2007-07-02 <aconway@redhat.com

         * qpid/sys/Shlib.h, .cpp: Portable shared library abstraction.
          - Shlib: load, unload, getSymbol
          - AutoShlib: unload in destructor.
         * qpid/sys/apr/Shlib.cpp sys/posix/Shlib.cpp: APR/Posix impls

         * qpid/sys/Module.h: Reimplemented Module in terms of AutoShlib.
         * qpid/Plugin.cpp, .h: Removed dlopen - use Shlib instead.

         * qpid/broker/Broker.cpp: Added missing #include "qpid/log/Statement.h"
         * tests/Shlib.cpp, shlibtest.cpp: Unit test


git-svn-id: https://svn.apache.org/repos/asf/incubator/qpid/trunk/qpid@553056 13f79535-47bb-0310-9956-ffa450edef68

10 files changed, 293 insertions, 323 deletions

diff --git a/cpp/src/qpid/Plugin.cpp b/cpp/src/qpid/Plugin.cpp
index 31fab65995..c6513d33e8 100644
--- a/cpp/src/qpid/Plugin.cpp
+++ b/cpp/src/qpid/Plugin.cpp
@@ -1,18 +1,20 @@
 /*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
  *
- * Copyright (c) 2006 The Apache Software Foundation
+ *   http://www.apache.org/licenses/LICENSE-2.0
  *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *    http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
  *
  */
 
@@ -34,38 +36,5 @@ Options*  PluginProvider::getOptions() { return 0; }
 const std::vector<PluginProvider*>& PluginProvider::getProviders() {
     return providers;
 }
-} // namespace qpid
-
-// TODO aconway 2007-06-28: GNU lib has portable dlopen if we go that way.
 
-#ifdef USE_APR_PLATFORM
-
-#include "qpid/sys/apr/APRBase.h"
-#include "qpid/sys/apr/APRPool.h"
-#include <apr_dso.h>
-
-namespace qpid {
-void dlopen(const char* name) {
-    apr_dso_handle_t* handle;
-    CHECK_APR_SUCCESS(
-        apr_dso_load(&handle, name, sys::APRPool::get()));
-}
 } // namespace qpid
-
-#else // Posix
-
-#include "qpid/sys/posix/check.h"
-#include <dlfcn.h>
-
-namespace qpid {
-void dlopen(const char* name) {
-    ::dlerror();
-    ::dlopen(name, RTLD_NOW);
-    const char* error = ::dlerror();
-    if (error) {
-        THROW_QPID_ERROR(INTERNAL_ERROR, error);
-    }
-}
-} // namespace qpidpp
-
-#endif // USE_APR_PLATFORM
diff --git a/cpp/src/qpid/Plugin.h b/cpp/src/qpid/Plugin.h
index 48fb16a541..f50e97eb00 100644
--- a/cpp/src/qpid/Plugin.h
+++ b/cpp/src/qpid/Plugin.h
@@ -2,20 +2,22 @@
 #define QPID_PLUGIN_H
 
 /*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
  *
- * Copyright (c) 2006 The Apache Software Foundation
+ *   http://www.apache.org/licenses/LICENSE-2.0
  *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *    http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
  *
  */
 
@@ -53,7 +55,6 @@ struct PluginUser : boost::noncopyable {
     virtual void use(const shared_ptr<Plugin>& plugin) = 0;
 };
 
-
 /**
  * Base for classes that provide plug-ins.
  */
@@ -97,15 +98,6 @@ class PluginProvider : boost::noncopyable
     static std::vector<PluginProvider*> providers;
 };
  
-/** Load a shared library, registering any PluginProvider it contains.
- * 
- * This is just a convenient portable wrapper for normal shared
- * library loading. A global PluginProvider instance loaded or
- * linked in any way will get registered.
- */
-void dlopen(const char* libname);
-
-   
 } // namespace qpid
 
