Fix loading of the dbus-1 DLL built by MinGW on Windows

QLibrary does not append the version suffix on Windows by itself, since
there's no established practice on how to do this. The MinGW builds of
dbus-1 call it "libdbus-1-3.dll", so we need append the suffix
ourselves.

Unfortunately, other names like "dbus-1.dll" have been seen in the wild,
so we need to try both basenames (Windows doesn't prepend the "lib"
prefix). Both basenames work on Unix, so give "libdbus-1" on Unix since
that will result in one fewer stat.

Change-Id: I92506df5fd30c7674216568406bf86b25bf646b8
Reviewed-by: Simon Hausmann <simon.hausmann@digia.com>

1 files changed, 20 insertions, 5 deletions

diff --git a/src/dbus/qdbus_symbols.cpp b/src/dbus/qdbus_symbols.cpp
index 8c642c8887..e475a23f48 100644
--- a/src/dbus/qdbus_symbols.cpp
+++ b/src/dbus/qdbus_symbols.cpp
@@ -84,14 +84,29 @@ bool qdbus_loadLibDBus()
     triedToLoadLibrary = true;
 
     static int majorversions[] = { 3, 2, -1 };
+    const QString baseNames[] = {
+#ifdef Q_OS_WIN
+        QStringLiteral("dbus-1"),
+#endif
+        QStringLiteral("libdbus-1")
+    };
+
     lib->unload();
-    lib->setFileName(QLatin1String("dbus-1"));
     for (uint i = 0; i < sizeof(majorversions) / sizeof(majorversions[0]); ++i) {
-        lib->setFileNameAndVersion(lib->fileName(), majorversions[i]);
-        if (lib->load() && lib->resolve("dbus_connection_open_private"))
-            return true;
+        for (uint j = 0; j < sizeof(baseNames) / sizeof(baseNames[0]); ++j) {
+#ifdef Q_OS_WIN
+            QString suffix;
+            if (majorversions[i] != -1)
+                suffix = QString::number(- majorversions[i]); // negative so it prepends the dash
+            lib->setFileName(baseNames[j] + suffix);
+#else
+            lib->setFileNameAndVersion(baseNames[j], majorversions[i]);
+#endif
+            if (lib->load() && lib->resolve("dbus_connection_open_private"))
+                return true;
 
-        lib->unload();
+            lib->unload();
+        }
     }
 
     delete lib;