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. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed by the University of 16 * California, Berkeley and its contributors. 17 * 4. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 * 33 * @(#) Copyright (c) 1980, 1987, 1992, 1993 The Regents of the University of California. All rights reserved. 34 * @(#)head.c 8.2 (Berkeley) 5/4/95 35 * $FreeBSD: src/usr.bin/head/head.c,v 1.10.2.1 2002/02/16 12:29:04 dwmalone Exp $ 36 * $DragonFly: src/usr.bin/head/head.c,v 1.5 2005/03/12 11:10:02 liamfoy Exp $ 37 */ 38 39 #include <ctype.h> 40 #include <err.h> 41 #include <stdio.h> 42 #include <stdlib.h> 43 #include <string.h> 44 #include <unistd.h> 45 46 /* 47 * head - give the first few lines of a stream or of each of a set of files 48 * 49 * Bill Joy UCB August 24, 1977 50 */ 51 52 static void head(FILE *, size_t); 53 static void head_bytes(FILE *, size_t); 54 static void obsolete(char *[]); 55 static void usage(void); 56 57 int 58 main(int argc, char **argv) 59 { 60 int ch; 61 FILE *fp; 62 int first, linecnt = -1, bytecnt = -1, eval = 0; 63 char *ep; 64 65 obsolete(argv); 66 while ((ch = getopt(argc, argv, "n:c:")) != -1) 67 switch(ch) { 68 case 'c': 69 bytecnt = strtol(optarg, &ep, 10); 70 if (*ep != NULL || bytecnt <= 0) 71 errx(1, "illegal byte count -- %s", optarg); 72 break; 73 case 'n': 74 linecnt = strtol(optarg, &ep, 10); 75 if (*ep != NULL || linecnt <= 0) 76 errx(1, "illegal line count -- %s", optarg); 77 break; 78 default: 79 usage(); 80 } 81 argc -= optind; 82 argv += optind; 83 84 if (linecnt != -1 && bytecnt != -1) 85 errx(1, "can't combine line and byte counts"); 86 if (linecnt == -1 ) 87 linecnt = 10; 88 if (*argv) { 89 for (first = 1; *argv; ++argv) { 90 if ((fp = fopen(*argv, "r")) == NULL) { 91 warn("%s", *argv); 92 eval = 1; 93 continue; 94 } 95 if (argc > 1) { 96 printf("%s==> %s <==\n", 97 first ? "" : "\n", *argv); 98 first = 0; 99 } 100 if (bytecnt == -1) 101 head(fp, linecnt); 102 else 103 head_bytes(fp, bytecnt); 104 fclose(fp); 105 } 106 } else if (bytecnt == -1) 107 head(stdin, linecnt); 108 else 109 head_bytes(stdin, bytecnt); 110 111 exit(eval); 112 } 113 114 static void 115 head(FILE *fp, size_t cnt) 116 { 117 char *cp; 118 size_t error, readlen; 119 120 while (cnt && (cp = fgetln(fp, &readlen)) != NULL) { 121 error = fwrite(cp, sizeof(char), readlen, stdout); 122 if (error != readlen) 123 err(1, "stdout"); 124 cnt--; 125 } 126 } 127 128 static void 129 head_bytes(FILE *fp, size_t cnt) 130 { 131 char buf[4096]; 132 size_t readlen; 133 134 while (cnt) { 135 if (cnt < sizeof(buf)) 136 readlen = cnt; 137 else 138 readlen = sizeof(buf); 139 readlen = fread(buf, sizeof(char), readlen, fp); 140 if (readlen == 0) 141 break; 142 if (fwrite(buf, sizeof(char), readlen, stdout) != readlen) 143 err(1, "stdout"); 144 cnt -= readlen; 145 } 146 } 147 148 static void 149 obsolete(char **argv) 150 { 151 char *ap; 152 153 while ((ap = *++argv)) { 154 /* Return if "--" or not "-[0-9]*". */ 155 if (ap[0] != '-' || ap[1] == '-' || !isdigit(ap[1])) 156 return; 157 if ((ap = malloc(strlen(*argv) + 2)) == NULL) 158 err(1, "malloc failed"); 159 ap[0] = '-'; 160 ap[1] = 'n'; 161 strcpy(ap + 2, *argv + 1); 162 *argv = ap; 163 } 164 } 165 166 static void 167 usage(void) 168 { 169 fprintf(stderr, "usage: head [-n lines | -c bytes] [file ...]\n"); 170 exit(1); 171 } 172