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/types.h> 34 #include <sys/stat.h> 35 36 #include <err.h> 37 #include <errno.h> 38 #include <stdio.h> 39 #include <stdlib.h> 40 #include <string.h> 41 #include <unistd.h> 42 43 #include "extern.h" 44 45 int Fflag, fflag, qflag, rflag, rval, no_files; 46 47 file_info_t *files; 48 49 static void obsolete(char **); 50 static void usage(void); 51 52 int 53 main(int argc, char *argv[]) 54 { 55 struct stat sb; 56 const char *fn; 57 FILE *fp; 58 off_t off; 59 enum STYLE style; 60 int i, ch, first; 61 file_info_t *file; 62 char *p; 63 64 /* 65 * Tail's options are weird. First, -n10 is the same as -n-10, not 66 * -n+10. Second, the number options are 1 based and not offsets, 67 * so -n+1 is the first line, and -c-1 is the last byte. Third, the 68 * number options for the -r option specify the number of things that 69 * get displayed, not the starting point in the file. The one major 70 * incompatibility in this version as compared to historical versions 71 * is that the 'r' option couldn't be modified by the -lbc options, 72 * i.e. it was always done in lines. This version treats -rc as a 73 * number of characters in reverse order. Finally, the default for 74 * -r is the entire file, not 10 lines. 75 */ 76 #define ARG(units, forward, backward) { \ 77 if (style) \ 78 usage(); \ 79 off = strtoll(optarg, &p, 10) * (units); \ 80 if (*p) \ 81 errx(1, "illegal offset -- %s", optarg); \ 82 switch (optarg[0]) { \ 83 case '+': \ 84 if (off) \ 85 off -= (units); \ 86 style = (forward); \ 87 break; \ 88 case '-': \ 89 off = -off; \ 90 /* FALLTHROUGH */ \ 91 default: \ 92 style = (backward); \ 93 break; \ 94 } \ 95 } 96 97 obsolete(argv); 98 style = NOTSET; 99 off = 0; 100 while ((ch = getopt(argc, argv, "Fb:c:fn:qr")) != -1) 101 switch (ch) { 102 case 'F': /* -F is superset of (and implies) -f */ 103 Fflag = fflag = 1; 104 break; 105 case 'b': 106 ARG(512, FBYTES, RBYTES); 107 break; 108 case 'c': 109 ARG(1, FBYTES, RBYTES); 110 break; 111 case 'f': 112 fflag = 1; 113 break; 114 case 'n': 115 ARG(1, FLINES, RLINES); 116 break; 117 case 'q': 118 qflag = 1; 119 break; 120 case 'r': 121 rflag = 1; 122 break; 123 case '?': 124 default: 125 usage(); 126 } 127 argc -= optind; 128 argv += optind; 129 130 no_files = argc ? argc : 1; 131 132 /* 133 * If displaying in reverse, don't permit follow option, and convert 134 * style values. 135 */ 136 if (rflag) { 137 if (fflag) 138 usage(); 139 if (style == FBYTES) 140 style = RBYTES; 141 else if (style == FLINES) 142 style = RLINES; 143 } 144 145 /* 146 * If style not specified, the default is the whole file for -r, and 147 * the last 10 lines if not -r. 148 */ 149 if (style == NOTSET) { 150 if (rflag) { 151 off = 0; 152 style = REVERSE; 153 } else { 154 off = 10; 155 style = RLINES; 156 } 157 } 158 159 if (*argv && fflag) { 160 files = (struct file_info *)malloc(no_files * 161 sizeof (struct file_info)); 162 if (!files) 163 err(1, "Couldn't malloc space for file descriptors."); 164 165 for (file = files; (fn = *argv++); file++) { 166 file->file_name = strdup(fn); 167 if (! file->file_name) 168 errx(1, "Couldn't malloc space for file name."); 169 if ((file->fp = fopen(file->file_name, "r")) == NULL || 170 fstat(fileno(file->fp), &file->st)) { 171 if (file->fp != NULL) { 172 (void) fclose(file->fp); 173 file->fp = NULL; 174 } 175 if (!Fflag || errno != ENOENT) 176 ierr(file->file_name); 177 } 178 } 179 follow(files, style, off); 180 for (i = 0, file = files; i < no_files; i++, file++) { 181 free(file->file_name); 182 } 183 free(files); 184 } else if (*argv) { 185 for (first = 1; (fn = *argv++); ) { 186 if ((fp = fopen(fn, "r")) == NULL || 187 fstat(fileno(fp), &sb)) { 188 ierr(fn); 189 continue; 190 } 191 if (argc > 1 && !qflag) { 192 (void) printf("%s==> %s <==\n", 193 first ? "" : "\n", fn); 194 first = 0; 195 (void) fflush(stdout); 196 } 197 198 if (rflag) 199 reverse(fp, fn, style, off, &sb); 200 else 201 forward(fp, fn, style, off, &sb); 202 } 203 } else { 204 fn = "stdin"; 205 206 if (fstat(fileno(stdin), &sb)) { 207 ierr(fn); 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, fn, style, off, &sb); 223 else 224 forward(stdin, fn, 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][Ffr] that isn't 232 * the option argument for a -b, -c or -n option gets converted. 233 */ 234 static void 235 obsolete(char *argv[]) 236 { 237 char *ap, *p, *t; 238 size_t len; 239 char *start; 240 241 while ((ap = *++argv)) { 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 err(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 == '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 errx(1, "illegal option -- %s", *argv); 288 } 289 *p++ = *argv[0]; 290 (void) strcpy(p, ap); 291 *argv = start; 292 continue; 293 294 /* 295 * Legacy Solaris tail supports "+c" "-c", "+l", "-l", 296 * "+b", and "-b" with an default number of 10. Map 297 * these arguments to an explicit +/-10 for FreeBSD. 298 * New argument will be of the form -[bcn][+-]10 299 */ 300 case 'b': 301 case 'c': 302 case 'l': 303 if ((start = p = malloc(6)) == NULL) 304 err(1, "malloc"); 305 *p++ = '-'; 306 switch (ap[0]) { 307 case 'c': 308 *p++ = ap[0]; 309 break; 310 case 'b': 311 *p++ = ap[0]; 312 break; 313 case 'l': 314 *p++ = 'n'; 315 break; 316 } 317 (void) snprintf(p, 6, "%c10", *argv[0]); 318 *argv = start; 319 320 continue; 321 /* 322 * Options w/ arguments, skip the argument and continue 323 * with the next option. 324 */ 325 case 'n': 326 if (!ap[1]) 327 ++argv; 328 /* FALLTHROUGH */ 329 /* Options w/o arguments, continue with the next option. */ 330 case 'F': 331 case 'f': 332 case 'r': 333 continue; 334 335 /* Illegal option, return and let getopt handle it. */ 336 default: 337 return; 338 } 339 } 340 } 341 342 static void 343 usage(void) 344 { 345 (void) fprintf(stderr, 346 "usage: tail [-F | -f | -r] [-q] [-b # | -c # | -n #]" 347 " [file ...]\n"); 348 exit(1); 349 } 350