1/* $OpenBSD: tail.c,v 1.24 2022/12/04 23:50:49 cheloha Exp $ */ 2 3/*- 4 * Copyright (c) 1991, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * This code is derived from software contributed to Berkeley by 8 * Edward Sze-Tyan Wang. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 */ 34 35#include <sys/types.h> 36#include <sys/stat.h> 37 38#include <err.h> 39#include <errno.h> 40#include <stdio.h> 41#include <stdlib.h> 42#include <string.h> 43#include <unistd.h> 44 45#include "extern.h" 46 47int fflag, rflag, rval; 48 49static void obsolete(char **); 50static void usage(void); 51 52int 53main(int argc, char *argv[]) 54{ 55 struct tailfile *tf; 56 off_t off = 0; 57 enum STYLE style; 58 int ch; 59 int i; 60 char *p; 61 62 if (pledge("stdio rpath", NULL) == -1) 63 err(1, "pledge"); 64 65 /* 66 * Tail's options are weird. First, -n10 is the same as -n-10, not 67 * -n+10. Second, the number options are 1 based and not offsets, 68 * so -n+1 is the first line, and -c-1 is the last byte. Third, the 69 * number options for the -r option specify the number of things that 70 * get displayed, not the starting point in the file. The one major 71 * incompatibility in this version as compared to historical versions 72 * is that the 'r' option couldn't be modified by the -lbc options, 73 * i.e. it was always done in lines. This version treats -rc as a 74 * number of characters in reverse order. Finally, the default for 75 * -r is the entire file, not 10 lines. 76 */ 77#define ARG(units, forward, backward) { \ 78 if (style) \ 79 usage(); \ 80 off = strtoll(optarg, &p, 10) * (units); \ 81 if (*p) \ 82 errx(1, "illegal offset -- %s", optarg); \ 83 switch(optarg[0]) { \ 84 case '+': \ 85 if (off) \ 86 off -= (units); \ 87 style = (forward); \ 88 break; \ 89 case '-': \ 90 off = -off; \ 91 /* FALLTHROUGH */ \ 92 default: \ 93 style = (backward); \ 94 break; \ 95 } \ 96} 97 98 obsolete(argv); 99 style = NOTSET; 100 while ((ch = getopt(argc, argv, "b:c:fn:r")) != -1) 101 switch(ch) { 102 case 'b': 103 ARG(512, FBYTES, RBYTES); 104 break; 105 case 'c': 106 ARG(1, FBYTES, RBYTES); 107 break; 108 case 'f': 109 fflag = 1; 110 break; 111 case 'n': 112 ARG(1, FLINES, RLINES); 113 break; 114 case 'r': 115 rflag = 1; 116 break; 117 default: 118 usage(); 119 } 120 argc -= optind; 121 argv += optind; 122 123 /* 124 * If displaying in reverse, don't permit follow option, and convert 125 * style values. 126 */ 127 if (rflag) { 128 if (fflag) 129 usage(); 130 if (style == FBYTES) 131 style = RBYTES; 132 else if (style == FLINES) 133 style = RLINES; 134 } 135 136 /* 137 * If style not specified, the default is the whole file for -r, and 138 * the last 10 lines if not -r. 139 */ 140 if (style == NOTSET) { 141 if (rflag) { 142 off = 0; 143 style = REVERSE; 144 } else { 145 off = 10; 146 style = RLINES; 147 } 148 } 149 150 if ((tf = reallocarray(NULL, argc ? argc : 1, sizeof(*tf))) == NULL) 151 err(1, "reallocarray"); 152 153 if (argc) { 154 for (i = 0; *argv; i++) { 155 tf[i].fname = *argv++; 156 if ((tf[i].fp = fopen(tf[i].fname, "r")) == NULL || 157 fstat(fileno(tf[i].fp), &(tf[i].sb))) { 158 ierr(tf[i].fname); 159 i--; 160 continue; 161 } 162 } 163 if (rflag) 164 reverse(tf, i, style, off); 165 else 166 forward(tf, i, style, off); 167 } 168 else { 169 if (pledge("stdio", NULL) == -1) 170 err(1, "pledge"); 171 172 tf[0].fname = "stdin"; 173 tf[0].fp = stdin; 174 175 if (fstat(fileno(stdin), &(tf[0].sb))) { 176 ierr(tf[0].fname); 177 exit(1); 178 } 179 180 /* 181 * Determine if input is a pipe. 4.4BSD will set the SOCKET 182 * bit in the st_mode field for pipes. Fix this then. 183 */ 184 if (lseek(fileno(tf[0].fp), (off_t)0, SEEK_CUR) == -1 && 185 errno == ESPIPE) { 186 errno = 0; 187 fflag = 0; /* POSIX.2 requires this. */ 188 } 189 190 if (rflag) 191 reverse(tf, 1, style, off); 192 else 193 forward(tf, 1, style, off); 194 } 195 exit(rval); 196} 197 198/* 199 * Convert the obsolete argument form into something that getopt can handle. 200 * This means that anything of the form [+-][0-9][0-9]*[lbc][fr] that isn't 201 * the option argument for a -b, -c or -n option gets converted. 202 */ 203static void 204obsolete(char *argv[]) 205{ 206 char *ap, *p, *t; 207 size_t len; 208 char *start; 209 210 while ((ap = *++argv)) { 211 /* Return if "--" or not an option of any form. */ 212 if (ap[0] != '-') { 213 if (ap[0] != '+') 214 return; 215 } else if (ap[1] == '-') 216 return; 217 218 switch(*++ap) { 219 /* Old-style option. */ 220 case '0': case '1': case '2': case '3': case '4': 221 case '5': case '6': case '7': case '8': case '9': 222 223 /* Malloc space for dash, new option and argument. */ 224 len = strlen(*argv); 225 if ((start = p = malloc(len + 4)) == NULL) 226 err(1, NULL); 227 *p++ = '-'; 228 229 /* 230 * Go to the end of the option argument. Save off any 231 * trailing options (-3lf) and translate any trailing 232 * output style characters. 233 */ 234 t = *argv + len - 1; 235 if (*t == 'f' || *t == 'r') { 236 *p++ = *t; 237 *t-- = '\0'; 238 } 239 switch(*t) { 240 case 'b': 241 *p++ = 'b'; 242 *t = '\0'; 243 break; 244 case 'c': 245 *p++ = 'c'; 246 *t = '\0'; 247 break; 248 case 'l': 249 *t = '\0'; 250 /* FALLTHROUGH */ 251 case '0': case '1': case '2': case '3': case '4': 252 case '5': case '6': case '7': case '8': case '9': 253 *p++ = 'n'; 254 break; 255 default: 256 errx(1, "illegal option -- %s", *argv); 257 } 258 *p++ = *argv[0]; 259 (void)strlcpy(p, ap, start + len + 4 - p); 260 *argv = start; 261 continue; 262 263 /* 264 * Options w/ arguments, skip the argument and continue 265 * with the next option. 266 */ 267 case 'b': 268 case 'c': 269 case 'n': 270 if (!ap[1]) 271 ++argv; 272 /* FALLTHROUGH */ 273 /* Options w/o arguments, continue with the next option. */ 274 case 'f': 275 case 'r': 276 continue; 277 278 /* Illegal option, return and let getopt handle it. */ 279 default: 280 return; 281 } 282 } 283} 284 285static void 286usage(void) 287{ 288 (void)fprintf(stderr, 289 "usage: tail [-f | -r] " 290 "[-b number | -c number | -n number | -number] [file ...]\n"); 291 exit(1); 292} 293