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 * 3. 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 * @(#)head.c 8.2 (Berkeley) 5/4/95 30 * $FreeBSD: src/usr.bin/head/head.c,v 1.10.2.1 2002/02/16 12:29:04 dwmalone Exp $ 31 */ 32 33 #include <ctype.h> 34 #include <err.h> 35 #include <stdbool.h> 36 #include <stdio.h> 37 #include <stdlib.h> 38 #include <string.h> 39 #include <unistd.h> 40 41 /* 42 * head - give the first few lines of a stream or of each of a set of files 43 * 44 * Bill Joy UCB August 24, 1977 45 */ 46 47 static void head(FILE *, size_t); 48 static void head_bytes(FILE *, size_t); 49 static void obsolete(char *[]); 50 static void usage(void) __dead2; 51 52 int 53 main(int argc, char **argv) 54 { 55 int ch; 56 FILE *fp; 57 bool first; 58 bool qflag = false, vflag = false; 59 int linecnt = -1, bytecnt = -1, eval = 0; 60 char *ep; 61 62 obsolete(argv); 63 while ((ch = getopt(argc, argv, "c:n:qv")) != -1) { 64 switch(ch) { 65 case 'c': 66 bytecnt = strtol(optarg, &ep, 10); 67 if (*ep != 0 || bytecnt <= 0) 68 errx(1, "illegal byte count -- %s", optarg); 69 break; 70 case 'n': 71 linecnt = strtol(optarg, &ep, 10); 72 if (*ep != 0 || linecnt <= 0) 73 errx(1, "illegal line count -- %s", optarg); 74 break; 75 case 'q': 76 qflag = true; 77 vflag = false; 78 break; 79 case 'v': 80 vflag = true; 81 qflag = false; 82 break; 83 default: 84 usage(); 85 } 86 } 87 argc -= optind; 88 argv += optind; 89 90 if (linecnt != -1 && bytecnt != -1) 91 errx(1, "can't combine line and byte counts"); 92 if (linecnt == -1 ) 93 linecnt = 10; 94 if (*argv) { 95 first = true; 96 for (; *argv; ++argv) { 97 if ((fp = fopen(*argv, "r")) == NULL) { 98 warn("%s", *argv); 99 eval = 1; 100 continue; 101 } 102 if (vflag || (!qflag && argc > 1)) { 103 printf("%s==> %s <==\n", 104 first ? "" : "\n", *argv); 105 first = false; 106 } 107 if (bytecnt == -1) 108 head(fp, linecnt); 109 else 110 head_bytes(fp, bytecnt); 111 fclose(fp); 112 } 113 } else if (bytecnt == -1) 114 head(stdin, linecnt); 115 else 116 head_bytes(stdin, bytecnt); 117 118 exit(eval); 119 } 120 121 static void 122 head(FILE *fp, size_t cnt) 123 { 124 char *cp; 125 size_t error, readlen; 126 127 while (cnt && (cp = fgetln(fp, &readlen)) != NULL) { 128 error = fwrite(cp, sizeof(char), readlen, stdout); 129 if (error != readlen) 130 err(1, "stdout"); 131 cnt--; 132 } 133 } 134 135 static void 136 head_bytes(FILE *fp, size_t cnt) 137 { 138 char buf[4096]; 139 size_t readlen; 140 141 while (cnt) { 142 if (cnt < sizeof(buf)) 143 readlen = cnt; 144 else 145 readlen = sizeof(buf); 146 readlen = fread(buf, sizeof(char), readlen, fp); 147 if (readlen == 0) 148 break; 149 if (fwrite(buf, sizeof(char), readlen, stdout) != readlen) 150 err(1, "stdout"); 151 cnt -= readlen; 152 } 153 } 154 155 static void 156 obsolete(char **argv) 157 { 158 char *ap; 159 160 while ((ap = *++argv)) { 161 /* Return if "--" or not "-[0-9]*". */ 162 if (ap[0] != '-' || ap[1] == '-' || !isdigit(ap[1])) 163 return; 164 if ((ap = malloc(strlen(*argv) + 2)) == NULL) 165 err(1, "malloc failed"); 166 ap[0] = '-'; 167 ap[1] = 'n'; 168 strcpy(ap + 2, *argv + 1); 169 *argv = ap; 170 } 171 } 172 173 static void __dead2 174 usage(void) 175 { 176 fprintf(stderr, 177 "usage: head [-q | -v] [-n lines | -c bytes] [file ...]\n"); 178 exit(1); 179 } 180