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. 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/cdefs.h> 34 #ifndef lint 35 __COPYRIGHT("@(#) Copyright (c) 1991, 1993\ 36 The Regents of the University of California. All rights reserved."); 37 #endif /* not lint */ 38 39 #ifndef lint 40 #if 0 41 static char sccsid[] = "@(#)tail.c 8.1 (Berkeley) 6/6/93"; 42 #endif 43 __RCSID("$NetBSD: tail.c,v 1.14 2009/04/13 23:33:25 lukem Exp $"); 44 #endif /* not lint */ 45 46 #include <sys/types.h> 47 #include <sys/stat.h> 48 #include <errno.h> 49 #include <unistd.h> 50 #include <stdio.h> 51 #include <stdlib.h> 52 #include <string.h> 53 #include "extern.h" 54 55 int fflag, rflag, rval; 56 const char *fname; 57 58 int main(int, char **); 59 static void obsolete(char **); 60 static void usage(void); 61 62 int 63 main(int argc, char *argv[]) 64 { 65 struct stat sb; 66 FILE *fp; 67 off_t off; 68 enum STYLE style; 69 int ch, first; 70 char *p; 71 72 off = 0; 73 /* 74 * Tail's options are weird. First, -n10 is the same as -n-10, not 75 * -n+10. Second, the number options are 1 based and not offsets, 76 * so -n+1 is the first line, and -c-1 is the last byte. Third, the 77 * number options for the -r option specify the number of things that 78 * get displayed, not the starting point in the file. The one major 79 * incompatibility in this version as compared to historical versions 80 * is that the 'r' option couldn't be modified by the -lbc options, 81 * i.e. it was always done in lines. This version treats -rc as a 82 * number of characters in reverse order. Finally, the default for 83 * -r is the entire file, not 10 lines. 84 */ 85 #define ARG(units, forward, backward) { \ 86 if (style) \ 87 usage(); \ 88 off = strtoll(optarg, &p, 10) * (units); \ 89 if (*p) \ 90 err(1, "illegal offset -- %s", optarg); \ 91 switch(optarg[0]) { \ 92 case '+': \ 93 if (off) \ 94 off -= (units); \ 95 style = (forward); \ 96 break; \ 97 case '-': \ 98 off = -off; \ 99 /* FALLTHROUGH */ \ 100 default: \ 101 style = (backward); \ 102 break; \ 103 } \ 104 } 105 106 obsolete(argv); 107 style = NOTSET; 108 while ((ch = getopt(argc, argv, "Fb:c:fn:r")) != -1) 109 switch(ch) { 110 case 'F': 111 fflag = 2; 112 break; 113 case 'b': 114 ARG(512, FBYTES, RBYTES); 115 break; 116 case 'c': 117 ARG(1, FBYTES, RBYTES); 118 break; 119 case 'f': 120 fflag = 1; 121 break; 122 case 'n': 123 ARG(1, FLINES, RLINES); 124 break; 125 case 'r': 126 rflag = 1; 127 break; 128 case '?': 129 default: 130 usage(); 131 } 132 argc -= optind; 133 argv += optind; 134 135 if (fflag && argc > 1) 136 err(1, "-f and -F options only appropriate for a single file"); 137 138 /* 139 * If displaying in reverse, don't permit follow option, and convert 140 * style values. 