1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
|
/*-
* Copyright (c) 1990, 1993
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Chris Torek.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#if defined(LIBC_SCCS) && !defined(lint)
static char rcsid[] = "$OpenBSD: ungetc.c,v 1.7 2005/04/30 09:25:17 espie Exp $";
#endif /* LIBC_SCCS and not lint */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "local.h"
static int __submore(FILE *);
/*
* Expand the ungetc buffer `in place'. That is, adjust fp->_p when
* the buffer moves, so that it points the same distance from the end,
* and move the bytes in the buffer around as necessary so that they
* are all at the end (stack-style).
*/
static int
__submore(FILE *fp)
{
int i;
unsigned char *p;
if (_UB(fp)._base == fp->_ubuf) {
/*
* Get a new buffer (rather than expanding the old one).
*/
if ((p = malloc((size_t)BUFSIZ)) == NULL)
return (EOF);
_UB(fp)._base = p;
_UB(fp)._size = BUFSIZ;
p += BUFSIZ - sizeof(fp->_ubuf);
for (i = sizeof(fp->_ubuf); --i >= 0;)
p[i] = fp->_ubuf[i];
fp->_p = p;
return (0);
}
i = _UB(fp)._size;
p = realloc(_UB(fp)._base, i << 1);
if (p == NULL)
return (EOF);
/* no overlap (hence can use memcpy) because we doubled the size */
(void)memcpy((void *)(p + i), (void *)p, (size_t)i);
fp->_p = p + i;
_UB(fp)._base = p;
_UB(fp)._size = i << 1;
return (0);
}
int
ungetc(int c, FILE *fp)
{
if (c == EOF)
return (EOF);
if (!__sdidinit)
__sinit();
if ((fp->_flags & __SRD) == 0) {
/*
* Not already reading: no good unless reading-and-writing.
* Otherwise, flush any current write stuff.
*/
if ((fp->_flags & __SRW) == 0)
return (EOF);
if (fp->_flags & __SWR) {
if (__sflush(fp))
return (EOF);
fp->_flags &= ~__SWR;
fp->_w = 0;
fp->_lbfsize = 0;
}
fp->_flags |= __SRD;
}
c = (unsigned char)c;
/*
* If we are in the middle of ungetc'ing, just continue.
* This may require expanding the current ungetc buffer.
*/
if (HASUB(fp)) {
if (fp->_r >= _UB(fp)._size && __submore(fp))
return (EOF);
*--fp->_p = c;
fp->_r++;
return (c);
}
fp->_flags &= ~__SEOF;
/*
* If we can handle this by simply backing up, do so,
* but never replace the original character.
* (This makes sscanf() work when scanning `const' data.)
*/
if (fp->_bf._base != NULL && fp->_p > fp->_bf._base &&
fp->_p[-1] == c) {
fp->_p--;
fp->_r++;
return (c);
}
/*
* Create an ungetc buffer.
* Initially, we will use the `reserve' buffer.
*/
fp->_ur = fp->_r;
fp->_up = fp->_p;
_UB(fp)._base = fp->_ubuf;
_UB(fp)._size = sizeof(fp->_ubuf);
fp->_ubuf[sizeof(fp->_ubuf) - 1] = c;
fp->_p = &fp->_ubuf[sizeof(fp->_ubuf) - 1];
fp->_r = 1;
return (c);
}
|
