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 static char sccsid[] = "@(#)tail.c 8.1 (Berkeley) 6/6/93"; 45 #endif /* not lint */ 46 47 #include <sys/types.h> 48 #include <sys/stat.h> 49 #include <errno.h> 50 #include <unistd.h> 51 #include <stdio.h> 52 #include <stdlib.h> 53 #include <string.h> 54 #include <err.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 int 64 main(argc, argv) 65 int argc; 66 char *argv[]; 67 { 68 struct stat sb; 69 FILE *fp; 70 long off; 71 enum STYLE style; 72 int ch, first; 73 char *p; 74 75 /* 76 * Tail's options are weird. First, -n10 is the same as -n-10, not 77 * -n+10. Second, the number options are 1 based and not offsets, 78 * so -n+1 is the first line, and -c-1 is the last byte. Third, the 79 * number options for the -r option specify the number of things that 80 * get displayed, not the starting point in the file. The one major 81 * incompatibility in this version as compared to historical versions 82 * is that the 'r' option couldn't be modified by the -lbc options, 83 * i.e. it was always done in lines. This version treats -rc as a 84 * number of characters in reverse order. Finally, the default for 85 * -r is the entire file, not 10 lines. 86 */ 87 #define ARG(units, forward, backward) { \ 88 if (style) \ 89 usage(); \ 90 off = strtol(optarg, &p, 10) * (units); \ 91 if (*p) \ 92 errx(1, "illegal offset -- %s", optarg); \ 93 switch(optarg[0]) { \ 94 case '+': \ 95 if (off) \ 96 off -= (units); \ 97 style = (forward); \ 98 break; \ 99 case '-': \ 100 off = -off; \ 101 /* FALLTHROUGH */ \ 102 default: \ 103 style = (backward); \ 104 break; \ 105 } \ 106 } 107 108 obsolete(argv); 109 style = NOTSET; 110 while ((ch = getopt(argc, argv, "b:c:fn:r")) != EOF) 111 switch(ch) { 112 case 'b': 113 ARG(512, FBYTES, RBYTES); 114 break; 115 case 'c': 116 ARG(1, FBYTES, RBYTES); 117 break; 118 case 'f': 119 fflag = 1; 120 break; 121 case 'n': 122 ARG(1, FLINES, RLINES); 123 break; 124 case 'r': 125 rflag = 1; 126 break; 127 case '?': 128 default: 129 usage(); 130 } 131 argc -= optind; 132 argv += optind; 133 134 if (fflag && argc > 1) 135 errx(1, "-f option only appropriate for a single file"); 136 137 /* 138 * If displaying in reverse, don't permit follow option, and convert 139 * style values. 140 */ 141 if (rflag) { 142 if (fflag) 143 usage(); 144 if (style == FBYTES) 145 style = RBYTES; 146 else if (style == FLINES) 147 style = RLINES; 148 } 149 150 /* 151 * If style not specified, the default is the whole file for -r, and 152 * the last 10 lines if not -r. 153 */ 154 if (style == NOTSET) 155 if (rflag) { 156 off = 0; 157 style = REVERSE; 158 } else { 159 off = 10; 160 style = RLINES; 161 } 162 163 if (*argv) 164 for (first = 1; fname = *argv++;) { 165 if ((fp = fopen(fname, "r")) == NULL || 166 fstat(fileno(fp), &sb)) { 167 ierr(); 168 continue; 169 } 170 if (argc > 1) { 171 (void)printf("%s==> %s <==\n", 172 first ? "" : "\n", fname); 173 first = 0; 174 (void)fflush(stdout); 175 } 176 177 if (rflag) 178 reverse(fp, style, off, &sb); 179 else 180 forward(fp, style, off, &sb); 181 (void)fclose(fp); 182 } 183 else { 184 fname = "stdin"; 185 186 if (fstat(fileno(stdin), &sb)) { 187 ierr(); 188 exit(1); 189 } 190 191 /* 192 * Determine if input is a pipe. 4.4BSD will set the SOCKET 193 * bit in the st_mode field for pipes. Fix this then. 194 */ 195 if (lseek(fileno(stdin), (off_t)0, SEEK_CUR) == -1 && 196 errno == ESPIPE) { 197 errno = 0; 198 fflag = 0; /* POSIX.2 requires this. */ 199 } 200 201 if (rflag) 202 reverse(stdin, style, off, &sb); 203 else 204 forward(stdin, style, off, &sb); 205 } 206 exit(rval); 207 } 208 209 /* 210 * Convert the obsolete argument form into something that getopt can handle. 211 * This means that anything of the form [+-][0-9][0-9]*[lbc][fr] that isn't 212 * the option argument for a -b, -c or -n option gets converted. 213 */ 214 static void 215 obsolete(argv) 216 char *argv[]; 217 { 218 register char *ap, *p, *t; 219 int len; 220 char *start; 221 222 while (ap = *++argv) { 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, "malloc"); 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 errx(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() 299 { 300 (void)fprintf(stderr, 301 "usage: tail [-f | -r] [-b # | -c # | -n #] [file ...]\n"); 302 exit(1); 303 } 304