games/factor/factor.c

   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  * Landon Curt Noll.
   7  *
   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. Neither the name of the University nor the names of its contributors
  17  *    may be used to endorse or promote products derived from this software
  18  *    without specific prior written permission.
  19  *
  20  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  30  * SUCH DAMAGE.
  31  *
  32  * @(#) Copyright (c) 1989, 1993 The Regents of the University of California.  All rights reserved.
  33  * @(#)factor.c 8.4 (Berkeley) 5/4/95
  34  * $NetBSD: factor.c,v 1.13 2002/06/18 23:07:36 simonb Exp $
  35  * $FreeBSD: src/games/factor/factor.c,v 1.9.2.2 2002/10/23 14:59:14 fanf Exp $
  36  * $DragonFly: src/games/factor/factor.c,v 1.2 2003/06/17 04:25:23 dillon Exp $
  37  */
  38
  39 /*
  40  * factor - factor a number into primes
  41  *
  42  * By: Landon Curt Noll   chongo@toad.com,   ...!{sun,tolsoft}!hoptoad!chongo
  43  *
  44  *   chongo <for a good prime call: 391581 * 2^216193 - 1> /\oo/\
  45  *
  46  * usage:
  47  *      factor [-h] [number] ...
  48  *
  49  * The form of the output is:
  50  *
  51  *      number: factor1 factor1 factor2 factor3 factor3 factor3 ...
  52  *
  53  * where factor1 < factor2 < factor3 < ...
  54  *
  55  * If no args are given, the list of numbers are read from stdin.
  56  */
  57
  58 #include <ctype.h>
  59 #include <err.h>
  60 #include <errno.h>
  61 #include <limits.h>
  62 #include <stdio.h>
  63 #include <stdlib.h>
  64 #include <unistd.h>
  65
  66 #include "primes.h"
  67
  68 #ifdef HAVE_OPENSSL
  69 #include <openssl/bn.h>
  70 #define PRIME_CHECKS    5
  71 static void     pollard_pminus1(BIGNUM *); /* print factors for big numbers */
  72 #else
  73 typedef ubig    BIGNUM;
  74 typedef u_long  BN_ULONG;
  75
  76 #define BN_CTX                  int
  77 #define BN_CTX_new()            NULL
  78 #define BN_new()                ((BIGNUM *)calloc(sizeof(BIGNUM), 1))
  79 #define BN_is_zero(v)           (*(v) == 0)
  80 #define BN_is_one(v)            (*(v) == 1)
  81 #define BN_mod_word(a, b)       (*(a) % (b))
  82
  83 static int      BN_dec2bn(BIGNUM **a, const char *str);
  84 static int      BN_hex2bn(BIGNUM **a, const char *str);
  85 static BN_ULONG BN_div_word(BIGNUM *, BN_ULONG);
  86 static void     BN_print_fp(FILE *, const BIGNUM *);
  87 #endif
  88
  89 static void     BN_print_dec_fp(FILE *, const BIGNUM *);
  90
  91 static void     pr_fact(BIGNUM *);      /* print factors of a value */
  92 static void     pr_print(BIGNUM *);     /* print a prime */
  93 static void     usage(void);
  94
  95 static BN_CTX   *ctx;                   /* just use a global context */
  96 static int      hflag;
  97
  98 int
  99 main(int argc, char *argv[])
 100 {
 101         BIGNUM *val;
 102         int ch;
 103         char *p, buf[LINE_MAX];         /* > max number of digits. */
 104
 105         ctx = BN_CTX_new();
 106         val = BN_new();
 107         if (val == NULL)
 108                 errx(1, "can't initialise bignum");
 109
 110         while ((ch = getopt(argc, argv, "h")) != -1)
 111                 switch (ch) {
 112                 case 'h':
 113                         hflag++;
 114                         break;
 115                 case '?':
 116                 default:
 117                         usage();
 118                 }
 119         argc -= optind;
 120         argv += optind;
 121
 122         /* No args supplied, read numbers from stdin. */
 123         if (argc == 0)
 124                 for (;;) {
 125                         if (fgets(buf, sizeof(buf), stdin) == NULL) {
 126                                 if (ferror(stdin))
 127                                         err(1, "stdin");
 128                                 exit (0);
 129                         }
 130                         for (p = buf; isblank(*p); ++p);
 131                         if (*p == '\n' || *p == '\0')
 132                                 continue;
 133                         if (*p == '-')
 134                                 errx(1, "negative numbers aren't permitted.");
 135                         if (BN_dec2bn(&val, buf) == 0 &&
 136                             BN_hex2bn(&val, buf) == 0)
 137                                 errx(1, "%s: illegal numeric format.", buf);
 138                         pr_fact(val);
 139                 }
 140         /* Factor the arguments. */
 141         else
 142                 for (; *argv != NULL; ++argv) {
 143                         if (argv[0][0] == '-')
 144                                 errx(1, "negative numbers aren't permitted.");
 145                         if (BN_dec2bn(&val, argv[0]) == 0 &&
 146                             BN_hex2bn(&val, argv[0]) == 0)
 147                                 errx(1, "%s: illegal numeric format.", argv[0]);
 148                         pr_fact(val);
 149                 }
 150         exit(0);
 151 }
 152
 153 /*
 154  * pr_fact - print the factors of a number
 155  *
 156  * Print the factors of the number, from the lowest to the highest.
 157  * A factor will be printed multiple times if it divides the value
 158  * multiple times.
 159  *
 160  * Factors are printed with leading tabs.