 #endif  /*!QPID_PLUGIN_H*/
diff --git a/cpp/src/qpid/broker/Broker.cpp b/cpp/src/qpid/broker/Broker.cpp
index 43a5567b3d..9c8e98ec9a 100644
--- a/cpp/src/qpid/broker/Broker.cpp
+++ b/cpp/src/qpid/broker/Broker.cpp
@@ -21,22 +21,24 @@
 
 #include "Broker.h"
 
-#include "qpid/framing/AMQFrame.h"
-#include "qpid/framing/HandlerUpdater.h"
+#include "Connection.h"
 #include "DirectExchange.h"
-#include "TopicExchange.h"
 #include "FanOutExchange.h"
 #include "HeadersExchange.h"
 #include "MessageStoreModule.h"
 #include "NullMessageStore.h"
-#include "qpid/framing/ProtocolInitiation.h"
 #include "RecoveryManagerImpl.h"
-#include "Connection.h"
+#include "TopicExchange.h"
+
+#include "qpid/log/Statement.h"
+#include "qpid/Url.h"
+#include "qpid/framing/AMQFrame.h"
+#include "qpid/framing/HandlerUpdater.h"
+#include "qpid/framing/ProtocolInitiation.h"
 #include "qpid/sys/Acceptor.h"
 #include "qpid/sys/ConnectionInputHandler.h"
 #include "qpid/sys/ConnectionInputHandlerFactory.h"
 #include "qpid/sys/TimeoutHandler.h"
-#include "qpid/Url.h"
 
 #include <iostream>
 #include <memory>
diff --git a/cpp/src/qpid/sys/Module.h b/cpp/src/qpid/sys/Module.h
index e812f57d7a..79793ed0ca 100644
--- a/cpp/src/qpid/sys/Module.h
+++ b/cpp/src/qpid/sys/Module.h
@@ -1,5 +1,5 @@
-#ifndef _sys_Module_h
-#define _sys_Module_h
+#ifndef QPID_SYS_MODULE_H
+#define QPID_SYS_MODULE_H
 
 /*
  *
@@ -21,11 +21,30 @@
  * under the License.
  *
  */
- 
-#ifdef USE_APR_PLATFORM
-#include "apr/Module.h"
-#else 
-#include "posix/Module.h"
-#endif
 
