Windows: use QSystemLibrary instead of LoadLibrary directly (qt#77)

* Windows: use QSystemLibrary instead of LoadLibrary directly

Using QSystemLibrary ensures that it will only use the expected copy of
the system library and not one that has been placed in the application's
working directory or elsewhere in the PATH environment variable.

Pick-to: 5.15 6.2 6.3
Change-Id: Ic4234334f73482b38ee5f06345bf11f8c029edc5
Reviewed-by: Laszlo Agocs <laszlo.agocs@qt.io>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>

* Windows: use QSystemLibrary instead of LoadLibrary directly (5.15)

This is the rest of the patch that is specific to Qt 5.15.

Using QSystemLibrary ensures that it will only use the expected copy of
the system library and not one that has been placed in the application's
working directory or elsewhere in the PATH environment variable.

Change-Id: Ic559957f5ca2e53193a1c230577f877b09e90859

Co-authored-by: Andy Shaw <andy.shaw@qt.io>
Co-authored-by: Keith Kyzivat <keith.kyzivat@qt.io>

src/corelib/io/qlockfile_win.cpp

@@ -48,6 +48,8 @@
 #include "QtCore/qdebug.h"
 #include "QtCore/qthread.h"
 
+#include "private/qsystemlibrary_p.h"
+
 QT_BEGIN_NAMESPACE
 
 static inline bool fileExists(const wchar_t *fileName)
@@ -150,7 +152,7 @@ QString QLockFilePrivate::processNameByPid(qint64 pid)
 #if !defined(Q_OS_WINRT)
  typedef DWORD (WINAPI *GetModuleFileNameExFunc)(HANDLE, HMODULE, LPTSTR, DWORD);
 
- HMODULE hPsapi = LoadLibraryA("psapi");
+ HMODULE hPsapi = QSystemLibrary::load(L"psapi");
  if (!hPsapi)
  return QString();
  GetModuleFileNameExFunc qGetModuleFileNameEx = reinterpret_cast<GetModuleFileNameExFunc>(

src/network/kernel/qauthenticator.cpp

@@ -50,6 +50,7 @@
 #include <qstring.h>
 #include <qdatetime.h>
 #include <qrandom.h>
+#include "private/qsystemlibrary_p.h"
 
 #ifdef Q_OS_WIN
 #include <qmutex.h>
@@ -1542,7 +1543,7 @@ static bool q_SSPI_library_load()
 
  // Initialize security interface
  if (pSecurityFunctionTable == nullptr) {
- securityDLLHandle = LoadLibrary(L"secur32.dll");
+ securityDLLHandle = QSystemLibrary::load(L"secur32");
  if (securityDLLHandle != nullptr) {
  INIT_SECURITY_INTERFACE pInitSecurityInterface =
  reinterpret_cast<INIT_SECURITY_INTERFACE>(

src/plugins/platforms/windows/qwindowsglcontext.cpp

@@ -48,6 +48,7 @@
 #include <qpa/qplatformnativeinterface.h>
 #include <QtPlatformHeaders/qwglnativecontext.h>
 
+#include <private/qsystemlibrary_p.h>
 #include <algorithm>
 
 #include <wingdi.h>
@@ -162,19 +163,25 @@ QFunctionPointer QWindowsOpengl32DLL::resolve(const char *name)
 
 bool QWindowsOpengl32DLL::init(bool softwareRendering)
 {
- const QByteArray opengl32 = QByteArrayLiteral("opengl32.dll");
- const QByteArray swopengl = QByteArrayLiteral("opengl32sw.dll");
+ const QByteArray opengl32 = QByteArrayLiteral("opengl32");
+ const QByteArray swopengl = QByteArrayLiteral("opengl32sw");
+ bool useSystemLib = false;
 
  QByteArray openglDll = qgetenv("QT_OPENGL_DLL");
- if (openglDll.isEmpty())
+ if (openglDll.isEmpty()) {
  openglDll = softwareRendering ? swopengl : opengl32;
+ useSystemLib = !softwareRendering;
+ }
 
  openglDll = openglDll.toLower();
  m_nonOpengl32 = openglDll != opengl32;
 
  qCDebug(lcQpaGl) << "Qt: Using WGL and OpenGL from" << openglDll;
 
- m_lib = ::LoadLibraryA(openglDll.constData());
+ if (useSystemLib)
+ m_lib = QSystemLibrary::load((wchar_t*)(QString::fromLatin1(openglDll).utf16()));
+ else
+ m_lib = LoadLibraryA(openglDll.constData());
  if (!m_lib) {
  qErrnoWarning(::GetLastError(), "Failed to load %s", openglDll.constData());
  return false;
@@ -184,7 +191,7 @@ bool QWindowsOpengl32DLL::init(bool softwareRendering)
  // Load opengl32.dll always. GDI functions like ChoosePixelFormat do
  // GetModuleHandle for opengl32.dll and behave differently (and call back into
  // opengl32) when the module is present. This is fine for dummy contexts and windows.
- ::LoadLibraryA("opengl32.dll");
+ QSystemLibrary::load(L"opengl32");
  }
 
  wglCreateContext = reinterpret_cast<HGLRC (WINAPI *)(HDC)>(resolve("wglCreateContext"));

src/plugins/platforms/windows/qwindowsopengltester.cpp

@@ -49,6 +49,7 @@
 #include <QtCore/qstandardpaths.h>
 #include <QtCore/qlibraryinfo.h>
 #include <QtCore/qhash.h>
+#include <private/qsystemlibrary_p.h>
 
 #ifndef QT_NO_OPENGL
 #include <private/qopengl_p.h>
@@ -396,7 +397,7 @@ bool QWindowsOpenGLTester::testDesktopGL()
 
  // Test #1: Load opengl32.dll and try to resolve an OpenGL 2 function.
  // This will typically fail on systems that do not have a real OpenGL driver.
- lib = LoadLibraryA("opengl32.dll");
+ lib = QSystemLibrary::load(L"opengl32");
  if (lib) {
  CreateContext = reinterpret_cast<CreateContextType>(
  reinterpret_cast<QFunctionPointer>(::GetProcAddress(lib, "wglCreateContext")));