Clean up:
[dragonfly.git] / games / caesar / caesar.c
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1/*
2 * Copyright (c) 1989, 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 * Rick Adams.
7 *
8 * Authors:
9 * Stan King, John Eldridge, based on algorithm suggested by
10 * Bob Morris
11 * 29-Sep-82
12 *
13 * Redistribution and use in source and binary forms, with or without
14 * modification, are permitted provided that the following conditions
15 * are met:
16 * 1. Redistributions of source code must retain the above copyright
17 * notice, this list of conditions and the following disclaimer.
18 * 2. Redistributions in binary form must reproduce the above copyright
19 * notice, this list of conditions and the following disclaimer in the
20 * documentation and/or other materials provided with the distribution.
21 * 3. All advertising materials mentioning features or use of this software
22 * must display the following acknowledgement:
23 * This product includes software developed by the University of
24 * California, Berkeley and its contributors.
25 * 4. Neither the name of the University nor the names of its contributors
26 * may be used to endorse or promote products derived from this software
27 * without specific prior written permission.
28 *
29 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
30 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
31 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
32 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
33 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
34 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
35 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
36 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
37 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
38 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
39 * SUCH DAMAGE.
40 *
41 * $FreeBSD: src/games/caesar/caesar.c,v 1.8.2.1 2000/08/17 06:13:06 jhb Exp $
851dc90d 42 * $DragonFly: src/games/caesar/caesar.c,v 1.3 2003/11/12 14:53:52 eirikn Exp $
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43 *
44 * @(#) Copyright (c) 1989, 1993 The Regents of the University of California. All rights reserved.
45 * @(#)caesar.c 8.1 (Berkeley) 5/31/93
46 * $FreeBSD: src/games/caesar/caesar.c,v 1.8.2.1 2000/08/17 06:13:06 jhb Exp $
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47 */
48
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49#include <errno.h>
50#include <math.h>
51#include <stdio.h>
52#include <stdlib.h>
53#include <string.h>
54#include <ctype.h>
55#include <unistd.h>
56
57#define LINELENGTH 2048
58#define ROTATE(ch, perm) \
59 isascii(ch) ? ( \
60 isupper(ch) ? ('A' + (ch - 'A' + perm) % 26) : \
61 islower(ch) ? ('a' + (ch - 'a' + perm) % 26) : ch) : ch
62
63/*
64 * letter frequencies (taken from some unix(tm) documentation)
65 * (unix is a trademark of Bell Laboratories)
66 */
67double stdf[26] = {
68 7.97, 1.35, 3.61, 4.78, 12.37, 2.01, 1.46, 4.49, 6.39, 0.04,
69 0.42, 3.81, 2.69, 5.92, 6.96, 2.91, 0.08, 6.63, 8.77, 9.68,
70 2.62, 0.81, 1.88, 0.23, 2.07, 0.06,
71};
72
851dc90d 73void printit (char *);
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74
75int
76main(argc, argv)
77 int argc;
78 char **argv;
79{
80 int ch, dot, i, nread, winnerdot = 0;
81 char *inbuf;
82 int obs[26], try, winner;
83
84 /* revoke setgid privileges */
85 setgid(getgid());
86
87 if (argc > 1)
88 printit(argv[1]);
89
90 if (!(inbuf = malloc(LINELENGTH))) {
91 (void)fprintf(stderr, "caesar: out of memory.\n");
92 exit(1);
93 }
94
95 /* adjust frequency table to weight low probs REAL low */
96 for (i = 0; i < 26; ++i)
97 stdf[i] = log(stdf[i]) + log(26.0 / 100.0);
98
99 /* zero out observation table */
100 bzero(obs, 26 * sizeof(int));
101
102 if ((nread = read(STDIN_FILENO, inbuf, LINELENGTH)) < 0) {
103 (void)fprintf(stderr, "caesar: %s\n", strerror(errno));
104 exit(1);
105 }
106 for (i = nread; i--;) {
107 ch = (unsigned char) inbuf[i];
108 if (isascii(ch)) {
109 if (islower(ch))
110 ++obs[ch - 'a'];
111 else if (isupper(ch))
112 ++obs[ch - 'A'];
113 }
114 }
115
116 /*
117 * now "dot" the freqs with the observed letter freqs
118 * and keep track of best fit
119 */
120 for (try = winner = 0; try < 26; ++try) { /* += 13) { */
121 dot = 0;
122 for (i = 0; i < 26; i++)
123 dot += obs[i] * stdf[(i + try) % 26];
124 /* initialize winning score */
125 if (try == 0)
126 winnerdot = dot;
127 if (dot > winnerdot) {
128 /* got a new winner! */
129 winner = try;
130 winnerdot = dot;
131 }
132 }
133
134 for (;;) {
135 for (i = 0; i < nread; ++i) {
136 ch = (unsigned char) inbuf[i];
137 putchar(ROTATE(ch, winner));
138 }
139 if (nread < LINELENGTH)
140 break;
141 if ((nread = read(STDIN_FILENO, inbuf, LINELENGTH)) < 0) {
142 (void)fprintf(stderr, "caesar: %s\n", strerror(errno));
143 exit(1);
144 }
145 }
146 exit(0);
147}
148
149void printit(arg)
150 char *arg;
151{
152 int ch, rot;
153
154 if ((rot = atoi(arg)) < 0) {
155 (void)fprintf(stderr, "caesar: bad rotation value.\n");
156 exit(1);
157 }
158 while ((ch = getchar()) != EOF)
159 putchar(ROTATE(ch, rot));
160 exit(0);
161}