1 /*- 2 * Copyright (c) 1991 The Regents of the University of California. 3 * 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 char copyright[] = 39 "@(#) Copyright (c) 1991 The Regents of the University of California.\n\ 40 All rights reserved.\n"; 41 #endif /* not lint */ 42 43 #ifndef lint 44 /*static char sccsid[] = "from: @(#)tail.c 5.7 (Berkeley) 2/12/92";*/ 45 static char rcsid[] = "$Id: tail.c,v 1.3 1994/04/24 20:19:19 deraadt Exp $"; 46 #endif /* not lint */ 47 48 #include <sys/types.h> 49 #include <sys/stat.h> 50 #include <errno.h> 51 #include <unistd.h> 52 #include <stdio.h> 53 #include <stdlib.h> 54 #include <string.h> 55 #include "extern.h" 56 57 int fflag, rflag, rval; 58 char *fname; 59 60 static void obsolete __P((char **)); 61 static void usage __P((void)); 62 63 main(argc, argv) 64 int argc; 65 char **argv; 66 { 67 struct stat sb; 68 FILE *fp; 69 long off; 70 enum STYLE style; 71 int ch; 72 char *p; 73 74 /* 75 * Tail's options are weird. First, -n10 is the same as -n-10, not 76 * -n+10. Second, the number options are 1 based and not offsets, 77 * so -n+1 is the first line, and -c-1 is the last byte. Third, the 78 * number options for the -r option specify the number of things that 79 * get displayed, not the starting point in the file. The one major 80 * incompatibility in this version as compared to historical versions 81 * is that the 'r' option couldn't be modified by the -lbc options, 82 * i.e. it was always done in lines. This version treats -rc as a 83 * number of characters in reverse order. Finally, the default for 84 * -r is the entire file, not 10 lines. 85 */ 86 #define ARG(units, forward, backward) { \ 87 if (style) \ 88 usage(); \ 89 off = strtol(optarg, &p, 10) * (units); \ 90 if (*p) \ 91 err("illegal offset -- %s", optarg); \ 92 switch(optarg[0]) { \ 93 case '+': \ 94 if (off) \ 95 off -= (units); \ 96 style = (forward); \ 97 break; \ 98 case '-': \ 99 off = -off; \ 100 /* FALLTHROUGH */ \ 101 default: \ 102 style = (backward); \ 103 break; \ 104 } \ 105 } 106 107 obsolete(argv); 108 style = NOTSET; 109 while ((ch = getopt(argc, argv, "b:c:fn:r")) != EOF) 110 switch(ch) { 111 case 'b': 112 ARG(512, FBYTES, RBYTES); 113 break; 114 case 'c': 115 ARG(1, FBYTES, RBYTES); 116 break; 117 case 'f': 118 fflag = 1; 119 break; 120 case 'n': 121 ARG(1, FLINES, RLINES); 122 break; 123 case 'r': 124 rflag = 1; 125 break; 126 case '?': 127 default: 128 usage(); 129 } 130 argc -= optind; 131 argv += optind; 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 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 if (fname = *argv) { 160 if ((fp = fopen(fname, "r")) == NULL) 161 ierr(); 162 } else { 163 fp = stdin; 164 fname = "stdin"; 165 } 166 167 if (fstat(fileno(fp), &sb)) 168 ierr(); 169 170 /* 171 * Determine if input is a pipe. 4.4BSD will set the SOCKET 172 * bit in the st_mode field for pipes. Fix this then. 173 */ 174 if (lseek(fileno(fp), 0, SEEK_CUR) == -1 && errno == ESPIPE) { 175 errno = 0; 176 fflag = 0; /* POSIX.2 requires this. */ 177 } 178 179 if (rflag) 180 reverse(fp, style, off, &sb); 181 else 182 forward(fp, style, off, &sb); 183 exit(rval); 184 } 185 186 /* 187 * Convert the obsolete argument form into something that getopt can handle. 188 * This means that anything of the form [+-][0-9][0-9]*[lbc][fr] that isn't 189 * the option argument for a -b, -c or -n option gets converted. 190 */ 191 static void 192 obsolete(argv) 193 char **argv; 194 { 195 register char *ap, *p, *t; 196 int len; 197 char *start; 198 199 while (ap = *++argv) { 200 /* Return if "--" or not an option of any form. */ 201 if (ap[0] != '-') { 202 if (ap[0] != '+') 203 return; 204 } else if (ap[1] == '-') 205 return; 206 207 switch(*++ap) { 208 /* Old-style option. */ 209 case '0': case '1': case '2': case '3': case '4': 210 case '5': case '6': case '7': case '8': case '9': 211 212 /* Malloc space for dash, new option and argument. */ 213 len = strlen(*argv); 214 if ((start = p = malloc(len + 3)) == NULL) 215 err("%s", strerror(errno)); 216 *p++ = '-'; 217 218 /* 219 * Go to the end of the option argument. Save off any 220 * trailing options (-3lf) and translate any trailing 221 * output style characters. 222 */ 223 t = *argv + len - 1; 224 if (*t == 'f' || *t == 'r') { 225 *p++ = *t; 226 *t-- = '\0'; 227 } 228 switch(*t) { 229 case 'b': 230 *p++ = 'b'; 231 *t = '\0'; 232 break; 233 case 'c': 234 *p++ = 'c'; 235 *t = '\0'; 236 break; 237 case 'l': 238 *t = '\0'; 239 /* FALLTHROUGH */ 240 case '0': case '1': case '2': case '3': case '4': 241 case '5': case '6': case '7': case '8': case '9': 242 *p++ = 'n'; 243 break; 244 default: 245 err("illegal option -- %s", *argv); 246 } 247 *p++ = *argv[0]; 248 (void)strcpy(p, ap); 249 *argv = start; 250 continue; 251 252 /* 253 * Options w/ arguments, skip the argument and continue 254 * with the next option. 255 */ 256 case 'b': 257 case 'c': 258 case 'n': 259 if (!ap[1]) 260 ++argv; 261 /* FALLTHROUGH */ 262 /* Options w/o arguments, continue with the next option. */ 263 case 'f': 264 case 'r': 265 continue; 266 267 /* Illegal option, return and let getopt handle it. */ 268 default: 269 return; 270 } 271 } 272 } 273 274 static void 275 usage() 276 { 277 (void)fprintf(stderr, 278 "usage: tail [-f | -r] [-b # | -c # | -n #] [file]\n"); 279 exit(1); 280 } 281