-#endif //ifndef _sys_Module_h
+#include "qpid/sys/Shlib.h"
+#include <boost/noncopyable.hpp>
+
+namespace qpid {
+namespace sys {
+
+template <class T> class Module : public AutoShlib, private boost::noncopyable
+{
+  public:
+    Module(const std::string& name) :
+        AutoShlib(name),
+        ptr(getSymbol<T*(*)()>("create")()) {}
+                
+    T* get() { return ptr; }
+    T* operator->() { return ptr; }
+    ~Module() throw() {
+        getSymbol<void (*)(T*)>("destroy")(ptr);
+    }
+
+  private:
+    T* ptr;
+};
+
+}}
+
+#endif  /*!QPID_SYS_MODULE_H*/
diff --git a/cpp/src/qpid/sys/Shlib.cpp b/cpp/src/qpid/sys/Shlib.cpp
new file mode 100644
index 0000000000..8fd3f42cc6
--- /dev/null
+++ b/cpp/src/qpid/sys/Shlib.cpp
@@ -0,0 +1,38 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ *
+ */
+
+#include "Shlib.h"
+
+#include "qpid/log/Statement.h"
+
+namespace qpid {
+namespace sys {
+
+AutoShlib::~AutoShlib() throw() {
+    try {
+        unload();
+    } catch(const std::exception& e) {
+        QPID_LOG(error, "Unloading shared library: " << e.what());
+    }
+}
+
+// Note: Other functions are defined in apr/Shlib.cpp or posix/Shlib.cpp.
+    
+}} // namespace qpid::sys
diff --git a/cpp/src/qpid/sys/Shlib.h b/cpp/src/qpid/sys/Shlib.h
new file mode 100644
index 0000000000..debf231125
--- /dev/null
+++ b/cpp/src/qpid/sys/Shlib.h
@@ -0,0 +1,82 @@
+#ifndef QPID_SYS_SHLIB_H
+#define QPID_SYS_SHLIB_H
+
+/*
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ * 
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ *
+ */
+ 
+#include <boost/noncopyable.hpp>
+#include <iostream>
+#include <dlfcn.h>
+
+namespace qpid {
+namespace sys {
+
+/** Encapsulates a shared library handle.
+ *@see AutoShlib
+ */
+class Shlib {
+  public:
+    /** Load a shared library */
+    Shlib(const char* libname) { load(libname); }
+
+    /** Load a shared library */
+    Shlib(const std::string& libname) { load(libname.c_str()); }
+
+    /** Unload shared library. */
+    void unload();
+
+    /** Look up symbol. */
+    void* getSymbol(const char* symbol);
+
+    /** Look up symbol in shared library, cast it to the desired
+     * pointer type, void* by default.
+     */
+    template <class T>
+    T getSymbol(const char* symbol) {
+        // Double cast avoids warning about casting object to function pointer
+        return reinterpret_cast<T>(reinterpret_cast<intptr_t>(
+                                       this->getSymbol(symbol)));
+    }
+    
+    /** Look up symbol in shared library. */
+        template <class T*>
+    void* getSymbol(const std::string& symbol) {
+        return getSymbol<T>(symbol.c_str());
+    }
+
+  private:
+    void* handle;
+    void load(const char* libname);
+};
+
+/** A shared library handle that unloads the shlib in it's dtor */
+class AutoShlib : public Shlib {
+  public:
+    /** Load shared library */
+    AutoShlib(const std::string& libname) : Shlib(libname) {}
+    /** Calls unload() */
+    ~AutoShlib() throw();
+};
+
+    
+}} // namespace qpid::sys
+
+#endif  /*!QPID_SYS_SHLIB_H*/
diff --git a/cpp/src/qpid/sys/apr/Module.h b/cpp/src/qpid/sys/apr/Module.h
deleted file mode 100644
index ff93a0eaf0..0000000000
--- a/cpp/src/qpid/sys/apr/Module.h
+++ /dev/null
@@ -1,114 +0,0 @@
-#ifndef _sys_apr_Module_h
-#define _sys_apr_Module_h
-
-/*
- *
- * Licensed to the Apache Software Foundation (ASF) under one
- * or more contributor license agreements.  See the NOTICE file
- * distributed with this work for additional information
- * regarding copyright ownership.  The ASF licenses this file
- * to you under the Apache License, Version 2.0 (the
- * "License"); you may not use this file except in compliance
- * with the License.  You may obtain a copy of the License at
- * 
- *   http://www.apache.org/licenses/LICENSE-2.0
- * 
- * Unless required by applicable law or agreed to in writing,
- * software distributed under the License is distributed on an
- * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
