Index: source/ps/DllLoader.cpp
===================================================================
--- source/ps/DllLoader.cpp	(revision 7732)
+++ source/ps/DllLoader.cpp	(revision 7795)
@@ -1,4 +1,4 @@
-/* Copyright (C) 2009 Wildfire Games.
+/* Copyright (C) 2010 Wildfire Games.
  * This file is part of 0 A.D.
  *
  * 0 A.D. is free software: you can redistribute it and/or modify
@@ -19,19 +19,25 @@
 
 #include "DllLoader.h"
 
+#include "lib/timer.h"
 #include "lib/posix/posix_dlfcn.h"
 #include "ps/CStr.h"
 #include "ps/CLogger.h"
+#include "ps/GameSetup/Config.h"
 
 void* const HANDLE_UNAVAILABLE = (void*)-1;
 
+// directory to search for libraries (optionally set by --libdir at build-time,
+// optionally overridden by -libdir at run-time in the test executable);
+// if we don't have an explicit libdir then the linker will look in DT_RUNPATH
+// (which we set to $ORIGIN) to find it in the executable's directory
+#ifdef INSTALLED_LIBDIR
+static CStr g_Libdir = STRINGIZE(INSTALLED_LIBDIR);
+#else
+static CStr g_Libdir = "";
+#endif
 
-// TODO Use path_util instead, get the actual path to the ps_dbg exe and append
-// the library name.
-
-// note: on Linux, lib is prepended to the SO file name;
-// we don't use a path with '/' so the linker will look in DT_RUNPATH
-// (which we set to $ORIGIN) to find it in the executable's directory
+// note: on Linux, lib is prepended to the SO file name
 #if OS_UNIX
 static const char* prefix = "lib";
 #else
@@ -41,15 +47,26 @@
 // but for debugging/performance we prefer to use the same version as the app.
 // note: on Windows, the extension is replaced with .dll by dlopen.
 #ifndef NDEBUG
-static const char* suffix = "_dbg.so";
+static const char* primarySuffix = "_dbg.so";
+static const char* secondarySuffix = ".so";
 #else
-static const char* suffix = ".so";
+static const char* primarySuffix = ".so";
+static const char* secondarySuffix = "_dbg.so";
 #endif
 
 // (This class is currently only used by 'Collada' and 'AtlasUI' which follow
 // the naming/location convention above - it'll need to be changed if we want
 // to support other DLLs.)
 
+static CStr GenerateFilename(const CStr& name, const CStr& suffix)
+{
+	CStr n;
+	if (!g_Libdir.empty())
+		n = g_Libdir + "/";
+	n += prefix + name + suffix;
+	return n;
+}
+
 DllLoader::DllLoader(const char* name)
 : m_Name(name), m_Handle(0)
 {
@@ -72,23 +89,39 @@
 	// postcondition: m_Handle valid or == HANDLE_UNAVAILABLE.
 	if (m_Handle == 0)
 	{
-		CStr filename = CStr(prefix) + m_Name + suffix;
+		TIMER(L"LoadDLL");
 
 		// we don't really care when relocations take place, but one of
 		// {RTLD_NOW, RTLD_LAZY} must be passed. go with the former because
 		// it is safer and matches the Windows load behavior.
 		const int flags = RTLD_LOCAL|RTLD_NOW;
 
+		CStr filename = GenerateFilename(m_Name, primarySuffix);
 		m_Handle = dlopen(filename, flags);
 
+		char* primaryError = NULL;
+
 		// open failed (mostly likely SO not found)
 		if (! m_Handle)
 		{
-			const char* error = dlerror();
-			if (error)
-				LOG(CLogger::Error, L"", L"dlopen error: %hs", error);
+			primaryError = dlerror();
+			if (primaryError)
+				primaryError = strdup(primaryError); // don't get overwritten by next dlopen
+
+			// Try to open the other debug/release version
+			filename = GenerateFilename(m_Name, secondarySuffix);
+			m_Handle = dlopen(filename, flags);
+		}
+
+		// open still failed; report the first error
+		if (! m_Handle)
+		{
+			if (primaryError)
+				LOGERROR(L"dlopen error: %hs", primaryError);
 			m_Handle = HANDLE_UNAVAILABLE;
 		}
+
+		free(primaryError);
 	}
 
 	return (m_Handle != HANDLE_UNAVAILABLE);
@@ -117,3 +150,8 @@
 	if (*fptr == NULL)
 		throw PSERROR_DllLoader_SymbolNotFound();
 }
+
+void DllLoader::OverrideLibdir(const CStr& libdir)
+{
+	g_Libdir = libdir;
+}