dsetpos.c

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/*

  Copyright (C) 2000, 2001, Silicon Graphics, Inc.  All Rights Reserved.

  This program is free software; you can redistribute it and/or modify it
  under the terms of version 2.1 of the GNU Lesser General Public License 
  as published by the Free Software Foundation.

  This program is distributed in the hope that it would be useful, but
  WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  

  Further, this software is distributed without any warranty that it is
  free of the rightful claim of any third person regarding infringement 
  or the like.  Any license provided herein, whether implied or 
  otherwise, applies only to this software file.  Patent licenses, if
  any, provided herein do not apply to combinations of this program with 
  other software, or any other product whatsoever.  

  You should have received a copy of the GNU Lesser General Public 
  License along with this program; if not, write the Free Software 
  Foundation, Inc., 59 Temple Place - Suite 330, Boston MA 02111-1307, 
  USA.

  Contact information:  Silicon Graphics, Inc., 1600 Amphitheatre Pky,
  Mountain View, CA 94043, or:

  http://www.sgi.com

  For further information regarding this notice, see:

  http://oss.sgi.com/projects/GenInfo/NoticeExplan

*/



#pragma ident "@(#) libf/fio/dsetpos.c  92.1    06/18/99 10:21:14"

#include <foreign.h>
#include <errno.h>
#include <liberrno.h>
#include "fio.h"

/*
 *      internal setpos routine
 */
int
_setpos(
FIOSPTR css,            /* statement state */
unit    *cup,           /* unit pointer */
int     *pa,            /* original user's Position Array. maybe tape... */
int     len)            /* length of pa */
{
        int     ret;
        int     pos;
        long    offset;
        int     whence;
        int     retstat;
        struct fdinfo *fio;
        int     fp_parm[2];

        retstat = 0;

/*
 *      Wait for completion of a preceding asynchronous BUFFER IN/OUT.
 */
        WAITIO(cup, return(cup->uffsw.sw_error));

        cup->urecpos = 0;
        if (cup->uwrt) {
                if (cup->utrunc) {
                        ret = _unit_trunc(cup);
                        if (ret != 0)
                                return(ret);
                }
                cup->uwrt = 0;
        }
/*
 *      According to the file structure make the appropriate call to set
 *      the file position.  Positioning routines are file structure dependent.
 */
        pos = pa[0];
        switch( cup->ufs ) {

        case  FS_TEXT:
        case  STD:
                if ( pos == -1 || pos == -2 ) {
                        offset = 0;
                        whence = 2;
                }
                else {
                        offset = pos; 
                        whence = 0;
                }
/*
 *              If unformatted file, then positioning is done to a word
 *              boundary.  Converto to bytes
 */
                if ( cup->ufmt == NO )
                        offset = _dshiftl(offset, offset, 3);

                ret = fseek(cup->ufp.std, offset, whence);
                if (ret != 0)
                        return(errno);

                break;

        case  FS_FDC:
                fio = cup->ufp.fdc;
                
                if ((cup->uflagword & FFC_SEEKA) ||
                    ((pos == -1 || pos == -2) && (cup->uflagword & FFC_SEEKE))){

                        if ( pos == -1 || pos == -2 ) {

                                if ( XRCALL(fio, seekrtn) fio, 0, 2,
                                                           &cup->uffsw) < 0)
                                        return(cup->uffsw.sw_error);

                        }
                        else {
#if     defined(__mips) || defined(_LITTLE_ENDIAN)
        /* A couple of problems will need to be solved before we can */
        /* use the ffio posrtn on MIPS. That routine is currently */
        /* documented as expecting longs in the 3rd parameter for */
        /* FP_BSEEK . But more importantly, FP_BSEEK isn't supported */
        /* yet for MIPS, because  longs are not sufficiently large */
        /* to contain all possible file positions. */
                                return(FDC_ERR_NOSUP);
#else
/*
 *                              If formatted file, then positioning is done
 *                              to a byte boundary.  If unformatted, input pos
 *                              is in words.  Convert to bits.
 */
                                if ( cup->ufmt == YES )
                                        fp_parm[0] = _dshiftl(pos, pos, 3);
                                else
                                        fp_parm[0] = _dshiftl(pos, pos, 6);
/*
 *                              Check for Invalid argument.  If shifted result
 *                              is negative, we have a problem.
 */
                                if ( fp_parm[0] < 0 )
                                        return(FEBIOISP);
                                        
                                fp_parm[1] = 0;
                                ret = XRCALL(fio, posrtn) fio, 
                                        FP_BSEEK, fp_parm, 2, &cup->uffsw);

                                if (ret < 0)
                                        return(cup->uffsw.sw_error);
#endif
                        }
                }
                else {
/*
 *                      Assume that positioning is done via a 'magic cookie'.
 *                      Just pass it through.
 */
                        if( XRCALL(fio, posrtn)
                                fio, FP_SETPOS, pa, len, &cup->uffsw) < 0)
                                return(cup->uffsw.sw_error);
                }

                break;

        case FS_AUX:
                return(FEMIXAUX);
        default:
                return(FEINTFST);
        }
/*
 *      Set the end flag if going to EOD, else clear it.
 */
        if (pos == -1 && len == 1) {
                if (cup->ufs != FS_FDC)
                        cup->uend = LOGICAL_ENDFILE;
                else {
                        /*
                         * We are after the terminal endfile record of the file,
                         * but we must decide if it's a logical or physical 
                         * endfile record.
                         */
                        if ((cup->uflagword & FFC_WEOF) == 0)
                                cup->uend = LOGICAL_ENDFILE;
                        else {
                                off_t fbytepos; /* byte offset within file */

                                switch (fio->class) {
                                case CLASS_COS:
                                        /*
                                         * Since seekrtn for the cos layer
                                         * when called with 0,2 does NOT return
                                         * the resulting byte offset, we
                                         * must query the position with this
                                         * seekrtn call.  The only case
                                         * where 0 might be returned is when                                             * the file is empty.
                                         */
                                        fbytepos = XRCALL(fio, seekrtn) fio, 0,
                                                1, &cup->uffsw);
                                        if (fbytepos > 0)
                                                cup->uend = PHYSICAL_ENDFILE;
                                        else
                                                cup->uend = LOGICAL_ENDFILE;
                                        break;
                                default:
                                        return(FEBIOSNT);
                                }
                        }
                }
        }
        else
                /* 
                 * Sadly, we may be positioned after an endfile record, 
                 * and not know it.   This should be fixed. 
                 */
                cup->uend = BEFORE_ENDFILE;
        return(OK);
}