Add dylib_error

dynamic.c

@@ -337,6 +337,7 @@ static void load_symbols(enum rarch_core_type type)
             {
                RARCH_ERR("Failed to open libretro core: \"%s\"\n",
                      settings->libretro);
+               RARCH_ERR("Error(s): %s\n", dylib_error());
                rarch_fail(1, "load_dynamic()");
             }
 #endif

libretro-common/dynamic/dylib.c

@@ -31,6 +31,26 @@
 #include <dlfcn.h>
 #endif
 
+#ifdef _WIN32
+static char last_dyn_error[512];
+
+static void set_dl_error(void)
+{
+   DWORD err = GetLastError();
+
+   if (FormatMessage(FORMAT_MESSAGE_IGNORE_INSERTS |
+            FORMAT_MESSAGE_FROM_SYSTEM,
+            NULL,
+            err,
+            MAKELANGID(LANG_ENGLISH, SUBLANG_DEFAULT),
+            last_dyn_error,
+            sizeof(last_dyn_error) - 1,
+            NULL) == 0)
+      snprintf(last_dyn_error, sizeof(last_dyn_error) - 1,
+            "unknown error %lu", err);
+}
+#endif
+
 /**
  * dylib_load:
  * @path                         : Path to libretro core library.
@@ -42,13 +62,34 @@
 dylib_t dylib_load(const char *path)
 {
 #ifdef _WIN32
-   dylib_t lib = LoadLibrary(path);
+   int prevmode = SetErrorMode(SEM_FAILCRITICALERRORS | SEM_NOOPENFILEERRORBOX);
+   dylib_t lib  = LoadLibrary(path);
+
+   SetErrorMode(prevmode);
+
+   if (!lib)
+   {
+      set_dl_error();
+      return NULL;
+   }
+   last_dyn_error[0] = 0;
 #else
    dylib_t lib = dlopen(path, RTLD_LAZY);
 #endif
    return lib;
 }
 
+char *dylib_error(void)
+{
+#ifdef _WIN32
+   if (last_dyn_error[0])
+      return last_dyn_error;
+   return NULL;
+#else
+   return dlerror();
+#endif
+}
+
 function_t dylib_proc(dylib_t lib, const char *proc)
 {
    function_t sym;
@@ -59,6 +100,12 @@ function_t dylib_proc(dylib_t lib, const char *proc)
 #ifdef _WIN32
    sym = (function_t)GetProcAddress(lib ?
          (HMODULE)lib : GetModuleHandle(NULL), proc);
+   if (!sym)
+   {
+      set_dl_error();
+      return NULL;
+   }
+   last_dyn_error[0] = 0;
 #else
    if (lib)
       ptr_sym = dlsym(lib, proc);
@@ -89,7 +136,9 @@ function_t dylib_proc(dylib_t lib, const char *proc)
 void dylib_close(dylib_t lib)
 {
 #ifdef _WIN32
-   FreeLibrary((HMODULE)lib);
+   if (!FreeLibrary((HMODULE)lib))
+      set_dl_error();
+   last_dyn_error[0] = 0;
 #else
 #ifndef NO_DLCLOSE
    dlclose(lib);

libretro-common/include/dynamic/dylib.h

@@ -61,6 +61,8 @@ dylib_t dylib_load(const char *path);
  **/
 void dylib_close(dylib_t lib);
 
+char *dylib_error(void);
+
 function_t dylib_proc(dylib_t lib, const char *proc);
 #endif