1 /* $OpenBSD: tail.c,v 1.21 2016/02/03 12:23:57 halex Exp $ */ 2 3 /*- 4 * Copyright (c) 1991, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * This code is derived from software contributed to Berkeley by 8 * Edward Sze-Tyan Wang. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 */ 34 35 #include <sys/types.h> 36 #include <sys/stat.h> 37 38 #include <err.h> 39 #include <errno.h> 40 #include <stdio.h> 41 #include <stdlib.h> 42 #include <string.h> 43 #include <unistd.h> 44 45 #include "extern.h" 46 47 int fflag, rflag, rval; 48 int is_stdin; 49 50 static void obsolete(char **); 51 static void usage(void); 52 53 int 54 main(int argc, char *argv[]) 55 { 56 struct tailfile *tf; 57 off_t off = 0; 58 enum STYLE style; 59 int ch; 60 int i; 61 char *p; 62 63 if (pledge("stdio rpath", NULL) == -1) 64 err(1, "pledge"); 65 66 /* 67 * Tail's options are weird. First, -n10 is the same as -n-10, not 68 * -n+10. Second, the number options are 1 based and not offsets, 69 * so -n+1 is the first line, and -c-1 is the last byte. Third, the 70 * number options for the -r option specify the number of things that 71 * get displayed, not the starting point in the file. The one major 72 * incompatibility in this version as compared to historical versions 73 * is that the 'r' option couldn't be modified by the -lbc options, 74 * i.e. it was always done in lines. This version treats -rc as a 75 * number of characters in reverse order. Finally, the default for 76 * -r is the entire file, not 10 lines. 77 */ 78 #define ARG(units, forward, backward) { \ 79 if (style) \ 80 usage(); \ 81 off = strtoll(optarg, &p, 10) * (units); \ 82 if (*p) \ 83 errx(1, "illegal offset -- %s", optarg); \ 84 switch(optarg[0]) { \ 85 case '+': \ 86 if (off) \ 87 off -= (units); \ 88 style = (forward); \ 89 break; \ 90 case '-': \ 91 off = -off; \ 92 /* FALLTHROUGH */ \ 93 default: \ 94 style = (backward); \ 95 break; \ 96 } \ 97 } 98 99 obsolete(argv); 100 style = NOTSET; 101 while ((ch = getopt(argc, argv, "b:c:fn:r")) != -1) 102 switch(ch) { 103 case 'b': 104 ARG(512, FBYTES, RBYTES); 105 break; 106 case 'c': 107 ARG(1, FBYTES, RBYTES); 108 break; 109 case 'f': 110 fflag = 1; 111 break; 112 case 'n': 113 ARG(1, FLINES, RLINES); 114 break; 115 case 'r': 116 rflag = 1; 117 break; 118 case '?': 119 default: 120 usage(); 121 } 122 argc -= optind; 123 argv += optind; 124 125 /* 126 * If displaying in reverse, don't permit follow option, and convert 127 * style values. 128 */ 129 if (rflag) { 130 if (fflag) 131 usage(); 132 if (style == FBYTES) 133 style = RBYTES; 134 else if (style == FLINES) 135 style = RLINES; 136 } 137 138 /* 139 * If style not specified, the default is the whole file for -r, and 140 * the last 10 lines if not -r. 141 */ 142 if (style == NOTSET) { 143 if (rflag) { 144 off = 0; 145 style = REVERSE; 146 } else { 147 off = 10; 148 style = RLINES; 149 } 150 } 151 152 if ((tf = reallocarray(NULL, argc ? argc : 1, sizeof(*tf))) == NULL) 153 err(1, "reallocarray"); 154 155 if (argc) { 156 for (i = 0; *argv; i++) { 157 tf[i].fname = *argv++; 158 if ((tf[i].fp = fopen(tf[i].fname, "r")) == NULL || 159 fstat(fileno(tf[i].fp), &(tf[i].sb))) { 160 ierr(tf[i].fname); 161 i--; 162 continue; 163 } 164 } 165 if (rflag) 166 reverse(tf, i, style, off); 167 else 168 forward(tf, i, style, off); 169 } 170 else { 171 if (pledge("stdio", NULL) == -1) 172 err(1, "pledge"); 173 174 tf[0].fname = "stdin"; 175 tf[0].fp = stdin; 176 is_stdin = 1; 177 178 if (fstat(fileno(stdin), &(tf[0].sb))) { 179 ierr(tf[0].fname); 180 exit(1); 181 } 182 183 /* 184 * Determine if input is a pipe. 4.4BSD will set the SOCKET 185 * bit in the st_mode field for pipes. Fix this then. 186 */ 187 if (lseek(fileno(tf[0].fp), (off_t)0, SEEK_CUR) == -1 && 188 errno == ESPIPE) { 189 errno = 0; 190 fflag = 0; /* POSIX.2 requires this. */ 191 } 192 193 if (rflag) 194 reverse(tf, 1, style, off); 195 else 196 forward(tf, 1, style, off); 197 } 198 exit(rval); 199 } 200 201 /* 202 * Convert the obsolete argument form into something that getopt can handle. 203 * This means that anything of the form [+-][0-9][0-9]*[lbc][fr] that isn't 204 * the option argument for a -b, -c or -n option gets converted. 205 */ 206 static void 207 obsolete(char *argv[]) 208 { 209 char *ap, *p, *t; 210 size_t len; 211 char *start; 212 213 while ((ap = *++argv)) { 214 /* Return if "--" or not an option of any form. */ 215 if (ap[0] != '-') { 216 if (ap[0] != '+') 217 return; 218 } else if (ap[1] == '-') 219 return; 220 221 switch(*++ap) { 222 /* Old-style option. */ 223 case '0': case '1': case '2': case '3': case '4': 224 case '5': case '6': case '7': case '8': case '9': 225 226 /* Malloc space for dash, new option and argument. */ 227 len = strlen(*argv); 228 if ((start = p = malloc(len + 4)) == NULL) 229 err(1, NULL); 230 *p++ = '-'; 231 232 /* 233 * Go to the end of the option argument. Save off any 234 * trailing options (-3lf) and translate any trailing 235 * output style characters. 236 */ 237 t = *argv + len - 1; 238 if (*t == 'f' || *t == 'r') { 239 *p++ = *t; 240 *t-- = '\0'; 241 } 242 switch(*t) { 243 case 'b': 244 *p++ = 'b'; 245 *t = '\0'; 246 break; 247 case 'c': 248 *p++ = 'c'; 249 *t = '\0'; 250 break; 251 case 'l': 252 *t = '\0'; 253 /* FALLTHROUGH */ 254 case '0': case '1': case '2': case '3': case '4': 255 case '5': case '6': case '7': case '8': case '9': 256 *p++ = 'n'; 257 break; 258 default: 259 errx(1, "illegal option -- %s", *argv); 260 } 261 *p++ = *argv[0]; 262 (void)strlcpy(p, ap, start + len + 4 - p); 263 *argv = start; 264 continue; 265 266 /* 267 * Options w/ arguments, skip the argument and continue 268 * with the next option. 269 */ 270 case 'b': 271 case 'c': 272 case 'n': 273 if (!ap[1]) 274 ++argv; 275 /* FALLTHROUGH */ 276 /* Options w/o arguments, continue with the next option. */ 277 case 'f': 278 case 'r': 279 continue; 280 281 /* Illegal option, return and let getopt handle it. */ 282 default: 283 return; 284 } 285 } 286 } 287 288 static void 289 usage(void) 290 { 291 (void)fprintf(stderr, 292 "usage: tail [-f | -r] " 293 "[-b number | -c number | -n number | -number] [file ...]\n"); 294 exit(1); 295 } 296