tail.c revision 146656
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#include <sys/cdefs.h> 38 39__FBSDID("$FreeBSD: head/usr.bin/tail/tail.c 146656 2005-05-26 22:14:37Z eivind $"); 40 41#ifndef lint 42static const char copyright[] = 43"@(#) Copyright (c) 1991, 1993\n\ 44 The Regents of the University of California. All rights reserved.\n"; 45#endif 46 47#ifndef lint 48static const char sccsid[] = "@(#)tail.c 8.1 (Berkeley) 6/6/93"; 49#endif 50 51#include <sys/types.h> 52#include <sys/stat.h> 53 54#include <err.h> 55#include <errno.h> 56#include <stdio.h> 57#include <stdlib.h> 58#include <string.h> 59#include <unistd.h> 60 61#include "extern.h" 62 63int Fflag, fflag, rflag, rval, no_files; 64const char *fname; 65 66file_info_t *files; 67 68static void obsolete(char **); 69static void usage(void); 70 71int 72main(int argc, char *argv[]) 73{ 74 struct stat sb; 75 FILE *fp; 76 off_t off; 77 enum STYLE style; 78 int i, ch, first; 79 file_info_t *file; 80 char *p; 81 82 /* 83 * Tail's options are weird. First, -n10 is the same as -n-10, not 84 * -n+10. Second, the number options are 1 based and not offsets, 85 * so -n+1 is the first line, and -c-1 is the last byte. Third, the 86 * number options for the -r option specify the number of things that 87 * get displayed, not the starting point in the file. The one major 88 * incompatibility in this version as compared to historical versions 89 * is that the 'r' option couldn't be modified by the -lbc options, 90 * i.e. it was always done in lines. This version treats -rc as a 91 * number of characters in reverse order. Finally, the default for 92 * -r is the entire file, not 10 lines. 93 */ 94#define ARG(units, forward, backward) { \ 95 if (style) \ 96 usage(); \ 97 off = strtoll(optarg, &p, 10) * (units); \ 98 if (*p) \ 99 errx(1, "illegal offset -- %s", optarg); \ 100 switch(optarg[0]) { \ 101 case '+': \ 102 if (off) \ 103 off -= (units); \ 104 style = (forward); \ 105 break; \ 106 case '-': \ 107 off = -off; \ 108 /* FALLTHROUGH */ \ 109 default: \ 110 style = (backward); \ 111 break; \ 112 } \ 113} 114 115 obsolete(argv); 116 style = NOTSET; 117 while ((ch = getopt(argc, argv, "Fb:c:fn:r")) != -1) 118 switch(ch) { 119 case 'F': /* -F is superset of (and implies) -f */ 120 Fflag = fflag = 1; 121 break; 122 case 'b': 123 ARG(512, FBYTES, RBYTES); 124 break; 125 case 'c': 126 ARG(1, FBYTES, RBYTES); 127 break; 128 case 'f': 129 fflag = 1; 130 break; 131 case 'n': 132 ARG(1, FLINES, RLINES); 133 break; 134 case 'r': 135 rflag = 1; 136 break; 137 case '?': 138 default: 139 usage(); 140 } 141 argc -= optind; 142 argv += optind; 143 144 no_files = argc ? argc : 1; 145 146 /* 147 * If displaying in reverse, don't permit follow option, and convert 148 * style values. 149 */ 150 if (rflag) { 151 if (fflag) 152 usage(); 153 if (style == FBYTES) 154 style = RBYTES; 155 else if (style == FLINES) 156 style = RLINES; 157 } 158 159 /* 160 * If style not specified, the default is the whole file for -r, and 161 * the last 10 lines if not -r. 162 */ 163 if (style == NOTSET) { 164 if (rflag) { 165 off = 0; 166 style = REVERSE; 167 } else { 168 off = 10; 169 style = RLINES; 170 } 171 } 172 173 if (*argv && fflag) { 174 files = (struct file_info *) malloc(no_files * sizeof(struct file_info)); 175 if (! files) 176 err(1, "Couldn't malloc space for file descriptors."); 177 178 for (file = files; (fname = *argv++); file++) { 179 file->file_name = malloc(strlen(fname)+1); 180 if (! file->file_name) 181 errx(1, "Couldn't malloc space for file name."); 182 strncpy(file->file_name, fname, strlen(fname)+1); 183 if ((file->fp = fopen(file->file_name, "r")) == NULL || 184 fstat(fileno(file->fp), &file->st)) { 185 file->fp = NULL; 186 ierr(); 187 continue; 188 } 189 } 190 follow(files, style, off); 191 for (i = 0, file = files; i < no_files; i++, file++) { 192 free(file->file_name); 193 } 194 free(files); 195 } else if (*argv) { 196 for (first = 1; (fname = *argv++);) { 197 if ((fp = fopen(fname, "r")) == NULL || 198 fstat(fileno(fp), &sb)) { 199 ierr(); 200 continue; 201 } 202 if (argc > 1) { 203 (void)printf("%s==> %s <==\n", 204 first ? "" : "\n", fname); 205 first = 0; 206 (void)fflush(stdout); 207 } 208 209 if (rflag) 210 reverse(fp, style, off, &sb); 211 else 212 forward(fp, style, off, &sb); 213 } 214 } else { 215 fname = "stdin"; 216 217 if (fstat(fileno(stdin), &sb)) { 218 ierr(); 219 exit(1); 220 } 221 222 if ((sb.st_mode & S_IFMT) == S_IFSOCK || (sb.st_mode & S_IFMT) == S_IFIFO) { 223 errno = 0; 224 fflag = 0; /* POSIX.2 requires this. */ 225 } 226 227 if (rflag) 228 reverse(stdin, style, off, &sb); 229 else 230 forward(stdin, style, off, &sb); 231 } 232 exit(rval); 233} 234 235/* 236 * Convert the obsolete argument form into something that getopt can handle. 237 * This means that anything of the form [+-][0-9][0-9]*[lbc][Ffr] that isn't 238 * the option argument for a -b, -c or -n option gets converted. 239 */ 240static void 241obsolete(char *argv[]) 242{ 243 char *ap, *p, *t; 244 size_t len; 245 char *start; 246 247 while ((ap = *++argv)) { 248 /* Return if "--" or not an option of any form. */ 249 if (ap[0] != '-') { 250 if (ap[0] != '+') 251 return; 252 } else if (ap[1] == '-') 253 return; 254 255 switch(*++ap) { 256 /* Old-style option. */ 257 case '0': case '1': case '2': case '3': case '4': 258 case '5': case '6': case '7': case '8': case '9': 259 260 /* Malloc space for dash, new option and argument. */ 261 len = strlen(*argv); 262 if ((start = p = malloc(len + 3)) == NULL) 263 err(1, "malloc"); 264 *p++ = '-'; 265 266 /* 267 * Go to the end of the option argument. Save off any 268 * trailing options (-3lf) and translate any trailing 269 * output style characters. 270 */ 271 t = *argv + len - 1; 272 if (*t == 'F' || *t == 'f' || *t == 'r') { 273 *p++ = *t; 274 *t-- = '\0'; 275 } 276 switch(*t) { 277 case 'b': 278 *p++ = 'b'; 279 *t = '\0'; 280 break; 281 case 'c': 282 *p++ = 'c'; 283 *t = '\0'; 284 break; 285 case 'l': 286 *t = '\0'; 287 /* FALLTHROUGH */ 288 case '0': case '1': case '2': case '3': case '4': 289 case '5': case '6': case '7': case '8': case '9': 290 *p++ = 'n'; 291 break; 292 default: 293 errx(1, "illegal option -- %s", *argv); 294 } 295 *p++ = *argv[0]; 296 (void)strcpy(p, ap); 297 *argv = start; 298 continue; 299 300 /* 301 * Options w/ arguments, skip the argument and continue 302 * with the next option. 303 */ 304 case 'b': 305 case 'c': 306 case 'n': 307 if (!ap[1]) 308 ++argv; 309 /* FALLTHROUGH */ 310 /* Options w/o arguments, continue with the next option. */ 311 case 'F': 312 case 'f': 313 case 'r': 314 continue; 315 316 /* Illegal option, return and let getopt handle it. */ 317 default: 318 return; 319 } 320 } 321} 322 323static void 324usage(void) 325{ 326 (void)fprintf(stderr, 327 "usage: tail [-F | -f | -r] [-b # | -c # | -n #] [file ...]\n"); 328 exit(1); 329} 330