sftell.c revision 3e14f97f673e8a630f076077de35afdd43dc1587
/***********************************************************************
* *
* This software is part of the ast package *
* Copyright (c) 1985-2010 AT&T Intellectual Property *
* and is licensed under the *
* Common Public License, Version 1.0 *
* by AT&T Intellectual Property *
* *
* A copy of the License is available at *
* http://www.opensource.org/licenses/cpl1.0.txt *
* (with md5 checksum 059e8cd6165cb4c31e351f2b69388fd9) *
* *
* Information and Software Systems Research *
* AT&T Research *
* Florham Park NJ *
* *
* Glenn Fowler <gsf@research.att.com> *
* David Korn <dgk@research.att.com> *
* Phong Vo <kpv@research.att.com> *
* *
***********************************************************************/
#include "sfhdr.h"
/* Tell the current location in a given stream
**
** Written by Kiem-Phong Vo.
*/
#if __STD_C
Sfoff_t sftell(Sfio_t* f)
#else
Sfoff_t sftell(f)
Sfio_t *f;
#endif
{
reg int mode;
Sfoff_t p;
SFMTXDECL(f);
SFMTXENTER(f, (Sfoff_t)(-1));
/* set the stream to the right mode */
if((mode = f->mode&SF_RDWR) != (int)f->mode && _sfmode(f,mode,0) < 0)
SFMTXRETURN(f, (Sfoff_t)(-1));
/* throw away ungetc data */
if(f->disc == _Sfudisc)
(void)sfclose((*_Sfstack)(f,NIL(Sfio_t*)));
if(f->flags&SF_STRING)
SFMTXRETURN(f, (Sfoff_t)(f->next-f->data));
/* let sfseek() handle the hard case */
if(f->extent >= 0 && (f->flags&(SF_SHARE|SF_APPENDWR)) )
p = sfseek(f,(Sfoff_t)0,SEEK_CUR);
else p = f->here + ((f->mode&SF_WRITE) ? f->next-f->data : f->next-f->endb);
SFMTXRETURN(f,p);
}