1/* 2 * Copyright (c) 1980, 1987, 1992, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 4. Neither the name of the University nor the names of its contributors 14 * may be used to endorse or promote products derived from this software 15 * without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 */ 29 30#ifndef lint 31static const char copyright[] = 32"@(#) Copyright (c) 1980, 1987, 1992, 1993\n\ 33 The Regents of the University of California. All rights reserved.\n"; 34#endif /* not lint */ 35 36#ifndef lint 37#if 0 38static char sccsid[] = "@(#)head.c 8.2 (Berkeley) 5/4/95"; 39#endif 40#endif /* not lint */ 41#include <sys/cdefs.h> 42__FBSDID("$FreeBSD: stable/11/usr.bin/head/head.c 332482 2018-04-13 17:57:00Z kevans $"); 43 44#include <sys/types.h> 45 46#include <ctype.h> 47#include <err.h> 48#include <getopt.h> 49#include <inttypes.h> 50#include <stdio.h> 51#include <stdlib.h> 52#include <string.h> 53#include <unistd.h> 54 55/* 56 * head - give the first few lines of a stream or of each of a set of files 57 * 58 * Bill Joy UCB August 24, 1977 59 */ 60 61static void head(FILE *, int); 62static void head_bytes(FILE *, off_t); 63static void obsolete(char *[]); 64static void usage(void); 65 66static const struct option long_opts[] = 67{ 68 {"bytes", required_argument, NULL, 'c'}, 69 {"lines", required_argument, NULL, 'n'}, 70 {NULL, no_argument, NULL, 0} 71}; 72 73int 74main(int argc, char *argv[]) 75{ 76 int ch; 77 FILE *fp; 78 int first, linecnt = -1, eval = 0; 79 off_t bytecnt = -1; 80 char *ep; 81 82 obsolete(argv); 83 while ((ch = getopt_long(argc, argv, "+n:c:", long_opts, NULL)) != -1) 84 switch(ch) { 85 case 'c': 86 bytecnt = strtoimax(optarg, &ep, 10); 87 if (*ep || bytecnt <= 0) 88 errx(1, "illegal byte count -- %s", optarg); 89 break; 90 case 'n': 91 linecnt = strtol(optarg, &ep, 10); 92 if (*ep || linecnt <= 0) 93 errx(1, "illegal line count -- %s", optarg); 94 break; 95 case '?': 96 default: 97 usage(); 98 } 99 argc -= optind; 100 argv += optind; 101 102 if (linecnt != -1 && bytecnt != -1) 103 errx(1, "can't combine line and byte counts"); 104 if (linecnt == -1 ) 105 linecnt = 10; 106 if (*argv) { 107 for (first = 1; *argv; ++argv) { 108 if ((fp = fopen(*argv, "r")) == NULL) { 109 warn("%s", *argv); 110 eval = 1; 111 continue; 112 } 113 if (argc > 1) { 114 (void)printf("%s==> %s <==\n", 115 first ? "" : "\n", *argv); 116 first = 0; 117 } 118 if (bytecnt == -1) 119 head(fp, linecnt); 120 else 121 head_bytes(fp, bytecnt); 122 (void)fclose(fp); 123 } 124 } else if (bytecnt == -1) 125 head(stdin, linecnt); 126 else 127 head_bytes(stdin, bytecnt); 128 129 exit(eval); 130} 131 132static void 133head(FILE *fp, int cnt) 134{ 135 char *cp; 136 size_t error, readlen; 137 138 while (cnt && (cp = fgetln(fp, &readlen)) != NULL) { 139 error = fwrite(cp, sizeof(char), readlen, stdout); 140 if (error != readlen) 141 err(1, "stdout"); 142 cnt--; 143 } 144} 145 146static void 147head_bytes(FILE *fp, off_t cnt) 148{ 149 char buf[4096]; 150 size_t readlen; 151 152 while (cnt) { 153 if ((uintmax_t)cnt < sizeof(buf)) 154 readlen = cnt; 155 else 156 readlen = sizeof(buf); 157 readlen = fread(buf, sizeof(char), readlen, fp); 158 if (readlen == 0) 159 break; 160 if (fwrite(buf, sizeof(char), readlen, stdout) != readlen) 161 err(1, "stdout"); 162 cnt -= readlen; 163 } 164} 165 166static void 167obsolete(char *argv[]) 168{ 169 char *ap; 170 171 while ((ap = *++argv)) { 172 /* Return if "--" or not "-[0-9]*". */ 173 if (ap[0] != '-' || ap[1] == '-' || !isdigit(ap[1])) 174 return; 175 if ((ap = malloc(strlen(*argv) + 2)) == NULL) 176 err(1, NULL); 177 ap[0] = '-'; 178 ap[1] = 'n'; 179 (void)strcpy(ap + 2, *argv + 1); 180 *argv = ap; 181 } 182} 183 184static void 185usage(void) 186{ 187 188 (void)fprintf(stderr, "usage: head [-n lines | -c bytes] [file ...]\n"); 189 exit(1); 190} 191