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  * @(#)tail.c   8.1 (Berkeley) 6/6/93
  33  * $FreeBSD: src/usr.bin/tail/tail.c,v 1.6.2.2 2001/12/19 20:29:31 iedowse Exp $
  34  */
  35
  36 #include <sys/types.h>
  37 #include <sys/stat.h>
  38 #include <errno.h>
  39 #include <unistd.h>
  40 #include <stdio.h>
  41 #include <stdlib.h>
  42 #include <string.h>
  43 #include <err.h>
  44 #include "extern.h"
  45
  46 int Fflag, fflag, qflag, rflag, vflag, rval, no_files;
  47 const char *fname;
  48
  49 #ifndef BOOTSTRAPPING
  50 file_info_t *files;
  51 #endif
  52
  53 static void obsolete(char **);
  54 static void usage(void) __dead2;
  55 static void getarg(int, enum STYLE, enum STYLE, enum STYLE *, int *, off_t *);
  56
  57 int
  58 main(int argc, char **argv)
  59 {
  60         const char *optstring;
  61         struct stat sb;
  62         FILE *fp;
  63         off_t off = 0;
  64         enum STYLE style;
  65         int style_set;
  66         int i, ch;
  67 #ifndef BOOTSTRAPPING
  68         file_info_t *file;
  69 #endif
  70
  71         if (strcmp(getprogname(), "tac") == 0) {
  72                 optstring = "";
  73                 qflag = 1;
  74                 rflag = 1;
  75                 vflag = 0;
  76         } else {
  77                 /* tail */
  78                 optstring = "Fb:c:fn:qrv";
  79         }
  80
  81         obsolete(argv);
  82         style_set = 0;
  83         while ((ch = getopt(argc, argv, optstring)) != -1) {
  84                 switch(ch) {
  85                 case 'F':       /* -F is superset of (and implies) -f */
  86 #ifndef BOOTSTRAPPING
  87                         Fflag = fflag = 1;
  88 #endif
  89                         break;
  90                 case 'b':
  91                         getarg(512, FBYTES, RBYTES, &style, &style_set, &off);
  92                         break;
  93                 case 'c':
  94                         getarg(1, FBYTES, RBYTES, &style, &style_set, &off);
  95                         break;
  96                 case 'f':
  97 #ifndef BOOTSTRAPPING
  98                         fflag = 1;
  99 #endif
 100                         break;
 101                 case 'n':
 102                         getarg(1, FLINES, RLINES, &style, &style_set, &off);
 103                         break;
 104                 case 'q':
 105                         qflag = 1;
 106                         vflag = 0;
 107                         break;
 108                 case 'r':
 109                         rflag = 1;
 110                         break;
 111                 case 'v':
 112                         vflag = 1;
 113                         qflag = 0;
 114                         break;
 115                 default:
 116                         usage();
 117                 }
 118         }
 119         argc -= optind;
 120         argv += optind;
 121
 122         no_files = argc ? argc : 1;
 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_set) {
 142                 if (rflag) {
 143                         off = 0;
 144                         style = REVERSE;
 145                 } else {
 146                         off = 10;
 147                         style = RLINES;
 148                 }
 149         }
 150
 151 #ifndef BOOTSTRAPPING
 152         if (*argv && fflag) {
 153                 files = malloc(no_files * sizeof(struct file_info));
 154                 if (files == NULL)
 155                         err(1, "Couldn't malloc space for files descriptors.");
 156
 157                 for (file = files; (fname = *argv++) != NULL; file++) {
 158                         file->file_name = strdup(fname);
 159                         if (! file->file_name)
 160                                 errx(1, "Couldn't alloc space for file name.");
 161                         file->fp = fopen(file->file_name, "r");
 162                         if (file->fp == NULL ||
 163                             fstat(fileno(file->fp), &file->st) == -1) {
 164                                 file->fp = NULL;
 165                                 ierr();
 166                         }
 167                 }
 168                 follow(files, style, off);
 169                 for (i = 0, file = files; i < no_files; i++, file++)
 170                         free(file->file_name);
 171                 free(files);
 172         } else
 173 #endif
 174         if (*argv) {
 175                 for (i = 0; (fname = *argv++) != NULL; ++i) {
 176                         if ((fp = fopen(fname, "r")) == NULL ||
 177                             fstat(fileno(fp), &sb)) {
 178                                 ierr();
 179                                 continue;
 180                         }
 181                         if (vflag || argc > 1) {
 182                                 showfilename(i, fname);
 183                                 (void)fflush(stdout);
 184                         }
 185
 186                         if (rflag)
 187                                 reverse(fp, style, off, &sb);
 188                         else
 189                                 forward(fp, style, off, &sb);
 190                         (void)fclose(fp);
 191                 }
 192         } else {
 193                 fname = "stdin";
 194
 195                 if (fstat(fileno(stdin), &sb)) {
 196                         ierr();
 197                         exit(1);
 198                 }
 199
 200                 /*
 201                  * Determine if input is a pipe.  4.4BSD will set the SOCKET
 202                  * bit in the st_mode field for pipes.  Fix this then.
