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used to report outdated information)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, 22 insertions, 17 deletions

diff --git a/mysys/my_write.c b/mysys/my_write.c
index d7eb390bdd2..3eac1364f46 100644
--- a/mysys/my_write.c
+++ b/mysys/my_write.c
@@ -20,14 +20,14 @@
 
 	/* Write a chunk of bytes to a file */
 
-size_t my_write(int Filedes, const uchar *Buffer, size_t Count, myf MyFlags)
+size_t my_write(File Filedes, const uchar *Buffer, size_t Count, myf MyFlags)
 {
-  size_t writenbytes, written;
+  size_t writtenbytes, written;
   uint errors;
   DBUG_ENTER("my_write");
-  DBUG_PRINT("my",("Fd: %d  Buffer: 0x%lx  Count: %lu  MyFlags: %d",
-		   Filedes, (long) Buffer, (ulong) Count, MyFlags));
-  errors=0; written=0;
+  DBUG_PRINT("my",("fd: %d  Buffer: %p  Count: %lu  MyFlags: %d",
+		   Filedes, Buffer, (ulong) Count, MyFlags));
+  errors= 0; written= 0;
 
   /* The behavior of write(fd, buf, 0) is not portable */
   if (unlikely(!Count))
@@ -35,17 +35,22 @@ size_t my_write(int Filedes, const uchar *Buffer, size_t Count, myf MyFlags)
   
   for (;;)
   {
-    if ((writenbytes= write(Filedes, Buffer, Count)) == Count)
+#ifdef _WIN32
+    writtenbytes= my_win_write(Filedes, Buffer, Count);
+#else
+    writtenbytes= write(Filedes, Buffer, Count);
+#endif
+    if (writtenbytes == Count)
       break;
-    if (writenbytes != (size_t) -1)
+    if (writtenbytes != (size_t) -1)
     {						/* Safeguard */
-      written+=writenbytes;
-      Buffer+=writenbytes;
-      Count-=writenbytes;
+      written+= writtenbytes;
+      Buffer+= writtenbytes;
+      Count-= writtenbytes;
     }
-    my_errno=errno;
+    my_errno= errno;
     DBUG_PRINT("error",("Write only %ld bytes, error: %d",
-			(long) writenbytes, my_errno));
+			(long) writtenbytes, my_errno));
 #ifndef NO_BACKGROUND
 #ifdef THREAD
     if (my_thread_var->abort)
@@ -59,19 +64,19 @@ size_t my_write(int Filedes, const uchar *Buffer, size_t Count, myf MyFlags)
       continue;
     }
 
-    if ((writenbytes == 0 || writenbytes == (size_t) -1))
+    if ((writtenbytes == 0 || writtenbytes == (size_t) -1))
     {
       if (my_errno == EINTR)
       {
         DBUG_PRINT("debug", ("my_write() was interrupted and returned %ld",
-                             (long) writenbytes));
+                             (long) writtenbytes));
         continue;                               /* Interrupted */
       }
 
-      if (!writenbytes && !errors++)		/* Retry once */
+      if (!writtenbytes && !errors++)		/* Retry once */
       {
         /* We may come here if the file quota is exeeded */
-        errno=EFBIG;				/* Assume this is the error */
+        errno= EFBIG;				/* Assume this is the error */
         continue;
       }
     }
@@ -92,5 +97,5 @@ size_t my_write(int Filedes, const uchar *Buffer, size_t Count, myf MyFlags)
   }
   if (MyFlags & (MY_NABP | MY_FNABP))
     DBUG_RETURN(0);			/* Want only errors */
-  DBUG_RETURN(writenbytes+written);
+  DBUG_RETURN(writtenbytes+written);
 } /* my_write */