Unable to load plugin DLLs compiled with the '/clr' option

Before loading the plugins, to make sure we are loading a valid one,
we call qt_plugin_query_verification_data() and verify the version
information. The DLLS built with '/clr' compiler flag, needs full
initialization before a function can be called.
With a prior patch, as an optimaization we had changed LoadLibrary()
to LoadLibraryEx(), this will not initialize or load the dependencies,
so it crashed when calling that function. Now this exception is
caught and LoadLibrary(equivalent) is called.

Task-number: QTBUG-10012
Reviewed-by: Jan-Arve

1 files changed, 96 insertions, 44 deletions

diff --git a/src/corelib/plugin/qlibrary.cpp b/src/corelib/plugin/qlibrary.cpp
index 0f99948..2ed113d 100644
--- a/src/corelib/plugin/qlibrary.cpp
+++ b/src/corelib/plugin/qlibrary.cpp
@@ -609,6 +609,46 @@ bool QLibrary::isLibrary(const QString &fileName)
 
 }
 
+#if defined (Q_OS_WIN) && defined(_MSC_VER) && _MSC_VER >= 1400  && !defined(Q_CC_INTEL)
+#define QT_USE_MS_STD_EXCEPTION 1
+const char* qt_try_versioninfo(void *pfn, bool *exceptionThrown)
+{
+    *exceptionThrown = false;
+    const char *szData = 0;
+    typedef const char * (*VerificationFunction)();
+    VerificationFunction func = reinterpret_cast<VerificationFunction>(pfn);
+    __try {
+        if(func)
+            szData =  func();
+    } __except(EXCEPTION_EXECUTE_HANDLER) {
+        *exceptionThrown = true;
+    }
+    return szData;
+}
+#endif
+
+#ifdef Q_CC_BOR
+typedef const char * __stdcall (*QtPluginQueryVerificationDataFunction)();
+#else
+typedef const char * (*QtPluginQueryVerificationDataFunction)();
+#endif
+
+bool qt_get_verificationdata(QtPluginQueryVerificationDataFunction pfn, uint *qt_version, bool *debug, QByteArray *key, bool *exceptionThrown)
+{
+    *exceptionThrown = false;
+    const char *szData = 0;
+    if (!pfn)
+        return false;
+#ifdef QT_USE_MS_STD_EXCEPTION
+    szData = qt_try_versioninfo((void *)pfn, exceptionThrown);
+    if (*exceptionThrown)
+        return false;
+#else
+    szData = pfn();
+#endif
+    return qt_parse_pattern(szData, qt_version, debug, key);
+}
+
 bool QLibraryPrivate::isPlugin(QSettings *settings)
 {
     errorString.clear();
@@ -684,70 +724,82 @@ bool QLibraryPrivate::isPlugin(QSettings *settings)
         } else
 #endif
         {
-            bool temporary_load = false;
+            bool retryLoadLibrary = false;    // Only used on Windows with MS compiler.(false in other cases)
+            do {
+                bool temporary_load = false;
 #ifdef Q_OS_WIN
-            HMODULE hTempModule = 0;
+                HMODULE hTempModule = 0;
 #endif
-            if (!pHnd) {
+                if (!pHnd) {
 #ifdef Q_OS_WIN
-                //avoid 'Bad Image' message box
-                UINT oldmode = SetErrorMode(SEM_FAILCRITICALERRORS|SEM_NOOPENFILEERRORBOX);
-                hTempModule = ::LoadLibraryEx((wchar_t*)QDir::toNativeSeparators(fileName).utf16(), 0, DONT_RESOLVE_DLL_REFERENCES);
-                SetErrorMode(oldmode);
+                    DWORD dwFlags = (retryLoadLibrary) ? 0: DONT_RESOLVE_DLL_REFERENCES;
+                    //avoid 'Bad Image' message box
+                    UINT oldmode = SetErrorMode(SEM_FAILCRITICALERRORS|SEM_NOOPENFILEERRORBOX);
+                    hTempModule = ::LoadLibraryEx((wchar_t*)QDir::toNativeSeparators(fileName).utf16(), 0, dwFlags);
+                    SetErrorMode(oldmode);
 #else
 #  if defined(Q_OS_SYMBIAN)
-                //Guard against accidentally trying to load non-plugin libraries by making sure the stub exists
-                if (fileinfo.exists())
+                    //Guard against accidentally trying to load non-plugin libraries by making sure the stub exists
+                    if (fileinfo.exists())
 #  endif
-                temporary_load =  load_sys();
+                        temporary_load =  load_sys();
 #endif
-            }
-#  ifdef Q_CC_BOR
-            typedef const char * __stdcall (*QtPluginQueryVerificationDataFunction)();
-#  else
-            typedef const char * (*QtPluginQueryVerificationDataFunction)();
-#  endif
+                }
 #ifdef Q_OS_WIN
-            QtPluginQueryVerificationDataFunction qtPluginQueryVerificationDataFunction = hTempModule
-                ? (QtPluginQueryVerificationDataFunction)