141 */ 142 if (rflag) { 143 if (fflag) 144 usage(); 145 if (style == FBYTES) 146 style = RBYTES; 147 else if (style == FLINES) 148 style = RLINES; 149 } 150 151 /* 152 * If style not specified, the default is the whole file for -r, and 153 * the last 10 lines if not -r. 154 */ 155 if (style == NOTSET) { 156 if (rflag) { 157 off = 0; 158 style = REVERSE; 159 } else { 160 off = 10; 161 style = RLINES; 162 } 163 } 164 if (*argv) 165 for (first = 1; (fname = *argv++) != NULL;) { 166 if ((fp = fopen(fname, "r")) == NULL || 167 fstat(fileno(fp), &sb)) { 168 ierr(); 169 continue; 170 } 171 if (argc > 1) { 172 (void)printf("%s==> %s <==\n", 173 first ? "" : "\n", fname); 174 first = 0; 175 (void)fflush(stdout); 176 } 177 178 if (rflag) 179 reverse(fp, style, off, &sb); 180 else 181 forward(fp, style, off, &sb); 182 (void)fclose(fp); 183 } 184 else { 185 fname = "stdin"; 186 187 if (fstat(fileno(stdin), &sb)) { 188 ierr(); 189 exit(1); 190 } 191 192 /* 193 * Determine if input is a pipe. 4.4BSD will set the SOCKET 194 * bit in the st_mode field for pipes. Fix this then. 195 */ 196 if (lseek(fileno(stdin), (off_t)0, SEEK_CUR) == -1 && 197 errno == ESPIPE) { 198 errno = 0; 199 fflag = 0; /* POSIX.2 requires this. */ 200 } 201 202 if (rflag) 203 reverse(stdin, style, off, &sb); 204 else 205 forward(stdin, style, off, &sb); 206 } 207 exit(rval); 208 } 209 210 /* 211 * Convert the obsolete argument form into something that getopt can handle. 212 * This means that anything of the form [+-][0-9][0-9]*[lbc][fr] that isn't 213 * the option argument for a -b, -c or -n option gets converted. 214 */ 215 static void 216 obsolete(char *argv[]) 217 { 218 char *ap, *p, *t; 219 int len; 220 char *start; 221 222 while ((ap = *++argv) != NULL) { 223 /* Return if "--" or not an option of any form. */ 224 if (ap[0] != '-') { 225 if (ap[0] != '+') 226 return; 227 } else if (ap[1] == '-') 228 return; 229 230 switch (*++ap) { 231 /* Old-style option. */ 232 case '0': case '1': case '2': case '3': case '4': 233 case '5': case '6': case '7': case '8': case '9': 234 235 /* Malloc space for dash, new option and argument. */ 236 len = strlen(*argv); 237 if ((start = p = malloc(len + 3)) == NULL) 238 err(1, "%s", strerror(errno)); 239 *p++ = '-'; 240 241 /* 242 * Go to the end of the option argument. Save off any 243 * trailing options (-3lf) and translate any trailing 244 * output style characters. 245 */ 246 t = *argv + len - 1; 247 if (*t == 'f' || *t == 'r') { 248 *p++ = *t; 249 *t-- = '\0'; 250 } 251 switch(*t) { 252 case 'b': 253 *p++ = 'b'; 254 *t = '\0'; 255 break; 256 case 'c': 257 *p++ = 'c'; 258 *t = '\0'; 259 break; 260 case 'l': 261 *t = '\0'; 262 /* FALLTHROUGH */ 263 case '0': case '1': case '2': case '3': case '4': 264 case '5': case '6': case '7': case '8': case '9': 265 *p++ = 'n'; 266 break; 267 default: 268 err(1, "illegal option -- %s", *argv); 269 } 270 *p++ = *argv[0]; 271 (void)strcpy(p, ap); 272 *argv = start; 273 continue; 274 275 /* 276 * Options w/ arguments, skip the argument and continue 277 * with the next option. 278 */ 279 case 'b': 280 case 'c': 281 case 'n': 282 if (!ap[1]) 283 ++argv; 284 /* FALLTHROUGH */ 285 /* Options w/o arguments, continue with the next option. */ 286 case 'f': 287 case 'r': 288 continue; 289 290 /* Illegal option, return and let getopt handle it. */ 291 default: 292 return; 293 } 294 } 295 } 296 297 static void 298 usage(void) 299 { 300 (void)fprintf(stderr, 301 "usage: tail [-f | -F | -r] [-b # | -c # | -n #] [file ...]\n"); 302 exit(1); 303 } 304