1 /* $OpenBSD: tail.c,v 1.22 2019/01/04 15:04:28 martijn 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 49 static void obsolete(char **); 50 static void usage(void); 51 52 int 53 main(int argc, char *argv[]) 54 { 55 struct tailfile *tf; 56 off_t off = 0; 57 enum STYLE style; 58 int ch; 59 int i; 60 char *p; 61 62 if (pledge("stdio rpath", NULL) == -1) 63 err(1, "pledge"); 64 65 /* 66 * Tail's options are weird. First, -n10 is the same as -n-10, not 67 * -n+10. Second, the number options are 1 based and not offsets, 68 * so -n+1 is the first line, and -c-1 is the last byte. Third, the 69 * number options for the -r option specify the number of things that 70 * get displayed, not the starting point in the file. The one major 71 * incompatibility in this version as compared to historical versions 72 * is that the 'r' option couldn't be modified by the -lbc options, 73 * i.e. it was always done in lines. This version treats -rc as a 74 * number of characters in reverse order. Finally, the default for 75 * -r is the entire file, not 10 lines. 76 */ 77 #define ARG(units, forward, backward) { \ 78 if (style) \ 79 usage(); \ 80 off = strtoll(optarg, &p, 10) * (units); \ 81 if (*p) \ 82 errx(1, "illegal offset -- %s", optarg); \ 83 switch(optarg[0]) { \ 84 case '+': \ 85 if (off) \ 86 off -= (units); \ 87 style = (forward); \ 88 break; \ 89 case '-': \ 90 off = -off; \ 91 /* FALLTHROUGH */ \ 92 default: \ 93 style = (backward); \ 94 break; \ 95 } \ 96 } 97 98 obsolete(argv); 99 style = NOTSET; 100 while ((ch = getopt(argc, argv, "b:c:fn:r")) != -1) 101 switch(ch) { 102 case 'b': 103 ARG(512, FBYTES, RBYTES); 104 break; 105 case 'c': 106 ARG(1, FBYTES, RBYTES); 107 break; 108 case 'f': 109 fflag = 1; 110 break; 111 case 'n': 112 ARG(1, FLINES, RLINES); 113 break; 114 case 'r': 115 rflag = 1; 116 break; 117 case '?': 118 default: 119 usage(); 120 } 121 argc -= optind; 122 argv += optind; 123 124 /* 125 * If displaying in reverse, don't permit follow option, and convert 126 * style values. 127 */ 128 if (rflag) { 129 if (fflag) 130 usage(); 131 if (style == FBYTES) 132 style = RBYTES; 133 else if (style == FLINES) 134 style = RLINES; 135 } 136 137 /* 138 * If style not specified, the default is the whole file for -r, and 139 * the last 10 lines if not -r. 140 */ 141 if (style == NOTSET) { 142 if (rflag) { 143 off = 0; 144 style = REVERSE; 145 } else { 146 off = 10; 147 style = RLINES; 148 } 149 } 150 151 if ((tf = reallocarray(NULL, argc ? argc : 1, sizeof(*tf))) == NULL) 152 err(1, "reallocarray"); 153 154 if (argc) { 155 for (i = 0; *argv; i++) { 156 tf[i].fname = *argv++; 157 if ((tf[i].fp = fopen(tf[i].fname, "r")) == NULL || 158 fstat(fileno(tf[i].fp), &(tf[i].sb))) { 159 ierr(tf[i].fname); 160 i--; 161 continue; 162 } 163 } 164 if (rflag) 165 reverse(tf, i, style, off); 166 else 167 forward(tf, i, style, off); 168 } 169 else { 170 if (pledge("stdio", NULL) == -1) 171 err(1, "pledge"); 172 173 tf[0].fname = "stdin"; 174 tf[0].fp = stdin; 175 176 if (fstat(fileno(stdin), &(tf[0].sb))) { 177 ierr(tf[0].fname); 178 exit(1); 179 } 180 181 /* 182 * Determine if input is a pipe. 4.4BSD will set the SOCKET 183 * bit in the st_mode field for pipes. Fix this then. 184 */ 185 if (lseek(fileno(tf[0].fp), (off_t)0, SEEK_CUR) == -1 && 186 errno == ESPIPE) { 187 errno = 0; 188 fflag = 0; /* POSIX.2 requires this. */ 189 } 190 191 if (rflag) 192 reverse(tf, 1, style, off); 193 else 194 forward(tf, 1, style, off); 195 } 196 exit(rval); 197 } 198 199 /* 200 * Convert the obsolete argument form into something that getopt can handle. 201 * This means that anything of the form [+-][0-9][0-9]*[lbc][fr] that isn't 202 * the option argument for a -b, -c or -n option gets converted. 203 */ 204 static void 205 obsolete(char *argv[]) 206 { 207 char *ap, *p, *t; 208 size_t len; 209 char *start; 210 211 while ((ap = *++argv)) { 212 /* Return if "--" or not an option of any form. */ 213 if (ap[0] != '-') { 214 if (ap[0] != '+') 215 return; 216 } else if (ap[1] == '-') 217 return; 218 219 switch(*++ap) { 220 /* Old-style option. */ 221 case '0': case '1': case '2': case '3': case '4': 222 case '5': case '6': case '7': case '8': case '9': 223 224 /* Malloc space for dash, new option and argument. */ 225 len = strlen(*argv); 226 if ((start = p = malloc(len + 4)) == NULL) 227 err(1, NULL); 228 *p++ = '-'; 229 230 /* 231 * Go to the end of the option argument. Save off any 232 * trailing options (-3lf) and translate any trailing 233 * output style characters. 234 */ 235 t = *argv + len - 1; 236 if (*t == 'f' || *t == 'r') { 237 *p++ = *t; 238 *t-- = '\0'; 239 } 240 switch(*t) { 241 case 'b': 242 *p++ = 'b'; 243 *t = '\0'; 244 break; 245 case 'c': 246 *p++ = 'c'; 247 *t = '\0'; 248 break; 249 case 'l': 250 *t = '\0'; 251 /* FALLTHROUGH */ 252 case '0': case '1': case '2': case '3': case '4': 253 case '5': case '6': case '7': case '8': case '9': 254 *p++ = 'n'; 255 break; 256 default: 257 errx(1, "illegal option -- %s", *argv); 258 } 259 *p++ = *argv[0]; 260 (void)strlcpy(p, ap, start + len + 4 - p); 261 *argv = start; 262 continue; 263 264 /* 265 * Options w/ arguments, skip the argument and continue 266 * with the next option. 267 */ 268 case 'b': 269 case 'c': 270 case 'n': 271 if (!ap[1]) 272 ++argv; 273 /* FALLTHROUGH */ 274 /* Options w/o arguments, continue with the next option. */ 275 case 'f': 276 case 'r': 277 continue; 278 279 /* Illegal option, return and let getopt handle it. */ 280 default: 281 return; 282 } 283 } 284 } 285 286 static void 287 usage(void) 288 { 289 (void)fprintf(stderr, 290 "usage: tail [-f | -r] " 291 "[-b number | -c number | -n number | -number] [file ...]\n"); 292 exit(1); 293 } 294