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