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. 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.
  35  *
  36  * @(#) Copyright (c) 1989, 1993 The Regents of the University of California.  All rights reserved.
  37  * @(#)factor.c 8.4 (Berkeley) 5/4/95
  38  * $NetBSD: factor.c,v 1.13 2002/06/18 23:07:36 simonb Exp $
  39  * $FreeBSD: src/games/factor/factor.c,v 1.9.2.2 2002/10/23 14:59:14 fanf Exp $
  40  * $DragonFly: src/games/factor/factor.c,v 1.2 2003/06/17 04:25:23 dillon Exp $
  41  */
  42
  43 /*
  44  * factor - factor a number into primes
  45  *
  46  * By: Landon Curt Noll   chongo@toad.com,   ...!{sun,tolsoft}!hoptoad!chongo
  47  *
  48  *   chongo <for a good prime call: 391581 * 2^216193 - 1> /\oo/\
  49  *
  50  * usage:
  51  *      factor [-h] [number] ...
  52  *
  53  * The form of the output is:
  54  *
  55  *      number: factor1 factor1 factor2 factor3 factor3 factor3 ...
  56  *
  57  * where factor1 < factor2 < factor3 < ...
  58  *
  59  * If no args are given, the list of numbers are read from stdin.
  60  */
  61
  62 #include <ctype.h>
  63 #include <err.h>
  64 #include <errno.h>
  65 #include <limits.h>
  66 #include <stdio.h>
  67 #include <stdlib.h>
  68 #include <unistd.h>
  69
  70 #include "primes.h"
  71
  72 #ifdef HAVE_OPENSSL
  73
  74 #include <openssl/bn.h>
  75
  76 #define PRIME_CHECKS    5
  77
  78 static void     pollard_pminus1(BIGNUM *); /* print factors for big numbers */
  79
  80 #else
  81
  82 typedef ubig    BIGNUM;
  83 typedef u_long  BN_ULONG;
  84
  85 #define BN_CTX                  int
  86 #define BN_CTX_new()            NULL
  87 #define BN_new()                ((BIGNUM *)calloc(sizeof(BIGNUM), 1))
  88 #define BN_is_zero(v)           (*(v) == 0)
  89 #define BN_is_one(v)            (*(v) == 1)
  90 #define BN_mod_word(a, b)       (*(a) % (b))
  91
  92 static int      BN_dec2bn(BIGNUM **a, const char *str);
  93 static int      BN_hex2bn(BIGNUM **a, const char *str);
  94 static BN_ULONG BN_div_word(BIGNUM *, BN_ULONG);
  95 static void     BN_print_fp(FILE *, const BIGNUM *);
  96
  97 #endif
  98
  99 static void     BN_print_dec_fp(FILE *, const BIGNUM *);
 100
 101 static void     pr_fact(BIGNUM *);      /* print factors of a value */
 102 static void     pr_print(BIGNUM *);     /* print a prime */
 103 static void     usage(void);
 104
 105 static BN_CTX   *ctx;                   /* just use a global context */
 106 static int      hflag;
 107
 108 int
 109 main(int argc, char *argv[])
 110 {
 111         BIGNUM *val;
 112         int ch;
 113         char *p, buf[LINE_MAX];         /* > max number of digits. */
 114
 115         ctx = BN_CTX_new();
 116         val = BN_new();
 117         if (val == NULL)
 118                 errx(1, "can't initialise bignum");
 119
 120         while ((ch = getopt(argc, argv, "h")) != -1)
 121                 switch (ch) {
 122                 case 'h':
 123                         hflag++;
 124                         break;
 125                 case '?':
 126                 default:
 127                         usage();
 128                 }
 129         argc -= optind;
 130         argv += optind;
 131
 132         /* No args supplied, read numbers from stdin. */
 133         if (argc == 0)
 134                 for (;;) {
 135                         if (fgets(buf, sizeof(buf), stdin) == NULL) {
 136                                 if (ferror(stdin))
 137                                         err(1, "stdin");
 138                                 exit (0);
 139                         }
 140                         for (p = buf; isblank(*p); ++p);
 141                         if (*p == '\n' || *p == '\0')
 142                                 continue;
 143                         if (*p == '-')
 144                                 errx(1, "negative numbers aren't permitted.");
 145                         if (BN_dec2bn(&val, buf) == 0 &&
 146                             BN_hex2bn(&val, buf) == 0)
 147                                 errx(1, "%s: illegal numeric format.", buf);
 148                         pr_fact(val);
 149                 }
 150         /* Factor the arguments. */
 151         else
 152                 for (; *argv != NULL; ++argv) {
 153                         if (argv[0][0] == '-')
 154                                 errx(1, "negative numbers aren't permitted.");
 155                         if (BN_dec2bn(&val, argv[0]) == 0 &&
 156                             BN_hex2bn(&val, argv[0]) == 0)
 157                                 errx(1, "%s: illegal numeric format.", argv[0]);
 158                         pr_fact(val);
 159                 }
 160         exit(0);
 161 }
 162
 163 /*
 164  * pr_fact - print the factors of a number
 165  *
 166  * Print the factors of the number, from the lowest to the highest.
 167  * A factor will be printed multiple times if it divides the value
 168  * multiple times.
 169  *
 170  * Factors are printed with leading tabs.
