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 34 #ifndef lint 35 static const char copyright[] = 36 "@(#) Copyright (c) 1980, 1987, 1992, 1993\n\ 37 The Regents of the University of California. All rights reserved.\n"; 38 #endif /* not lint */ 39 40 #ifndef lint 41 #if 0 42 static char sccsid[] = "@(#)head.c 8.2 (Berkeley) 5/4/95"; 43 #endif 44 #endif /* not lint */ 45 #include <sys/cdefs.h> 46 __FBSDID("$FreeBSD$"); 47 48 #include <sys/types.h> 49 50 #include <ctype.h> 51 #include <err.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 *, size_t); 65 static void obsolete(char *[]); 66 static void usage(void); 67 68 int 69 main(int argc, char *argv[]) 70 { 71 int ch; 72 FILE *fp; 73 int first, linecnt = -1, bytecnt = -1, eval = 0; 74 char *ep; 75 76 obsolete(argv); 77 while ((ch = getopt(argc, argv, "n:c:")) != -1) 78 switch(ch) { 79 case 'c': 80 bytecnt = strtol(optarg, &ep, 10); 81 if (*ep || bytecnt <= 0) 82 errx(1, "illegal byte count -- %s", optarg); 83 break; 84 case 'n': 85 linecnt = strtol(optarg, &ep, 10); 86 if (*ep || linecnt <= 0) 87 errx(1, "illegal line count -- %s", optarg); 88 break; 89 case '?': 90 default: 91 usage(); 92 } 93 argc -= optind; 94 argv += optind; 95 96 if (linecnt != -1 && bytecnt != -1) 97 errx(1, "can't combine line and byte counts"); 98 if (linecnt == -1 ) 99 linecnt = 10; 100 if (*argv) { 101 for (first = 1; *argv; ++argv) { 102 if ((fp = fopen(*argv, "r")) == NULL) { 103 warn("%s", *argv); 104 eval = 1; 105 continue; 106 } 107 if (argc > 1) { 108 (void)printf("%s==> %s <==\n", 109 first ? "" : "\n", *argv); 110 first = 0; 111 } 112 if (bytecnt == -1) 113 head(fp, linecnt); 114 else 115 head_bytes(fp, bytecnt); 116 (void)fclose(fp); 117 } 118 } else if (bytecnt == -1) 119 head(stdin, linecnt); 120 else 121 head_bytes(stdin, bytecnt); 122 123 exit(eval); 124 } 125 126 static void 127 head(FILE *fp, int cnt) 128 { 129 char *cp; 130 size_t error, readlen; 131 132 while (cnt && (cp = fgetln(fp, &readlen)) != NULL) { 133 error = fwrite(cp, sizeof(char), readlen, stdout); 134 if (error != readlen) 135 err(1, "stdout"); 136 cnt--; 137 } 138 } 139 140 static void 141 head_bytes(FILE *fp, size_t cnt) 142 { 143 char buf[4096]; 144 size_t readlen; 145 146 while (cnt) { 147 if (cnt < sizeof(buf)) 148 readlen = cnt; 149 else 150 readlen = sizeof(buf); 151 readlen = fread(buf, sizeof(char), readlen, fp); 152 if (readlen == 0) 153 break; 154 if (fwrite(buf, sizeof(char), readlen, stdout) != readlen) 155 err(1, "stdout"); 156 cnt -= readlen; 157 } 158 } 159 160 static void 161 obsolete(char *argv[]) 162 { 163 char *ap; 164 165 while ((ap = *++argv)) { 166 /* Return if "--" or not "-[0-9]*". */ 167 if (ap[0] != '-' || ap[1] == '-' || !isdigit(ap[1])) 168 return; 169 if ((ap = malloc(strlen(*argv) + 2)) == NULL) 170 err(1, NULL); 171 ap[0] = '-'; 172 ap[1] = 'n'; 173 (void)strcpy(ap + 2, *argv + 1); 174 *argv = ap; 175 } 176 } 177 178 static void 179 usage(void) 180 { 181 182 (void)fprintf(stderr, "usage: head [-n lines | -c bytes] [file ...]\n"); 183 exit(1); 184 } 185