/*
    (C) 1995-96 AROS - The Amiga Replacement OS
    $Id: seek.c,v 1.6 1997/01/27 00:36:30 ldp Exp $
    $Log: seek.c,v $
    Revision 1.6  1997/01/27 00:36:30  ldp
    Polish

    Revision 1.5  1996/12/09 13:53:42  aros
    Added empty templates for all missing functions

    Moved #include's into first column

    Revision 1.4  1996/10/24 15:50:36  aros
    Use the official AROS macros over the __AROS versions.

    Revision 1.3  1996/08/13 13:52:51  digulla
    Replaced <dos/dosextens.h> by "dos_intern.h" or added "dos_intern.h"
    Replaced AROS_LA by AROS_LHA

    Revision 1.2  1996/08/01 17:40:57  digulla
    Added standard header for all files

    Desc:
    Lang: english
*/
#include <proto/exec.h>
#include <dos/filesystem.h>
#include "dos_intern.h"

/*****************************************************************************

    NAME */
#include <proto/dos.h>

	AROS_LH3(LONG, Seek,

/*  SYNOPSIS */
	AROS_LHA(BPTR, file,     D1),
	AROS_LHA(LONG, position, D2),
	AROS_LHA(LONG, mode,     D3),

/*  LOCATION */
	struct DosLibrary *, DOSBase, 11, Dos)

/*  FUNCTION
	Changes the actual read/write position in a file and/or
	reads the actual position, e.g to get the actual position
	do a Seek(file,0,OFFSET_CURRENT).

	This function may fail (obviously) on certain devices such
	as pipes or console handlers.

    INPUTS
	file	 - filehandle
	position - relative offset in bytes (positive, negative or 0).
	mode	 - Where to count from. Either OFFSET_BEGINNING,
		   OFFSET_CURRENT or OFFSET_END.

    RESULT
	Absolute position in bytes before the Seek(), -1 if an error
	happened. IoErr() will give additional information in that case.

    NOTES

    EXAMPLE

    BUGS

    SEE ALSO

    INTERNALS

    HISTORY
	29-10-95    digulla automatically created from
			    dos_lib.fd and clib/dos_protos.h

*****************************************************************************/
{
    AROS_LIBFUNC_INIT
    AROS_LIBBASE_EXT_DECL(struct DosLibrary *,DOSBase)

    /* Get pointer to filehandle */
    struct FileHandle *fh=(struct FileHandle *)BADDR(file);

    /* Get pointer to process structure */
    struct Process *me=(struct Process *)FindTask(NULL);

    /* Get pointer to I/O request. Use stackspace for now. */
    struct IOFileSys io,*iofs=&io;

    /* Prepare I/O request. */
    iofs->IOFS.io_Message.mn_Node.ln_Type=NT_REPLYMSG;
    iofs->IOFS.io_Message.mn_ReplyPort	 =&me->pr_MsgPort;
    iofs->IOFS.io_Message.mn_Length	 =sizeof(struct IOFileSys);
    iofs->IOFS.io_Device =fh->fh_Device;
    iofs->IOFS.io_Unit	 =fh->fh_Unit;
    iofs->IOFS.io_Command=FSA_SEEK;
    iofs->IOFS.io_Flags  =0;
    iofs->io_Args[0]=position<0?-1:0;
    iofs->io_Args[1]=position;
    iofs->io_Args[2]=mode;

    /* Send the request. */
    DoIO(&iofs->IOFS);

    /* return */
    if((me->pr_Result2=iofs->io_DosError))
	return -1;
    else
	return iofs->io_Args[1];
    AROS_LIBFUNC_EXIT
} /* Seek */