usr.bin/tail/tail.c

   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. Neither the name of the University nor the names of its contributors
  17  *    may be used to endorse or promote products derived from this software
  18  *    without specific prior written permission.
  19  *
  20  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  30  * SUCH DAMAGE.
  31  *
  32  * @(#) Copyright (c) 1991, 1993 The Regents of the University of California.  All rights reserved.
  33  * @(#)tail.c   8.1 (Berkeley) 6/6/93
  34  * $FreeBSD: src/usr.bin/tail/tail.c,v 1.6.2.2 2001/12/19 20:29:31 iedowse Exp $
  35  */
  36
  37 #include <sys/types.h>
  38 #include <sys/stat.h>
  39 #include <errno.h>
  40 #include <unistd.h>
  41 #include <stdio.h>
  42 #include <stdlib.h>
  43 #include <string.h>
  44 #include <err.h>
  45 #include "extern.h"
  46
  47 int Fflag, fflag, qflag, rflag, rval, no_files;
  48 const char *fname;
  49
  50 file_info_t *files;
  51
  52 static void obsolete(char **);
  53 static void usage(void);
  54 static void getarg(int, enum STYLE, enum STYLE, enum STYLE *, int *, off_t *);
  55
  56 int
  57 main(int argc, char **argv)
  58 {
  59         struct stat sb;
  60         FILE *fp;
  61         off_t off = 0;
  62         enum STYLE style;
  63         int style_set;
  64         int i, ch;
  65         file_info_t *file;
  66
  67         obsolete(argv);
  68         style_set = 0;
  69         while ((ch = getopt(argc, argv, "Fb:c:fn:qr")) != -1)
  70                 switch(ch) {
  71                 case 'F':       /* -F is superset of (and implies) -f */
  72                         Fflag = fflag = 1;
  73                         break;
  74                 case 'b':
  75                         getarg(512, FBYTES, RBYTES, &style, &style_set, &off);
  76                         break;
  77                 case 'c':
  78                         getarg(1, FBYTES, RBYTES, &style, &style_set, &off);
  79                         break;
  80                 case 'f':
  81                         fflag = 1;
  82                         break;
  83                 case 'n':
  84                         getarg(1, FLINES, RLINES, &style, &style_set, &off);
  85                         break;
  86                 case 'q':
  87                         qflag = 1;
  88                         break;
  89                 case 'r':
  90                         rflag = 1;
  91                         break;
  92                 case '?':
  93                 default:
  94                         usage();
  95                 }
  96         argc -= optind;
  97         argv += optind;
  98
  99         no_files = argc ? argc : 1;
 100
 101         /*
 102          * If displaying in reverse, don't permit follow option, and convert
 103          * style values.
 104          */
 105         if (rflag) {
 106                 if (fflag)
 107                         usage();
 108                 if (style == FBYTES)
 109                         style = RBYTES;
 110                 else if (style == FLINES)
 111                         style = RLINES;
 112         }
 113
 114         /*
 115          * If style not specified, the default is the whole file for -r, and
 116          * the last 10 lines if not -r.
 117          */
 118         if (!style_set) {
 119                 if (rflag) {
 120                         off = 0;
 121                         style = REVERSE;
 122                 } else {
 123                         off = 10;
 124                         style = RLINES;
 125                 }
 126         }
 127
 128         if (*argv && fflag) {
 129                 files = malloc(no_files * sizeof(struct file_info));
 130                 if (files == NULL)
 131                         err(1, "Couldn't malloc space for files descriptors.");
 132
 133                 for (file = files; (fname = *argv++) != NULL; file++) {
 134                         file->file_name = strdup(fname);
 135                         if (! file->file_name)
 136                                 errx(1, "Couldn't alloc space for file name.");
 137                         file->fp = fopen(file->file_name, "r");
 138                         if (file->fp == NULL ||
 139                             fstat(fileno(file->fp), &file->st) == -1) {
 140                                 file->fp = NULL;
 141                                 ierr();
 142                         }
 143                 }
 144                 follow(files, style, off);
 145                 for (i = 0, file = files; i < no_files; i++, file++)
 146                         free(file->file_name);
 147                 free(files);
 148         } else if (*argv) {
 149                 for (i = 0; (fname = *argv++) != NULL; ++i) {
 150                         if ((fp = fopen(fname, "r")) == NULL ||
 151                             fstat(fileno(fp), &sb)) {
 152                                 ierr();
 153                                 continue;
 154                         }
 155                         if (argc > 1) {
 156                                 showfilename(i, fname);
 157                                 (void)fflush(stdout);
 158                         }
 159
 160                         if (rflag)
 161                                 reverse(fp, style, off, &sb);
 162                         else
 163                                 forward(fp, style, off, &sb);
 164                         (void)fclose(fp);
 165                 }
 166         } else {
 167                 fname = "stdin";
 168
 169                 if (fstat(fileno(stdin), &sb)) {
 170                         ierr();
 171                         exit(1);
 172                 }
 173
 174                 /*
 175                  * Determine if input is a pipe.  4.4BSD will set the SOCKET
 176                  * bit in the st_mode field for pipes.  Fix this then.
