-/* $NetBSD: caesar.c,v 1.13 2004/01/01 16:00:34 jsm Exp $ */
+/* $NetBSD: caesar.c,v 1.22 2008/07/20 01:03:21 lukem Exp $ */
/*
* Copyright (c) 1989, 1993
* Stan King, John Eldridge, based on algorithm suggested by
* Bob Morris
* 29-Sep-82
+ * Roland Illig, 2005
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
#include <sys/cdefs.h>
#ifndef lint
-__COPYRIGHT("@(#) Copyright (c) 1989, 1993\n\
- The Regents of the University of California. All rights reserved.\n");
+__COPYRIGHT("@(#) Copyright (c) 1989, 1993\
+ The Regents of the University of California. All rights reserved.");
#endif /* not lint */
#ifndef lint
#if 0
static char sccsid[] = "@(#)caesar.c 8.1 (Berkeley) 5/31/93";
#else
-__RCSID("$NetBSD: caesar.c,v 1.13 2004/01/01 16:00:34 jsm Exp $");
+__RCSID("$NetBSD: caesar.c,v 1.22 2008/07/20 01:03:21 lukem Exp $");
#endif
#endif /* not lint */
-#include <ctype.h>
#include <err.h>
#include <errno.h>
+#include <limits.h>
#include <math.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
-#include <unistd.h>
-#define LINELENGTH 2048
-#define ROTATE(ch, perm) \
- isupper(ch) ? ('A' + (ch - 'A' + perm) % 26) : \
- islower(ch) ? ('a' + (ch - 'a' + perm) % 26) : ch
+#define NCHARS (1 << CHAR_BIT)
+#define LETTERS (26)
/*
* letter frequencies (taken from some unix(tm) documentation)
* (unix is a trademark of Bell Laboratories)
*/
-double stdf[26] = {
+static const unsigned char upper[LETTERS] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
+static const unsigned char lower[LETTERS] = "abcdefghijklmnopqrstuvwxyz";
+static double stdf[LETTERS] = {
7.97, 1.35, 3.61, 4.78, 12.37, 2.01, 1.46, 4.49, 6.39, 0.04,
0.42, 3.81, 2.69, 5.92, 6.96, 2.91, 0.08, 6.63, 8.77, 9.68,
- 2.62, 0.81, 1.88, 0.23, 2.07, 0.06,
+ 2.62, 0.81, 1.88, 0.23, 2.07, 0.06
};
+static unsigned char rottbl[NCHARS];
-int main __P((int, char *[]));
-void printit __P((const char *)) __attribute__((__noreturn__));
-int
-main(argc, argv)
- int argc;
- char **argv;
+static void
+init_rottbl(int rot)
{
- int ch, i, nread;
- double dot, winnerdot;
- char *inbuf;
- int obs[26], try, winner;
+ size_t i;
+
+ rot %= LETTERS; /* prevent integer overflow */
+
+ for (i = 0; i < NCHARS; i++)
+ rottbl[i] = (unsigned char)i;
+
+ for (i = 0; i < LETTERS; i++)
+ rottbl[upper[i]] = upper[(i + rot) % LETTERS];
+
+ for (i = 0; i < LETTERS; i++)
+ rottbl[lower[i]] = lower[(i + rot) % LETTERS];
+}
+
+static void
+print_file(void)
+{
+ int ch;
- /* revoke setgid privileges */
- setgid(getgid());
+ while ((ch = getchar()) != EOF) {
+ if (putchar(rottbl[ch]) == EOF) {
+ err(EXIT_FAILURE, "<stdout>");
+ /* NOTREACHED */
+ }
+ }
+}
+
+static void
+print_array(const unsigned char *a, size_t len)
+{
+ size_t i;
+
+ for (i = 0; i < len; i++) {
+ if (putchar(rottbl[a[i]]) == EOF) {
+ err(EXIT_FAILURE, "<stdout>");
+ /* NOTREACHED */
+ }
+ }
+}
- winnerdot = 0;
- if (argc > 1)
- printit(argv[1]);
+static int