 171  */
 172 static void
 173 pr_fact(BIGNUM *val)
 174 {
 175         const ubig *fact;       /* The factor found. */
 176
 177         /* Firewall - catch 0 and 1. */
 178         if (BN_is_zero(val))    /* Historical practice; 0 just exits. */
 179                 exit(0);
 180         if (BN_is_one(val)) {
 181                 printf("1: 1\n");
 182                 return;
 183         }
 184
 185         /* Factor value. */
 186
 187         if (hflag) {
 188                 fputs("0x", stdout);
 189                 BN_print_fp(stdout, val);
 190         } else
 191                 BN_print_dec_fp(stdout, val);
 192         putchar(':');
 193         for (fact = &prime[0]; !BN_is_one(val); ++fact) {
 194                 /* Look for the smallest factor. */
 195                 do {
 196                         if (BN_mod_word(val, (BN_ULONG)*fact) == 0)
 197                                 break;
 198                 } while (++fact <= pr_limit);
 199
 200                 /* Watch for primes larger than the table. */
 201                 if (fact > pr_limit) {
 202 #ifdef HAVE_OPENSSL
 203                         BIGNUM *bnfact;
 204
 205                         bnfact = BN_new();
 206                         BN_set_word(bnfact, *(fact - 1));
 207                         BN_sqr(bnfact, bnfact, ctx);
 208                         if (BN_cmp(bnfact, val) > 0)
 209                                 pr_print(val);
 210                         else
 211                                 pollard_pminus1(val);
 212 #else
 213                         pr_print(val);
 214 #endif
 215                         break;
 216                 }
 217
 218                 /* Divide factor out until none are left. */
 219                 do {
 220                         printf(hflag ? " 0x%lx" : " %lu", *fact);
 221                         BN_div_word(val, (BN_ULONG)*fact);
 222                 } while (BN_mod_word(val, (BN_ULONG)*fact) == 0);
 223
 224                 /* Let the user know we're doing something. */
 225                 fflush(stdout);
 226         }
 227         putchar('\n');
 228 }
 229
 230 static void
 231 pr_print(BIGNUM *val)
 232 {
 233         if (hflag) {
 234                 fputs(" 0x", stdout);
 235                 BN_print_fp(stdout, val);
 236         } else {
 237                 putchar(' ');
 238                 BN_print_dec_fp(stdout, val);
 239         }
 240 }
 241
 242 static void
 243 usage(void)
 244 {
 245         fprintf(stderr, "usage: factor [-h] [value ...]\n");
 246         exit(1);
 247 }
 248
 249 #ifdef HAVE_OPENSSL
 250
 251 /* pollard rho, algorithm from Jim Gillogly, May 2000 */
 252 static void
 253 pollard_pminus1(BIGNUM *val)
 254 {
 255         BIGNUM *base, *num, *i, *x;
 256
 257         base = BN_new();
 258         num = BN_new();
 259         i = BN_new();
 260         x = BN_new();
 261
 262         BN_set_word(i, 2);
 263         BN_set_word(base, 2);
 264
 265         for (;;) {
 266                 BN_mod_exp(base, base, i, val, ctx);
 267
 268                 BN_copy(x, base);
 269                 BN_sub_word(x, 1);
 270                 BN_gcd(x, x, val, ctx);
 271
 272                 if (!BN_is_one(x)) {
 273                         if (BN_is_prime(x, PRIME_CHECKS, NULL, NULL,
 274                             NULL) == 1)
 275                                 pr_print(x);
 276                         else
 277                                 pollard_pminus1(x);
 278                         fflush(stdout);
 279
 280                         BN_div(num, NULL, val, x, ctx);
 281                         if (BN_is_one(num))
 282                                 return;
 283                         if (BN_is_prime(num, PRIME_CHECKS, NULL, NULL,
 284                             NULL) == 1) {
 285                                 pr_print(num);
 286                                 fflush(stdout);
 287                                 return;
 288                         }
 289                         BN_copy(val, num);
 290                 }
 291                 BN_add_word(i, 1);
 292         }
 293 }
 294
 295 /*
 296  * Sigh..  No _decimal_ output to file functions in BN.
 297  */
 298 static void
 299 BN_print_dec_fp(FILE *fp, const BIGNUM *num)
 300 {
 301         char *buf;
 302
 303         buf = BN_bn2dec(num);
 304         if (buf == NULL)
 305                 return; /* XXX do anything here? */
 306         fprintf(fp, buf);
 307         free(buf);
 308 }
 309
 310 #else
 311
 312 static void
 313 BN_print_fp(FILE *fp, const BIGNUM *num)
 314 {
 315         fprintf(fp, "%lx", (unsigned long)*num);
 316 }
 317
 318 static void
 319 BN_print_dec_fp(FILE *fp, const BIGNUM *num)
 320 {
 321         fprintf(fp, "%lu", (unsigned long)*num);
 322 }
 323
 324 static int
 325 BN_dec2bn(BIGNUM **a, const char *str)
 326 {
 327         char *p;
 328
 329         errno = 0;
 330         **a = strtoul(str, &p, 10);
 331         return (errno == 0 && (*p == '\n' || *p == '\0'));
 332 }
 333
 334 static int
 335 BN_hex2bn(BIGNUM **a, const char *str)
 336 {
 337         char *p;
 338
 339         errno = 0;
 340         **a = strtoul(str, &p, 16);
 341         return (errno == 0 && (*p == '\n' || *p == '\0'));
 342 }
 343
 344 static BN_ULONG
 345 BN_div_word(BIGNUM *a, BN_ULONG b)
 346 {
 347         BN_ULONG mod;
 348
 349         mod = *a % b;
 350         *a /= b;
 351         return mod;
 352 }
 353
 354 #endif