1/*- 2 * Copyright (c) 1991, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * This code is derived from software contributed to Berkeley by 6 * Edward Sze-Tyan Wang. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. Neither the name of the University nor the names of its contributors 17 * may be used to endorse or promote products derived from this software 18 * without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 */ 32 33#include <sys/cdefs.h> 34#ifndef lint 35__COPYRIGHT("@(#) Copyright (c) 1991, 1993\ 36 The Regents of the University of California. All rights reserved."); 37#endif /* not lint */ 38 39#ifndef lint 40#if 0 41static char sccsid[] = "@(#)tail.c 8.1 (Berkeley) 6/6/93"; 42#endif 43__RCSID("$NetBSD: tail.c,v 1.21 2023/08/07 19:11:25 tnn Exp $"); 44#endif /* not lint */ 45 46#include <sys/types.h> 47#include <sys/stat.h> 48#include <errno.h> 49#include <unistd.h> 50#include <stdio.h> 51#include <stdlib.h> 52#include <string.h> 53#include "extern.h" 54 55int fflag, rflag, rval; 56const char *fname; 57 58static void obsolete(char **); 59static void usage(void) __dead; 60 61int 62main(int argc, char *argv[]) 63{ 64 struct stat sb; 65 FILE *fp; 66 off_t off; 67 enum STYLE style; 68 int ch, first; 69 char *p; 70 int qflag = 0; 71 int vflag = 0; 72 73 setprogname(argv[0]); 74 off = 0; 75 /* 76 * Tail's options are weird. First, -n10 is the same as -n-10, not 77 * -n+10. Second, the number options are 1 based and not offsets, 78 * so -n+1 is the first line, and -c-1 is the last byte. Third, the 79 * number options for the -r option specify the number of things that 80 * get displayed, not the starting point in the file. The one major 81 * incompatibility in this version as compared to historical versions 82 * is that the 'r' option couldn't be modified by the -lbc options, 83 * i.e., it was always done in lines. This version treats -rc as a 84 * number of characters in reverse order. Finally, the default for 85 * -r is the entire file, not 10 lines. 86 */ 87#define ARG(units, forward, backward) { \ 88 if (style) \ 89 usage(); \ 90 off = strtoll(optarg, &p, 10) * (units); \ 91 if (*p) \ 92 xerrx(1, "illegal offset -- %s", optarg); \ 93 switch(optarg[0]) { \ 94 case '+': \ 95 if (off) \ 96 off -= (units); \ 97 style = (forward); \ 98 break; \ 99 case '-': \ 100 off = -off; \ 101 /* FALLTHROUGH */ \ 102 default: \ 103 style = (backward); \ 104 break; \ 105 } \ 106} 107 108 obsolete(argv); 109 style = NOTSET; 110 if (strcmp(getprogname(), "tac") == 0) { 111 qflag = 1; 112 vflag = 0; 113 rflag = 1; 114 argc -= 1; 115 argv += 1; 116 } else { /* tail */ 117 while ((ch = getopt(argc, argv, "Fb:c:fn:rqv")) != -1) 118 switch(ch) { 119 case 'F': 120 fflag = 2; 121 break; 122 case 'b': 123 ARG(512, FBYTES, RBYTES); 124 break; 125 case 'c': 126 ARG(1, FBYTES, RBYTES); 127 break; 128 case 'f': 129 fflag = 1; 130 break; 131 case 'n': 132 ARG(1, FLINES, RLINES); 133 break; 134 case 'r': 135 rflag = 1; 136 break; 137 case 'q': 138 qflag = 1; 139 vflag = 0; 140 break; 141 case 'v': 142 qflag = 0; 143 vflag = 1; 144 break; 145 case '?': 146 default: 147 usage(); 148 } 149 argc -= optind; 150 argv += optind; 151 } 152 153 if (fflag && argc > 1) 154 xerrx(1, 155 "-f and -F options only appropriate for a single file"); 156 157 /* 158 * If displaying in reverse, don't permit follow option, and convert 159 * style values. 