 203                  */
 204                 if (lseek(fileno(stdin), (off_t)0, SEEK_CUR) == -1 &&
 205                     errno == ESPIPE) {
 206                         errno = 0;
 207                         fflag = 0;              /* POSIX.2 requires this. */
 208                 }
 209
 210                 if (rflag)
 211                         reverse(stdin, style, off, &sb);
 212                 else
 213                         forward(stdin, style, off, &sb);
 214         }
 215         exit(rval);
 216 }
 217
 218 /*
 219  * Tail's options are weird.  First, -n10 is the same as -n-10, not
 220  * -n+10.  Second, the number options are 1 based and not offsets,
 221  * so -n+1 is the first line, and -c-1 is the last byte.  Third, the
 222  * number options for the -r option specify the number of things that
 223  * get displayed, not the starting point in the file.  The one major
 224  * incompatibility in this version as compared to historical versions
 225  * is that the 'r' option couldn't be modified by the -lbc options,
 226  * i.e. it was always done in lines.  This version treats -rc as a
 227  * number of characters in reverse order.  Finally, the default for
 228  * -r is the entire file, not 10 lines.
 229  */
 230 static void
 231 getarg(int units, enum STYLE forward_style, enum STYLE backward_style,
 232        enum STYLE *style, int *style_set, off_t *off)
 233 {
 234         char *p;
 235
 236         if (*style_set)
 237                 usage();
 238
 239         *off = strtoll(optarg, &p, 10) * units;
 240         if (*p != '\0')
 241                 errx(1, "illegal offset -- %s", optarg);
 242         switch (optarg[0]) {
 243         case '+':
 244                 if (*off != 0)
 245                         *off -= (units);
 246                 *style = forward_style;
 247                 break;
 248         case '-':
 249                 *off = -*off;
 250                 /* FALLTHROUGH */
 251         default:
 252                 *style = backward_style;
 253                 break;
 254         }
 255
 256         *style_set = 1;
 257 }
 258
 259 /*
 260  * Convert the obsolete argument form into something that getopt can handle.
 261  * This means that anything of the form [+-][0-9][0-9]*[lbc][Ffr] that isn't
 262  * the option argument for a -b, -c or -n option gets converted.
 263  */
 264 static void
 265 obsolete(char **argv)
 266 {
 267         char *ap, *p, *t;
 268         size_t len;
 269         char *start;
 270
 271         while ((ap = *++argv) != NULL) {
 272                 /* Return if "--" or not an option of any form. */
 273                 if (ap[0] != '-') {
 274                         if (ap[0] != '+')
 275                                 return;
 276                 } else if (ap[1] == '-')
 277                         return;
 278
 279                 switch(*++ap) {
 280                 /* Old-style option. */
 281                 case '0': case '1': case '2': case '3': case '4':
 282                 case '5': case '6': case '7': case '8': case '9':
 283
 284                         /* Malloc space for dash, new option and argument. */
 285                         len = strlen(*argv);
 286                         if ((start = p = malloc(len + 3)) == NULL)
 287                                 err(1, "malloc");
 288                         *p++ = '-';
 289
 290                         /*
 291                          * Go to the end of the option argument.  Save off any
 292                          * trailing options (-3lf) and translate any trailing
 293                          * output style characters.
 294                          */
 295                         t = *argv + len - 1;
 296                         if (*t == 'F' || *t == 'f' || *t == 'r') {
 297                                 *p++ = *t;
 298                                 *t-- = '\0';
 299                         }
 300                         switch(*t) {
 301                         case 'b':
 302                                 *p++ = 'b';
 303                                 *t = '\0';
 304                                 break;
 305                         case 'c':
 306                                 *p++ = 'c';
 307                                 *t = '\0';
 308                                 break;
 309                         case 'l':
 310                                 *t = '\0';
 311                                 /* FALLTHROUGH */
 312                         case '0': case '1': case '2': case '3': case '4':
 313                         case '5': case '6': case '7': case '8': case '9':
 314                                 *p++ = 'n';
 315                                 break;
 316                         default:
 317                                 errx(1, "illegal option -- %s", *argv);
 318                         }
 319                         *p++ = *argv[0];
 320                         (void)strcpy(p, ap);
 321                         *argv = start;
 322                         continue;
 323
 324                 /*
 325                  * Options w/ arguments, skip the argument and continue
 326                  * with the next option.
 327                  */
 328                 case 'b':
 329                 case 'c':
 330                 case 'n':
 331                         if (!ap[1])
 332                                 ++argv;
 333                         /* FALLTHROUGH */
 334                 /* Options w/o arguments, continue with the next option. */
 335                 case 'F':
 336                 case 'f':
 337                 case 'r':
 338                         continue;
 339
 340                 /* Illegal option, return and let getopt handle it. */
 341                 default:
 342                         return;
 343                 }
 344         }
 345 }
 346
 347 static void __dead2
 348 usage(void)
 349 {
 350         if (strcmp(getprogname(), "tac") == 0) {
 351                 fprintf(stderr, "usage: tac [file ...]\n");
 352         } else {
 353                 fprintf(stderr,
 354                         "usage: tail [-F | -f | -r] [-q | -v] "
 355                         "[-b # | -c # | -n #] [file ...]\n");
 356         }
 357         exit(1);
 358 }