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 1.9 2002/06/14 00:47:41 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(int, char **); 63 static void obsolete(char **); 64 static void usage(void); 65 66 int 67 main(int argc, char *argv[]) 68 { 69 struct stat sb; 70 FILE *fp; 71 long off; 72 enum STYLE style; 73 int ch, first; 74 char *p; 75 76 off = 0; 77 /* 78 * Tail's options are weird. First, -n10 is the same as -n-10, not 79 * -n+10. Second, the number options are 1 based and not offsets, 80 * so -n+1 is the first line, and -c-1 is the last byte. Third, the 81 * number options for the -r option specify the number of things that 82 * get displayed, not the starting point in the file. The one major 83 * incompatibility in this version as compared to historical versions 84 * is that the 'r' option couldn't be modified by the -lbc options, 85 * i.e. it was always done in lines. This version treats -rc as a 86 * number of characters in reverse order. Finally, the default for 87 * -r is the entire file, not 10 lines. 88 */ 89 #define ARG(units, forward, backward) { \ 90 if (style) \ 91 usage(); \ 92 off = strtol(optarg, &p, 10) * (units); \ 93 if (*p) \ 94 err(1, "illegal offset -- %s", optarg); \ 95 switch(optarg[0]) { \ 96 case '+': \ 97 if (off) \ 98 off -= (units); \ 99 style = (forward); \ 100 break; \ 101 case '-': \ 102 off = -off; \ 103 /* FALLTHROUGH */ \ 104 default: \ 105 style = (backward); \ 106 break; \ 107 } \ 108 } 109 110 obsolete(argv); 111 style = NOTSET; 112 while ((ch = getopt(argc, argv, "Fb:c:fn:r")) != -1) 113 switch(ch) { 114 case 'F': 115 fflag = 2; 116 break; 117 case 'b': 118 ARG(512, FBYTES, RBYTES); 119 break; 120 case 'c': 121 ARG(1, FBYTES, RBYTES); 122 break; 123 case 'f': 124 fflag = 1; 125 break; 126 case 'n': 127 ARG(1, FLINES, RLINES); 128 break; 129 case 'r': 130 rflag = 1; 131 break; 132 case '?': 133 default: 134 usage(); 135 } 136 argc -= optind; 137 argv += optind; 138 139 if (fflag && argc > 1) 140 err(1, "-f and -F options only appropriate for a single file"); 141 142 /* 143 * If displaying in reverse, don't permit follow option, and convert 144 * style values. 145 */ 146 if (rflag) { 147 if (fflag) 148 usage(); 149 if (style == FBYTES) 150 style = RBYTES; 151 else if (style == FLINES) 152 style = RLINES; 153 } 154 155 /* 156 * If style not specified, the default is the whole file for -r, and 157 * the last 10 lines if not -r. 158 */ 159 if (style == NOTSET) { 160 if (rflag) { 161 off = 0; 162 style = REVERSE; 163 } else { 164 off = 10; 165 style = RLINES; 166 } 167 } 168 if (*argv) 169 for (first = 1; (fname = *argv++) != NULL;) { 170 if ((fp = fopen(fname, "r")) == NULL || 171 fstat(fileno(fp), &sb)) { 172 ierr(); 173 continue; 174 } 175 if (argc > 1) { 176 (void)printf("%s==> %s <==\n", 177 first ? "" : "\n", fname); 178 first = 0; 179 (void)fflush(stdout); 180 } 181 182 if (rflag) 183 reverse(fp, style, off, &sb); 184 else 185 forward(fp, style, off, &sb); 186 (void)fclose(fp); 187 } 188 else { 189 fname = "stdin"; 190 191 if (fstat(fileno(stdin), &sb)) { 192 ierr(); 193 exit(1); 194 } 195 196 /* 197 * Determine if input is a pipe. 4.4BSD will set the SOCKET 198 * bit in the st_mode field for pipes. Fix this then. 199 */ 200 if (lseek(fileno(stdin), (off_t)0, SEEK_CUR) == -1 && 201 errno == ESPIPE) { 202 errno = 0; 203 fflag = 0; /* POSIX.2 requires this. */ 204 } 205 206 if (rflag) 207 reverse(stdin, style, off, &sb); 208 else 209 forward(stdin, style, off, &sb); 210 } 211 exit(rval); 212 } 213 214 /* 215 * Convert the obsolete argument form into something that getopt can handle. 216 * This means that anything of the form [+-][0-9][0-9]*[lbc][fr] that isn't 217 * the option argument for a -b, -c or -n option gets converted. 218 */ 219 static void 220 obsolete(char *argv[]) 221 { 222 char *ap, *p, *t; 223 int len; 224 char *start; 225 226 while ((ap = *++argv) != NULL) { 227 /* Return if "--" or not an option of any form. */ 228 if (ap[0] != '-') { 229 if (ap[0] != '+') 230 return; 231 } else if (ap[1] == '-') 232 return; 233 234 switch(*++ap) { 235 /* Old-style option. */ 236 case '0': case '1': case '2': case '3': case '4': 237 case '5': case '6': case '7': case '8': case '9': 238 239 /* Malloc space for dash, new option and argument. */ 240 len = strlen(*argv); 241 if ((start = p = malloc(len + 3)) == NULL) 242 err(1, "%s", strerror(errno)); 243 *p++ = '-'; 244 245 /* 246 * Go to the end of the option argument. Save off any 247 * trailing options (-3lf) and translate any trailing 248 * output style characters. 249 */ 250 t = *argv + len - 1; 251 if (*t == 'f' || *t == 'r') { 252 *p++ = *t; 253 *t-- = '\0'; 254 } 255 switch(*t) { 256 case 'b': 257 *p++ = 'b'; 258 *t = '\0'; 259 break; 260 case 'c': 261 *p++ = 'c'; 262 *t = '\0'; 263 break; 264 case 'l': 265 *t = '\0'; 266 /* FALLTHROUGH */ 267 case '0': case '1': case '2': case '3': case '4': 268 case '5': case '6': case '7': case '8': case '9': 269 *p++ = 'n'; 270 break; 271 default: 272 err(1, "illegal option -- %s", *argv); 273 } 274 *p++ = *argv[0]; 275 (void)strcpy(p, ap); 276 *argv = start; 277 continue; 278 279 /* 280 * Options w/ arguments, skip the argument and continue 281 * with the next option. 282 */ 283 case 'b': 284 case 'c': 285 case 'n': 286 if (!ap[1]) 287 ++argv; 288 /* FALLTHROUGH */ 289 /* Options w/o arguments, continue with the next option. */ 290 case 'f': 291 case 'r': 292 continue; 293 294 /* Illegal option, return and let getopt handle it. */ 295 default: 296 return; 297 } 298 } 299 } 300 301 static void 302 usage(void) 303 { 304 (void)fprintf(stderr, 305 "usage: tail [-f | -F | -r] [-b # | -c # | -n #] [file ...]\n"); 306 exit(1); 307 } 308