| 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 | * 4. Neither the name of the University nor the names of its contributors␊ |
| 17 | * may be used to endorse or promote products derived from this software␊ |
| 18 | * without specific prior written permission.␊ |
| 19 | *␊ |
| 20 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND␊ |
| 21 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE␊ |
| 22 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE␊ |
| 23 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE␊ |
| 24 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL␊ |
| 25 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS␊ |
| 26 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)␊ |
| 27 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT␊ |
| 28 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY␊ |
| 29 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF␊ |
| 30 | * SUCH DAMAGE.␊ |
| 31 | */␊ |
| 32 | ␊ |
| 33 | #if defined(LIBC_SCCS) && !defined(lint)␊ |
| 34 | static char sccsid[] = "@(#)ungetc.c␉8.2 (Berkeley) 11/3/93";␊ |
| 35 | #endif /* LIBC_SCCS and not lint */␊ |
| 36 | #include <sys/cdefs.h>␊ |
| 37 | //__FBSDID("$FreeBSD: src/lib/libc/stdio/ungetc.c,v 1.18 2008/04/17 22:17:54 jhb Exp $");␊ |
| 38 | ␊ |
| 39 | #include "stdio.h"␊ |
| 40 | #include "errno.h"␊ |
| 41 | #include "namespace.h"␊ |
| 42 | #include "un-namespace.h"␊ |
| 43 | #include "local.h"␊ |
| 44 | ␊ |
| 45 | ␊ |
| 46 | static int __submore(FILE *);␊ |
| 47 | ␊ |
| 48 | /*␊ |
| 49 | * Expand the ungetc buffer `in place'. That is, adjust fp->_p when␊ |
| 50 | * the buffer moves, so that it points the same distance from the end,␊ |
| 51 | * and move the bytes in the buffer around as necessary so that they␊ |
| 52 | * are all at the end (stack-style).␊ |
| 53 | */␊ |
| 54 | static int␊ |
| 55 | __submore(FILE *fp)␊ |
| 56 | {␊ |
| 57 | ␉int i;␊ |
| 58 | ␉unsigned char *p;␊ |
| 59 | ␊ |
| 60 | ␉if (fp->_ub._base == fp->_ubuf) {␊ |
| 61 | ␉␉/*␊ |
| 62 | ␉␉ * Get a new buffer (rather than expanding the old one).␊ |
| 63 | ␉␉ */␊ |
| 64 | ␉␉if ((p = malloc((size_t)BUFSIZ)) == NULL)␊ |
| 65 | ␉␉␉return (EOF);␊ |
| 66 | ␉␉fp->_ub._base = p;␊ |
| 67 | ␉␉fp->_ub._size = BUFSIZ;␊ |
| 68 | ␉␉p += BUFSIZ - sizeof(fp->_ubuf);␊ |
| 69 | ␉␉for (i = sizeof(fp->_ubuf); --i >= 0;)␊ |
| 70 | ␉␉␉p[i] = fp->_ubuf[i];␊ |
| 71 | ␉␉fp->_p = p;␊ |
| 72 | ␉␉return (0);␊ |
| 73 | ␉}␊ |
| 74 | ␉i = fp->_ub._size;␊ |
| 75 | ␉p = realloc(fp->_ub._base, (size_t)(i << 1));␊ |
| 76 | ␉if (p == NULL)␊ |
| 77 | ␉␉return (EOF);␊ |
