From e7748e3f73073df38d5f1485d964273b570d6d8f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Cl=C3=A9ment=20Vuchener?= <clement.vuchener@gmail.com>
Date: Tue, 29 Dec 2020 17:03:50 +0100
Subject: [PATCH] Add an error message when LoadLibrary fails

---
 library/PlugLoad-windows.cpp | 21 +++++++++++++++++++--
 1 file changed, 19 insertions(+), 2 deletions(-)

diff --git a/library/PlugLoad-windows.cpp b/library/PlugLoad-windows.cpp
index 8d64e315c..96c2e900a 100644
--- a/library/PlugLoad-windows.cpp
+++ b/library/PlugLoad-windows.cpp
@@ -24,6 +24,7 @@ distribution.
 
 #define DFhackCExport extern "C" __declspec(dllexport)
 
+#define NOMINMAX
 #include <windows.h>
 #include <stdint.h>
 #include <vector>
@@ -35,6 +36,7 @@ distribution.
 
 #include "tinythread.h"
 #include "modules/Graphic.h"
+#include "../plugins/uicommon.h"
 
 /*
  * Plugin loading functions
@@ -44,7 +46,22 @@ namespace DFHack
     DFLibrary* GLOBAL_NAMES = (DFLibrary*)GetModuleHandle(nullptr);
     DFLibrary * OpenPlugin (const char * filename)
     {
-        return (DFLibrary *) LoadLibrary(filename);
+        DFLibrary *ret = (DFLibrary *) LoadLibrary(filename);
+        if (!ret) {
+            DWORD error = GetLastError();
+            LPSTR buf = NULL;
+            DWORD len = FormatMessageA(FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS,
+                    NULL, error, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), (LPSTR)&buf, 0, NULL);
+            if (len > 0) {
+                std::string message = buf;
+                std::cerr << "LoadLibrary " << filename << ": " << rtrim(message) << " (" << error << ")" << std::endl;
+                LocalFree(buf);
+            }
+            else {
+                std::cerr << "LoadLibrary " << filename << ": unknown error " << error << std::endl;
+            }
+        }
+        return ret;
     }
     void * LookupPlugin (DFLibrary * plugin ,const char * function)
     {
@@ -54,4 +71,4 @@ namespace DFHack
     {
         FreeLibrary((HMODULE) plugin);
     }
-}
\ No newline at end of file
+}