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 1.4 2004/11/28 20:20:42 liamfoy Exp $ 37 */ 38 39 #include <sys/types.h> 40 41 #include <ctype.h> 42 #include <err.h> 43 #include <stdio.h> 44 #include <stdlib.h> 45 #include <string.h> 46 #include <unistd.h> 47 48 /* 49 * head - give the first few lines of a stream or of each of a set of files 50 * 51 * Bill Joy UCB August 24, 1977 52 */ 53 54 static void head(FILE *, size_t); 55 static void head_bytes(FILE *, size_t); 56 static void obsolete(char *[]); 57 static void usage(void); 58 59 int 60 main(int argc, char **argv) 61 { 62 int ch; 63 FILE *fp; 64 int first, linecnt = -1, bytecnt = -1, eval = 0; 65 char *ep; 66 67 obsolete(argv); 68 while ((ch = getopt(argc, argv, "n:c:")) != -1) 69 switch(ch) { 70 case 'c': 71 bytecnt = strtol(optarg, &ep, 10); 72 if (*ep || bytecnt <= 0) 73 errx(1, "illegal byte count -- %s", optarg); 74 break; 75 case 'n': 76 linecnt = strtol(optarg, &ep, 10); 77 if (*ep || linecnt <= 0) 78 errx(1, "illegal line count -- %s", optarg); 79 break; 80 default: 81 usage(); 82 } 83 argc -= optind; 84 argv += optind; 85 86 if (linecnt != -1 && bytecnt != -1) 87 errx(1, "can't combine line and byte counts"); 88 if (linecnt == -1 ) 89 linecnt = 10; 90 if (*argv) { 91 for (first = 1; *argv; ++argv) { 92 if ((fp = fopen(*argv, "r")) == NULL) { 93 warn("%s", *argv); 94 eval = 1; 95 continue; 96 } 97 if (argc > 1) { 98 (void)printf("%s==> %s <==\n", 99 first ? "" : "\n", *argv); 100 first = 0; 101 } 102 if (bytecnt == -1) 103 head(fp, linecnt); 104 else 105 head_bytes(fp, bytecnt); 106 (void)fclose(fp); 107 } 108 } else if (bytecnt == -1) 109 head(stdin, linecnt); 110 else 111 head_bytes(stdin, bytecnt); 112 113 exit(eval); 114 } 115 116 static void 117 head(FILE *fp, size_t cnt) 118 { 119 char *cp; 120 size_t error, readlen; 121 122 while (cnt && (cp = fgetln(fp, &readlen)) != NULL) { 123 error = fwrite(cp, sizeof(char), readlen, stdout); 124 if (error != readlen) 125 err(1, "stdout"); 126 cnt--; 127 } 128 } 129 130 static void 131 head_bytes(FILE *fp, size_t cnt) 132 { 133 char buf[4096]; 134 size_t readlen; 135 136 while (cnt) { 137 if (cnt < sizeof(buf)) 138 readlen = cnt; 139 else 140 readlen = sizeof(buf); 141 readlen = fread(buf, sizeof(char), readlen, fp); 142 if (readlen == 0) 143 break; 144 if (fwrite(buf, sizeof(char), readlen, stdout) != readlen) 145 err(1, "stdout"); 146 cnt -= readlen; 147 } 148 } 149 150 static void 151 obsolete(char **argv) 152 { 153 char *ap; 154 155 while ((ap = *++argv)) { 156 /* Return if "--" or not "-[0-9]*". */ 157 if (ap[0] != '-' || ap[1] == '-' || !isdigit(ap[1])) 158 return; 159 if ((ap = malloc(strlen(*argv) + 2)) == NULL) 160 err(1, NULL); 161 ap[0] = '-'; 162 ap[1] = 'n'; 163 (void)strcpy(ap + 2, *argv + 1); 164 *argv = ap; 165 } 166 } 167 168 static void 169 usage(void) 170 { 171 172 (void)fprintf(stderr, "usage: head [-n lines | -c bytes] [file ...]\n"); 173 exit(1); 174 } 175