| 78 | ␉/* no overlap (hence can use memcpy) because we doubled the size */␊ |
| 79 | ␉(void)memcpy((void *)(p + i), (void *)p, (size_t)i);␊ |
| 80 | ␉fp->_p = p + i;␊ |
| 81 | ␉fp->_ub._base = p;␊ |
| 82 | ␉fp->_ub._size = i << 1;␊ |
| 83 | ␉return (0);␊ |
| 84 | }␊ |
| 85 | ␊ |
| 86 | ␊ |
| 87 | int␊ |
| 88 | ungetc(int c, FILE *fp)␊ |
| 89 | {␊ |
| 90 | ␉int ret;␊ |
| 91 | ␊ |
| 92 | ␉if (!__sdidinit)␊ |
| 93 | ␉␉__sinit();␊ |
| 94 | ␉ORIENT(fp, -1);␊ |
| 95 | ␉ret = __ungetc(c, fp);␊ |
| 96 | ␉return (ret);␊ |
| 97 | }␊ |
| 98 | ␊ |
| 99 | /*␊ |
| 100 | * Non-MT-safe version␊ |
| 101 | */␊ |
| 102 | int␊ |
| 103 | __ungetc(int c, FILE *fp)␊ |
| 104 | {␊ |
| 105 | ␊ |
| 106 | ␉if (c == EOF)␊ |
| 107 | ␉␉return (EOF);␊ |
| 108 | ␉if ((fp->_flags & __SRD) == 0) {␊ |
| 109 | ␉␉/*␊ |
| 110 | ␉␉ * Not already reading: no good unless reading-and-writing.␊ |
| 111 | ␉␉ * Otherwise, flush any current write stuff.␊ |
| 112 | ␉␉ */␊ |
| 113 | ␉␉if ((fp->_flags & __SRW) == 0)␊ |
| 114 | ␉␉␉return (EOF);␊ |
| 115 | ␉␉if (fp->_flags & __SWR) {␊ |
| 116 | ␉␉␉if (__sflush(fp))␊ |
| 117 | ␉␉␉␉return (EOF);␊ |
| 118 | ␉␉␉fp->_flags &= ~__SWR;␊ |
| 119 | ␉␉␉fp->_w = 0;␊ |
| 120 | ␉␉␉fp->_lbfsize = 0;␊ |
| 121 | ␉␉}␊ |
| 122 | ␉␉fp->_flags |= __SRD;␊ |
| 123 | ␉}␊ |
| 124 | ␉c = (unsigned char)c;␊ |
| 125 | ␊ |
| 126 | ␉/*␊ |
| 127 | ␉ * If we are in the middle of ungetc'ing, just continue.␊ |
| 128 | ␉ * This may require expanding the current ungetc buffer.␊ |
| 129 | ␉ */␊ |
| 130 | ␉if (HASUB(fp)) {␊ |
| 131 | ␉␉if (fp->_r >= fp->_ub._size && __submore(fp))␊ |
| 132 | ␉␉␉return (EOF);␊ |
| 133 | ␉␉*--fp->_p = c;␊ |
| 134 | ␉␉fp->_r++;␊ |
| 135 | ␉␉return (c);␊ |
| 136 | ␉}␊ |
| 137 | ␉fp->_flags &= ~__SEOF;␊ |
| 138 | ␊ |
| 139 | ␉/*␊ |
| 140 | ␉ * If we can handle this by simply backing up, do so,␊ |
| 141 | ␉ * but never replace the original character.␊ |
| 142 | ␉ * (This makes sscanf() work when scanning `const' data.)␊ |
| 143 | ␉ */␊ |
| 144 | ␉if (fp->_bf._base != NULL && fp->_p > fp->_bf._base &&␊ |
| 145 | ␉ fp->_p[-1] == c) {␊ |
| 146 | ␉␉fp->_p--;␊ |
| 147 | ␉␉fp->_r++;␊ |
| 148 | ␉␉return (c);␊ |
| 149 | ␉}␊ |
| 150 | ␊ |
| 151 | ␉/*␊ |
| 152 | ␉ * Create an ungetc buffer.␊ |
| 153 | ␉ * Initially, we will use the `reserve' buffer.␊ |
| 154 | ␉ */␊ |
| 155 | ␉fp->_ur = fp->_r;␊ |
| 156 | ␉fp->_up = fp->_p;␊ |
| 157 | ␉fp->_ub._base = fp->_ubuf;␊ |
| 158 | ␉fp->_ub._size = sizeof(fp->_ubuf);␊ |
| 159 | ␉fp->_ubuf[sizeof(fp->_ubuf) - 1] = c;␊ |
| 160 | ␉fp->_p = &fp->_ubuf[sizeof(fp->_ubuf) - 1];␊ |
| 161 | ␉fp->_r = 1;␊ |
| 162 | ␉return (c);␊ |
| 163 | }␊ |
| 164 | |
