improve win32 support

C/load_dll.c

@@ -36,7 +36,15 @@ Yap_FindExecutable(void)
 void *
 Yap_LoadForeignFile(char *file, int flags)
 {
-  return (void *)LoadLibrary(file);
+ void *ptr= (void *)LoadLibrary(file);
+ if (!ptr) {
+   LOCAL_ErrorSay[0]='\0';
+   FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS,
+		 NULL, GetLastError(), 
+		 MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), LOCAL_ErrorSay, 256,
+		 NULL);
+ }
+ return ptr;
 }
 
 int
@@ -78,6 +86,7 @@ LoadForeign(StringList ofiles, StringList libs,
 		      NULL, GetLastError(), 
 		      MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), LOCAL_ErrorSay, 256,
 		      NULL);
+	//fprintf(stderr,"WinError: %s\n", LOCAL_ErrorSay);
       }
     ofiles = ofiles->next;
   }

C/load_foreign.c

@@ -136,6 +136,7 @@ p_open_shared_object( USES_REGS1 ) {
   
   s = RepAtom(AtomOfTerm(t))->StrOfAE;
   if ((handle = Yap_LoadForeignFile(s, IntegerOfTerm(tflags)))==NULL) {
+    Yap_Error(EXISTENCE_ERROR_SOURCE_SINK,t,"open_shared_object_failed for %s with %s\n", s, LOCAL_ErrorSay);
     return FALSE;
   } else {
     return Yap_unify(MkIntegerTerm((Int)handle),ARG3);

H/pl-incl.h

@@ -10,6 +10,7 @@
 #include <windows/uxnt.h>
 #define O_HASDRIVES 1
 #define O_HASSHARES 1
+#define EMULATE_DLOPEN 1
 #endif
 
 #if defined(__GNUC__) && !defined(MAY_ALIAS)

os/pl-nt.c

@@ -694,7 +694,7 @@ PRED_IMPL("win_add_dll_directory", 2, win_add_dll_directory, 0)
     if ( _xos_os_filenameW(dirs, dirw, len+10) == NULL )
       return PL_representation_error("file_name");
     if ( load_library_search_flags() )
-    { if ( (cookie = (*f_AddDllDirectoryW)(dirw)) )
+      { if ( (cookie = (*f_AddDllDirectoryW)(dirw)) )
 	return PL_unify_int64(A2, (int64_t)cookie);
       return PL_error(NULL, 0, WinError(), ERR_SYSCALL, "AddDllDirectory()");
     } else