From a8187e7dc47cd344fd309a2be3675e4687f95aaa Mon Sep 17 00:00:00 2001
From: isanae <14251494+isanae@users.noreply.github.com>
Date: Sat, 7 Nov 2020 16:31:35 -0500
Subject: moved dlls stuff to MOApplication

---
 src/moapplication.cpp | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 48 insertions(+)

(limited to 'src/moapplication.cpp')

diff --git a/src/moapplication.cpp b/src/moapplication.cpp
index 659b5a12..f514050f 100644
--- a/src/moapplication.cpp
+++ b/src/moapplication.cpp
@@ -19,6 +19,7 @@ along with Mod Organizer.  If not, see <http://www.gnu.org/licenses/>.
 
 #include "moapplication.h"
 #include "settings.h"
+#include "env.h"
 #include <iplugingame.h>
 #include <report.h>
 #include <utility.h>
@@ -32,6 +33,12 @@ along with Mod Organizer.  If not, see <http://www.gnu.org/licenses/>.
 #include <QStyleOption>
 #include <QDebug>
 
+// see addDllsToPath() below
+#pragma comment(linker, "/manifestDependency:\"" \
+    "name='dlls' " \
+    "processorArchitecture='x86' " \
+    "version='1.0.0.0' " \
+    "type='win32' \"")
 
 using namespace MOBase;
 
@@ -73,6 +80,45 @@ public:
 };
 
 
+// This adds the `dlls` directory to the path so the dlls can be found. How
+// MO is able to find dlls in there is a bit convoluted:
+//
+// Dependencies on DLLs can be baked into an executable by passing a
+// `manifestdependency` option to the linker. This can be done on the command
+// line or with a pragma. Typically, the dependency will not be a hardcoded
+// filename, but an assembly name, such as Microsoft.Windows.Common-Controls.
+//
+// When Windows loads the exe, it will look for this assembly in a variety of
+// places, such as in the WinSxS folder, but also in the program's folder. It
+// will look for `assemblyname.dll` or `assemblyname/assemblyname.dll` and try
+// to load that.
+//
+// If these files don't exist, then the loader gets creative and looks for
+// `assemblyname.manifest` and `assemblyname/assemblyname.manifest`. A manifest
+// file is just an XML file that can contain a list of DLLs to load for this
+// assembly.
+//
+// In MO's case, there's a `pragma` at the beginning of this file which adds
+// `dlls` as an "assembly" dependency. This is a bit of a hack to just force
+// the loader to eventually find `dlls/dlls.manifest`, which contains the list
+// of all the DLLs MO requires to load.
+//
+// This file was handwritten in `modorganizer/src/dlls.manifest.qt5` and
+// is copied and renamed in CMakeLists.txt into `bin/dlls/dlls.manifest`. Note
+// that the useless and incorrect .qt5 extension is removed.
+//
+void addDllsToPath()
+{
+  const auto dllsPath = QDir::toNativeSeparators(
+    QCoreApplication::applicationDirPath() + "/dlls");
+
+  QCoreApplication::setLibraryPaths(
+    QStringList(dllsPath) + QCoreApplication::libraryPaths());
+
+  env::prependToPath(dllsPath);
+}
+
+
 MOApplication::MOApplication(int& argc, char** argv)
   : QApplication(argc, argv)
 {
@@ -83,11 +129,13 @@ MOApplication::MOApplication(int& argc, char** argv)
 
   m_DefaultStyle = style()->objectName();
   setStyle(new ProxyStyle(style()));
+  addDllsToPath();
 }
 
 MOApplication MOApplication::create(int& argc, char** argv)
 {
   QApplication::setAttribute(Qt::AA_EnableHighDpiScaling);
+
   return MOApplication(argc, argv);
 }
 
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