360 lines
8.2 KiB
C
360 lines
8.2 KiB
C
/* $NetBSD: factor.c,v 1.15 2004/02/08 11:47:36 jsm Exp $ */
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/*
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* Copyright (c) 1989, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* Landon Curt Noll.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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#ifndef lint
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__COPYRIGHT("@(#) Copyright (c) 1989, 1993\n\
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The Regents of the University of California. All rights reserved.\n");
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#endif /* not lint */
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#ifndef lint
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#if 0
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static char sccsid[] = "@(#)factor.c 8.4 (Berkeley) 5/4/95";
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#else
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__RCSID("$NetBSD: factor.c,v 1.15 2004/02/08 11:47:36 jsm Exp $");
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#endif
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#endif /* not lint */
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/*
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* factor - factor a number into primes
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*
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* By: Landon Curt Noll chongo@toad.com, ...!{sun,tolsoft}!hoptoad!chongo
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*
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* chongo <for a good prime call: 391581 * 2^216193 - 1> /\oo/\
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*
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* usage:
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* factor [number] ...
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*
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* The form of the output is:
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*
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* number: factor1 factor1 factor2 factor3 factor3 factor3 ...
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*
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* where factor1 < factor2 < factor3 < ...
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*
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* If no args are given, the list of numbers are read from stdin.
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*/
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#include <ctype.h>
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#include <err.h>
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#include <errno.h>
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#include <limits.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#ifdef HAVE_OPENSSL
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#include <openssl/bn.h>
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#else
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typedef long BIGNUM;
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typedef u_long BN_ULONG;
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int BN_dec2bn(BIGNUM **a, const char *str);
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#define BN_new() ((BIGNUM *)calloc(sizeof(BIGNUM), 1))
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#define BN_is_zero(v) (*(v) == 0)
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#define BN_is_one(v) (*(v) == 1)
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#define BN_new() ((BIGNUM *)calloc(sizeof(BIGNUM), 1))
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#define BN_is_zero(v) (*(v) == 0)
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#define BN_is_one(v) (*(v) == 1)
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#define BN_mod_word(a, b) (*(a) % (b))
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#endif
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#include "primes.h"
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/*
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* prime[i] is the (i-1)th prime.
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*
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* We are able to sieve 2^32-1 because this byte table yields all primes
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* up to 65537 and 65537^2 > 2^32-1.
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*/
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extern const ubig prime[];
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extern const ubig *pr_limit; /* largest prime in the prime array */
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#define PRIME_CHECKS 5
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#ifdef HAVE_OPENSSL
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BN_CTX *ctx; /* just use a global context */
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#endif
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int main(int, char *[]);
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void pr_fact(BIGNUM *); /* print factors of a value */
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void BN_print_dec_fp(FILE *, const BIGNUM *);
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void usage(void) __attribute__((__noreturn__));
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#ifdef HAVE_OPENSSL
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void pollard_pminus1(BIGNUM *); /* print factors for big numbers */
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#else
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char *BN_bn2dec(const BIGNUM *);
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BN_ULONG BN_div_word(BIGNUM *, BN_ULONG);
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#endif
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#ifndef HAVE_OPENSSL
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int
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BN_dec2bn(BIGNUM **a, const char *str)
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{
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char *p;
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errno = 0;
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**a = strtoul(str, &p, 10);
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if (errno)
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err(1, "%s", str);
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return (*p == '\n' || *p == '\0');
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}
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#endif
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int
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main(int argc, char *argv[])
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{
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BIGNUM *val;
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int ch;
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char *p, buf[LINE_MAX]; /* > max number of digits. */
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#ifdef HAVE_OPENSSL
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ctx = BN_CTX_new();
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#endif
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val = BN_new();
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if (val == NULL)
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errx(1, "can't initialise bignum");
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/* Revoke setgid privileges */
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setregid(getgid(), getgid());
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while ((ch = getopt(argc, argv, "")) != -1)
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switch (ch) {
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case '?':
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default:
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usage();
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}
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argc -= optind;
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argv += optind;
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/* No args supplied, read numbers from stdin. */
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if (argc == 0)
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for (;;) {
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if (fgets(buf, sizeof(buf), stdin) == NULL) {
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if (ferror(stdin))
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err(1, "stdin");
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exit (0);
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}
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for (p = buf; isblank(*p); ++p);
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if (*p == '\n' || *p == '\0')
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continue;
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if (*p == '-')
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errx(1, "negative numbers aren't permitted.");
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if (BN_dec2bn(&val, buf) == 0)
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errx(1, "%s: illegal numeric format.", argv[0]);
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pr_fact(val);
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}
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/* Factor the arguments. */
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else
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for (; *argv != NULL; ++argv) {
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if (argv[0][0] == '-')
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errx(1, "negative numbers aren't permitted.");
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if (BN_dec2bn(&val, argv[0]) == 0)
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errx(1, "%s: illegal numeric format.", argv[0]);
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pr_fact(val);
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}
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exit(0);
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}
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/*
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* pr_fact - print the factors of a number
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*
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* If the number is 0 or 1, then print the number and return.
