1 /*- 2 * Copyright (c) 1990, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * This code is derived from software contributed to Berkeley by 6 * Chris Torek. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by the University of 19 * California, Berkeley and its contributors. 20 * 4. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 */ 36 37 #if defined(LIBC_SCCS) && !defined(lint) 38 #if 0 39 static char sccsid[] = "@(#)fpurge.c 8.1 (Berkeley) 6/4/93"; 40 #endif 41 static const char rcsid[] = 42 "$Id$"; 43 #endif /* LIBC_SCCS and not lint */ 44 45 #include <errno.h> 46 #include <stdio.h> 47 #include <stdlib.h> 48 #include "local.h" 49 #ifdef _THREAD_SAFE 50 #include <pthread.h> 51 #include "pthread_private.h" 52 #endif 53 54 /* 55 * fpurge: like fflush, but without writing anything: leave the 56 * given FILE's buffer empty. 57 */ 58 int 59 fpurge(fp) 60 register FILE *fp; 61 { 62 int retval; 63 #ifdef _THREAD_SAFE 64 _thread_flockfile(fp,__FILE__,__LINE__); 65 #endif 66 if (!fp->_flags) { 67 errno = EBADF; 68 retval = EOF; 69 } else { 70 if (HASUB(fp)) 71 FREEUB(fp); 72 fp->_p = fp->_bf._base; 73 fp->_r = 0; 74 fp->_w = fp->_flags & (__SLBF|__SNBF) ? 0 : fp->_bf._size; 75 retval = 0; 76 } 77 #ifdef _THREAD_SAFE 78 _thread_funlockfile(fp); 79 #endif 80 return (retval); 81 } 82