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c9be6cfe | 1 | /*- |
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2 | * Copyright (c) 1990, 1993 |
3 | * The Regents of the University of California. All rights reserved. | |
c9be6cfe KB |
4 | * |
5 | * This code is derived from software contributed to Berkeley by | |
6 | * Chris Torek. | |
7 | * | |
ad787160 C |
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 | * 3. All advertising materials mentioning features or use of this software | |
17 | * must display the following acknowledgement: | |
18 | * This product includes software developed by the University of | |
19 | * California, Berkeley and its contributors. | |
20 | * 4. Neither the name of the University nor the names of its contributors | |
21 | * may be used to endorse or promote products derived from this software | |
22 | * without specific prior written permission. | |
23 | * | |
24 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND | |
25 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE | |
26 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE | |
27 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE | |
28 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL | |
29 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS | |
30 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) | |
31 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT | |
32 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY | |
33 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF | |
34 | * SUCH DAMAGE. | |
c9be6cfe KB |
35 | */ |
36 | ||
2ce81398 | 37 | #if defined(LIBC_SCCS) && !defined(lint) |
ed554bc5 | 38 | static char sccsid[] = "@(#)ungetc.c 8.2 (Berkeley) 11/3/93"; |
c9be6cfe | 39 | #endif /* LIBC_SCCS and not lint */ |
bec69c1e | 40 | |
52dc310d | 41 | #include <stdio.h> |
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42 | #include <stdlib.h> |
43 | #include <string.h> | |
44 | #include "local.h" | |
45 | ||
46 | /* | |
47 | * Expand the ungetc buffer `in place'. That is, adjust fp->_p when | |
48 | * the buffer moves, so that it points the same distance from the end, | |
49 | * and move the bytes in the buffer around as necessary so that they | |
50 | * are all at the end (stack-style). | |
51 | */ | |
52 | static | |
53 | __submore(fp) | |
54 | register FILE *fp; | |
55 | { | |
56 | register int i; | |
57 | register unsigned char *p; | |
58 | ||
59 | if (fp->_ub._base == fp->_ubuf) { | |
60 | /* | |
61 | * Get a new buffer (rather than expanding the old one). | |
62 | */ | |
63 | if ((p = malloc((size_t)BUFSIZ)) == NULL) | |
64 | return (EOF); | |
65 | fp->_ub._base = p; | |
66 | fp->_ub._size = BUFSIZ; | |
67 | p += BUFSIZ - sizeof(fp->_ubuf); | |
68 | for (i = sizeof(fp->_ubuf); --i >= 0;) | |
69 | p[i] = fp->_ubuf[i]; | |
70 | fp->_p = p; | |
71 | return (0); | |
72 | } | |
73 | i = fp->_ub._size; | |
74 | p = realloc(fp->_ub._base, i << 1); | |
75 | if (p == NULL) | |
76 | return (EOF); | |
594acd1e CT |
77 | /* no overlap (hence can use memcpy) because we doubled the size */ |
78 | (void)memcpy((void *)(p + i), (void *)p, (size_t)i); | |
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79 | fp->_p = p + i; |
80 | fp->_ub._base = p; | |
81 | fp->_ub._size = i << 1; | |
82 | return (0); | |
83 | } | |
52dc310d | 84 | |
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85 | ungetc(c, fp) |
86 | int c; | |
87 | register FILE *fp; | |
52dc310d | 88 | { |
c9be6cfe | 89 | if (c == EOF) |
41e01b3e | 90 | return (EOF); |
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91 | if (!__sdidinit) |
92 | __sinit(); | |
93 | if ((fp->_flags & __SRD) == 0) { | |
94 | /* | |
95 | * Not already reading: no good unless reading-and-writing. | |
96 | * Otherwise, flush any current write stuff. | |
97 | */ | |
98 | if ((fp->_flags & __SRW) == 0) | |
99 | return (EOF); | |
100 | if (fp->_flags & __SWR) { | |
9c4d87d3 | 101 | if (__sflush(fp)) |
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102 | return (EOF); |
103 | fp->_flags &= ~__SWR; | |
104 | fp->_w = 0; | |
105 | fp->_lbfsize = 0; | |
106 | } | |
107 | fp->_flags |= __SRD; | |
108 | } | |
109 | c = (unsigned char)c; | |
41e01b3e | 110 | |
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111 | /* |
112 | * If we are in the middle of ungetc'ing, just continue. | |
113 | * This may require expanding the current ungetc buffer. | |
114 | */ | |
115 | if (HASUB(fp)) { | |
116 | if (fp->_r >= fp->_ub._size && __submore(fp)) | |
7d03a2b9 | 117 | return (EOF); |
c9be6cfe KB |
118 | *--fp->_p = c; |
119 | fp->_r++; | |
120 | return (c); | |
121 | } | |
dcd40c0c | 122 | fp->_flags &= ~__SEOF; |
41e01b3e | 123 | |
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124 | /* |
125 | * If we can handle this by simply backing up, do so, | |
126 | * but never replace the original character. | |
127 | * (This makes sscanf() work when scanning `const' data.) | |
128 | */ | |
129 | if (fp->_bf._base != NULL && fp->_p > fp->_bf._base && | |
130 | fp->_p[-1] == c) { | |
131 | fp->_p--; | |
132 | fp->_r++; | |
133 | return (c); | |
134 | } | |
41e01b3e | 135 | |
c9be6cfe KB |
136 | /* |
137 | * Create an ungetc buffer. | |
138 | * Initially, we will use the `reserve' buffer. | |
139 | */ | |
140 | fp->_ur = fp->_r; | |
141 | fp->_up = fp->_p; | |
142 | fp->_ub._base = fp->_ubuf; | |
143 | fp->_ub._size = sizeof(fp->_ubuf); | |
144 | fp->_ubuf[sizeof(fp->_ubuf) - 1] = c; | |
145 | fp->_p = &fp->_ubuf[sizeof(fp->_ubuf) - 1]; | |
146 | fp->_r = 1; | |
bec69c1e | 147 | return (c); |
52dc310d | 148 | } |