 161  */
 162 static void
 163 pr_fact(BIGNUM *val)
 164 {
 165         const ubig *fact;       /* The factor found. */
 166
 167         /* Firewall - catch 0 and 1. */
 168         if (BN_is_zero(val))    /* Historical practice; 0 just exits. */
 169                 exit(0);
 170         if (BN_is_one(val)) {
 171                 printf("1: 1\n");
 172                 return;
 173         }
 174
 175         /* Factor value. */
 176
 177         if (hflag) {
 178                 fputs("0x", stdout);
 179                 BN_print_fp(stdout, val);
 180         } else
 181                 BN_print_dec_fp(stdout, val);
 182         putchar(':');
 183         for (fact = &prime[0]; !BN_is_one(val); ++fact) {
 184                 /* Look for the smallest factor. */
 185                 do {
 186                         if (BN_mod_word(val, (BN_ULONG)*fact) == 0)
 187                                 break;
 188                 } while (++fact <= pr_limit);
 189
 190                 /* Watch for primes larger than the table. */
 191                 if (fact > pr_limit) {
 192 #ifdef HAVE_OPENSSL
 193                         BIGNUM *bnfact;
 194
 195                         bnfact = BN_new();
 196                         BN_set_word(bnfact, *(fact - 1));
 197                         BN_sqr(bnfact, bnfact, ctx);
 198                         if (BN_cmp(bnfact, val) > 0)
 199                                 pr_print(val);
 200                         else
 201                                 pollard_pminus1(val);
 202 #else
 203                         pr_print(val);
 204 #endif
 205                         break;
 206                 }
 207
 208                 /* Divide factor out until none are left. */
 209                 do {
 210                         printf(hflag ? " 0x%lx" : " %lu", *fact);
 211                         BN_div_word(val, (BN_ULONG)*fact);
 212                 } while (BN_mod_word(val, (BN_ULONG)*fact) == 0);
 213
 214                 /* Let the user know we're doing something. */
 215                 fflush(stdout);
 216         }
 217         putchar('\n');
 218 }
 219
 220 static void
 221 pr_print(BIGNUM *val)
 222 {
 223         if (hflag) {
 224                 fputs(" 0x", stdout);
 225                 BN_print_fp(stdout, val);
 226         } else {
 227                 putchar(' ');
 228                 BN_print_dec_fp(stdout, val);
 229         }
 230 }
 231
 232 static void
 233 usage(void)
 234 {
 235         fprintf(stderr, "usage: factor [-h] [value ...]\n");
 236         exit(1);
 237 }
 238
 239 #ifdef HAVE_OPENSSL
 240
 241 /* pollard p-1, algorithm from Jim Gillogly, May 2000 */
 242 static void
 243 pollard_pminus1(BIGNUM *val)
 244 {
 245         BIGNUM *base, *num, *i, *x;
 246
 247         base = BN_new();
 248         num = BN_new();
 249         i = BN_new();
 250         x = BN_new();
 251
 252         BN_set_word(i, 2);
 253         BN_set_word(base, 2);
 254
 255         for (;;) {
 256                 BN_mod_exp(base, base, i, val, ctx);
 257
 258                 BN_copy(x, base);
 259                 BN_sub_word(x, 1);
 260                 BN_gcd(x, x, val, ctx);
 261
 262                 if (!BN_is_one(x)) {
 263                         if (BN_is_prime(x, PRIME_CHECKS, NULL, NULL,
 264                             NULL) == 1)
 265                                 pr_print(x);
 266                         else
 267                                 pollard_pminus1(x);
 268                         fflush(stdout);
 269
 270                         BN_div(num, NULL, val, x, ctx);
 271                         if (BN_is_one(num))
 272                                 return;
 273                         if (BN_is_prime(num, PRIME_CHECKS, NULL, NULL,
 274                             NULL) == 1) {
 275                                 pr_print(num);
 276                                 fflush(stdout);
 277                                 return;
 278                         }
 279                         BN_copy(val, num);
 280                 }
 281                 BN_add_word(i, 1);
 282         }
 283 }
 284
 285 /*
 286  * Sigh..  No _decimal_ output to file functions in BN.
 287  */
 288 static void
 289 BN_print_dec_fp(FILE *fp, const BIGNUM *num)
 290 {
 291         char *buf;
 292
 293         buf = BN_bn2dec(num);
 294         if (buf == NULL)
 295                 return; /* XXX do anything here? */
 296         fprintf(fp, buf);
 297         free(buf);
 298 }
 299
 300 #else
 301
 302 static void
 303 BN_print_fp(FILE *fp, const BIGNUM *num)
 304 {
 305         fprintf(fp, "%lx", (unsigned long)*num);
 306 }
 307
 308 static void
 309 BN_print_dec_fp(FILE *fp, const BIGNUM *num)
 310 {
 311         fprintf(fp, "%lu", (unsigned long)*num);
 312 }
 313
 314 static int
 315 BN_dec2bn(BIGNUM **a, const char *str)
 316 {
 317         char *p;
 318
 319         errno = 0;
 320         **a = strtoul(str, &p, 10);
 321         return (errno == 0 && (*p == '\n' || *p == '\0'));
 322 }
 323
 324 static int
 325 BN_hex2bn(BIGNUM **a, const char *str)
 326 {
 327         char *p;
 328
 329         errno = 0;
 330         **a = strtoul(str, &p, 16);
 331         return (errno == 0 && (*p == '\n' || *p == '\0'));
 332 }
 333
 334 static BN_ULONG
 335 BN_div_word(BIGNUM *a, BN_ULONG b)
 336 {
 337         BN_ULONG mod;
 338
 339         mod = *a % b;
 340         *a /= b;
 341         return mod;
 342 }
 343
 344 #endif