 177                  */
 178                 if (lseek(fileno(stdin), (off_t)0, SEEK_CUR) == -1 &&
 179                     errno == ESPIPE) {
 180                         errno = 0;
 181                         fflag = 0;              /* POSIX.2 requires this. */
 182                 }
 183
 184                 if (rflag)
 185                         reverse(stdin, style, off, &sb);
 186                 else
 187                         forward(stdin, style, off, &sb);
 188         }
 189         exit(rval);
 190 }
 191
 192 /*
 193  * Tail's options are weird.  First, -n10 is the same as -n-10, not
 194  * -n+10.  Second, the number options are 1 based and not offsets,
 195  * so -n+1 is the first line, and -c-1 is the last byte.  Third, the
 196  * number options for the -r option specify the number of things that
 197  * get displayed, not the starting point in the file.  The one major
 198  * incompatibility in this version as compared to historical versions
 199  * is that the 'r' option couldn't be modified by the -lbc options,
 200  * i.e. it was always done in lines.  This version treats -rc as a
 201  * number of characters in reverse order.  Finally, the default for
 202  * -r is the entire file, not 10 lines.
 203  */
 204 static void
 205 getarg(int units, enum STYLE forward_style, enum STYLE backward_style,
 206        enum STYLE *style, int *style_set, off_t *off)
 207 {
 208         char *p;
 209
 210         if (*style_set)
 211                 usage();
 212
 213         *off = strtoll(optarg, &p, 10) * units;
 214         if (*p != '\0')
 215                 errx(1, "illegal offset -- %s", optarg);
 216         switch (optarg[0]) {
 217         case '+':
 218                 if (*off != 0)
 219                         *off -= (units);
 220                 *style = forward_style;
 221                 break;
 222         case '-':
 223                 *off = -*off;
 224                 /* FALLTHROUGH */
 225         default:
 226                 *style = backward_style;
 227                 break;
 228         }
 229
 230         *style_set = 1;
 231 }
 232
 233 /*
 234  * Convert the obsolete argument form into something that getopt can handle.
 235  * This means that anything of the form [+-][0-9][0-9]*[lbc][Ffr] that isn't
 236  * the option argument for a -b, -c or -n option gets converted.
 237  */
 238 static void
 239 obsolete(char **argv)
 240 {
 241         char *ap, *p, *t;
 242         size_t len;
 243         char *start;
 244
 245         while ((ap = *++argv) != NULL) {
 246                 /* Return if "--" or not an option of any form. */
 247                 if (ap[0] != '-') {
 248                         if (ap[0] != '+')
 249                                 return;
 250                 } else if (ap[1] == '-')
 251                         return;
 252
 253                 switch(*++ap) {
 254                 /* Old-style option. */
 255                 case '0': case '1': case '2': case '3': case '4':
 256                 case '5': case '6': case '7': case '8': case '9':
 257
 258                         /* Malloc space for dash, new option and argument. */
 259                         len = strlen(*argv);
 260                         if ((start = p = malloc(len + 3)) == NULL)
 261                                 err(1, "malloc");
 262                         *p++ = '-';
 263
 264                         /*
 265                          * Go to the end of the option argument.  Save off any
 266                          * trailing options (-3lf) and translate any trailing
 267                          * output style characters.
 268                          */
 269                         t = *argv + len - 1;
 270                         if (*t == 'F' || *t == 'f' || *t == 'r') {
 271                                 *p++ = *t;
 272                                 *t-- = '\0';
 273                         }
 274                         switch(*t) {
 275                         case 'b':
 276                                 *p++ = 'b';
 277                                 *t = '\0';
 278                                 break;
 279                         case 'c':
 280                                 *p++ = 'c';
 281                                 *t = '\0';
 282                                 break;
 283                         case 'l':
 284                                 *t = '\0';
 285                                 /* FALLTHROUGH */
 286                         case '0': case '1': case '2': case '3': case '4':
 287                         case '5': case '6': case '7': case '8': case '9':
 288                                 *p++ = 'n';
 289                                 break;
 290                         default:
 291                                 errx(1, "illegal option -- %s", *argv);
 292                         }
 293                         *p++ = *argv[0];
 294                         (void)strcpy(p, ap);
 295                         *argv = start;
 296                         continue;
 297
 298                 /*
 299                  * Options w/ arguments, skip the argument and continue
 300                  * with the next option.
 301                  */
 302                 case 'b':
 303                 case 'c':
 304                 case 'n':
 305                         if (!ap[1])
 306                                 ++argv;
 307                         /* FALLTHROUGH */
 308                 /* Options w/o arguments, continue with the next option. */
 309                 case 'F':
 310                 case 'f':
 311                 case 'r':
 312                         continue;
 313
 314                 /* Illegal option, return and let getopt handle it. */
 315                 default:
 316                         return;
 317                 }
 318         }
 319 }
 320
 321 static void
 322 usage(void)
 323 {
 324         (void)fprintf(stderr,
 325             "usage: tail [-F | -f | -r] [-b # | -c # | -n #] [file ...]\n");
 326         exit(1);
 327 }