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 "namespace.h"␊ |
40 | #include <stdio.h>␊ |
41 | #include <stdlib.h>␊ |
42 | #include <string.h>␊ |
43 | #include "un-namespace.h"␊ |
44 | #include "local.h"␊ |
45 | ␊ |
46 | ␊ |
47 | static int __submore(FILE *);␊ |
48 | ␊ |
49 | /*␊ |
50 | * Expand the ungetc buffer `in place'. That is, adjust fp->_p when␊ |
51 | * the buffer moves, so that it points the same distance from the end,␊ |
52 | * and move the bytes in the buffer around as necessary so that they␊ |
53 | * are all at the end (stack-style).␊ |
54 | */␊ |
55 | static int␊ |
56 | __submore(FILE *fp)␊ |
57 | {␊ |
58 | ␉int i;␊ |
59 | ␉unsigned char *p;␊ |
60 | ␊ |
61 | ␉if (fp->_ub._base == fp->_ubuf) {␊ |
62 | ␉␉/*␊ |
63 | ␉␉ * Get a new buffer (rather than expanding the old one).␊ |
64 | ␉␉ */␊ |
65 | ␉␉if ((p = malloc((size_t)BUFSIZ)) == NULL)␊ |
66 | ␉␉␉return (EOF);␊ |
67 | ␉␉fp->_ub._base = p;␊ |
68 | ␉␉fp->_ub._size = BUFSIZ;␊ |
69 | ␉␉p += BUFSIZ - sizeof(fp->_ubuf);␊ |
70 | ␉␉for (i = sizeof(fp->_ubuf); --i >= 0;)␊ |
71 | ␉␉␉p[i] = fp->_ubuf[i];␊ |
72 | ␉␉fp->_p = p;␊ |
73 | ␉␉return (0);␊ |
74 | ␉}␊ |
75 | ␉i = fp->_ub._size;␊ |
76 | ␉p = realloc(fp->_ub._base, (size_t)(i << 1));␊ |
77 | ␉if (p == NULL)␊ |
78 | ␉␉return (EOF);␊ |
79 | ␉/* no overlap (hence can use memcpy) because we doubled the size */␊ |
80 | ␉(void)memcpy((void *)(p + i), (void *)p, (size_t)i);␊ |
81 | ␉fp->_p = p + i;␊ |
82 | ␉fp->_ub._base = p;␊ |
83 | ␉fp->_ub._size = i << 1;␊ |
84 | ␉return (0);␊ |
85 | }␊ |
86 | ␊ |
87 | ␊ |
88 | int␊ |
89 | ungetc(int c, FILE *fp)␊ |
90 | {␊ |
91 | ␉int ret;␊ |
92 | ␊ |
93 | ␉if (!__sdidinit)␊ |
94 | ␉␉__sinit();␊ |
95 | ␉ORIENT(fp, -1);␊ |
96 | ␉ret = __ungetc(c, fp);␊ |
97 | ␉return (ret);␊ |
98 | }␊ |
99 | ␊ |
100 | /*␊ |
101 | * Non-MT-safe version␊ |
102 | */␊ |
103 | int␊ |
104 | __ungetc(int c, FILE *fp)␊ |
105 | {␊ |
106 | ␊ |
107 | ␉if (c == EOF)␊ |
108 | ␉␉return (EOF);␊ |
109 | ␉if ((fp->_flags & __SRD) == 0) {␊ |
110 | ␉␉/*␊ |
111 | ␉␉ * Not already reading: no good unless reading-and-writing.␊ |
112 | ␉␉ * Otherwise, flush any current write stuff.␊ |
113 | ␉␉ */␊ |
114 | ␉␉if ((fp->_flags & __SRW) == 0)␊ |
115 | ␉␉␉return (EOF);␊ |
116 | ␉␉if (fp->_flags & __SWR) {␊ |
117 | ␉␉␉if (__sflush(fp))␊ |
118 | ␉␉␉␉return (EOF);␊ |
119 | ␉␉␉fp->_flags &= ~__SWR;␊ |
120 | ␉␉␉fp->_w = 0;␊ |
121 | ␉␉␉fp->_lbfsize = 0;␊ |
122 | ␉␉}␊ |
123 | ␉␉fp->_flags |= __SRD;␊ |
124 | ␉}␊ |
125 | ␉c = (unsigned char)c;␊ |
126 | ␊ |
127 | ␉/*␊ |
128 | ␉ * If we are in the middle of ungetc'ing, just continue.␊ |
129 | ␉ * This may require expanding the current ungetc buffer.␊ |
130 | ␉ */␊ |
131 | ␉if (HASUB(fp)) {␊ |
132 | ␉␉if (fp->_r >= fp->_ub._size && __submore(fp))␊ |
133 | ␉␉␉return (EOF);␊ |
134 | ␉␉*--fp->_p = c;␊ |
135 | ␉␉fp->_r++;␊ |
136 | ␉␉return (c);␊ |
137 | ␉}␊ |
138 | ␉fp->_flags &= ~__SEOF;␊ |
139 | ␊ |
140 | ␉/*␊ |
141 | ␉ * If we can handle this by simply backing up, do so,␊ |
142 | ␉ * but never replace the original character.␊ |
143 | ␉ * (This makes sscanf() work when scanning `const' data.)␊ |
144 | ␉ */␊ |
145 | ␉if (fp->_bf._base != NULL && fp->_p > fp->_bf._base &&␊ |
146 | ␉ fp->_p[-1] == c) {␊ |
147 | ␉␉fp->_p--;␊ |
148 | ␉␉fp->_r++;␊ |
149 | ␉␉return (c);␊ |
150 | ␉}␊ |
151 | ␊ |
152 | ␉/*␊ |
153 | ␉ * Create an ungetc buffer.␊ |
154 | ␉ * Initially, we will use the `reserve' buffer.␊ |
155 | ␉ */␊ |
156 | ␉fp->_ur = fp->_r;␊ |
157 | ␉fp->_up = fp->_p;␊ |
158 | ␉fp->_ub._base = fp->_ubuf;␊ |
159 | ␉fp->_ub._size = sizeof(fp->_ubuf);␊ |
160 | ␉fp->_ubuf[sizeof(fp->_ubuf) - 1] = c;␊ |
161 | ␉fp->_p = &fp->_ubuf[sizeof(fp->_ubuf) - 1];␊ |
162 | ␉fp->_r = 1;␊ |
163 | ␉return (c);␊ |
164 | }␊ |
165 | |