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. 16249808Semaste * 3. Neither the name of the University nor the names of its contributors 171573Srgrimes * may be used to endorse or promote products derived from this software 181573Srgrimes * without specific prior written permission. 191573Srgrimes * 201573Srgrimes * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 211573Srgrimes * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 221573Srgrimes * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 231573Srgrimes * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 241573Srgrimes * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 251573Srgrimes * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 261573Srgrimes * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 271573Srgrimes * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 281573Srgrimes * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 291573Srgrimes * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 301573Srgrimes * SUCH DAMAGE. 311573Srgrimes */ 321573Srgrimes 331573Srgrimes#if defined(LIBC_SCCS) && !defined(lint) 341573Srgrimesstatic char sccsid[] = "@(#)ungetc.c 8.2 (Berkeley) 11/3/93"; 351573Srgrimes#endif /* LIBC_SCCS and not lint */ 3692986Sobrien#include <sys/cdefs.h> 3792986Sobrien__FBSDID("$FreeBSD: stable/11/lib/libc/stdio/ungetc.c 320942 2017-07-13 09:27:11Z kib $"); 381573Srgrimes 3971579Sdeischen#include "namespace.h" 401573Srgrimes#include <stdio.h> 411573Srgrimes#include <stdlib.h> 421573Srgrimes#include <string.h> 4371579Sdeischen#include "un-namespace.h" 441573Srgrimes#include "local.h" 4535129Sjb#include "libc_private.h" 461573Srgrimes 4792905Sobrienstatic int __submore(FILE *); 4816586Sjraynard 491573Srgrimes/* 501573Srgrimes * Expand the ungetc buffer `in place'. That is, adjust fp->_p when 511573Srgrimes * the buffer moves, so that it points the same distance from the end, 521573Srgrimes * and move the bytes in the buffer around as necessary so that they 531573Srgrimes * are all at the end (stack-style). 541573Srgrimes */ 5513545Sjulianstatic int 5671579Sdeischen__submore(FILE *fp) 571573Srgrimes{ 5871579Sdeischen int i; 5971579Sdeischen unsigned char *p; 601573Srgrimes 611573Srgrimes if (fp->_ub._base == fp->_ubuf) { 621573Srgrimes /* 631573Srgrimes * Get a new buffer (rather than expanding the old one). 641573Srgrimes */ 651573Srgrimes if ((p = malloc((size_t)BUFSIZ)) == NULL) 661573Srgrimes return (EOF); 671573Srgrimes fp->_ub._base = p; 681573Srgrimes fp->_ub._size = BUFSIZ; 691573Srgrimes p += BUFSIZ - sizeof(fp->_ubuf); 701573Srgrimes for (i = sizeof(fp->_ubuf); --i >= 0;) 711573Srgrimes p[i] = fp->_ubuf[i]; 721573Srgrimes fp->_p = p; 731573Srgrimes return (0); 741573Srgrimes } 751573Srgrimes i = fp->_ub._size; 76316613Spfg p = reallocarray(fp->_ub._base, i, 2); 771573Srgrimes if (p == NULL) 781573Srgrimes return (EOF); 791573Srgrimes /* no overlap (hence can use memcpy) because we doubled the size */ 801573Srgrimes (void)memcpy((void *)(p + i), (void *)p, (size_t)i); 811573Srgrimes fp->_p = p + i; 821573Srgrimes fp->_ub._base = p; 83316613Spfg fp->_ub._size = i * 2; 841573Srgrimes return (0); 851573Srgrimes} 861573Srgrimes 8771579Sdeischen/* 8871579Sdeischen * MT-safe version 8971579Sdeischen */ 9013545Sjulianint 9171579Sdeischenungetc(int c, FILE *fp) 921573Srgrimes{ 9371579Sdeischen int ret; 9471579Sdeischen 951573Srgrimes if (!__sdidinit) 961573Srgrimes __sinit(); 97320942Skib FLOCKFILE_CANCELSAFE(fp); 98126809Stjr ORIENT(fp, -1); 9971579Sdeischen ret = __ungetc(c, fp); 100320942Skib FUNLOCKFILE_CANCELSAFE(); 10171579Sdeischen return (ret); 10271579Sdeischen} 10371579Sdeischen 10471579Sdeischen/* 10571579Sdeischen * Non-MT-safe version 10671579Sdeischen */ 10771579Sdeischenint 10871579Sdeischen__ungetc(int c, FILE *fp) 10971579Sdeischen{ 110101776Stjr 11171579Sdeischen if (c == EOF) 11271579Sdeischen return (EOF); 1131573Srgrimes if ((fp->_flags & __SRD) == 0) { 1141573Srgrimes /* 1151573Srgrimes * Not already reading: no good unless reading-and-writing. 1161573Srgrimes * Otherwise, flush any current write stuff. 1171573Srgrimes */ 11871579Sdeischen if ((fp->_flags & __SRW) == 0) 1191573Srgrimes return (EOF); 1201573Srgrimes if (fp->_flags & __SWR) { 12171579Sdeischen if (__sflush(fp)) 1221573Srgrimes return (EOF); 1231573Srgrimes fp->_flags &= ~__SWR; 1241573Srgrimes fp->_w = 0; 1251573Srgrimes fp->_lbfsize = 0; 1261573Srgrimes } 1271573Srgrimes fp->_flags |= __SRD; 1281573Srgrimes } 1291573Srgrimes c = (unsigned char)c; 1301573Srgrimes 1311573Srgrimes /* 1321573Srgrimes * If we are in the middle of ungetc'ing, just continue. 1331573Srgrimes * This may require expanding the current ungetc buffer. 1341573Srgrimes */ 1351573Srgrimes if (HASUB(fp)) { 13671579Sdeischen if (fp->_r >= fp->_ub._size && __submore(fp)) 1371573Srgrimes return (EOF); 1381573Srgrimes *--fp->_p = c; 1391573Srgrimes fp->_r++; 1401573Srgrimes return (c); 1411573Srgrimes } 1421573Srgrimes fp->_flags &= ~__SEOF; 1431573Srgrimes 1441573Srgrimes /* 1451573Srgrimes * If we can handle this by simply backing up, do so, 1461573Srgrimes * but never replace the original character. 1471573Srgrimes * (This makes sscanf() work when scanning `const' data.) 1481573Srgrimes */ 1491573Srgrimes if (fp->_bf._base != NULL && fp->_p > fp->_bf._base && 1501573Srgrimes fp->_p[-1] == c) { 1511573Srgrimes fp->_p--; 1521573Srgrimes fp->_r++; 1531573Srgrimes return (c); 1541573Srgrimes } 1551573Srgrimes 1561573Srgrimes /* 1571573Srgrimes * Create an ungetc buffer. 1581573Srgrimes * Initially, we will use the `reserve' buffer. 1591573Srgrimes */ 1601573Srgrimes fp->_ur = fp->_r; 161178287Sjhb fp->_up = fp->_p; 1621573Srgrimes fp->_ub._base = fp->_ubuf; 1631573Srgrimes fp->_ub._size = sizeof(fp->_ubuf); 1641573Srgrimes fp->_ubuf[sizeof(fp->_ubuf) - 1] = c; 1651573Srgrimes fp->_p = &fp->_ubuf[sizeof(fp->_ubuf) - 1]; 1661573Srgrimes fp->_r = 1; 1671573Srgrimes return (c); 1681573Srgrimes} 169