rom/dos/internalflush.c

   1 /*
   2     Copyright © 2002-2013, The AROS Development Team. All rights reserved.
   3     $Id$
   4 */
   5
   6 #include <exec/types.h>
   7 #include <proto/dos.h>
   8
   9 #define DEBUG 0
  10 #include <aros/debug.h>
  11
  12 #include "dos_intern.h"
  13
  14 LONG InternalFlush( struct FileHandle *fh, struct DosLibrary *DOSBase )
  15 {
  16     LONG position, pos;
  17
  18     /* Make sure the input parameters are sane. */
  19     ASSERT_VALID_PTR( fh );
  20     ASSERT_VALID_PTR( BADDR(fh->fh_Buf) );
  21
  22     ASSERT(fh->fh_End >  0);
  23     ASSERT(fh->fh_Pos >= 0);
  24     ASSERT(fh->fh_Pos <= fh->fh_End );
  25
  26     /* If other task is flushing the buffer wait for completion.
  27        Currently we just delay 1 tick, we assume task that is flushing will
  28        be scheduled during first Delay() call so we have to wait only once.
  29     */
  30     while (fh->fh_Flags & FHF_FLUSHING)
  31         Delay(1);
  32
  33     /* TODO: Is following line race free ? */
  34     fh->fh_Flags |= FHF_FLUSHING;
  35
  36     /* Write the data, in many pieces if the first one isn't enough. */
  37     position = 0;
  38     /* Remember current position */
  39     pos = fh->fh_Pos;
  40
  41     while( position < pos )
  42     {
  43         LONG size;
  44
  45         size = Write( MKBADDR(fh), BADDR(fh->fh_Buf) + position, fh->fh_Pos - position );
  46
  47         /* An error happened? No success. */
  48         if( size < 0 )
  49         {
  50             fh->fh_Flags &= ~(FHF_WRITE | FHF_FLUSHING);
  51
  52             return FALSE;
  53         }
  54
  55         position += size;
  56     }
  57
  58     /* Reset the buffer. */
  59     if (fh->fh_Pos == pos)
  60         fh->fh_Pos = 0;
  61     else
  62     {
  63         /* If we are here it means that During Flush() characters were added
  64            to the buffer. Try to remove only the part that was flushed.
  65            This implementation is not fully race free but we try our best to
  66            reduce data loss as much as possible.
  67         */
  68         D(bug("Characters written during Flush(); pos=%d, fh->fh_Pos=%d\n"
  69               "\tfh->fh_Buf='%0.*s'\n",
  70               pos, fh->fh_Pos,
  71               fh->fh_Pos, fh->fh_Buf
  72         ));
  73         int i, len = fh->fh_Pos - pos;
  74         char *dest = BADDR(fh->fh_Buf);
  75         const char *src = dest + pos;
  76         fh->fh_Pos -= pos;
  77         for (i = 0; i < len; i++)
  78             *dest++ = *src++;
  79     }
  80
  81     fh->fh_Flags &= ~FHF_FLUSHING;
  82
  83     return TRUE;
  84 }