fpurge.c revision 16586
11573Srgrimes/*- 21573Srgrimes * Copyright (c) 1990, 1993 31573Srgrimes * The Regents of the University of California. All rights reserved. 41573Srgrimes * 51573Srgrimes * This code is derived from software contributed to Berkeley by 61573Srgrimes * Chris Torek. 71573Srgrimes * 81573Srgrimes * Redistribution and use in source and binary forms, with or without 91573Srgrimes * modification, are permitted provided that the following conditions 101573Srgrimes * are met: 111573Srgrimes * 1. Redistributions of source code must retain the above copyright 121573Srgrimes * notice, this list of conditions and the following disclaimer. 131573Srgrimes * 2. Redistributions in binary form must reproduce the above copyright 141573Srgrimes * notice, this list of conditions and the following disclaimer in the 151573Srgrimes * documentation and/or other materials provided with the distribution. 161573Srgrimes * 3. All advertising materials mentioning features or use of this software 171573Srgrimes * must display the following acknowledgement: 181573Srgrimes * This product includes software developed by the University of 191573Srgrimes * California, Berkeley and its contributors. 201573Srgrimes * 4. Neither the name of the University nor the names of its contributors 211573Srgrimes * may be used to endorse or promote products derived from this software 221573Srgrimes * without specific prior written permission. 231573Srgrimes * 241573Srgrimes * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 251573Srgrimes * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 261573Srgrimes * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 271573Srgrimes * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 281573Srgrimes * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 291573Srgrimes * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 301573Srgrimes * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 311573Srgrimes * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 321573Srgrimes * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 331573Srgrimes * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 341573Srgrimes * SUCH DAMAGE. 351573Srgrimes */ 361573Srgrimes 371573Srgrimes#if defined(LIBC_SCCS) && !defined(lint) 3816586Sjraynard#if 0 391573Srgrimesstatic char sccsid[] = "@(#)fpurge.c 8.1 (Berkeley) 6/4/93"; 4016586Sjraynard#endif 4116586Sjraynardstatic const char rcsid[] = 4216586Sjraynard "$Id$"; 431573Srgrimes#endif /* LIBC_SCCS and not lint */ 441573Srgrimes 451573Srgrimes#include <errno.h> 461573Srgrimes#include <stdio.h> 471573Srgrimes#include <stdlib.h> 481573Srgrimes#include "local.h" 4913545Sjulian#ifdef _THREAD_SAFE 5013545Sjulian#include <pthread.h> 5113545Sjulian#include "pthread_private.h" 5213545Sjulian#endif 531573Srgrimes 541573Srgrimes/* 551573Srgrimes * fpurge: like fflush, but without writing anything: leave the 561573Srgrimes * given FILE's buffer empty. 571573Srgrimes */ 581573Srgrimesint 591573Srgrimesfpurge(fp) 601573Srgrimes register FILE *fp; 611573Srgrimes{ 6213545Sjulian int retval; 6313545Sjulian#ifdef _THREAD_SAFE 6413545Sjulian _thread_flockfile(fp,__FILE__,__LINE__); 6513545Sjulian#endif 661573Srgrimes if (!fp->_flags) { 671573Srgrimes errno = EBADF; 6813545Sjulian retval = EOF; 6913545Sjulian } else { 7013545Sjulian if (HASUB(fp)) 7113545Sjulian FREEUB(fp); 7213545Sjulian fp->_p = fp->_bf._base; 7313545Sjulian fp->_r = 0; 7413545Sjulian fp->_w = fp->_flags & (__SLBF|__SNBF) ? 0 : fp->_bf._size; 7513545Sjulian retval = 0; 761573Srgrimes } 7713545Sjulian#ifdef _THREAD_SAFE 7813545Sjulian _thread_funlockfile(fp); 7913545Sjulian#endif 8013545Sjulian return (retval); 811573Srgrimes} 82