/*- * Copyright (c) 1990, 1993 * The Regents of the University of California. All rights reserved. * * This code is derived from software contributed to Berkeley by * Chris Torek. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by the University of * California, Berkeley and its contributors. * 4. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ #if defined(LIBC_SCCS) && !defined(lint) static char sccsid[] = "@(#)ftell.c 8.1 (Berkeley) 6/4/93"; #endif /* LIBC_SCCS and not lint */ #include <stdio.h> #include <errno.h> #include "local.h" /* * ftell: return current offset. */ long ftell(fp) register const FILE *fp; { register fpos_t pos; if (fp->_seek == NULL) { errno = ESPIPE; /* historic practice */ return (-1L); } /* * Find offset of underlying I/O object, then * adjust for buffered bytes. */ if (fp->_flags & __SOFF) pos = fp->_offset; else { pos = (*fp->_seek)(fp->_cookie, (fpos_t)0, SEEK_CUR); if (pos == -1L) return (pos); } if (fp->_flags & __SRD) { /* * Reading. Any unread characters (including * those from ungetc) cause the position to be * smaller than that in the underlying object. */ pos -= fp->_r; if (HASUB(fp)) pos -= fp->_ur; } else if (fp->_flags & __SWR && fp->_p != NULL) { /* * Writing. Any buffered characters cause the * position to be greater than that in the * underlying object. */ pos += fp->_p - fp->_bf._base; } return (pos); }