VM: fix so that errno is set if MoveFileEx fails, should fix #1490

basis/io/files/windows/windows-tests.factor

@@ -1,8 +1,8 @@
 ! Copyright (C) 2010 Doug Coleman.
 ! See http://factorcode.org/license.txt for BSD license.
 USING: combinators continuations io.backend io.directories io.files
-io.files.temp io.files.windows io.pathnames kernel memory sequences
-splitting tools.test windows.kernel32 ;
+io.files.temp io.files.windows io.pathnames kernel kernel.private libc
+literals memory sequences splitting tools.test windows.kernel32 ;
 IN: io.files.windows.tests
 
 [ f ] [ "\\foo" absolute-path? ] unit-test
@@ -68,7 +68,7 @@ IN: io.files.windows.tests
 ] unit-test
 
 ! set-file-attributes & save-image
-{ { "kernel-error" 1 13 f } } [
+{ ${ "kernel-error" ERROR-IO EIO f } } [
     [
         "read-only.image" temp-file {
             [ ?delete-file ]

vm/os-windows.cpp

@@ -137,9 +137,18 @@ long getpagesize() {
   return g_pagesize;
 }
 
-// MoveFileEx returns FALSE on fail
+
 bool move_file(const vm_char* path1, const vm_char* path2) {
-  return !(MoveFileEx((path1), (path2), MOVEFILE_REPLACE_EXISTING) == FALSE);
+  /* MoveFileEx returns FALSE on fail. */
+  BOOL val = MoveFileEx((path1), (path2), MOVEFILE_REPLACE_EXISTING);
+  if (val == FALSE) {
+    /* MoveFileEx doesn't set errno, which primitive_save_image()
+       reads the error code from. Instead of converting from
+       GetLastError() to errno values, we ust set it to the generic
+       EIO value. */
+    errno = EIO;
+  }
+  return val == TRUE;
 }
 
 void factor_vm::init_signals() {}