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 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 char rcsid[] = "$NetBSD: tail.c,v 1.4 1994/11/23 07:42:16 jtc 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 static void obsolete __P((char **)); 63 static void usage __P((void)); 64 65 int 66 main(argc, argv) 67 int argc; 68 char *argv[]; 69 { 70 struct stat sb; 71 FILE *fp; 72 long off; 73 enum STYLE style; 74 int ch, first; 75 char *p; 76 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, "b:c:fn:r")) != EOF) 113 switch(ch) { 114 case 'b': 115 ARG(512, FBYTES, RBYTES); 116 break; 117 case 'c': 118 ARG(1, FBYTES, RBYTES); 119 break; 120 case 'f': 121 fflag = 1; 122 break; 123 case 'n': 124 ARG(1, FLINES, RLINES); 125 break; 126 case 'r': 127 rflag = 1; 128 break; 129 case '?': 130 default: 131 usage(); 132 } 133 argc -= optind; 134 argv += optind; 135 136 if (fflag && argc > 1) 137 err(1, "-f option only appropriate for a single file"); 138 139 /* 140 * If displaying in reverse, don't permit follow option, and convert 141 * style values. 142 */ 143 if (rflag) { 144 if (fflag) 145 usage(); 146 if (style == FBYTES) 147 style = RBYTES; 148 else if (style == FLINES) 149 style = RLINES; 150 } 151 152 /* 153 * If style not specified, the default is the whole file for -r, and 154 * the last 10 lines if not -r. 155 */ 156 if (style == NOTSET) 157 if (rflag) { 158 off = 0; 159 style = REVERSE; 160 } else { 161 off = 10; 162 style = RLINES; 163 } 164 165 if (*argv) 166 for (first = 1; fname = *argv++;) { 167 if ((fp = fopen(fname, "r")) == NULL || 168 fstat(fileno(fp), &sb)) { 169 ierr(); 170 continue; 171 } 172 if (argc > 1) { 173 (void)printf("%s==> %s <==\n", 174 first ? "" : "\n", fname); 175 first = 0; 176 (void)fflush(stdout); 177 } 178 179 if (rflag) 180 reverse(fp, style, off, &sb); 181 else 182 forward(fp, style, off, &sb); 183 (void)fclose(fp); 184 } 185 else { 186 fname = "stdin"; 187 188 if (fstat(fileno(stdin), &sb)) { 189 ierr(); 190 exit(1); 191 } 192 193 /* 194 * Determine if input is a pipe. 4.4BSD will set the SOCKET 195 * bit in the st_mode field for pipes. Fix this then. 196 */ 197 if (lseek(fileno(stdin), (off_t)0, SEEK_CUR) == -1 && 198 errno == ESPIPE) { 199 errno = 0; 200 fflag = 0; /* POSIX.2 requires this. */ 201 } 202 203 if (rflag) 204 reverse(stdin, style, off, &sb); 205 else 206 forward(stdin, style, off, &sb); 207 } 208 exit(rval); 209 } 210 211 /* 212 * Convert the obsolete argument form into something that getopt can handle. 213 * This means that anything of the form [+-][0-9][0-9]*[lbc][fr] that isn't 214 * the option argument for a -b, -c or -n option gets converted. 215 */ 216 static void 217 obsolete(argv) 218 char *argv[]; 219 { 220 register char *ap, *p, *t; 221 int len; 222 char *start; 223 224 while (ap = *++argv) { 225 /* Return if "--" or not an option of any form. */ 226 if (ap[0] != '-') { 227 if (ap[0] != '+') 228 return; 229 } else if (ap[1] == '-') 230 return; 231 232 switch(*++ap) { 233 /* Old-style option. */ 234 case '0': case '1': case '2': case '3': case '4': 235 case '5': case '6': case '7': case '8': case '9': 236 237 /* Malloc space for dash, new option and argument. */ 238 len = strlen(*argv); 239 if ((start = p = malloc(len + 3)) == NULL) 240 err(1, "%s", strerror(errno)); 241 *p++ = '-'; 242 243 /* 244 * Go to the end of the option argument. Save off any 245 * trailing options (-3lf) and translate any trailing 246 * output style characters. 247 */ 248 t = *argv + len - 1; 249 if (*t == 'f' || *t == 'r') { 250 *p++ = *t; 251 *t-- = '\0'; 252 } 253 switch(*t) { 254 case 'b': 255 *p++ = 'b'; 256 *t = '\0'; 257 break; 258 case 'c': 259 *p++ = 'c'; 260 *t = '\0'; 261 break; 262 case 'l': 263 *t = '\0'; 264 /* FALLTHROUGH */ 265 case '0': case '1': case '2': case '3': case '4': 266 case '5': case '6': case '7': case '8': case '9': 267 *p++ = 'n'; 268 break; 269 default: 270 err(1, "illegal option -- %s", *argv); 271 } 272 *p++ = *argv[0]; 273 (void)strcpy(p, ap); 274 *argv = start; 275 continue; 276 277 /* 278 * Options w/ arguments, skip the argument and continue 279 * with the next option. 280 */ 281 case 'b': 282 case 'c': 283 case 'n': 284 if (!ap[1]) 285 ++argv; 286 /* FALLTHROUGH */ 287 /* Options w/o arguments, continue with the next option. */ 288 case 'f': 289 case 'r': 290 continue; 291 292 /* Illegal option, return and let getopt handle it. */ 293 default: 294 return; 295 } 296 } 297 } 298 299 static void 300 usage() 301 { 302 (void)fprintf(stderr, 303 "usage: tail [-f | -r] [-b # | -c # | -n #] [file ...]\n"); 304 exit(1); 305 } 306