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* If the number is < 0, print -1, negate the number and continue
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* processing.
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*
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* Print the factors of the number, from the lowest to the highest.
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* A factor will be printed numtiple times if it divides the value
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* multiple times.
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*
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* Factors are printed with leading tabs.
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*/
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void
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pr_fact(BIGNUM *val)
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{
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const ubig *fact; /* The factor found. */
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/* Firewall - catch 0 and 1. */
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if (BN_is_zero(val)) /* Historical practice; 0 just exits. */
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exit(0);
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if (BN_is_one(val)) {
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printf("1: 1\n");
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return;
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}
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/* Factor value. */
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BN_print_dec_fp(stdout, val);
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putchar(':');
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for (fact = &prime[0]; !BN_is_one(val); ++fact) {
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/* Look for the smallest factor. */
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do {
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if (BN_mod_word(val, (BN_ULONG)*fact) == 0)
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break;
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} while (++fact <= pr_limit);
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/* Watch for primes larger than the table. */
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if (fact > pr_limit) {
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#ifdef HAVE_OPENSSL
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BIGNUM *bnfact;
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bnfact = BN_new();
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BN_set_word(bnfact, *(fact - 1));
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BN_sqr(bnfact, bnfact, ctx);
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if (BN_cmp(bnfact, val) > 0
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|| BN_is_prime(val, PRIME_CHECKS, NULL, NULL,
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NULL) == 1) {
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putchar(' ');
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BN_print_dec_fp(stdout, val);
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} else
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pollard_pminus1(val);
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#else
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printf(" %s", BN_bn2dec(val));
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#endif
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break;
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}
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/* Divide factor out until none are left. */
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do {
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printf(" %lu", *fact);
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BN_div_word(val, (BN_ULONG)*fact);
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} while (BN_mod_word(val, (BN_ULONG)*fact) == 0);
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/* Let the user know we're doing something. */
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fflush(stdout);
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}
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putchar('\n');
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}
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/*
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* Sigh.. No _decimal_ output to file functions in BN.
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*/
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void
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BN_print_dec_fp(FILE *fp, const BIGNUM *num)
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{
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char *buf;
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buf = BN_bn2dec(num);
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if (buf == NULL)
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return; /* XXX do anything here? */
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fprintf(fp, buf);
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free(buf);
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}
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void
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usage(void)
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{
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fprintf(stderr, "usage: factor [value ...]\n");
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exit (0);
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}
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#ifdef HAVE_OPENSSL
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/* pollard p-1, algorithm from Jim Gillogly, May 2000 */
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void
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pollard_pminus1(BIGNUM *val)
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{
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BIGNUM *base, *rbase, *num, *i, *x;
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base = BN_new();
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rbase = BN_new();
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num = BN_new();
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i = BN_new();
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x = BN_new();
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BN_set_word(rbase, 1);
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newbase:
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BN_add_word(rbase, 1);
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BN_set_word(i, 2);
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BN_copy(base, rbase);
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for (;;) {
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BN_mod_exp(base, base, i, val, ctx);
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if (BN_is_one(base))
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goto newbase;
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BN_copy(x, base);
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BN_sub_word(x, 1);
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BN_gcd(x, x, val, ctx);
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if (!BN_is_one(x)) {
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if (BN_is_prime(x, PRIME_CHECKS, NULL, NULL,
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NULL) == 1) {
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putchar(' ');
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BN_print_dec_fp(stdout, x);
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} else
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pollard_pminus1(x);
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fflush(stdout);
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BN_div(num, NULL, val, x, ctx);
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if (BN_is_one(num))
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return;
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if (BN_is_prime(num, PRIME_CHECKS, NULL, NULL,
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NULL) == 1) {
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putchar(' ');
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BN_print_dec_fp(stdout, num);
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fflush(stdout);
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return;
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}
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BN_copy(val, num);
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}
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BN_add_word(i, 1);
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}
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}
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#else
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char *
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BN_bn2dec(const BIGNUM *val)
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{
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char *buf;
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buf = malloc(100);
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if (!buf)
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return buf;
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snprintf(buf, 100, "%ld", (long)*val);
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return buf;
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}
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BN_ULONG
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BN_div_word(BIGNUM *a, BN_ULONG b)
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{
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BN_ULONG mod;
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mod = *a % b;
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*a /= b;
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return mod;
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}
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#endif
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