
                 throw std::invalid_argument("fixed and bounded structure array not supported");
 
             // Type type = Type.structureArray;
-            StructureConstPtr elementStructure = std::tr1::static_pointer_cast<const Structure>(control->cachedDeserialize(buffer));
+            StructureConstPtr elementStructure = std::tr1::dynamic_pointer_cast<const Structure>(control->cachedDeserialize(buffer));
+            if(!elementStructure)
+                throw std::invalid_argument("Expected Structure");
             // TODO use std::make_shared
             std::tr1::shared_ptr<Field> sp(new StructureArray(elementStructure));
             Helper::cache(this, sp);
@@ -1577,7 +1579,9 @@ FieldConstPtr FieldCreate::deserialize(ByteBuffer* buffer, DeserializableControl
                 throw std::invalid_argument("fixed and bounded structure array not supported");
 
             // Type type = Type.unionArray;
-            UnionConstPtr elementUnion = std::tr1::static_pointer_cast<const Union>(control->cachedDeserialize(buffer));
+            UnionConstPtr elementUnion = std::tr1::dynamic_pointer_cast<const Union>(control->cachedDeserialize(buffer));
+            if(!elementUnion)
+                throw std::invalid_argument("Expected Union");
             // TODO use std::make_shared
             std::tr1::shared_ptr<Field> sp(new UnionArray(elementUnion));
             Helper::cache(this, sp);
diff --git a/testApp/misc/testSerialization.cpp b/testApp/misc/testSerialization.cpp
index dcbef23..617586a 100644
--- a/testApp/misc/testSerialization.cpp
+++ b/testApp/misc/testSerialization.cpp
@@ -849,11 +849,38 @@ void testFromString(int byteOrder)
     testOk1(_data->getSubFieldT<PVString>("Y")->get()=="testing");
 }
 
+void testDeserializeTypeFail(const char *buf, size_t buflen)
+{
+
+    std::vector<char> bytes(buf, buf + buflen);
+    ByteBuffer B(&bytes[0], bytes.size(), EPICS_ENDIAN_BIG);
+
+    try{
+        FieldConstPtr ptr(getFieldCreate()->deserialize(&B, control));
+    }catch(std::exception& e) {
+        testPass("Expected exception: %s", e.what());
+        return;
+    }
+    testFail("Unexpected success? %d", __LINE__);
+}
+
+void testMalformed()
+{
+    testDiag("testMalformed()");
+
+#define CASE(STR) testDeserializeTypeFail(STR, sizeof(STR)-1)
+    // a structure array where the element type is not a structure
+    CASE("\x88\x83\x2b\x01\x01");
+    // a union array where ...
+    CASE("\x89\x83\x2b\x01\x01");
+#undef CASE
+}
+
 } // end namespace
 
 MAIN(testSerialization) {
 
-    testPlan(234);
+    testPlan(236);
 
     flusher = new SerializableControlImpl();
     control = new DeserializableControlImpl();
@@ -880,6 +907,8 @@ MAIN(testSerialization) {
     testFromString(EPICS_ENDIAN_BIG);
     testFromString(EPICS_ENDIAN_LITTLE);
 
+    testMalformed();
+
     delete buffer;
     delete control;
     delete flusher;