+                QtPluginQueryVerificationDataFunction qtPluginQueryVerificationDataFunction = hTempModule ? (QtPluginQueryVerificationDataFunction)
 #ifdef Q_OS_WINCE
-                    ::GetProcAddress(hTempModule, L"qt_plugin_query_verification_data")
+                        ::GetProcAddress(hTempModule, L"qt_plugin_query_verification_data")
 #else
-                    ::GetProcAddress(hTempModule, "qt_plugin_query_verification_data")
+                        ::GetProcAddress(hTempModule, "qt_plugin_query_verification_data")
 #endif
                 : (QtPluginQueryVerificationDataFunction) resolve("qt_plugin_query_verification_data");
 #else
-            QtPluginQueryVerificationDataFunction qtPluginQueryVerificationDataFunction = NULL;
+                QtPluginQueryVerificationDataFunction qtPluginQueryVerificationDataFunction = NULL;
 #  if defined(Q_OS_SYMBIAN)
-            if (temporary_load) {
-                qtPluginQueryVerificationDataFunction = (QtPluginQueryVerificationDataFunction) resolve("qt_plugin_query_verification_data");
-                // If resolving with function name failed (i.e. not STDDLL), try resolving using known ordinal
-                if (!qtPluginQueryVerificationDataFunction)
-                    qtPluginQueryVerificationDataFunction = (QtPluginQueryVerificationDataFunction) resolve("1");
-            }
+                if (temporary_load) {
+                    qtPluginQueryVerificationDataFunction = (QtPluginQueryVerificationDataFunction) resolve("qt_plugin_query_verification_data");
+                    // If resolving with function name failed (i.e. not STDDLL), try resolving using known ordinal
+                    if (!qtPluginQueryVerificationDataFunction)
+                        qtPluginQueryVerificationDataFunction = (QtPluginQueryVerificationDataFunction) resolve("1");
+                }
 #  else
-            qtPluginQueryVerificationDataFunction = (QtPluginQueryVerificationDataFunction) resolve("qt_plugin_query_verification_data");
+                qtPluginQueryVerificationDataFunction = (QtPluginQueryVerificationDataFunction) resolve("qt_plugin_query_verification_data");
 #  endif
 #endif
-
-            if (!qtPluginQueryVerificationDataFunction
-                || !qt_parse_pattern(qtPluginQueryVerificationDataFunction(), &qt_version, &debug, &key)) {
-                qt_version = 0;
-                key = "unknown";
-                if (temporary_load)
-                    unload_sys();
-            } else {
-                success = true;
-            }
-#ifdef Q_OS_WIN
-            if (hTempModule) {
-                BOOL ok = ::FreeLibrary(hTempModule);
-                if (ok) {
-                    hTempModule = 0;
+                bool exceptionThrown = false;
+                bool ret = qt_get_verificationdata(qtPluginQueryVerificationDataFunction,
+                                                   &qt_version, &debug, &key, &exceptionThrown);
+                if (!exceptionThrown) {
+                    if (!ret) {
+                        qt_version = 0;
+                        key = "unknown";
+                        if (temporary_load)
+                            unload_sys();
+                    } else {
+                        success = true;
+                    }
+                    retryLoadLibrary = false;
+                }
+#ifdef QT_USE_MS_STD_EXCEPTION
+                else {
+                    // An exception was thrown when calling qt_plugin_query_verification_data().
+                    // This usually happens when plugin is compiled with the /clr compiler flag,
+                    // & will only work if the dependencies are loaded & DLLMain() is called.
+                    // LoadLibrary() will do this, try once with this & if it fails dont load.
+                    retryLoadLibrary = !retryLoadLibrary;
                 }
+#endif
+#ifdef Q_OS_WIN
+                if (hTempModule) {
+                    BOOL ok = ::FreeLibrary(hTempModule);
+                    if (ok) {
+                        hTempModule = 0;
+                    }
 
-            }
+                }
 #endif
+            } while(retryLoadLibrary);  // Will be 'false' in all cases other than when an
+                                        // exception is thrown(will happen only when using a MS compiler)
         }
 
         // Qt 4.5 compatibility: stl doesn't affect binary compatibility