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 1.15 2011/09/03 09:02:20 christos 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 71 setprogname(argv[0]); 72 off = 0; 73 /* 74 * Tail's options are weird. First, -n10 is the same as -n-10, not 75 * -n+10. Second, the number options are 1 based and not offsets, 76 * so -n+1 is the first line, and -c-1 is the last byte. Third, the 77 * number options for the -r option specify the number of things that 78 * get displayed, not the starting point in the file. The one major 79 * incompatibility in this version as compared to historical versions 80 * is that the 'r' option couldn't be modified by the -lbc options, 81 * i.e. it was always done in lines. This version treats -rc as a 82 * number of characters in reverse order. Finally, the default for 83 * -r is the entire file, not 10 lines. 84 */ 85#define ARG(units, forward, backward) { \ 86 if (style) \ 87 usage(); \ 88 off = strtoll(optarg, &p, 10) * (units); \ 89 if (*p) \ 90 xerrx(1, "illegal offset -- %s", optarg); \ 91 switch(optarg[0]) { \ 92 case '+': \ 93 if (off) \ 94 off -= (units); \ 95 style = (forward); \ 96 break; \ 97 case '-': \ 98 off = -off; \ 99 /* FALLTHROUGH */ \ 100 default: \ 101 style = (backward); \ 102 break; \ 103 } \ 104} 105 106 obsolete(argv); 107 style = NOTSET; 108 while ((ch = getopt(argc, argv, "Fb:c:fn:r")) != -1) 109 switch(ch) { 110 case 'F': 111 fflag = 2; 112 break; 113 case 'b': 114 ARG(512, FBYTES, RBYTES); 115 break; 116 case 'c': 117 ARG(1, FBYTES, RBYTES); 118 break; 119 case 'f': 120 fflag = 1; 121 break; 122 case 'n': 123 ARG(1, FLINES, RLINES); 124 break; 125 case 'r': 126 rflag = 1; 127 break; 128 case '?': 129 default: 130 usage(); 131 } 132 argc -= optind; 133 argv += optind; 134 135 if (fflag && argc > 1) 136 xerrx(1, 137 "-f and -F options only appropriate for a single file"); 138 139 /* 140 * If displaying in reverse, don't permit follow option, and convert 141 * style values. 142 */ 143 if (rflag) { 144 if (fflag) 145 usage(); 146 if (style == FBYTES) 147 style = RBYTES; 148 else if (style == FLINES) 149 style = RLINES; 150 } 151 152 /* 153 * If style not specified, the default is the whole file for -r, and 154 * the last 10 lines if not -r. 155 */ 156 if (style == NOTSET) { 157 if (rflag) { 158 off = 0; 159 style = REVERSE; 160 } else { 161 off = 10; 162 style = RLINES; 163 } 164 } 165 if (*argv) 166 for (first = 1; (fname = *argv++) != NULL;) { 167 if ((fp = fopen(fname, "r")) == NULL || 168 fstat(fileno(fp), &sb)) { 169 ierr(); 170 continue; 171 } 172 if (argc > 1) { 173 (void)printf("%s==> %s <==\n", 174 first ? "" : "\n", fname); 175 first = 0; 176 (void)fflush(stdout); 177 } 178 179 if (rflag) 180 reverse(fp, style, off, &sb); 181 else 182 forward(fp, style, off, &sb); 183 (void)fclose(fp); 184 } 185 else { 186 fname = "stdin"; 187 188 if (fstat(fileno(stdin), &sb)) { 189 ierr(); 190 exit(1); 191 } 192 193 /* 194 * Determine if input is a pipe. 4.4BSD will set the SOCKET 195 * bit in the st_mode field for pipes. Fix this then. 196 */ 197 if (lseek(fileno(stdin), (off_t)0, SEEK_CUR) == -1 && 198 errno == ESPIPE) { 199 errno = 0; 200 fflag = 0; /* POSIX.2 requires this. */ 201 } 202 203 if (rflag) 204 reverse(stdin, style, off, &sb); 205 else 206 forward(stdin, style, off, &sb); 207 } 208 exit(rval); 209} 210 211/* 212 * Convert the obsolete argument form into something that getopt can handle. 213 * This means that anything of the form [+-][0-9][0-9]*[lbc][fr] that isn't 214 * the option argument for a -b, -c or -n option gets converted. 215 */ 216static void 217obsolete(char *argv[]) 218{ 219 char *ap, *p, *t; 220 int len; 221 char *start; 222 223 while ((ap = *++argv) != NULL) { 224 /* Return if "--" or not an option of any form. */ 225 if (ap[0] != '-') { 226 if (ap[0] != '+') 227 return; 228 } else if (ap[1] == '-') 229 return; 230 231 switch (*++ap) { 232 /* Old-style option. */ 233 case '0': case '1': case '2': case '3': case '4': 234 case '5': case '6': case '7': case '8': case '9': 235 236 /* Malloc space for dash, new option and argument. */ 237 len = strlen(*argv); 238 if ((start = p = malloc(len + 3)) == NULL) 239 xerr(1, "malloc"); 240 *p++ = '-'; 241 242 /* 243 * Go to the end of the option argument. Save off any 244 * trailing options (-3lf) and translate any trailing 245 * output style characters. 246 */ 247 t = *argv + len - 1; 248 if (*t == 'f' || *t == 'r') { 249 *p++ = *t; 250 *t-- = '\0'; 251 } 252 switch(*t) { 253 case 'b': 254 *p++ = 'b'; 255 *t = '\0'; 256 break; 257 case 'c': 258 *p++ = 'c'; 259 *t = '\0'; 260 break; 261 case 'l': 262 *t = '\0'; 263 /* FALLTHROUGH */ 264 case '0': case '1': case '2': case '3': case '4': 265 case '5': case '6': case '7': case '8': case '9': 266 *p++ = 'n'; 267 break; 268 default: 269 xerrx(1, "illegal option -- %s", *argv); 270 } 271 *p++ = *argv[0]; 272 (void)strcpy(p, ap); 273 *argv = start; 274 continue; 275 276 /* 277 * Options w/ arguments, skip the argument and continue 278 * with the next option. 279 */ 280 case 'b': 281 case 'c': 282 case 'n': 283 if (!ap[1]) 284 ++argv; 285 /* FALLTHROUGH */ 286 /* Options w/o arguments, continue with the next option. */ 287 case 'f': 288 case 'r': 289 continue; 290 291 /* Illegal option, return and let getopt handle it. */ 292 default: 293 return; 294 } 295 } 296} 297 298static void 299usage(void) 300{ 301 (void)fprintf(stderr, 302 "Usage: %s [-f | -F | -r] [-b # | -c # | -n #] [file ...]\n", 303 getprogname()); 304 exit(1); 305} 306