1 /* $OpenBSD: factor.c,v 1.7 1999/09/26 05:29:41 pjanzen Exp $ */ 2 /* $NetBSD: factor.c,v 1.5 1995/03/23 08:28:07 cgd Exp $ */ 3 4 /* 5 * Copyright (c) 1989, 1993 6 * The Regents of the University of California. All rights reserved. 7 * 8 * This code is derived from software contributed to Berkeley by 9 * Landon Curt Noll. 10 * 11 * Redistribution and use in source and binary forms, with or without 12 * modification, are permitted provided that the following conditions 13 * are met: 14 * 1. Redistributions of source code must retain the above copyright 15 * notice, this list of conditions and the following disclaimer. 16 * 2. Redistributions in binary form must reproduce the above copyright 17 * notice, this list of conditions and the following disclaimer in the 18 * documentation and/or other materials provided with the distribution. 19 * 3. All advertising materials mentioning features or use of this software 20 * must display the following acknowledgement: 21 * This product includes software developed by the University of 22 * California, Berkeley and its contributors. 23 * 4. Neither the name of the University nor the names of its contributors 24 * may be used to endorse or promote products derived from this software 25 * without specific prior written permission. 26 * 27 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 28 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 29 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 30 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 31 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 32 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 33 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 34 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 35 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 36 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 37 * SUCH DAMAGE. 38 */ 39 40 #ifndef lint 41 static char copyright[] = 42 "@(#) Copyright (c) 1989, 1993\n\ 43 The Regents of the University of California. All rights reserved.\n"; 44 #endif /* not lint */ 45 46 #ifndef lint 47 #if 0 48 static char sccsid[] = "@(#)factor.c 8.4 (Berkeley) 5/4/95"; 49 #else 50 static char rcsid[] = "$OpenBSD: factor.c,v 1.7 1999/09/26 05:29:41 pjanzen Exp $"; 51 #endif 52 #endif /* not lint */ 53 54 /* 55 * factor - factor a number into primes 56 * 57 * By: Landon Curt Noll chongo@toad.com, ...!{sun,tolsoft}!hoptoad!chongo 58 * 59 * chongo <for a good prime call: 391581 * 2^216193 - 1> /\oo/\ 60 * 61 * usage: 62 * factor [number] ... 63 * 64 * The form of the output is: 65 * 66 * number: factor1 factor1 factor2 factor3 factor3 factor3 ... 67 * 68 * where factor1 < factor2 < factor3 < ... 69 * 70 * If no args are given, the list of numbers are read from stdin. 71 */ 72 73 #include <sys/types.h> 74 #include <err.h> 75 #include <ctype.h> 76 #include <errno.h> 77 #include <limits.h> 78 #include <stdio.h> 79 #include <stdlib.h> 80 #include <unistd.h> 81 82 #include "primes.h" 83 84 /* 85 * prime[i] is the (i+1)th prime. 86 * 87 * We are able to sieve 2^32-1 because this byte table yields all primes 88 * up to 65537 and 65537^2 > 2^32-1. 89 */ 90 extern const ubig prime[]; 91 extern const ubig *pr_limit; /* largest prime in the prime array */ 92 93 void pr_fact __P((ubig)); /* print factors of a value */ 94 void usage __P((void)); 95 96 int 97 main(argc, argv) 98 int argc; 99 char *argv[]; 100 { 101 ubig val; 102 int ch; 103 char *p, buf[100]; /* > max number of digits. */ 104 105 /* revoke privs */ 106 setegid(getgid()); 107 setgid(getgid()); 108 109 while ((ch = getopt(argc, argv, "")) != -1) 110 switch (ch) { 111 case '?': 112 default: 113 usage(); 114 } 115 argc -= optind; 116 argv += optind; 117 118 /* No args supplied, read numbers from stdin. */ 119 if (argc == 0) 120 for (;;) { 121 if (fgets(buf, sizeof(buf), stdin) == NULL) { 122 if (ferror(stdin)) 123 err(1, "stdin"); 124 exit (0); 125 } 126 for (p = buf; isblank(*p); ++p); 127 if (*p == '\n' || *p == '\0') 128 continue; 129 if (*p == '-') 130 errx(1, "negative numbers aren't permitted."); 131 errno = 0; 132 val = strtoul(buf, &p, 10); 133 if (errno) 134 err(1, "%s", buf); 135 if (*p != '\n') 136 errx(1, "%s: illegal numeric format.", buf); 137 pr_fact(val); 138 } 139 /* Factor the arguments. */ 140 else 141 for (; *argv != NULL; ++argv) { 142 if (argv[0][0] == '-') 143 errx(1, "negative numbers aren't permitted."); 144 errno = 0; 145 val = strtoul(argv[0], &p, 10); 146 if (errno) 147 err(1, "%s", argv[0]); 148 if (*p != '\0') 149 errx(1, "%s: illegal numeric format.", argv[0]); 150 pr_fact(val); 151 } 152 exit(0); 153 } 154 155 /* 156 * pr_fact - print the factors of a number 157 * 158 * If the number is 0 or 1, then print the number and return. 159 * If the number is < 0, print -1, negate the number and continue 160 * processing. 161 * 162 * Print the factors of the number, from the lowest to the highest. 163 * A factor will be printed numtiple times if it divides the value 164 * multiple times. 165 * 166 * Factors are printed with leading tabs. 167 */ 168 void 169 pr_fact(val) 170 ubig val; /* Factor this value. */ 171 { 172 const ubig *fact; /* The factor found. */ 173 174 /* Firewall - catch 0 and 1. */ 175 if (val == 0) /* Historical practice; 0 just exits. */ 176 exit(0); 177 if (val == 1) { 178 (void)printf("1: 1\n"); 179 return; 180 } 181 182 /* Factor value. */ 183 (void)printf("%lu:", val); 184 for (fact = &prime[0]; val > 1; ++fact) { 185 /* Look for the smallest factor. */ 186 do { 187 if (val % (long)*fact == 0) 188 break; 189 } while (++fact <= pr_limit); 190 191 /* Watch for primes larger than the table. */ 192 if (fact > pr_limit) { 193 (void)printf(" %lu", val); 194 break; 195 } 196 197 /* Divide factor out until none are left. */ 198 do { 199 (void)printf(" %lu", *fact); 200 val /= (long)*fact; 201 } while ((val % (long)*fact) == 0); 202 203 /* Let the user know we're doing something. */ 204 (void)fflush(stdout); 205 } 206 (void)putchar('\n'); 207 } 208 209 void 210 usage() 211 { 212 (void)fprintf(stderr, "usage: factor [value ...]\n"); 213 exit (0); 214 } 215