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. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by the University of 19 * California, Berkeley and its contributors. 20 * 4. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 */ 36 37 #include <sys/cdefs.h> 38 39 __FBSDID("$FreeBSD$"); 40 41 #ifndef lint 42 static const char copyright[] = 43 "@(#) Copyright (c) 1991, 1993\n\ 44 The Regents of the University of California. All rights reserved.\n"; 45 #endif 46 47 #ifndef lint 48 static const char sccsid[] = "@(#)tail.c 8.1 (Berkeley) 6/6/93"; 49 #endif 50 51 #include <sys/types.h> 52 #include <sys/stat.h> 53 54 #include <err.h> 55 #include <errno.h> 56 #include <stdio.h> 57 #include <stdlib.h> 58 #include <string.h> 59 #include <unistd.h> 60 61 #include "extern.h" 62 63 int Fflag, fflag, qflag, rflag, rval, no_files; 64 65 file_info_t *files; 66 67 static void obsolete(char **); 68 static void usage(void); 69 70 int 71 main(int argc, char *argv[]) 72 { 73 struct stat sb; 74 const char *fn; 75 FILE *fp; 76 off_t off; 77 enum STYLE style; 78 int i, ch, first; 79 file_info_t *file; 80 char *p; 81 82 /* 83 * Tail's options are weird. First, -n10 is the same as -n-10, not 84 * -n+10. Second, the number options are 1 based and not offsets, 85 * so -n+1 is the first line, and -c-1 is the last byte. Third, the 86 * number options for the -r option specify the number of things that 87 * get displayed, not the starting point in the file. The one major 88 * incompatibility in this version as compared to historical versions 89 * is that the 'r' option couldn't be modified by the -lbc options, 90 * i.e. it was always done in lines. This version treats -rc as a 91 * number of characters in reverse order. Finally, the default for 92 * -r is the entire file, not 10 lines. 93 */ 94 #define ARG(units, forward, backward) { \ 95 if (style) \ 96 usage(); \ 97 off = strtoll(optarg, &p, 10) * (units); \ 98 if (*p) \ 99 errx(1, "illegal offset -- %s", optarg); \ 100 switch(optarg[0]) { \ 101 case '+': \ 102 if (off) \ 103 off -= (units); \ 104 style = (forward); \ 105 break; \ 106 case '-': \ 107 off = -off; \ 108 /* FALLTHROUGH */ \ 109 default: \ 110 style = (backward); \ 111 break; \ 112 } \ 113 } 114 115 obsolete(argv); 116 style = NOTSET; 117 off = 0; 118 while ((ch = getopt(argc, argv, "Fb:c:fn:qr")) != -1) 119 switch(ch) { 120 case 'F': /* -F is superset of (and implies) -f */ 121 Fflag = fflag = 1; 122 break; 123 case 'b': 124 ARG(512, FBYTES, RBYTES); 125 break; 126 case 'c': 127 ARG(1, FBYTES, RBYTES); 128 break; 129 case 'f': 130 fflag = 1; 131 break; 132 case 'n': 133 ARG(1, FLINES, RLINES); 134 break; 135 case 'q': 136 qflag = 1; 137 break; 138 case 'r': 139 rflag = 1; 140 break; 141 case '?': 142 default: 143 usage(); 144 } 145 argc -= optind; 146 argv += optind; 147 148 no_files = argc ? argc : 1; 149 150 /* 151 * If displaying in reverse, don't permit follow option, and convert 152 * style values. 153 */ 154 if (rflag) { 155 if (fflag) 156 usage(); 157 if (style == FBYTES) 158 style = RBYTES; 159 else if (style == FLINES) 160 style = RLINES; 161 } 162 163 /* 164 * If style not specified, the default is the whole file for -r, and 165 * the last 10 lines if not -r. 166 */ 167 if (style == NOTSET) { 168 if (rflag) { 169 off = 0; 170 style = REVERSE; 171 } else { 172 off = 10; 173 style = RLINES; 174 } 175 } 176 177 if (*argv && fflag) { 178 files = (struct file_info *) malloc(no_files * 179 sizeof(struct file_info)); 180 if (!files) 181 err(1, "Couldn't malloc space for file descriptors."); 182 183 for (file = files; (fn = *argv++); file++) { 184 file->file_name = strdup(fn); 185 if (! file->file_name) 186 errx(1, "Couldn't malloc space for file name."); 187 if ((file->fp = fopen(file->file_name, "r")) == NULL || 188 fstat(fileno(file->fp), &file->st)) { 189 if (file->fp != NULL) { 190 fclose(file->fp); 191 file->fp = NULL; 192 } 193 if (!Fflag || errno != ENOENT) 194 ierr(file->file_name); 195 } 196 } 197 follow(files, style, off); 198 for (i = 0, file = files; i < no_files; i++, file++) { 199 free(file->file_name); 200 } 201 free(files); 202 } else if (*argv) { 203 for (first = 1; (fn = *argv++);) { 204 if ((fp = fopen(fn, "r")) == NULL || 205 fstat(fileno(fp), &sb)) { 206 ierr(fn); 207 continue; 208 } 209 if (argc > 1 && !qflag) { 210 (void)printf("%s==> %s <==\n", 211 first ? "" : "\n", fn); 212 first = 0; 213 (void)fflush(stdout); 214 } 215 216 if (rflag) 217 reverse(fp, fn, style, off, &sb); 218 else 219 forward(fp, fn, style, off, &sb); 220 } 221 } else { 222 fn = "stdin"; 223 224 if (fstat(fileno(stdin), &sb)) { 225 ierr(fn); 226 exit(1); 227 } 228 229 /* 230 * Determine if input is a pipe. 4.4BSD will set the SOCKET 231 * bit in the st_mode field for pipes. Fix this then. 232 */ 233 if (lseek(fileno(stdin), (off_t)0, SEEK_CUR) == -1 && 234 errno == ESPIPE) { 235 errno = 0; 236 fflag = 0; /* POSIX.2 requires this. */ 237 } 238 239 if (rflag) 240 reverse(stdin, fn, style, off, &sb); 241 else 242 forward(stdin, fn, style, off, &sb); 243 } 244 exit(rval); 245 } 246 247 /* 248 * Convert the obsolete argument form into something that getopt can handle. 249 * This means that anything of the form [+-][0-9][0-9]*[lbc][Ffr] that isn't 250 * the option argument for a -b, -c or -n option gets converted. 251 */ 252 static void 253 obsolete(char *argv[]) 254 { 255 char *ap, *p, *t; 256 size_t len; 257 char *start; 258 259 while ((ap = *++argv)) { 260 /* Return if "--" or not an option of any form. */ 261 if (ap[0] != '-') { 262 if (ap[0] != '+') 263 return; 264 } else if (ap[1] == '-') 265 return; 266 267 switch(*++ap) { 268 /* Old-style option. */ 269 case '0': case '1': case '2': case '3': case '4': 270 case '5': case '6': case '7': case '8': case '9': 271 272 /* Malloc space for dash, new option and argument. */ 273 len = strlen(*argv); 274 if ((start = p = malloc(len + 3)) == NULL) 275 err(1, "malloc"); 276 *p++ = '-'; 277 278 /* 279 * Go to the end of the option argument. Save off any 280 * trailing options (-3lf) and translate any trailing 281 * output style characters. 282 */ 283 t = *argv + len - 1; 284 if (*t == 'F' || *t == 'f' || *t == 'r') { 285 *p++ = *t; 286 *t-- = '\0'; 287 } 288 switch(*t) { 289 case 'b': 290 *p++ = 'b'; 291 *t = '\0'; 292 break; 293 case 'c': 294 *p++ = 'c'; 295 *t = '\0'; 296 break; 297 case 'l': 298 *t = '\0'; 299 /* FALLTHROUGH */ 300 case '0': case '1': case '2': case '3': case '4': 301 case '5': case '6': case '7': case '8': case '9': 302 *p++ = 'n'; 303 break; 304 default: 305 errx(1, "illegal option -- %s", *argv); 306 } 307 *p++ = *argv[0]; 308 (void)strcpy(p, ap); 309 *argv = start; 310 continue; 311 312 /* 313 * Options w/ arguments, skip the argument and continue 314 * with the next option. 315 */ 316 case 'b': 317 case 'c': 318 case 'n': 319 if (!ap[1]) 320 ++argv; 321 /* FALLTHROUGH */ 322 /* Options w/o arguments, continue with the next option. */ 323 case 'F': 324 case 'f': 325 case 'r': 326 continue; 327 328 /* Illegal option, return and let getopt handle it. */ 329 default: 330 return; 331 } 332 } 333 } 334 335 static void 336 usage(void) 337 { 338 (void)fprintf(stderr, 339 "usage: tail [-F | -f | -r] [-q] [-b # | -c # | -n #]" 340 " [file ...]\n"); 341 exit(1); 342 } 343