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 #ifndef lint 38 static const char copyright[] = 39 "@(#) Copyright (c) 1991, 1993\n\ 40 The Regents of the University of California. All rights reserved.\n"; 41 #endif /* not lint */ 42 43 #ifndef lint 44 #if 0 45 static char sccsid[] = "@(#)tail.c 8.1 (Berkeley) 6/6/93"; 46 #endif 47 static const char rcsid[] = 48 "$FreeBSD: src/usr.bin/tail/tail.c,v 1.6.2.2 2001/12/19 20:29:31 iedowse Exp $"; 49 #endif /* not lint */ 50 51 #include <sys/types.h> 52 #include <sys/stat.h> 53 #include <errno.h> 54 #include <unistd.h> 55 #include <stdio.h> 56 #include <stdlib.h> 57 #include <string.h> 58 #include <err.h> 59 #include "extern.h" 60 61 int Fflag, fflag, rflag, rval; 62 char *fname; 63 64 static void obsolete __P((char **)); 65 static void usage __P((void)); 66 67 int 68 main(argc, argv) 69 int argc; 70 char *argv[]; 71 { 72 struct stat sb; 73 FILE *fp; 74 off_t off; 75 enum STYLE style; 76 int ch, first; 77 char *p; 78 79 /* 80 * Tail's options are weird. First, -n10 is the same as -n-10, not 81 * -n+10. Second, the number options are 1 based and not offsets, 82 * so -n+1 is the first line, and -c-1 is the last byte. Third, the 83 * number options for the -r option specify the number of things that 84 * get displayed, not the starting point in the file. The one major 85 * incompatibility in this version as compared to historical versions 86 * is that the 'r' option couldn't be modified by the -lbc options, 87 * i.e. it was always done in lines. This version treats -rc as a 88 * number of characters in reverse order. Finally, the default for 89 * -r is the entire file, not 10 lines. 90 */ 91 #define ARG(units, forward, backward) { \ 92 if (style) \ 93 usage(); \ 94 off = strtoll(optarg, &p, 10) * (units); \ 95 if (*p) \ 96 errx(1, "illegal offset -- %s", optarg); \ 97 switch(optarg[0]) { \ 98 case '+': \ 99 if (off) \ 100 off -= (units); \ 101 style = (forward); \ 102 break; \ 103 case '-': \ 104 off = -off; \ 105 /* FALLTHROUGH */ \ 106 default: \ 107 style = (backward); \ 108 break; \ 109 } \ 110 } 111 112 obsolete(argv); 113 style = NOTSET; 114 while ((ch = getopt(argc, argv, "Fb:c:fn:r")) != -1) 115 switch(ch) { 116 case 'F': /* -F is superset of (and implies) -f */ 117 Fflag = fflag = 1; 118 break; 119 case 'b': 120 ARG(512, FBYTES, RBYTES); 121 break; 122 case 'c': 123 ARG(1, FBYTES, RBYTES); 124 break; 125 case 'f': 126 fflag = 1; 127 break; 128 case 'n': 129 ARG(1, FLINES, RLINES); 130 break; 131 case 'r': 132 rflag = 1; 133 break; 134 case '?': 135 default: 136 usage(); 137 } 138 argc -= optind; 139 argv += optind; 140 141 if (fflag && argc > 1) 142 errx(1, "-f option only appropriate for a single file"); 143 144 /* 145 * If displaying in reverse, don't permit follow option, and convert 146 * style values. 