[src/trunk]: src/games/caesar * fixed <ctype> bugs

[rillig <rillig%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/c8acaa9d14f7
branches:  trunk
changeset: 581079:c8acaa9d14f7
user:      rillig <rillig%NetBSD.org@localhost>
date:      Mon May 23 23:02:30 2005 +0000

description:
* fixed <ctype> bugs
* removed ASCII dependency
* added input data validation
* added bounds checking
* added error checking
* handle short reads (from pipes or sockets) correctly
  when trying to decode an encoded stream
* added lint(1) directives

diffstat:

 games/caesar/caesar.c |  168 ++++++++++++++++++++++++++++++-------------------
 1 files changed, 104 insertions(+), 64 deletions(-)

diffs (235 lines):

diff -r c3bbf16aa2dd -r c8acaa9d14f7 games/caesar/caesar.c
--- a/games/caesar/caesar.c     Mon May 23 22:17:20 2005 +0000
+++ b/games/caesar/caesar.c     Mon May 23 23:02:30 2005 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: caesar.c,v 1.14 2004/01/27 20:30:29 jsm Exp $  */
+/*     $NetBSD: caesar.c,v 1.15 2005/05/23 23:02:30 rillig Exp $       */
 
 /*
  * Copyright (c) 1989, 1993
@@ -11,6 +11,7 @@
  *     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
@@ -47,115 +48,154 @@
 #if 0
 static char sccsid[] = "@(#)caesar.c   8.1 (Berkeley) 5/31/93";
 #else
-__RCSID("$NetBSD: caesar.c,v 1.14 2004/01/27 20:30:29 jsm Exp $");
+__RCSID("$NetBSD: caesar.c,v 1.15 2005/05/23 23:02:30 rillig 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(int, char *[]);
-void   printit(const char *) __attribute__((__noreturn__));
+static void
+init_rottbl(int rot)
+{
+       size_t i;
+
+       rot %= LETTERS;
+
+       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 __attribute__((__noreturn__))
+printrot(const char *arg)
+{
+       int ch;
+       long rot;
+       char *endp;
+
+       errno = 0;
+       rot = strtol(arg, &endp, 10);
+       if (*endp != '\0') {
+               errx(EXIT_FAILURE, "bad rotation value: %s", arg);
+               /* NOTREACHED */
+       }
+       if (errno == ERANGE || rot < 0 || rot > INT_MAX) {
+               errx(EXIT_FAILURE, "rotation value out of range: %s", arg);
+               /* NOTREACHED */
+       }
+       init_rottbl((int)rot);
+
+       while ((ch = getchar()) != EOF) {
+               if (putchar(rottbl[ch]) == EOF) {
+                       err(EXIT_FAILURE, "writing to stdout");
+                       /* NOTREACHED */
+               }
+       }
+       exit(EXIT_SUCCESS);
+       /* NOTREACHED */
+}
 
 int
-main(argc, argv)
-       int argc;
-       char **argv;
+main(int argc, char **argv)
 {
-       int ch, i, nread;
+       ssize_t i, nread, ntotal;
        double dot, winnerdot;
-       char *inbuf;
-       int obs[26], try, winner;
+       int try, winner;
+       unsigned char inbuf[2048];
+       unsigned int obs[NCHARS];
 
        /* revoke setgid privileges */
-       setgid(getgid());
+       (void)setgid(getgid());
 
-       winnerdot = 0;
-       if (argc > 1)
-               printit(argv[1]);
-
-       if (!(inbuf = malloc(LINELENGTH)))
-               err(1, NULL);
+       if (argc > 1) {
+               printrot(argv[1]);
+               /* NOTREACHED */
+       }
 
        /* 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));
+       (void)memset(obs, 0, sizeof(obs));
 
-       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'];
+       for (ntotal = 0; (size_t) ntotal < sizeof(inbuf); ntotal += nread) {
+               nread = read(STDIN_FILENO, &inbuf[ntotal],
+                            sizeof(inbuf) - ntotal);
+               if (nread < 0) {
+                       err(EXIT_FAILURE, "reading from stdin");
+                       /* NOTREACHED */
+               }
+               if (nread == 0)
+                       break;
        }
 
+       for (i = 0; i < ntotal; 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;
                }
        }
+       init_rottbl(winner);
 
-       for (;;) {
-               for (i = 0; i < nread; ++i) {
-                       ch = inbuf[i];
-                       putchar(ROTATE(ch, winner));
+       while (ntotal > 0) {
+               for (i = 0; i < ntotal; i++) {
+                       if (putchar(rottbl[inbuf[i]]) == EOF) {
+                               err(EXIT_FAILURE, "writing to stdout");
+                               /* NOTREACHED */
+                       }
                }
-               if (nread < LINELENGTH)
-                       break;
-               if ((nread = read(STDIN_FILENO, inbuf, LINELENGTH)) < 0)
-                       err(1, "reading from stdin");
+               if ((ntotal = read(STDIN_FILENO, inbuf, sizeof(inbuf))) < 0) {
+                       err(EXIT_FAILURE, "reading from stdin");
+                       /* NOTREACHED */
+               }
        }
-       exit(0);
+       exit(EXIT_FAILURE);
+       /* NOTREACHED */
 }
-
-void
-printit(arg)
-       const char *arg;
-{
-       int ch, rot;
-
-       if ((rot = atoi(arg)) < 0)
-               errx(1, "bad rotation value.");
-       while ((ch = getchar()) != EOF)
-               putchar(ROTATE(ch, rot));
-       exit(0);
-}