160 */ 161 if (rflag) { 162 if (fflag) 163 usage(); 164 if (style == FBYTES) 165 style = RBYTES; 166 else if (style == FLINES) 167 style = RLINES; 168 } 169 170 /* 171 * If style not specified, the default is the whole file for -r, and 172 * the last 10 lines if not -r. 173 */ 174 if (style == NOTSET) { 175 if (rflag) { 176 off = 0; 177 style = REVERSE; 178 } else { 179 off = 10; 180 style = RLINES; 181 } 182 } 183 if (*argv) 184 for (first = 1; (fname = *argv++) != NULL;) { 185 if ((fp = fopen(fname, "r")) == NULL || 186 fstat(fileno(fp), &sb)) { 187 ierr(); 188 continue; 189 } 190 if (vflag || (qflag == 0 && argc > 1)) { 191 (void)printf("%s==> %s <==\n", 192 first ? "" : "\n", fname); 193 first = 0; 194 (void)fflush(stdout); 195 } 196 197 if (rflag) 198 reverse(fp, style, off, &sb); 199 else 200 forward(fp, style, off, &sb); 201 (void)fclose(fp); 202 } 203 else { 204 fname = "stdin"; 205 206 if (fstat(fileno(stdin), &sb)) { 207 ierr(); 208 exit(1); 209 } 210 211 /* 212 * Determine if input is a pipe. 4.4BSD will set the SOCKET 213 * bit in the st_mode field for pipes. Fix this then. 214 */ 215 if (lseek(fileno(stdin), (off_t)0, SEEK_CUR) == -1 && 216 errno == ESPIPE) { 217 errno = 0; 218 fflag = 0; /* POSIX.2 requires this. */ 219 } 220 221 if (rflag) 222 reverse(stdin, style, off, &sb); 223 else 224 forward(stdin, style, off, &sb); 225 } 226 exit(rval); 227} 228 229/* 230 * Convert the obsolete argument form into something that getopt can handle. 231 * This means that anything of the form [+-][0-9][0-9]*[lbc][fr] that isn't 232 * the option argument for a -b, -c or -n option gets converted. 233 */ 234static void 235obsolete(char *argv[]) 236{ 237 char *ap, *p, *t; 238 size_t len; 239 char *start; 240 241 while ((ap = *++argv) != NULL) { 242 /* Return if "--" or not an option of any form. */ 243 if (ap[0] != '-') { 244 if (ap[0] != '+') 245 return; 246 } else if (ap[1] == '-') 247 return; 248 249 switch (*++ap) { 250 /* Old-style option. */ 251 case '0': case '1': case '2': case '3': case '4': 252 case '5': case '6': case '7': case '8': case '9': 253 254 /* Malloc space for dash, new option and argument. */ 255 len = strlen(*argv); 256 if ((start = p = malloc(len + 3)) == NULL) 257 xerr(1, "malloc"); 258 *p++ = '-'; 259 260 /* 261 * Go to the end of the option argument. Save off any 262 * trailing options (-3lf) and translate any trailing 263 * output style characters. 264 */ 265 t = *argv + len - 1; 266 if (*t == 'f' || *t == 'r') { 267 *p++ = *t; 268 *t-- = '\0'; 269 } 270 switch(*t) { 271 case 'b': 272 *p++ = 'b'; 273 *t = '\0'; 274 break; 275 case 'c': 276 *p++ = 'c'; 277 *t = '\0'; 278 break; 279 case 'l': 280 *t = '\0'; 281 /* FALLTHROUGH */ 282 case '0': case '1': case '2': case '3': case '4': 283 case '5': case '6': case '7': case '8': case '9': 284 *p++ = 'n'; 285 break; 286 default: 287 xerrx(1, "illegal option -- %s", *argv); 288 } 289 *p++ = *argv[0]; 290 (void)strcpy(p, ap); 291 *argv = start; 292 continue; 293 294 /* 295 * Options w/ arguments, skip the argument and continue 296 * with the next option. 297 */ 298 case 'b': 299 case 'c': 300 case 'n': 301 if (!ap[1]) 302 ++argv; 303 /* FALLTHROUGH */ 304 /* Options w/o arguments, continue with the next option. */ 305 case 'f': 306 case 'r': 307 continue; 308 309 /* Illegal option, return and let getopt handle it. */ 310 default: 311 return; 312 } 313 } 314} 315 316static void 317usage(void) 318{ 319 (void)fprintf(stderr, 320 "Usage: %s [-qv] [-f | -F | -r] [-b # | -c # | -n #] [file ...]\n", 321 getprogname()); 322 exit(1); 323} 324