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 * @(#) Copyright (c) 1991, 1993 The Regents of the University of California. All rights reserved. 37 * @(#)tail.c 8.1 (Berkeley) 6/6/93 38 * $FreeBSD: src/usr.bin/tail/tail.c,v 1.6.2.2 2001/12/19 20:29:31 iedowse Exp $ 39 * $DragonFly: src/usr.bin/tail/tail.c,v 1.3 2003/10/04 20:36:52 hmp Exp $ 40 */ 41 42 #include <sys/types.h> 43 #include <sys/stat.h> 44 #include <errno.h> 45 #include <unistd.h> 46 #include <stdio.h> 47 #include <stdlib.h> 48 #include <string.h> 49 #include <err.h> 50 #include "extern.h" 51 52 int Fflag, fflag, rflag, rval; 53 char *fname; 54 55 static void obsolete(char **); 56 static void usage(void); 57 58 int 59 main(int argc, char **argv) 60 { 61 struct stat sb; 62 FILE *fp; 63 off_t off; 64 enum STYLE style; 65 int ch, first; 66 char *p; 67 68 /* 69 * Tail's options are weird. First, -n10 is the same as -n-10, not 70 * -n+10. Second, the number options are 1 based and not offsets, 71 * so -n+1 is the first line, and -c-1 is the last byte. Third, the 72 * number options for the -r option specify the number of things that 73 * get displayed, not the starting point in the file. The one major 74 * incompatibility in this version as compared to historical versions 75 * is that the 'r' option couldn't be modified by the -lbc options, 76 * i.e. it was always done in lines. This version treats -rc as a 77 * number of characters in reverse order. Finally, the default for 78 * -r is the entire file, not 10 lines. 79 */ 80 #define ARG(units, forward, backward) { \ 81 if (style) \ 82 usage(); \ 83 off = strtoll(optarg, &p, 10) * (units); \ 84 if (*p) \ 85 errx(1, "illegal offset -- %s", optarg); \ 86 switch(optarg[0]) { \ 87 case '+': \ 88 if (off) \ 89 off -= (units); \ 90 style = (forward); \ 91 break; \ 92 case '-': \ 93 off = -off; \ 94 /* FALLTHROUGH */ \ 95 default: \ 96 style = (backward); \ 97 break; \ 98 } \ 99 } 100 101 obsolete(argv); 102 style = NOTSET; 103 while ((ch = getopt(argc, argv, "Fb:c:fn:r")) != -1) 104 switch(ch) { 105 case 'F': /* -F is superset of (and implies) -f */ 106 Fflag = fflag = 1; 107 break; 108 case 'b': 109 ARG(512, FBYTES, RBYTES); 110 break; 111 case 'c': 112 ARG(1, FBYTES, RBYTES); 113 break; 114 case 'f': 115 fflag = 1; 116 break; 117 case 'n': 118 ARG(1, FLINES, RLINES); 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 if (fflag && argc > 1) 131 errx(1, "-f option only appropriate for a single file"); 132 133 /* 134 * If displaying in reverse, don't permit follow option, and convert 135 * style values. 136 */ 137 if (rflag) { 138 if (fflag) 139 usage(); 140 if (style == FBYTES) 141 style = RBYTES; 142 else if (style == FLINES) 143 style = RLINES; 144 } 145 146 /* 147 * If style not specified, the default is the whole file for -r, and 148 * the last 10 lines if not -r. 149 */ 150 if (style == NOTSET) { 151 if (rflag) { 152 off = 0; 153 style = REVERSE; 154 } else { 155 off = 10; 156 style = RLINES; 157 } 158 } 159 160 if (*argv) 161 for (first = 1; fname = *argv++;) { 162 if ((fp = fopen(fname, "r")) == NULL || 163 fstat(fileno(fp), &sb)) { 164 ierr(); 165 continue; 166 } 167 if (argc > 1) { 168 (void)printf("%s==> %s <==\n", 169 first ? "" : "\n", fname); 170 first = 0; 171 (void)fflush(stdout); 172 } 173 174 if (rflag) 175 reverse(fp, style, off, &sb); 176 else 177 forward(fp, style, off, &sb); 178 (void)fclose(fp); 179 } 180 else { 181 fname = "stdin"; 182 183 if (fstat(fileno(stdin), &sb)) { 184 ierr(); 185 exit(1); 186 } 187 188 /* 189 * Determine if input is a pipe. 4.4BSD will set the SOCKET 190 * bit in the st_mode field for pipes. Fix this then. 191 */ 192 if (lseek(fileno(stdin), (off_t)0, SEEK_CUR) == -1 && 193 errno == ESPIPE) { 194 errno = 0; 195 fflag = 0; /* POSIX.2 requires this. */ 196 } 197 198 if (rflag) 199 reverse(stdin, style, off, &sb); 200 else 201 forward(stdin, style, off, &sb); 202 } 203 exit(rval); 204 } 205 206 /* 207 * Convert the obsolete argument form into something that getopt can handle. 208 * This means that anything of the form [+-][0-9][0-9]*[lbc][Ffr] that isn't 209 * the option argument for a -b, -c or -n option gets converted. 210 */ 211 static void 212 obsolete(char **argv) 213 { 214 char *ap, *p, *t; 215 size_t len; 216 char *start; 217 218 while (ap = *++argv) { 219 /* Return if "--" or not an option of any form. */ 220 if (ap[0] != '-') { 221 if (ap[0] != '+') 222 return; 223 } else if (ap[1] == '-') 224 return; 225 226 switch(*++ap) { 227 /* Old-style option. */ 228 case '0': case '1': case '2': case '3': case '4': 229 case '5': case '6': case '7': case '8': case '9': 230 231 /* Malloc space for dash, new option and argument. */ 232 len = strlen(*argv); 233 if ((start = p = malloc(len + 3)) == NULL) 234 err(1, "malloc"); 235 *p++ = '-'; 236 237 /* 238 * Go to the end of the option argument. Save off any 239 * trailing options (-3lf) and translate any trailing 240 * output style characters. 241 */ 242 t = *argv + len - 1; 243 if (*t == 'F' || *t == 'f' || *t == 'r') { 244 *p++ = *t; 245 *t-- = '\0'; 246 } 247 switch(*t) { 248 case 'b': 249 *p++ = 'b'; 250 *t = '\0'; 251 break; 252 case 'c': 253 *p++ = 'c'; 254 *t = '\0'; 255 break; 256 case 'l': 257 *t = '\0'; 258 /* FALLTHROUGH */ 259 case '0': case '1': case '2': case '3': case '4': 260 case '5': case '6': case '7': case '8': case '9': 261 *p++ = 'n'; 262 break; 263 default: 264 errx(1, "illegal option -- %s", *argv); 265 } 266 *p++ = *argv[0]; 267 (void)strcpy(p, ap); 268 *argv = start; 269 continue; 270 271 /* 272 * Options w/ arguments, skip the argument and continue 273 * with the next option. 274 */ 275 case 'b': 276 case 'c': 277 case 'n': 278 if (!ap[1]) 279 ++argv; 280 /* FALLTHROUGH */ 281 /* Options w/o arguments, continue with the next option. */ 282 case 'F': 283 case 'f': 284 case 'r': 285 continue; 286 287 /* Illegal option, return and let getopt handle it. */ 288 default: 289 return; 290 } 291 } 292 } 293 294 static void 295 usage(void) 296 { 297 (void)fprintf(stderr, 298 "usage: tail [-F | -f | -r] [-b # | -c # | -n #] [file ...]\n"); 299 exit(1); 300 } 301