usr/src/lib/libast/common/sfio/sftell.c

   1 /***********************************************************************
   2 *                                                                      *
   3 *               This software is part of the ast package               *
   4 *          Copyright (c) 1985-2010 AT&T Intellectual Property          *
   5 *                      and is licensed under the                       *
   6 *                  Common Public License, Version 1.0                  *
   7 *                    by AT&T Intellectual Property                     *
   8 *                                                                      *
   9 *                A copy of the License is available at                 *
  10 *            http://www.opensource.org/licenses/cpl1.0.txt             *
  11 *         (with md5 checksum 059e8cd6165cb4c31e351f2b69388fd9)         *
  12 *                                                                      *
  13 *              Information and Software Systems Research               *
  14 *                            AT&T Research                             *
  15 *                           Florham Park NJ                            *
  16 *                                                                      *
  17 *                 Glenn Fowler <gsf@research.att.com>                  *
  18 *                  David Korn <dgk@research.att.com>                   *
  19 *                   Phong Vo <kpv@research.att.com>                    *
  20 *                                                                      *
  21 ***********************************************************************/
  22 #include        "sfhdr.h"
  23
  24 /*      Tell the current location in a given stream
  25 **
  26 **      Written by Kiem-Phong Vo.
  27 */
  28
  29 #if __STD_C
  30 Sfoff_t sftell(Sfio_t* f)
  31 #else
  32 Sfoff_t sftell(f)
  33 Sfio_t  *f;
  34 #endif
  35 {
  36         reg int mode;
  37         Sfoff_t p;
  38         SFMTXDECL(f);
  39
  40         SFMTXENTER(f, (Sfoff_t)(-1));
  41
  42         /* set the stream to the right mode */
  43         if((mode = f->mode&SF_RDWR) != (int)f->mode && _sfmode(f,mode,0) < 0)
  44                 SFMTXRETURN(f, (Sfoff_t)(-1));
  45
  46         /* throw away ungetc data */
  47         if(f->disc == _Sfudisc)
  48                 (void)sfclose((*_Sfstack)(f,NIL(Sfio_t*)));
  49
  50         if(f->flags&SF_STRING)
  51                 SFMTXRETURN(f, (Sfoff_t)(f->next-f->data));
  52
  53         /* let sfseek() handle the hard case */
  54         if(f->extent >= 0 && (f->flags&(SF_SHARE|SF_APPENDWR)) )
  55                 p = sfseek(f,(Sfoff_t)0,SEEK_CUR);
  56         else    p = f->here + ((f->mode&SF_WRITE) ? f->next-f->data : f->next-f->endb);
  57
  58         SFMTXRETURN(f,p);
  59 }