1 /** @file 2 Implementation of ungetc as declared in <stdio.h>. 3 4 Copyright (c) 2010 - 2011, Intel Corporation. All rights reserved.<BR> 5 This program and the accompanying materials are licensed and made available 6 under the terms and conditions of the BSD License that accompanies this 7 distribution. The full text of the license may be found at 8 http://opensource.org/licenses/bsd-license. 9 10 THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, 11 WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED. 12 13 Copyright (c) 1990, 1993 14 The Regents of the University of California. All rights reserved. 15 16 This code is derived from software contributed to Berkeley by 17 Chris Torek. 18 19 Redistribution and use in source and binary forms, with or without 20 modification, are permitted provided that the following conditions 21 are met: 22 - Redistributions of source code must retain the above copyright 23 notice, this list of conditions and the following disclaimer. 24 - Redistributions in binary form must reproduce the above copyright 25 notice, this list of conditions and the following disclaimer in the 26 documentation and/or other materials provided with the distribution. 27 - Neither the name of the University nor the names of its contributors 28 may be used to endorse or promote products derived from this software 29 without specific prior written permission. 30 31 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 32 AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 33 IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 34 ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR CONTRIBUTORS BE 35 LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 36 CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 37 SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 38 INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 39 CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 40 ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 41 POSSIBILITY OF SUCH DAMAGE. 42 43 NetBSD: ungetc.c,v 1.14 2003/08/07 16:43:34 agc Exp 44 ungetc.c 8.2 (Berkeley) 11/3/93 45 **/ 46 #include <LibConfig.h> 47 48 #include <assert.h> 49 #include <errno.h> 50 #include <stdio.h> 51 #include <stdlib.h> 52 #include <string.h> 53 #include "reentrant.h" 54 #include "local.h" 55 56 static int __submore(FILE *); 57 /* 58 * Expand the ungetc buffer `in place'. That is, adjust fp->_p when 59 * the buffer moves, so that it points the same distance from the end, 60 * and move the bytes in the buffer around as necessary so that they 61 * are all at the end (stack-style). 62 */ 63 static int 64 __submore(FILE *fp) 65 { 66 int i; 67 unsigned char *p; 68 69 _DIAGASSERT(fp != NULL); 70 if(fp == NULL) { 71 errno = EINVAL; 72 return (EOF); 73 } 74 75 if (_UB(fp)._base == fp->_ubuf) { 76 /* 77 * Get a new buffer (rather than expanding the old one). 78 */ 79 if ((p = malloc((size_t)BUFSIZ)) == NULL) 80 return (EOF); 81 _UB(fp)._base = p; 82 _UB(fp)._size = BUFSIZ; 83 p += BUFSIZ - sizeof(fp->_ubuf); 84 for (i = sizeof(fp->_ubuf); --i >= 0;) 85 p[i] = fp->_ubuf[i]; 86 fp->_p = p; 87 return (0); 88 } 89 i = _UB(fp)._size; 90 p = realloc(_UB(fp)._base, (size_t)(i << 1)); 91 if (p == NULL) 92 return (EOF); 93 /* no overlap (hence can use memcpy) because we doubled the size */ 94 (void)memcpy((void *)(p + i), (void *)p, (size_t)i); 95 fp->_p = p + i; 96 _UB(fp)._base = p; 97 _UB(fp)._size = i << 1; 98 return (0); 99 } 100 101 int 102 ungetc(int c, FILE *fp) 103 { 104 _DIAGASSERT(fp != NULL); 105 if(fp == NULL) { 106 errno = EINVAL; 107 return (EOF); 108 } 109 110 if (c == EOF) 111 return (EOF); 112 if (!__sdidinit) 113 __sinit(); 114 FLOCKFILE(fp); 115 _SET_ORIENTATION(fp, -1); 116 if ((fp->_flags & __SRD) == 0) { 117 /* 118 * Not already reading: no good unless reading-and-writing. 119 * Otherwise, flush any current write stuff. 120 */ 121 if ((fp->_flags & __SRW) == 0) { 122 FUNLOCKFILE(fp); 123 return (EOF); 124 } 125 if (fp->_flags & __SWR) { 126 if (__sflush(fp)) { 127 FUNLOCKFILE(fp); 128 return (EOF); 129 } 130 fp->_flags &= ~__SWR; 131 fp->_w = 0; 132 fp->_lbfsize = 0; 133 } 134 fp->_flags |= __SRD; 135 } 136 c = (unsigned char)c; 137 138 /* 139 * If we are in the middle of ungetc'ing, just continue. 140 * This may require expanding the current ungetc buffer. 141 */ 142 if (HASUB(fp)) { 143 if (fp->_r >= _UB(fp)._size && __submore(fp)) { 144 FUNLOCKFILE(fp); 145 return (EOF); 146 } 147 *--fp->_p = (unsigned char)c; 148 fp->_r++; 149 FUNLOCKFILE(fp); 150 return (c); 151 } 152 fp->_flags &= ~__SEOF; 153 154 /* 155 * If we can handle this by simply backing up, do so, 156 * but never replace the original character. 157 * (This makes sscanf() work when scanning `const' data.) 158 */ 159 if (fp->_bf._base != NULL && fp->_p > fp->_bf._base && 160 fp->_p[-1] == c) { 161 fp->_p--; 162 fp->_r++; 163 FUNLOCKFILE(fp); 164 return (c); 165 } 166 167 /* 168 * Create an ungetc buffer. 169 * Initially, we will use the `reserve' buffer. 170 */ 171 fp->_ur = fp->_r; 172 fp->_up = fp->_p; 173 _UB(fp)._base = fp->_ubuf; 174 _UB(fp)._size = sizeof(fp->_ubuf); 175 fp->_ubuf[sizeof(fp->_ubuf) - 1] = (unsigned char)c; 176 fp->_p = &fp->_ubuf[sizeof(fp->_ubuf) - 1]; 177 fp->_r = 1; 178 FUNLOCKFILE(fp); 179 return (c); 180 } 181
