From 845224f4756239963eeea896fe68539c95d71a6f Mon Sep 17 00:00:00 2001
From: Albrecht Schlosser <albrechts.fltk@online.de>
Date: Sun, 12 Jul 2020 21:14:16 +0200
Subject: [PATCH] Windows: convert error message to UTF-8

We need to get the error message in "wide character" format and
convert it to UTF-8. The conversion would truncate it if the
buffer was too small, hence we don't need to check for overflow.

Tested on Windows 10 with VS 2010, including (faked) error codes with
non-ASCII characters (German).
---
 src/scandir_win32.c | 28 ++++++++++++++--------------
 1 file changed, 14 insertions(+), 14 deletions(-)

diff --git a/src/scandir_win32.c b/src/scandir_win32.c
index 822770234..2210f7b49 100644
--- a/src/scandir_win32.c
+++ b/src/scandir_win32.c
@@ -1,7 +1,7 @@
 /*
  * Windows scandir function for the Fast Light Tool Kit (FLTK).
  *
- * Copyright 1998-2018 by Bill Spitzak and others.
+ * Copyright 1998-2020 by Bill Spitzak and others.
  *
  * This library is free software. Distribution and use rights are outlined in
  * the file "COPYING" which should have been included with this file.  If this
@@ -37,23 +37,23 @@ static void get_ms_errmsg(char *errmsg, int errmsg_sz) {
                 FORMAT_MESSAGE_IGNORE_INSERTS  |
                 FORMAT_MESSAGE_FROM_SYSTEM;
   DWORD langid = MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT);
-  LPSTR mbuf = 0;
+  LPWSTR mbuf = 0;
+  DWORD msize = 0;
 
-  // Early exit if parent doesn't want an errmsg
-  if (!errmsg || errmsg_sz<=0 ) return;
-  // Get error message from Windows
-  DWORD size = FormatMessageA(flags, 0, lastErr, langid, (LPSTR)&mbuf, 0, NULL);
-  if ( size == 0 ) {
+  /* Early exit if parent doesn't want an errmsg */
+  if (!errmsg || errmsg_sz <= 0 ) return;
+  /* Get error message from Windows */
+  msize = FormatMessageW(flags, 0, lastErr, langid, (LPWSTR)&mbuf, 0, NULL);
+  if ( msize == 0 ) {
     fl_snprintf(errmsg, errmsg_sz, "Error #%lu", (unsigned long)lastErr);
   } else {
-    int cnt = 0;
-    /* Copy mbuf -> errmsg, remove '\r's -- they screw up fl_alert()) */
-    for ( char *src=mbuf, *dst=errmsg; 1; src++ ) {
+    /* convert message to UTF-8 */
+    int mlen = fl_utf8fromwc(errmsg, errmsg_sz, mbuf, msize);
+    /* Remove '\r's -- they screw up fl_alert()) */
+    char *src = errmsg, *dst = errmsg;
+    for ( ; 1; src++ ) {
       if ( *src == '\0' ) { *dst = '\0'; break; }
-      if ( *src != '\r' ) {
-        if ( ++cnt >= errmsg_sz ) { *dst = '\0'; break; } // trunc on overflow
-        *dst++ = *src;
-      }
+      if ( *src != '\r' ) { *dst++ = *src; }
     }
     LocalFree(mbuf);    /* Free the buffer allocated by the system */
   }