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 const char *fname; 65 66 file_info_t *files; 67 68 static void obsolete(char **); 69 static void usage(void); 70 71 int 72 main(int argc, char *argv[]) 73 { 74 struct stat sb; 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 * sizeof(struct file_info)); 179 if (! files) 180 err(1, "Couldn't malloc space for file descriptors."); 181 182 for (file = files; (fname = *argv++); file++) { 183 file->file_name = malloc(strlen(fname)+1); 184 if (! file->file_name) 185 errx(1, "Couldn't malloc space for file name."); 186 strncpy(file->file_name, fname, strlen(fname)+1); 187 if ((file->fp = fopen(file->file_name, "r")) == NULL || 188 fstat(fileno(file->fp), &file->st)) { 189 file->fp = NULL; 190 ierr(); 191 continue; 192 } 193 } 194 follow(files, style, off); 195 for (i = 0, file = files; i < no_files; i++, file++) { 196 free(file->file_name); 197 } 198 free(files); 199 } else if (*argv) { 200 for (first = 1; (fname = *argv++);) { 201 if ((fp = fopen(fname, "r")) == NULL || 202 fstat(fileno(fp), &sb)) { 203 ierr(); 204 continue; 205 } 206 if (argc > 1 && !qflag) { 207 (void)printf("%s==> %s <==\n", 208 first ? "" : "\n", fname); 209 first = 0; 210 (void)fflush(stdout); 211 } 212 213 if (rflag) 214 reverse(fp, style, off, &sb); 215 else 216 forward(fp, style, off, &sb); 217 } 218 } else { 219 fname = "stdin"; 220 221 if (fstat(fileno(stdin), &sb)) { 222 ierr(); 223 exit(1); 224 } 225 226 /* 227 * Determine if input is a pipe. 4.4BSD will set the SOCKET 228 * bit in the st_mode field for pipes. Fix this then. 229 */ 230 if (lseek(fileno(stdin), (off_t)0, SEEK_CUR) == -1 && 231 errno == ESPIPE) { 232 errno = 0; 233 fflag = 0; /* POSIX.2 requires this. */ 234 } 235 236 if (rflag) 237 reverse(stdin, style, off, &sb); 238 else 239 forward(stdin, style, off, &sb); 240 } 241 exit(rval); 242 } 243 244 /* 245 * Convert the obsolete argument form into something that getopt can handle. 246 * This means that anything of the form [+-][0-9][0-9]*[lbc][Ffr] that isn't 247 * the option argument for a -b, -c or -n option gets converted. 248 */ 249 static void 250 obsolete(char *argv[]) 251 { 252 char *ap, *p, *t; 253 size_t len; 254 char *start; 255 256 while ((ap = *++argv)) { 257 /* Return if "--" or not an option of any form. */ 258 if (ap[0] != '-') { 259 if (ap[0] != '+') 260 return; 261 } else if (ap[1] == '-') 262 return; 263 264 switch(*++ap) { 265 /* Old-style option. */ 266 case '0': case '1': case '2': case '3': case '4': 267 case '5': case '6': case '7': case '8': case '9': 268 269 /* Malloc space for dash, new option and argument. */ 270 len = strlen(*argv); 271 if ((start = p = malloc(len + 3)) == NULL) 272 err(1, "malloc"); 273 *p++ = '-'; 274 275 /* 276 * Go to the end of the option argument. Save off any 277 * trailing options (-3lf) and translate any trailing 278 * output style characters. 279 */ 280 t = *argv + len - 1; 281 if (*t == 'F' || *t == 'f' || *t == 'r') { 282 *p++ = *t; 283 *t-- = '\0'; 284 } 285 switch(*t) { 286 case 'b': 287 *p++ = 'b'; 288 *t = '\0'; 289 break; 290 case 'c': 291 *p++ = 'c'; 292 *t = '\0'; 293 break; 294 case 'l': 295 *t = '\0'; 296 /* FALLTHROUGH */ 297 case '0': case '1': case '2': case '3': case '4': 298 case '5': case '6': case '7': case '8': case '9': 299 *p++ = 'n'; 300 break; 301 default: 302 errx(1, "illegal option -- %s", *argv); 303 } 304 *p++ = *argv[0]; 305 (void)strcpy(p, ap); 306 *argv = start; 307 continue; 308 309 /* 310 * Options w/ arguments, skip the argument and continue 311 * with the next option. 312 */ 313 case 'b': 314 case 'c': 315 case 'n': 316 if (!ap[1]) 317 ++argv; 318 /* FALLTHROUGH */ 319 /* Options w/o arguments, continue with the next option. */ 320 case 'F': 321 case 'f': 322 case 'r': 323 continue; 324 325 /* Illegal option, return and let getopt handle it. */ 326 default: 327 return; 328 } 329 } 330 } 331 332 static void 333 usage(void) 334 { 335 (void)fprintf(stderr, 336 "usage: tail [-F | -f | -r] [-q] [-b # | -c # | -n #]" 337 " [file ...]\n"); 338 exit(1); 339 } 340