+get_rotation(const char *arg)
+{
+ long rot;
+ char *endp;
+
+ errno = 0;
+ rot = strtol(arg, &endp, 10);
+ if (errno == 0 && (arg[0] == '\0' || *endp != '\0'))
+ errno = EINVAL;
+ if (errno == 0 && (rot < 0 || rot > INT_MAX))
+ errno = ERANGE;
+ if (errno)
+ err(EXIT_FAILURE, "Bad rotation value `%s'", arg);
+ return (int)rot;
+}
- if (!(inbuf = malloc(LINELENGTH)))
- err(1, NULL);
+static void
+guess_and_rotate(void)
+{
+ unsigned char inbuf[2048];
+ unsigned int obs[NCHARS];
+ size_t i, nread;
+ double dot, winnerdot;
+ int try, winner;
+ int ch;
/* adjust frequency table to weight low probs REAL low */
- for (i = 0; i < 26; ++i)
- stdf[i] = log(stdf[i]) + log(26.0 / 100.0);
+ for (i = 0; i < LETTERS; i++)
+ stdf[i] = log(stdf[i]) + log(LETTERS / 100.0);
/* zero out observation table */
- memset(obs, 0, 26 * sizeof(int));
-
- if ((nread = read(STDIN_FILENO, inbuf, LINELENGTH)) < 0)
- err(1, "reading from stdin");
- for (i = nread; i--;) {
- ch = inbuf[i];
- if (islower(ch))
- ++obs[ch - 'a'];
- else if (isupper(ch))
- ++obs[ch - 'A'];
+ (void)memset(obs, 0, sizeof(obs));
+
+ for (nread = 0; nread < sizeof(inbuf); nread++) {
+ if ((ch = getchar()) == EOF)
+ break;
+ inbuf[nread] = (unsigned char) ch;
}
+ for (i = 0; i < nread; i++)
+ obs[inbuf[i]]++;
+
/*
* now "dot" the freqs with the observed letter freqs
* and keep track of best fit
*/
- for (try = winner = 0; try < 26; ++try) { /* += 13) { */
- dot = 0;
- for (i = 0; i < 26; i++)
- dot += obs[i] * stdf[(i + try) % 26];
- /* initialize winning score */
- if (try == 0)
- winnerdot = dot;
- if (dot > winnerdot) {
+ winner = 0;
+ winnerdot = 0.0;
+ for (try = 0; try < LETTERS; try++) {
+ dot = 0.0;
+ for (i = 0; i < LETTERS; i++)
+ dot += (obs[upper[i]] + obs[lower[i]])
+ * stdf[(i + try) % LETTERS];
+
+ if (try == 0 || dot > winnerdot) {
/* got a new winner! */
winner = try;
winnerdot = dot;
}
}
- for (;;) {
- for (i = 0; i < nread; ++i) {
- ch = inbuf[i];
- putchar(ROTATE(ch, winner));
- }
- if (nread < LINELENGTH)
- break;
- if ((nread = read(STDIN_FILENO, inbuf, LINELENGTH)) < 0)
- err(1, "reading from stdin");
- }
- exit(0);
+ init_rottbl(winner);
+ print_array(inbuf, nread);
+ print_file();
}
-void
-printit(arg)
- const char *arg;
+int
+main(int argc, char **argv)
{
- int ch, rot;
- if ((rot = atoi(arg)) < 0)
- errx(1, "bad rotation value.");
- while ((ch = getchar()) != EOF)
- putchar(ROTATE(ch, rot));
- exit(0);
+ if (argc == 1) {
+ guess_and_rotate();
+ } else if (argc == 2) {
+ init_rottbl(get_rotation(argv[1]));
+ print_file();
+ } else {
+ (void)fprintf(stderr, "usage: caesar [rotation]\n");
+ exit(EXIT_FAILURE);
+ /* NOTREACHED */
+ }
+
+ if (ferror(stdin)) {
+ errx(EXIT_FAILURE, "<stdin>");
+ /* NOTREACHED */
+ }
+
+ (void)fflush(stdout);
+ if (ferror(stdout)) {
+ errx(EXIT_FAILURE, "<stdout>");
+ /* NOTREACHED */
+ }
+
+ return 0;
}
git.ckatri.com / bsdgames-darwin.git / blobdiff