- * KIND, either express or implied.  See the License for the
- * specific language governing permissions and limitations
- * under the License.
- *
- */
-#include "qpid/log/Statement.h"
-#include "qpid/QpidError.h"
-#include "APRBase.h"
-#include "APRPool.h"
-
-#include <boost/noncopyable.hpp>
-#include <iostream>
-#include <apr_dso.h>
-
-namespace qpid {
-namespace sys {
-
-typedef apr_dso_handle_t* dso_handle_t;
-
-template <class T> class Module : private boost::noncopyable
-{
-    typedef T* create_t();
-    typedef void destroy_t(T*);
-    
-    dso_handle_t handle;
-    destroy_t* destroy;
-    T* ptr;
-
-    void load(const std::string& name);
-    void unload();
-    void* getSymbol(const std::string& name);
-
-public:
-    Module(const std::string& name);
-    T* operator->(); 
-    T* get(); 
-    ~Module() throw();
-};
-
-template <class T> Module<T>::Module(const std::string& module) : destroy(0), ptr(0) 
-{
-    load(module);
-    //TODO: need a better strategy for symbol names to allow multiple
-    //modules to be loaded without clashes...
-
-    //Note: need the double cast to avoid errors in casting from void* to function pointer with -pedantic
-    create_t* create = reinterpret_cast<create_t*>(reinterpret_cast<intptr_t>(getSymbol("create")));
-    destroy = reinterpret_cast<destroy_t*>(reinterpret_cast<intptr_t>(getSymbol("destroy")));
-    ptr = create();
-}
-
-template <class T> T* Module<T>::operator->() 
-{ 
-    return ptr; 
-}
-
-template <class T> T* Module<T>::get() 
-{ 
-    return ptr; 
-}
-
-template <class T> Module<T>::~Module() throw()
-{
-    try {
-        if (handle && ptr) {
-            destroy(ptr);
-        }
-        if (handle) unload();
-    } catch (std::exception& e) {
-        QPID_LOG(error, "Error while destroying module: " << e.what());
-    }
-    destroy = 0;
-    handle = 0;
-    ptr = 0;
-}
-
-template <class T> void Module<T>::load(const std::string& name)
-{
-    CHECK_APR_SUCCESS(apr_dso_load(&handle, name.c_str(), APRPool::get()));
-}
-
-template <class T> void Module<T>::unload()
-{
-    CHECK_APR_SUCCESS(apr_dso_unload(handle));
-}
-
-template <class T> void* Module<T>::getSymbol(const std::string& name)
-{
-    apr_dso_handle_sym_t symbol;
-    CHECK_APR_SUCCESS(apr_dso_sym(&symbol, handle, name.c_str()));
-    return (void*) symbol;
-}
-
-}}
-#endif //ifndef _sys_apr_Module_h
-
diff --git a/cpp/src/qpid/sys/apr/Shlib.cpp b/cpp/src/qpid/sys/apr/Shlib.cpp
new file mode 100644
index 0000000000..b0ba706713
--- /dev/null
+++ b/cpp/src/qpid/sys/apr/Shlib.cpp
@@ -0,0 +1,49 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ *
+ */
+
+#include "qpid/sys/Shlib.h"
+#include "APRBase.h"
+#include "APRPool.h"
+#include <apr_dso.h>
+
+namespace qpid {
+namespace sys {
+
+void Shlib::load(const char* libname) {
+    apr_dso_handle_t* aprHandle; 
+    CHECK_APR_SUCCESS(
+        apr_dso_load(&aprHandle, libname, APRPool::get()));
+    handle=aprHandle;
+}
+
+void  Shlib::unload() {
+    CHECK_APR_SUCCESS(
+        apr_dso_unload(static_cast<apr_dso_handle_t*>(handle)));
+}
+
+void*  Shlib::getSymbol(const char* name) {
+    apr_dso_handle_sym_t symbol;
+    CHECK_APR_SUCCESS(apr_dso_sym(&symbol,
+                                  static_cast<apr_dso_handle_t*>(handle),
+                                  name));
+    return (void*) symbol;
+}
+
+}} // namespace qpid::sys
diff --git a/cpp/src/qpid/sys/posix/Module.h b/cpp/src/qpid/sys/posix/Module.h
deleted file mode 100644
index 5a0358a748..0000000000
--- a/cpp/src/qpid/sys/posix/Module.h
+++ /dev/null
@@ -1,127 +0,0 @@
-#ifndef _sys_posix_Module_h
-#define _sys_posix_Module_h
-
-/*
- *
- * Licensed to the Apache Software Foundation (ASF) under one
- * or more contributor license agreements.  See the NOTICE file
- * distributed with this work for additional information
- * regarding copyright ownership.  The ASF licenses this file
- * to you under the Apache License, Version 2.0 (the
- * "License"); you may not use this file except in compliance
