1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 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/cdefs.h> 36 37 __FBSDID("$FreeBSD$"); 38 39 #ifndef lint 40 static const char copyright[] = 41 "@(#) Copyright (c) 1991, 1993\n\ 42 The Regents of the University of California. All rights reserved.\n"; 43 #endif 44 45 #ifndef lint 46 static const char sccsid[] = "@(#)tail.c 8.1 (Berkeley) 6/6/93"; 47 #endif 48 49 #include <sys/types.h> 50 #include <sys/stat.h> 51 52 #include <err.h> 53 #include <errno.h> 54 #include <getopt.h> 55 #include <stdio.h> 56 #include <stdlib.h> 57 #include <string.h> 58 #include <unistd.h> 59 60 #include "extern.h" 61 62 int Fflag, fflag, qflag, rflag, rval, no_files; 63 64 static file_info_t *files; 65 66 static void obsolete(char **); 67 static void usage(void); 68 69 static const struct option long_opts[] = 70 { 71 {"blocks", required_argument, NULL, 'b'}, 72 {"bytes", required_argument, NULL, 'c'}, 73 {"lines", required_argument, NULL, 'n'}, 74 {NULL, no_argument, NULL, 0} 75 }; 76 77 int 78 main(int argc, char *argv[]) 79 { 80 struct stat sb; 81 const char *fn; 82 FILE *fp; 83 off_t off; 84 enum STYLE style; 85 int i, ch, first; 86 file_info_t *file; 87 char *p; 88 89 /* 90 * Tail's options are weird. First, -n10 is the same as -n-10, not 91 * -n+10. Second, the number options are 1 based and not offsets, 92 * so -n+1 is the first line, and -c-1 is the last byte. Third, the 93 * number options for the -r option specify the number of things that 94 * get displayed, not the starting point in the file. The one major 95 * incompatibility in this version as compared to historical versions 96 * is that the 'r' option couldn't be modified by the -lbc options, 97 * i.e. it was always done in lines. This version treats -rc as a 98 * number of characters in reverse order. Finally, the default for 99 * -r is the entire file, not 10 lines. 100 */ 101 #define ARG(units, forward, backward) { \ 102 if (style) \ 103 usage(); \ 104 off = strtoll(optarg, &p, 10) * (units); \ 105 if (*p) \ 106 errx(1, "illegal offset -- %s", optarg); \ 107 switch(optarg[0]) { \ 108 case '+': \ 109 if (off) \ 110 off -= (units); \ 111 style = (forward); \ 112 break; \ 113 case '-': \ 114 off = -off; \ 115 /* FALLTHROUGH */ \ 116 default: \ 117 style = (backward); \ 118 break; \ 119 } \ 120 } 121 122 obsolete(argv); 123 style = NOTSET; 124 off = 0; 125 while ((ch = getopt_long(argc, argv, "+Fb:c:fn:qr", long_opts, NULL)) != 126 -1) 127 switch(ch) { 128 case 'F': /* -F is superset of (and implies) -f */ 129 Fflag = fflag = 1; 130 break; 131 case 'b': 132 ARG(512, FBYTES, RBYTES); 133 break; 134 case 'c': 135 ARG(1, FBYTES, RBYTES); 136 break; 137 case 'f': 138 fflag = 1; 139 break; 140 case 'n': 141 ARG(1, FLINES, RLINES); 142 break; 143 case 'q': 144 qflag = 1; 145 break; 146 case 'r': 147 rflag = 1; 148 break; 149 case '?': 150 default: 151 usage(); 152 } 153 argc -= optind; 154 argv += optind; 155 156 no_files = argc ? argc : 1; 157 158 /* 159 * If displaying in reverse, don't permit follow option, and convert 160 * style values. 161 */ 162 if (rflag) { 163 if (fflag) 164 usage(); 165 if (style == FBYTES) 166 style = RBYTES; 167 else if (style == FLINES) 168 style = RLINES; 169 } 170 171 /* 172 * If style not specified, the default is the whole file for -r, and 173 * the last 10 lines if not -r. 174 */ 175 if (style == NOTSET) { 176 if (rflag) { 177 off = 0; 178 style = REVERSE; 179 } else { 180 off = 10; 181 style = RLINES; 182 } 183 } 184 185 if (*argv && fflag) { 186 files = (struct file_info *) malloc(no_files * 187 sizeof(struct file_info)); 188 if (!files) 189 err(1, "Couldn't malloc