This is the downport of

Bug#24509 - 2048 file descriptor limit on windows needs increasing, also 
WL#3049 - improved Windows I/O
                        
The patch replaces the use of the POSIX I/O interfaces in mysys on Windows with 
the Win32 API calls (CreateFile, WriteFile, etc). The Windows HANDLE for the open 
file is stored in the my_file_info struct, along with a flag for append mode 
because the Windows API does not support opening files in append mode in all cases)
The default max open files has been increased to 16384 and can be increased further
by setting --max-open-files=<value> during the server start.
                              
Another major change in this patch that almost all Windows specific file IO code
has been moved to a new file my_winfile.c, greatly reducing the amount of code 
in #ifdef blocks within mysys, thus improving readability.
                               
                                    
Minor enhancements:
- my_(f)stat() is changed to use __stati64 structure with  64 file size
and timestamps. It will return correct file size now (C runtime implementation
used to report outdated information)
- my_lock on Windows is prepared to handle additional timeout parameter
- after review : changed __WIN__ to _WIN32 in the new and changed code.

1 files changed, 3 insertions, 3 deletions

diff --git a/mysys/my_mmap.c b/mysys/my_mmap.c
index 023a06fd896..303d8efaf30 100644
--- a/mysys/my_mmap.c
+++ b/mysys/my_mmap.c
@@ -27,17 +27,17 @@ int my_msync(int fd, void *addr, size_t len, int flags)
   return my_sync(fd, MYF(0));
 }
 
-#elif defined(__WIN__)
+#elif defined(_WIN32)
 
 static SECURITY_ATTRIBUTES mmap_security_attributes=
   {sizeof(SECURITY_ATTRIBUTES), 0, TRUE};
 
 void *my_mmap(void *addr, size_t len, int prot,
-               int flags, int fd, my_off_t offset)
+               int flags, File fd, my_off_t offset)
 {
   HANDLE hFileMap;
   LPVOID ptr;
-  HANDLE hFile= (HANDLE)_get_osfhandle(fd);
+  HANDLE hFile= (HANDLE)my_get_osfhandle(fd);
   if (hFile == INVALID_HANDLE_VALUE)
     return MAP_FAILED;