ref: 65e0e1c3e37c966d0c18178ad8a4c54c0c0fbce9
dir: /sys/src/libstdio/ftell.c/
/* * pANS stdio -- ftell */ #include "iolib.h" long ftell(FILE *f){ long seekp=seek(f->fd, 0L, 1); if(seekp<0) return -1; /* enter error state? */ switch(f->state){ default: return seekp; case RD: return seekp-(f->wp-f->rp); case WR: return (f->flags&LINEBUF?f->lp:f->wp)-f->buf+seekp; } }