tail.c revision 332482
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 * 4. 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 35__FBSDID("$FreeBSD: stable/11/usr.bin/tail/tail.c 332482 2018-04-13 17:57:00Z kevans $"); 36 37#ifndef lint 38static const char copyright[] = 39"@(#) Copyright (c) 1991, 1993\n\ 40 The Regents of the University of California. All rights reserved.\n"; 41#endif 42 43#ifndef lint 44static const char sccsid[] = "@(#)tail.c 8.1 (Berkeley) 6/6/93"; 45#endif 46 47#include <sys/types.h> 48#include <sys/stat.h> 49 50#include <err.h> 51#include <errno.h> 52#include <getopt.h> 53#include <stdio.h> 54#include <stdlib.h> 55#include <string.h> 56#include <unistd.h> 57 58#include "extern.h" 59 60int Fflag, fflag, qflag, rflag, rval, no_files; 61 62static file_info_t *files; 63 64static void obsolete(char **); 65static void usage(void); 66 67static const struct option long_opts[] = 68{ 69 {"blocks", required_argument, NULL, 'b'}, 70 {"bytes", required_argument, NULL, 'c'}, 71 {"lines", required_argument, NULL, 'n'}, 72 {NULL, no_argument, NULL, 0} 73}; 74 75int 76main(int argc, char *argv[]) 77{ 78 struct stat sb; 79 const char *fn; 80 FILE *fp; 81 off_t off; 82 enum STYLE style; 83 int i, ch, first; 84 file_info_t *file; 85 char *p; 86 87 /* 88 * Tail's options are weird. First, -n10 is the same as -n-10, not 89 * -n+10. Second, the number options are 1 based and not offsets, 90 * so -n+1 is the first line, and -c-1 is the last byte. Third, the 91 * number options for the -r option specify the number of things that 92 * get displayed, not the starting point in the file. The one major 93 * incompatibility in this version as compared to historical versions 94 * is that the 'r' option couldn't be modified by the -lbc options, 95 * i.e. it was always done in lines. This version treats -rc as a 96 * number of characters in reverse order. Finally, the default for 97 * -r is the entire file, not 10 lines. 98 */ 99#define ARG(units, forward, backward) { \ 100 if (style) \ 101 usage(); \ 102 off = strtoll(optarg, &p, 10) * (units); \ 103 if (*p) \ 104 errx(1, "illegal offset -- %s", optarg); \ 105 switch(optarg[0]) { \ 106 case '+': \ 107 if (off) \ 108 off -= (units); \ 109 style = (forward); \ 110 break; \ 111 case '-': \ 112 off = -off; \ 113 /* FALLTHROUGH */ \ 114 default: \ 115 style = (backward); \ 116 break; \ 117 } \ 118} 119 120 obsolete(argv); 121 style = NOTSET; 122 off = 0; 123 while ((ch = getopt_long(argc, argv, "+Fb:c:fn:qr", long_opts, NULL)) != 124 -1) 125 switch(ch) { 126 case 'F': /* -F is superset of (and implies) -f */ 127 Fflag = fflag = 1; 128 break; 129 case 'b': 130 ARG(512, FBYTES, RBYTES); 131 break; 132 case 'c': 133 ARG(1, FBYTES, RBYTES); 134 break; 135 case 'f': 136 fflag = 1; 137 break; 138 case 'n': 139 ARG(1, FLINES, RLINES); 140 break; 141 case 'q': 142 qflag = 1; 143 break; 144 case 'r': 145 rflag = 1; 146 break; 147 case '?': 148 default: 149 usage(); 150 } 151 argc -= optind; 152 argv += optind; 153 154 no_files = argc ? argc : 1; 155 156 /* 157 * If displaying in reverse, don't permit follow option, and convert 158 * style values. 