- * with the License.  You may obtain a copy of the License at
- * 
- *   http://www.apache.org/licenses/LICENSE-2.0
- * 
- * Unless required by applicable law or agreed to in writing,
- * software distributed under the License is distributed on an
- * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
- * KIND, either express or implied.  See the License for the
- * specific language governing permissions and limitations
- * under the License.
- *
- */
- 
-#include "qpid/QpidError.h"
-#include "qpid/log/Statement.h"
-
-#include <boost/noncopyable.hpp>
-#include <iostream>
-#include <dlfcn.h>
-
-namespace qpid {
-namespace sys {
-
-typedef void* dso_handle_t;
-
-template <class T> class Module : private boost::noncopyable
-{
-    typedef T* create_t();
-    typedef void destroy_t(T*);
-    
-    dso_handle_t handle;
-    destroy_t* destroy;
-    T* ptr;
-
-    void load(const std::string& name);
-    void unload();
-    void* getSymbol(const std::string& name);
-
-public:
-    Module(const std::string& name);
-    T* operator->(); 
-    T* get(); 
-    ~Module() throw();
-};
-
-template <class T> Module<T>::Module(const std::string& module) : destroy(0), ptr(0) 
-{
-    load(module);
-    //TODO: need a better strategy for symbol names to allow multiple
-    //modules to be loaded without clashes...
-
-    //Note: need the double cast to avoid errors in casting from void* to function pointer with -pedantic
-    create_t* create = reinterpret_cast<create_t*>(reinterpret_cast<intptr_t>(getSymbol("create")));
-    destroy = reinterpret_cast<destroy_t*>(reinterpret_cast<intptr_t>(getSymbol("destroy")));
-    ptr = create();
-}
-
-template <class T> T* Module<T>::operator->() 
-{ 
-    return ptr; 
-}
-
-template <class T> T* Module<T>::get() 
-{ 
-    return ptr; 
-}
-
-template <class T> Module<T>::~Module() throw()
-{
-    try {
-        if (handle && ptr) {
-            destroy(ptr);
-        }
-        if (handle) unload();
-    } catch (std::exception& e) {
-        QPID_LOG(error, "Error while destroying module: " << e.what());
-    }
-    destroy = 0;
-    handle = 0;
-    ptr = 0;
-}
-
-template <class T> void Module<T>::load(const std::string& name)
-{
-    ::dlerror();
-    handle = ::dlopen(name.c_str(), RTLD_NOW);
-    const char* error = ::dlerror();
-    if (error) {
-        THROW_QPID_ERROR(INTERNAL_ERROR, error);
-    }
-}
-
-template <class T> void Module<T>::unload()
-{
-    dlerror();
-    dlclose(handle);
-    const char* error = dlerror();
-    if (error) {
-        THROW_QPID_ERROR(INTERNAL_ERROR, error);
-    }
-}
-
-template <class T> void* Module<T>::getSymbol(const std::string& name)
-{
-    dlerror();
-    void* sym = dlsym(handle, name.c_str());
-    const char* error = dlerror();
-    if (error) {
-        THROW_QPID_ERROR(INTERNAL_ERROR, error);
-    }
-    return sym;
-}
-
-}}
-#endif //ifndef _sys_posix_Module_h
-
diff --git a/cpp/src/qpid/sys/posix/Shlib.cpp b/cpp/src/qpid/sys/posix/Shlib.cpp
new file mode 100644
index 0000000000..2630337408
--- /dev/null
+++ b/cpp/src/qpid/sys/posix/Shlib.cpp
@@ -0,0 +1,60 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ *
+ */
+
+#include "qpid/sys/Shlib.h"
+
+#include <qpid/QpidError.h>
+#include <dlfcn.h>
+
+
+namespace qpid {
+namespace sys {
+
+void Shlib::load(const char* name) {
+    dlerror();
+    handle = ::dlopen(name, RTLD_NOW);
+    const char* error = ::dlerror();
+    if (error) {
+        THROW_QPID_ERROR(INTERNAL_ERROR, error);
+    }
+}
+
+void  Shlib::unload() {
+    if (handle) {
+        ::dlerror();
+        ::dlclose(handle);
+        const char* error = ::dlerror();
+        if (error) {
+            THROW_QPID_ERROR(INTERNAL_ERROR, error);
+        }
+        handle = 0;
+    }
+}
+
+void*  Shlib::getSymbol(const char* name) {
+    ::dlerror();
+    void* sym = ::dlsym(handle, name);
+    const char* error = ::dlerror();
+    if (error) 
+        THROW_QPID_ERROR(INTERNAL_ERROR, error);
+    return sym;
+}
+
+}} // namespace qpid::sys