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 FILE *fp; 79 char *ep; 80 off_t bytecnt; 81 int ch, first, linecnt, eval; 82 83 linecnt = -1; 84 eval = 0; 85 bytecnt = -1; 86 87 obsolete(argv); 88 while ((ch = getopt_long(argc, argv, "+n:c:", long_opts, NULL)) != -1) { 89 switch(ch) { 90 case 'c': 91 bytecnt = strtoimax(optarg, &ep, 10); 92 if (*ep || bytecnt <= 0) 93 errx(1, "illegal byte count -- %s", optarg); 94 break; 95 case 'n': 96 linecnt = strtol(optarg, &ep, 10); 97 if (*ep || linecnt <= 0) 98 errx(1, "illegal line count -- %s", optarg); 99 break; 100 case '?': 101 default: 102 usage(); 103 /* NOTREACHED */ 104 } 105 } 106 argc -= optind; 107 argv += optind; 108 109 if (linecnt != -1 && bytecnt != -1) 110 errx(1, "can't combine line and byte counts"); 111 if (linecnt == -1) 112 linecnt = 10; 113 if (*argv != NULL) { 114 for (first = 1; *argv != NULL; ++argv) { 115 if ((fp = fopen(*argv, "r")) == NULL) { 116 warn("%s", *argv); 117 eval = 1; 118 continue; 119 } 120 if (argc > 1) { 121 (void)printf("%s==> %s <==\n", 122 first ? "" : "\n", *argv); 123 first = 0; 124 } 125 if (bytecnt == -1) 126 head(fp, linecnt); 127 else 128 head_bytes(fp, bytecnt); 129 (void)fclose(fp); 130 } 131 } else if (bytecnt == -1) 132 head(stdin, linecnt); 133 else 134 head_bytes(stdin, bytecnt); 135 136 exit(eval); 137 } 138 139 static void 140 head(FILE *fp, int cnt) 141 { 142 char *cp; 143 size_t error, readlen; 144 145 while (cnt != 0 && (cp = fgetln(fp, &readlen)) != NULL) { 146 error = fwrite(cp, sizeof(char), readlen, stdout); 147 if (error != readlen) 148 err(1, "stdout"); 149 cnt--; 150 } 151 } 152 153 static void 154 head_bytes(FILE *fp, off_t cnt) 155 { 156 char buf[4096]; 157 size_t readlen; 158 159 while (cnt) { 160 if ((uintmax_t)cnt < sizeof(buf)) 161 readlen = cnt; 162 else 163 readlen = sizeof(buf); 164 readlen = fread(buf, sizeof(char), readlen, fp); 165 if (readlen == 0) 166 break; 167 if (fwrite(buf, sizeof(char), readlen, stdout) != readlen) 168 err(1, "stdout"); 169 cnt -= readlen; 170 } 171 } 172 173 static void 174 obsolete(char *argv[]) 175 { 176 char *ap; 177 178 while ((ap = *++argv)) { 179 /* Return if "--" or not "-[0-9]*". */ 180 if (ap[0] != '-' || ap[1] == '-' || !isdigit(ap[1])) 181 return; 182 if ((ap = malloc(strlen(*argv) + 2)) == NULL) 183 err(1, NULL); 184 ap[0] = '-'; 185 ap[1] = 'n'; 186 (void)strcpy(ap + 2, *argv + 1); 187 *argv = ap; 188 } 189 } 190 191 static void 192 usage(void) 193 { 194 195 (void)fprintf(stderr, "usage: head [-n lines | -c bytes] [file ...]\n"); 196 exit(1); 197 } 198