147 */ 148 if (rflag) { 149 if (fflag) 150 usage(); 151 if (style == FBYTES) 152 style = RBYTES; 153 else if (style == FLINES) 154 style = RLINES; 155 } 156 157 /* 158 * If style not specified, the default is the whole file for -r, and 159 * the last 10 lines if not -r. 160 */ 161 if (style == NOTSET) { 162 if (rflag) { 163 off = 0; 164 style = REVERSE; 165 } else { 166 off = 10; 167 style = RLINES; 168 } 169 } 170 171 if (*argv) 172 for (first = 1; fname = *argv++;) { 173 if ((fp = fopen(fname, "r")) == NULL || 174 fstat(fileno(fp), &sb)) { 175 ierr(); 176 continue; 177 } 178 if (argc > 1) { 179 (void)printf("%s==> %s <==\n", 180 first ? "" : "\n", fname); 181 first = 0; 182 (void)fflush(stdout); 183 } 184 185 if (rflag) 186 reverse(fp, style, off, &sb); 187 else 188 forward(fp, style, off, &sb); 189 (void)fclose(fp); 190 } 191 else { 192 fname = "stdin"; 193 194 if (fstat(fileno(stdin), &sb)) { 195 ierr(); 196 exit(1); 197 } 198 199 /* 200 * Determine if input is a pipe. 4.4BSD will set the SOCKET 201 * bit in the st_mode field for pipes. Fix this then. 202 */ 203 if (lseek(fileno(stdin), (off_t)0, SEEK_CUR) == -1 && 204 errno == ESPIPE) { 205 errno = 0; 206 fflag = 0; /* POSIX.2 requires this. */ 207 } 208 209 if (rflag) 210 reverse(stdin, style, off, &sb); 211 else 212 forward(stdin, style, off, &sb); 213 } 214 exit(rval); 215 } 216 217 /* 218 * Convert the obsolete argument form into something that getopt can handle. 219 * This means that anything of the form [+-][0-9][0-9]*[lbc][Ffr] that isn't 220 * the option argument for a -b, -c or -n option gets converted. 221 */ 222 static void 223 obsolete(argv) 224 char *argv[]; 225 { 226 char *ap, *p, *t; 227 size_t len; 228 char *start; 229 230 while (ap = *++argv) { 231 /* Return if "--" or not an option of any form. */ 232 if (ap[0] != '-') { 233 if (ap[0] != '+') 234 return; 235 } else if (ap[1] == '-') 236 return; 237 238 switch(*++ap) { 239 /* Old-style option. */ 240 case '0': case '1': case '2': case '3': case '4': 241 case '5': case '6': case '7': case '8': case '9': 242 243 /* Malloc space for dash, new option and argument. */ 244 len = strlen(*argv); 245 if ((start = p = malloc(len + 3)) == NULL) 246 err(1, "malloc"); 247 *p++ = '-'; 248 249 /* 250 * Go to the end of the option argument. Save off any 251 * trailing options (-3lf) and translate any trailing 252 * output style characters. 253 */ 254 t = *argv + len - 1; 255 if (*t == 'F' || *t == 'f' || *t == 'r') { 256 *p++ = *t; 257 *t-- = '\0'; 258 } 259 switch(*t) { 260 case 'b': 261 *p++ = 'b'; 262 *t = '\0'; 263 break; 264 case 'c': 265 *p++ = 'c'; 266 *t = '\0'; 267 break; 268 case 'l': 269 *t = '\0'; 270 /* FALLTHROUGH */ 271 case '0': case '1': case '2': case '3': case '4': 272 case '5': case '6': case '7': case '8': case '9': 273 *p++ = 'n'; 274 break; 275 default: 276 errx(1, "illegal option -- %s", *argv); 277 } 278 *p++ = *argv[0]; 279 (void)strcpy(p, ap); 280 *argv = start; 281 continue; 282 283 /* 284 * Options w/ arguments, skip the argument and continue 285 * with the next option. 286 */ 287 case 'b': 288 case 'c': 289 case 'n': 290 if (!ap[1]) 291 ++argv; 292 /* FALLTHROUGH */ 293 /* Options w/o arguments, continue with the next option. */ 294 case 'F': 295 case 'f': 296 case 'r': 297 continue; 298 299 /* Illegal option, return and let getopt handle it. */ 300 default: 301 return; 302 } 303 } 304 } 305 306 static void 307 usage() 308 { 309 (void)fprintf(stderr, 310 "usage: tail [-F | -f | -r] [-b # | -c # | -n #] [file ...]\n"); 311 exit(1); 312 } 313