1 /* 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 1980, 1987, 1992, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. Neither the name of the University nor the names of its contributors 16 * may be used to endorse or promote products derived from this software 17 * without specific prior written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 */ 31 32 #ifndef lint 33 static const char copyright[] = 34 "@(#) Copyright (c) 1980, 1987, 1992, 1993\n\ 35 The Regents of the University of California. All rights reserved.\n"; 36 #endif /* not lint */ 37 38 #ifndef lint 39 #if 0 40 static char sccsid[] = "@(#)head.c 8.2 (Berkeley) 5/4/95"; 41 #endif 42 #endif /* not lint */ 43 #include <sys/cdefs.h> 44 __FBSDID("$FreeBSD$"); 45 46 #include <sys/types.h> 47 48 #include <ctype.h> 49 #include <err.h> 50 #include <getopt.h> 51 #include <inttypes.h> 52 #include <stdio.h> 53 #include <stdlib.h> 54 #include <string.h> 55 #include <unistd.h> 56 57 /* 58 * head - give the first few lines of a stream or of each of a set of files 59 * 60 * Bill Joy UCB August 24, 1977 61 */ 62 63 static void head(FILE *, int); 64 static void head_bytes(FILE *, off_t); 65 static void obsolete(char *[]); 66 static void usage(void); 67 68 static const struct option long_opts[] = 69 { 70 {"bytes", required_argument, NULL, 'c'}, 71 {"lines", required_argument, NULL, 'n'}, 72 {NULL, no_argument, NULL, 0} 73 }; 74 75 int 76 main(int argc, char *argv[]) 77 { 78 int ch; 79 FILE *fp; 80 int first, linecnt = -1, eval = 0; 81 off_t bytecnt = -1; 82 char *ep; 83 84 obsolete(argv); 85 while ((ch = getopt_long(argc, argv, "+n:c:", long_opts, NULL)) != -1) 86 switch(ch) { 87 case 'c': 88 bytecnt = strtoimax(optarg, &ep, 10); 89 if (*ep || bytecnt <= 0) 90 errx(1, "illegal byte count -- %s", optarg); 91 break; 92 case 'n': 93 linecnt = strtol(optarg, &ep, 10); 94 if (*ep || linecnt <= 0) 95 errx(1, "illegal line count -- %s", optarg); 96 break; 97 case '?': 98 default: 99 usage(); 100 } 101 argc -= optind; 102 argv += optind; 103 104 if (linecnt != -1 && bytecnt != -1) 105 errx(1, "can't combine line and byte counts"); 106 if (linecnt == -1 ) 107 linecnt = 10; 108 if (*argv) { 109 for (first = 1; *argv; ++argv) { 110 if ((fp = fopen(*argv, "r")) == NULL) { 111 warn("%s", *argv); 112 eval = 1; 113 continue; 114 } 115 if (argc > 1) { 116 (void)printf("%s==> %s <==\n", 117 first ? "" : "\n", *argv); 118 first = 0; 119 } 120 if (bytecnt == -1) 121 head(fp, linecnt); 122 else 123 head_bytes(fp, bytecnt); 124 (void)fclose(fp); 125 } 126 } else if (bytecnt == -1) 127 head(stdin, linecnt); 128 else 129 head_bytes(stdin, bytecnt); 130 131 exit(eval); 132 } 133 134 static void 135 head(FILE *fp, int cnt) 136 { 137 char *cp; 138 size_t error, readlen; 139 140 while (cnt && (cp = fgetln(fp, &readlen)) != NULL) { 141 error = fwrite(cp, sizeof(char), readlen, stdout); 142 if (error != readlen) 143 err(1, "stdout"); 144 cnt--; 145 } 146 } 147 148 static void 149 head_bytes(FILE *fp, off_t cnt) 150 { 151 char buf[4096]; 152 size_t readlen; 153 154 while (cnt) { 155 if ((uintmax_t)cnt < sizeof(buf)) 156 readlen = cnt; 157 else 158 readlen = sizeof(buf); 159 readlen = fread(buf, sizeof(char), readlen, fp); 160 if (readlen == 0) 161 break; 162 if (fwrite(buf, sizeof(char), readlen, stdout) != readlen) 163 err(1, "stdout"); 164 cnt -= readlen; 165 } 166 } 167 168 static void 169 obsolete(char *argv[]) 170 { 171 char *ap; 172 173 while ((ap = *++argv)) { 174 /* Return if "--" or not "-[0-9]*". */ 175 if (ap[0] != '-' || ap[1] == '-' || !isdigit(ap[1])) 176 return; 177 if ((ap = malloc(strlen(*argv) + 2)) == NULL) 178 err(1, NULL); 179 ap[0] = '-'; 180 ap[1] = 'n'; 181 (void)strcpy(ap + 2, *argv + 1); 182 *argv = ap; 183 } 184 } 185 186 static void 187 usage(void) 188 { 189 190 (void)fprintf(stderr, "usage: head [-n lines | -c bytes] [file ...]\n"); 191 exit(1); 192 } 193