Piotr Caban : msvcrt: Don't write Unicode BOM if file is not empty in _wsopen_dispatch.

[Alexandre Julliard]

Module: wine
Branch: master
Commit: 00a024725e86f3dd3f8bb52849fd2597bbf58d40
URL:    https://source.winehq.org/git/wine.git/?a=commit;h=00a024725e86f3dd3f8bb5284...

Author: Piotr Caban <piotr(a)codeweavers.com>
Date:   Thu Nov 26 15:26:27 2020 +0100

msvcrt: Don't write Unicode BOM if file is not empty in _wsopen_dispatch.

Signed-off-by: Piotr Caban <piotr(a)codeweavers.com>
Signed-off-by: Alexandre Julliard <julliard(a)winehq.org>

---

 dlls/msvcrt/file.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/dlls/msvcrt/file.c b/dlls/msvcrt/file.c
index 1cf778cca07..3b1c7d549d9 100644
--- a/dlls/msvcrt/file.c
+++ b/dlls/msvcrt/file.c
@@ -2297,9 +2297,14 @@ int CDECL MSVCRT__wsopen_dispatch( const MSVCRT_wchar_t* path, int oflags, int s
 
   if (oflags & (MSVCRT__O_WTEXT|MSVCRT__O_U16TEXT|MSVCRT__O_U8TEXT))
   {
+      LARGE_INTEGER size = {{0}};
+
+      if ((access & GENERIC_WRITE) && (creation==OPEN_EXISTING || creation==OPEN_ALWAYS))
+          GetFileSizeEx(hand, &size);
+
       if ((access & GENERIC_WRITE) && (creation==CREATE_NEW
                   || creation==CREATE_ALWAYS || creation==TRUNCATE_EXISTING
-                  || (creation==OPEN_ALWAYS && GetLastError()==ERROR_ALREADY_EXISTS)))
+                  || ((creation==OPEN_EXISTING || creation==OPEN_ALWAYS) && !size.QuadPart)))
       {
           if (oflags & MSVCRT__O_U8TEXT)
           {