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 * @(#) Copyright (c) 1980, 1987, 1992, 1993 The Regents of the University of California. All rights reserved. 30 * @(#)head.c 8.2 (Berkeley) 5/4/95 31 * $FreeBSD: src/usr.bin/head/head.c,v 1.10.2.1 2002/02/16 12:29:04 dwmalone Exp $ 32 * $DragonFly: src/usr.bin/head/head.c,v 1.6 2008/06/05 18:06:33 swildner Exp $ 33 */ 34 35 #include <ctype.h> 36 #include <err.h> 37 #include <stdio.h> 38 #include <stdlib.h> 39 #include <string.h> 40 #include <unistd.h> 41 42 /* 43 * head - give the first few lines of a stream or of each of a set of files 44 * 45 * Bill Joy UCB August 24, 1977 46 */ 47 48 static void head(FILE *, size_t); 49 static void head_bytes(FILE *, size_t); 50 static void obsolete(char *[]); 51 static void usage(void); 52 53 int 54 main(int argc, char **argv) 55 { 56 int ch; 57 FILE *fp; 58 int first, linecnt = -1, bytecnt = -1, eval = 0; 59 char *ep; 60 61 obsolete(argv); 62 while ((ch = getopt(argc, argv, "n:c:")) != -1) 63 switch(ch) { 64 case 'c': 65 bytecnt = strtol(optarg, &ep, 10); 66 if (*ep != 0 || bytecnt <= 0) 67 errx(1, "illegal byte count -- %s", optarg); 68 break; 69 case 'n': 70 linecnt = strtol(optarg, &ep, 10); 71 if (*ep != 0 || linecnt <= 0) 72 errx(1, "illegal line count -- %s", optarg); 73 break; 74 default: 75 usage(); 76 } 77 argc -= optind; 78 argv += optind; 79 80 if (linecnt != -1 && bytecnt != -1) 81 errx(1, "can't combine line and byte counts"); 82 if (linecnt == -1 ) 83 linecnt = 10; 84 if (*argv) { 85 for (first = 1; *argv; ++argv) { 86 if ((fp = fopen(*argv, "r")) == NULL) { 87 warn("%s", *argv); 88 eval = 1; 89 continue; 90 } 91 if (argc > 1) { 92 printf("%s==> %s <==\n", 93 first ? "" : "\n", *argv); 94 first = 0; 95 } 96 if (bytecnt == -1) 97 head(fp, linecnt); 98 else 99 head_bytes(fp, bytecnt); 100 fclose(fp); 101 } 102 } else if (bytecnt == -1) 103 head(stdin, linecnt); 104 else 105 head_bytes(stdin, bytecnt); 106 107 exit(eval); 108 } 109 110 static void 111 head(FILE *fp, size_t cnt) 112 { 113 char *cp; 114 size_t error, readlen; 115 116 while (cnt && (cp = fgetln(fp, &readlen)) != NULL) { 117 error = fwrite(cp, sizeof(char), readlen, stdout); 118 if (error != readlen) 119 err(1, "stdout"); 120 cnt--; 121 } 122 } 123 124 static void 125 head_bytes(FILE *fp, size_t cnt) 126 { 127 char buf[4096]; 128 size_t readlen; 129 130 while (cnt) { 131 if (cnt < sizeof(buf)) 132 readlen = cnt; 133 else 134 readlen = sizeof(buf); 135 readlen = fread(buf, sizeof(char), readlen, fp); 136 if (readlen == 0) 137 break; 138 if (fwrite(buf, sizeof(char), readlen, stdout) != readlen) 139 err(1, "stdout"); 140 cnt -= readlen; 141 } 142 } 143 144 static void 145 obsolete(char **argv) 146 { 147 char *ap; 148 149 while ((ap = *++argv)) { 150 /* Return if "--" or not "-[0-9]*". */ 151 if (ap[0] != '-' || ap[1] == '-' || !isdigit(ap[1])) 152 return; 153 if ((ap = malloc(strlen(*argv) + 2)) == NULL) 154 err(1, "malloc failed"); 155 ap[0] = '-'; 156 ap[1] = 'n'; 157 strcpy(ap + 2, *argv + 1); 158 *argv = ap; 159 } 160 } 161 162 static void 163 usage(void) 164 { 165 fprintf(stderr, "usage: head [-n lines | -c bytes] [file ...]\n"); 166 exit(1); 167 } 168