#include "sfhdr.h"
#if __STD_C
Sfoff_t sftell(reg Sfio_t* f)
#else
Sfoff_t sftell(f)
reg Sfio_t *f;
#endif
{
reg int mode;
Sfoff_t p;
SFMTXSTART(f, (Sfoff_t)(-1));
if((mode = f->mode&SF_RDWR) != (int)f->mode && _sfmode(f,mode,0) < 0)
SFMTXRETURN(f, (Sfoff_t)(-1));
if(f->disc == _Sfudisc)
(void)sfclose((*_Sfstack)(f,NIL(Sfio_t*)));
if(f->flags&SF_STRING)
SFMTXRETURN(f, (Sfoff_t)(f->next-f->data));
if(f->extent >= 0 && (f->flags&(SF_SHARE|SF_APPENDWR)) )
p = sfseek(f,(Sfoff_t)0,1);
else p = f->here + ((f->mode&SF_WRITE) ? f->next-f->data : f->next-f->endb);
SFMTXRETURN(f,p);
}