159 */ 160 if (rflag) { 161 if (fflag) 162 usage(); 163 if (style == FBYTES) 164 style = RBYTES; 165 else if (style == FLINES) 166 style = RLINES; 167 } 168 169 /* 170 * If style not specified, the default is the whole file for -r, and 171 * the last 10 lines if not -r. 172 */ 173 if (style == NOTSET) { 174 if (rflag) { 175 off = 0; 176 style = REVERSE; 177 } else { 178 off = 10; 179 style = RLINES; 180 } 181 } 182 183 if (*argv && fflag) { 184 files = (struct file_info *) malloc(no_files * 185 sizeof(struct file_info)); 186 if (!files) 187 err(1, "Couldn't malloc space for file descriptors."); 188 189 for (file = files; (fn = *argv++); file++) { 190 file->file_name = strdup(fn); 191 if (! file->file_name) 192 errx(1, "Couldn't malloc space for file name."); 193 if ((file->fp = fopen(file->file_name, "r")) == NULL || 194 fstat(fileno(file->fp), &file->st)) { 195 if (file->fp != NULL) { 196 fclose(file->fp); 197 file->fp = NULL; 198 } 199 if (!Fflag || errno != ENOENT) 200 ierr(file->file_name); 201 } 202 } 203 follow(files, style, off); 204 for (i = 0, file = files; i < no_files; i++, file++) { 205 free(file->file_name); 206 } 207 free(files); 208 } else if (*argv) { 209 for (first = 1; (fn = *argv++);) { 210 if ((fp = fopen(fn, "r")) == NULL || 211 fstat(fileno(fp), &sb)) { 212 ierr(fn); 213 continue; 214 } 215 if (argc > 1 && !qflag) { 216 printfn(fn, !first); 217 first = 0; 218 } 219 220 if (rflag) 221 reverse(fp, fn, style, off, &sb); 222 else 223 forward(fp, fn, style, off, &sb); 224 } 225 } else { 226 fn = "stdin"; 227 228 if (fstat(fileno(stdin), &sb)) { 229 ierr(fn); 230 exit(1); 231 } 232 233 /* 234 * Determine if input is a pipe. 4.4BSD will set the SOCKET 235 * bit in the st_mode field for pipes. Fix this then. 236 */ 237 if (lseek(fileno(stdin), (off_t)0, SEEK_CUR) == -1 && 238 errno == ESPIPE) { 239 errno = 0; 240 fflag = 0; /* POSIX.2 requires this. */ 241 } 242 243 if (rflag) 244 reverse(stdin, fn, style, off, &sb); 245 else 246 forward(stdin, fn, style, off, &sb); 247 } 248 exit(rval); 249} 250 251/* 252 * Convert the obsolete argument form into something that getopt can handle. 253 * This means that anything of the form [+-][0-9][0-9]*[lbc][Ffr] that isn't 254 * the option argument for a -b, -c or -n option gets converted. 255 */ 256static void 257obsolete(char *argv[]) 258{ 259 char *ap, *p, *t; 260 size_t len; 261 char *start; 262 263 while ((ap = *++argv)) { 264 /* Return if "--" or not an option of any form. */ 265 if (ap[0] != '-') { 266 if (ap[0] != '+') 267 return; 268 } else if (ap[1] == '-') 269 return; 270 271 switch(*++ap) { 272 /* Old-style option. */ 273 case '0': case '1': case '2': case '3': case '4': 274 case '5': case '6': case '7': case '8': case '9': 275 276 /* Malloc space for dash, new option and argument. */ 277 len = strlen(*argv); 278 if ((start = p = malloc(len + 3)) == NULL) 279 err(1, "malloc"); 280 *p++ = '-'; 281 282 /* 283 * Go to the end of the option argument. Save off any 284 * trailing options (-3lf) and translate any trailing 285 * output style characters. 286 */ 287 t = *argv + len - 1; 288 if (*t == 'F' || *t == 'f' || *t == 'r') { 289 *p++ = *t; 290 *t-- = '\0'; 291 } 292 switch(*t) { 293 case 'b': 294 *p++ = 'b'; 295 *t = '\0'; 296 break; 297 case 'c': 298 *p++ = 'c'; 299 *t = '\0'; 300 break; 301 case 'l': 302 *t = '\0'; 303 /* FALLTHROUGH */ 304 case '0': case '1': case '2': case '3': case '4': 305 case '5': case '6': case '7': case '8': case '9': 306 *p++ = 'n'; 307 break; 308 default: 309 errx(1, "illegal option -- %s", *argv); 310 } 311 *p++ = *argv[0]; 312 (void)strcpy(p, ap); 313 *argv = start; 314 continue; 315 316 /* 317 * Options w/ arguments, skip the argument and continue 318 * with the next option. 319 */ 320 case 'b': 321 case 'c': 322 case 'n': 323 if (!ap[1]) 324 ++argv; 325 /* FALLTHROUGH */ 326 /* Options w/o arguments, continue with the next option. */ 327 case 'F': 328 case 'f': 329 case 'r': 330 continue; 331 332 /* Illegal option, return and let getopt handle it. */ 333 default: 334 return; 335 } 336 } 337} 338 339static void 340usage(void) 341{ 342 (void)fprintf(stderr, 343 "usage: tail [-F | -f | -r] [-q] [-b # | -c # | -n #]" 344 " [file ...]\n"); 345 exit(1); 346} 347