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 <inttypes.h> 53 #include <stdio.h> 54 #include <stdlib.h> 55 #include <string.h> 56 #include <unistd.h> 57 58 /* 59 * head - give the first few lines of a stream or of each of a set of files 60 * 61 * Bill Joy UCB August 24, 1977 62 */ 63 64 static void head(FILE *, int); 65 static void head_bytes(FILE *, off_t); 66 static void obsolete(char *[]); 67 static void usage(void); 68 69 int 70 main(int argc, char *argv[]) 71 { 72 int ch; 73 FILE *fp; 74 int first, linecnt = -1, eval = 0; 75 off_t bytecnt = -1; 76 char *ep; 77 78 obsolete(argv); 79 while ((ch = getopt(argc, argv, "n:c:")) != -1) 80 switch(ch) { 81 case 'c': 82 bytecnt = strtoimax(optarg, &ep, 10); 83 if (*ep || bytecnt <= 0) 84 errx(1, "illegal byte count -- %s", optarg); 85 break; 86 case 'n': 87 linecnt = strtol(optarg, &ep, 10); 88 if (*ep || linecnt <= 0) 89 errx(1, "illegal line count -- %s", optarg); 90 break; 91 case '?': 92 default: 93 usage(); 94 } 95 argc -= optind; 96 argv += optind; 97 98 if (linecnt != -1 && bytecnt != -1) 99 errx(1, "can't combine line and byte counts"); 100 if (linecnt == -1 ) 101 linecnt = 10; 102 if (*argv) { 103 for (first = 1; *argv; ++argv) { 104 if ((fp = fopen(*argv, "r")) == NULL) { 105 warn("%s", *argv); 106 eval = 1; 107 continue; 108 } 109 if (argc > 1) { 110 (void)printf("%s==> %s <==\n", 111 first ? "" : "\n", *argv); 112 first = 0; 113 } 114 if (bytecnt == -1) 115 head(fp, linecnt); 116 else 117 head_bytes(fp, bytecnt); 118 (void)fclose(fp); 119 } 120 } else if (bytecnt == -1) 121 head(stdin, linecnt); 122 else 123 head_bytes(stdin, bytecnt); 124 125 exit(eval); 126 } 127 128 static void 129 head(FILE *fp, int cnt) 130 { 131 char *cp; 132 size_t error, readlen; 133 134 while (cnt && (cp = fgetln(fp, &readlen)) != NULL) { 135 error = fwrite(cp, sizeof(char), readlen, stdout); 136 if (error != readlen) 137 err(1, "stdout"); 138 cnt--; 139 } 140 } 141 142 static void 143 head_bytes(FILE *fp, off_t cnt) 144 { 145 char buf[4096]; 146 size_t readlen; 147 148 while (cnt) { 149 if ((uintmax_t)cnt < sizeof(buf)) 150 readlen = cnt; 151 else 152 readlen = sizeof(buf); 153 readlen = fread(buf, sizeof(char), readlen, fp); 154 if (readlen == 0) 155 break; 156 if (fwrite(buf, sizeof(char), readlen, stdout) != readlen) 157 err(1, "stdout"); 158 cnt -= readlen; 159 } 160 } 161 162 static void 163 obsolete(char *argv[]) 164 { 165 char *ap; 166 167 while ((ap = *++argv)) { 168 /* Return if "--" or not "-[0-9]*". */ 169 if (ap[0] != '-' || ap[1] == '-' || !isdigit(ap[1])) 170 return; 171 if ((ap = malloc(strlen(*argv) + 2)) == NULL) 172 err(1, NULL); 173 ap[0] = '-'; 174 ap[1] = 'n'; 175 (void)strcpy(ap + 2, *argv + 1); 176 *argv = ap; 177 } 178 } 179 180 static void 181 usage(void) 182 { 183 184 (void)fprintf(stderr, "usage: head [-n lines | -c bytes] [file ...]\n"); 185 exit(1); 186 } 187