space for file descriptors."); 190 191 for (file = files; (fn = *argv++); file++) { 192 file->file_name = strdup(fn); 193 if (! file->file_name) 194 errx(1, "Couldn't malloc space for file name."); 195 if ((file->fp = fopen(file->file_name, "r")) == NULL || 196 fstat(fileno(file->fp), &file->st)) { 197 if (file->fp != NULL) { 198 fclose(file->fp); 199 file->fp = NULL; 200 } 201 if (!Fflag || errno != ENOENT) 202 ierr(file->file_name); 203 } 204 } 205 follow(files, style, off); 206 for (i = 0, file = files; i < no_files; i++, file++) { 207 free(file->file_name); 208 } 209 free(files); 210 } else if (*argv) { 211 for (first = 1; (fn = *argv++);) { 212 if ((fp = fopen(fn, "r")) == NULL || 213 fstat(fileno(fp), &sb)) { 214 ierr(fn); 215 continue; 216 } 217 if (argc > 1 && !qflag) { 218 printfn(fn, !first); 219 first = 0; 220 } 221 222 if (rflag) 223 reverse(fp, fn, style, off, &sb); 224 else 225 forward(fp, fn, style, off, &sb); 226 } 227 } else { 228 fn = "stdin"; 229 230 if (fstat(fileno(stdin), &sb)) { 231 ierr(fn); 232 exit(1); 233 } 234 235 /* 236 * Determine if input is a pipe. 4.4BSD will set the SOCKET 237 * bit in the st_mode field for pipes. Fix this then. 238 */ 239 if (lseek(fileno(stdin), (off_t)0, SEEK_CUR) == -1 && 240 errno == ESPIPE) { 241 errno = 0; 242 fflag = 0; /* POSIX.2 requires this. */ 243 } 244 245 if (rflag) 246 reverse(stdin, fn, style, off, &sb); 247 else 248 forward(stdin, fn, style, off, &sb); 249 } 250 exit(rval); 251 } 252 253 /* 254 * Convert the obsolete argument form into something that getopt can handle. 255 * This means that anything of the form [+-][0-9][0-9]*[lbc][Ffr] that isn't 256 * the option argument for a -b, -c or -n option gets converted. 257 */ 258 static void 259 obsolete(char *argv[]) 260 { 261 char *ap, *p, *t; 262 size_t len; 263 char *start; 264 265 while ((ap = *++argv)) { 266 /* Return if "--" or not an option of any form. */ 267 if (ap[0] != '-') { 268 if (ap[0] != '+') 269 return; 270 } else if (ap[1] == '-') 271 return; 272 273 switch(*++ap) { 274 /* Old-style option. */ 275 case '0': case '1': case '2': case '3': case '4': 276 case '5': case '6': case '7': case '8': case '9': 277 278 /* Malloc space for dash, new option and argument. */ 279 len = strlen(*argv); 280 if ((start = p = malloc(len + 3)) == NULL) 281 err(1, "malloc"); 282 *p++ = '-'; 283 284 /* 285 * Go to the end of the option argument. Save off any 286 * trailing options (-3lf) and translate any trailing 287 * output style characters. 288 */ 289 t = *argv + len - 1; 290 if (*t == 'F' || *t == 'f' || *t == 'r') { 291 *p++ = *t; 292 *t-- = '\0'; 293 } 294 switch(*t) { 295 case 'b': 296 *p++ = 'b'; 297 *t = '\0'; 298 break; 299 case 'c': 300 *p++ = 'c'; 301 *t = '\0'; 302 break; 303 case 'l': 304 *t = '\0'; 305 /* FALLTHROUGH */ 306 case '0': case '1': case '2': case '3': case '4': 307 case '5': case '6': case '7': case '8': case '9': 308 *p++ = 'n'; 309 break; 310 default: 311 errx(1, "illegal option -- %s", *argv); 312 } 313 *p++ = *argv[0]; 314 (void)strcpy(p, ap); 315 *argv = start; 316 continue; 317 318 /* 319 * Options w/ arguments, skip the argument and continue 320 * with the next option. 321 */ 322 case 'b': 323 case 'c': 324 case 'n': 325 if (!ap[1]) 326 ++argv; 327 /* FALLTHROUGH */ 328 /* Options w/o arguments, continue with the next option. */ 329 case 'F': 330 case 'f': 331 case 'r': 332 continue; 333 334 /* Illegal option, return and let getopt handle it. */ 335 default: 336 return; 337 } 338 } 339 } 340 341 static void 342 usage(void) 343 { 344 (void)fprintf(stderr, 345 "usage: tail [-F | -f | -r] [-q] [-b # | -c # | -n #]" 346 " [file ...]\n"); 347 exit(1); 348 } 349