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 #ifndef lint 39 __COPYRIGHT("@(#) 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 __RCSID("$NetBSD: tail.c,v 1.8 2002/04/29 20:12:31 wiz Exp $"); 48 #endif /* not lint */ 49 50 #include <sys/types.h> 51 #include <sys/stat.h> 52 #include <errno.h> 53 #include <unistd.h> 54 #include <stdio.h> 55 #include <stdlib.h> 56 #include <string.h> 57 #include "extern.h" 58 59 int fflag, rflag, rval; 60 char *fname; 61 62 int main __P((int, char **)); 63 static void obsolete __P((char **)); 64 static void usage __P((void)); 65 66 int 67 main(argc, argv) 68 int argc; 69 char *argv[]; 70 { 71 struct stat sb; 72 FILE *fp; 73 long off; 74 enum STYLE style; 75 int ch, first; 76 char *p; 77 78 off = 0; 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 = strtol(optarg, &p, 10) * (units); \ 95 if (*p) \ 96 err(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': 117 fflag = 2; 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 err(1, "-f and -F options 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 if (*argv) 171 for (first = 1; (fname = *argv++) != NULL;) { 172 if ((fp = fopen(fname, "r")) == NULL || 173 fstat(fileno(fp), &sb)) { 174 ierr(); 175 continue; 176 } 177 if (argc > 1) { 178 (void)printf("%s==> %s <==\n", 179 first ? "" : "\n", fname); 180 first = 0; 181 (void)fflush(stdout); 182 } 183 184 if (rflag) 185 reverse(fp, style, off, &sb); 186 else 187 forward(fp, style, off, &sb); 188 (void)fclose(fp); 189 } 190 else { 191 fname = "stdin"; 192 193 if (fstat(fileno(stdin), &sb)) { 194 ierr(); 195 exit(1); 196 } 197 198 /* 199 * Determine if input is a pipe. 4.4BSD will set the SOCKET 200 * bit in the st_mode field for pipes. Fix this then. 201 */ 202 if (lseek(fileno(stdin), (off_t)0, SEEK_CUR) == -1 && 203 errno == ESPIPE) { 204 errno = 0; 205 fflag = 0; /* POSIX.2 requires this. */ 206 } 207 208 if (rflag) 209 reverse(stdin, style, off, &sb); 210 else 211 forward(stdin, style, off, &sb); 212 } 213 exit(rval); 214 } 215 216 /* 217 * Convert the obsolete argument form into something that getopt can handle. 218 * This means that anything of the form [+-][0-9][0-9]*[lbc][fr] that isn't 219 * the option argument for a -b, -c or -n option gets converted. 220 */ 221 static void 222 obsolete(argv) 223 char *argv[]; 224 { 225 char *ap, *p, *t; 226 int len; 227 char *start; 228 229 while ((ap = *++argv) != NULL) { 230 /* Return if "--" or not an option of any form. */ 231 if (ap[0] != '-') { 232 if (ap[0] != '+') 233 return; 234 } else if (ap[1] == '-') 235 return; 236 237 switch(*++ap) { 238 /* Old-style option. */ 239 case '0': case '1': case '2': case '3': case '4': 240 case '5': case '6': case '7': case '8': case '9': 241 242 /* Malloc space for dash, new option and argument. */ 243 len = strlen(*argv); 244 if ((start = p = malloc(len + 3)) == NULL) 245 err(1, "%s", strerror(errno)); 246 *p++ = '-'; 247 248 /* 249 * Go to the end of the option argument. Save off any 250 * trailing options (-3lf) and translate any trailing 251 * output style characters. 252 */ 253 t = *argv + len - 1; 254 if (*t == 'f' || *t == 'r') { 255 *p++ = *t; 256 *t-- = '\0'; 257 } 258 switch(*t) { 259 case 'b': 260 *p++ = 'b'; 261 *t = '\0'; 262 break; 263 case 'c': 264 *p++ = 'c'; 265 *t = '\0'; 266 break; 267 case 'l': 268 *t = '\0'; 269 /* FALLTHROUGH */ 270 case '0': case '1': case '2': case '3': case '4': 271 case '5': case '6': case '7': case '8': case '9': 272 *p++ = 'n'; 273 break; 274 default: 275 err(1, "illegal option -- %s", *argv); 276 } 277 *p++ = *argv[0]; 278 (void)strcpy(p, ap); 279 *argv = start; 280 continue; 281 282 /* 283 * Options w/ arguments, skip the argument and continue 284 * with the next option. 285 */ 286 case 'b': 287 case 'c': 288 case 'n': 289 if (!ap[1]) 290 ++argv; 291 /* FALLTHROUGH */ 292 /* Options w/o arguments, continue with the next option. */ 293 case 'f': 294 case 'r': 295 continue; 296 297 /* Illegal option, return and let getopt handle it. */ 298 default: 299 return; 300 } 301 } 302 } 303 304 static void 305 usage() 306 { 307 (void)fprintf(stderr, 308 "usage: tail [-f | -F | -r] [-b # | -c # | -n #] [file ...]\n"); 309 exit(1); 310 } 311