rom/dos/flush.c

   1 /*
   2     Copyright © 1995-2013, The AROS Development Team. All rights reserved.
   3     $Id$
   4 */
   5
   6 #include <aros/debug.h>
   7
   8 #include <dos/dosextens.h>
   9 #include <proto/dos.h>
  10 #include "dos_intern.h"
  11
  12 /*****************************************************************************
  13
  14     NAME */
  15 #include <proto/dos.h>
  16
  17         AROS_LH1(LONG, Flush,
  18
  19 /*  SYNOPSIS */
  20         AROS_LHA(BPTR, file, D1),
  21
  22 /*  LOCATION */
  23         struct DosLibrary *, DOSBase, 60, Dos)
  24
  25 /*  FUNCTION
  26         Flushes any pending writes on the file. If the file was used
  27         for input and there is still some data to read it tries to
  28         seek back to the expected position.
  29
  30     INPUTS
  31         file - filehandle
  32
  33     RESULT
  34         != 0 on success, 0 on error. IoErr() gives additional information
  35         in that case.
  36
  37     NOTES
  38         On AROS calling Flush() from different tasks on the same file handle
  39         is serialised. This means that most of the time it is possible to
  40         do I/O in one task to a file handle where Flush() is being called
  41         in another task on that file handle.
  42         No multi-thread safety is guaranteed though and data may be lost if
  43         I/O is done in parallel from different tasks on the same file handle.
  44
  45     EXAMPLE
  46
  47     BUGS
  48
  49     SEE ALSO
  50
  51     INTERNALS
  52
  53 *****************************************************************************/
  54 {
  55     AROS_LIBFUNC_INIT
  56
  57     /* Get pointer to filehandle. */
  58     struct FileHandle *fh = (struct FileHandle *)BADDR(file);
  59
  60     if (!fh)
  61         return DOSTRUE;
  62
  63     /* The file must be in write mode. */
  64     if( fh->fh_Flags & FHF_WRITE )
  65     {
  66         /* Handle append mode. */
  67         if( fh->fh_Flags & FHF_APPEND )
  68         {
  69             InternalSeek( fh, 0, OFFSET_END, DOSBase );
  70         }
  71
  72         return InternalFlush( fh, DOSBase );
  73     }
  74     else if( fh->fh_Pos < fh->fh_End )
  75     {
  76         int offset = fh->fh_Pos - fh->fh_End;
  77
  78         fh->fh_Pos = fh->fh_End = 0;
  79
  80         /* Read mode. Try to seek back to the current position. */
  81         if( InternalSeek( fh, offset, OFFSET_CURRENT, DOSBase ) < 0 )
  82         {
  83             return FALSE;
  84         }
  85     }
  86
  87     return TRUE;
  88
  89     AROS_LIBFUNC_EXIT
  90 } /* Flush */