usr/src/cmd/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  * 4. 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
  33 #include <sys/types.h>
  34 #include <sys/stat.h>
  35
  36 #include <err.h>
  37 #include <errno.h>
  38 #include <stdio.h>
  39 #include <stdlib.h>
  40 #include <string.h>
  41 #include <unistd.h>
  42
  43 #include "extern.h"
  44
  45 int Fflag, fflag, qflag, rflag, rval, no_files;
  46
  47 file_info_t *files;
  48
  49 static void obsolete(char **);
  50 static void usage(void);
  51
  52 int
  53 main(int argc, char *argv[])
  54 {
  55         struct stat sb;
  56         const char *fn;
  57         FILE *fp;
  58         off_t off;
  59         enum STYLE style;
  60         int i, ch, first;
  61         file_info_t *file;
  62         char *p;
  63
  64         /*
  65          * Tail's options are weird.  First, -n10 is the same as -n-10, not
  66          * -n+10.  Second, the number options are 1 based and not offsets,
  67          * so -n+1 is the first line, and -c-1 is the last byte.  Third, the
  68          * number options for the -r option specify the number of things that
  69          * get displayed, not the starting point in the file.  The one major
  70          * incompatibility in this version as compared to historical versions
  71          * is that the 'r' option couldn't be modified by the -lbc options,
  72          * i.e. it was always done in lines.  This version treats -rc as a
  73          * number of characters in reverse order.  Finally, the default for
  74          * -r is the entire file, not 10 lines.
  75          */
  76 #define ARG(units, forward, backward) {                                 \
  77         if (style)                                                      \
  78                 usage();                                                \
  79         off = strtoll(optarg, &p, 10) * (units);                        \
  80         if (*p)                                                         \
  81                 errx(1, "illegal offset -- %s", optarg);                \
  82         switch (optarg[0]) {                                            \
  83         case '+':                                                       \
  84                 if (off)                                                \
  85                         off -= (units);                                 \
  86                         style = (forward);                              \
  87                 break;                                                  \
  88         case '-':                                                       \
  89                 off = -off;                                             \
  90                 /* FALLTHROUGH */                                       \
  91         default:                                                        \
  92                 style = (backward);                                     \
  93                 break;                                                  \
  94         }                                                               \
  95 }
  96
  97         obsolete(argv);
  98         style = NOTSET;
  99         off = 0;
 100         while ((ch = getopt(argc, argv, "Fb:c:fn:qr")) != -1)
 101                 switch (ch) {
 102                 case 'F':       /* -F is superset of (and implies) -f */
 103                         Fflag = fflag = 1;
 104                         break;
 105                 case 'b':
 106                         ARG(512, FBYTES, RBYTES);
 107                         break;
 108                 case 'c':
 109                         ARG(1, FBYTES, RBYTES);
 110                         break;
 111                 case 'f':
 112                         fflag = 1;
 113                         break;
 114                 case 'n':
 115                         ARG(1, FLINES, RLINES);
 116                         break;
 117                 case 'q':
 118                         qflag = 1;
 119                         break;
 120                 case 'r':
 121                         rflag = 1;
 122                         break;
 123                 case '?':
 124                 default:
 125                         usage();
 126                 }
 127         argc -= optind;
 128         argv += optind;
 129
 130         no_files = argc ? argc : 1;
 131
 132         /*
 133          * If displaying in reverse, don't permit follow option, and convert
 134          * style values.
 135          */
 136         if (rflag) {
 137                 if (fflag)
 138                         usage();
 139                 if (style == FBYTES)
 140                         style = RBYTES;
 141                 else if (style == FLINES)
 142                         style = RLINES;
 143         }
 144
 145         /*
 146          * If style not specified, the default is the whole file for -r, and
 147          * the last 10 lines if not -r.
 148          */
 149         if (style == NOTSET) {
 150                 if (rflag) {
 151                         off = 0;
 152                         style = REVERSE;
 153                 } else {
 154                         off = 10;
 155                         style = RLINES;
 156                 }
 157         }
 158
 159         if (*argv && fflag) {
 160                 files = (struct file_info *)malloc(no_files *
 161                     sizeof (struct file_info));
 162                 if (!files)
 163                         err(1, "Couldn't malloc space for file descriptors.");
 164
 165                 for (file = files; (fn = *argv++); file++) {
 166                         file->file_name = strdup(fn);
 167                         if (! file->file_name)
 168                                 errx(1, "Couldn't malloc space for file name.");
 169                         if ((file->fp = fopen(file->file_name, "r")) == NULL ||
 170                             fstat(fileno(file->fp), &file->st)) {
 171                                 if (file->fp != NULL) {
 172                                         (void) fclose(file->fp);
 173                                         file->fp = NULL;
 174                                 }
 175                                 if (!Fflag || errno != ENOENT)
 176                                         ierr(file->file_name);
 177                         }
 178                 }
 179                 follow(files, style, off);
 180                 for (i = 0, file = files; i < no_files; i++, file++) {
 181                     free(file->file_name);
 182                 }
 183                 free(files);
 184         } else if (*argv) {
 185                 for (first = 1; (fn = *argv++); ) {
 186                         if ((fp = fopen(fn, "r")) == NULL ||
 187                             fstat(fileno(fp), &sb)) {
 188                                 ierr(fn);
 189                                 continue;
 190                         }
 191                         if (argc > 1 && !qflag) {
 192                                 (void) printf("%s==> %s <==\n",
 193                                     first ? "" : "\n", fn);
 194                                 first = 0;
 195                                 (void) fflush(stdout);
 196                         }
 197
 198                         if (rflag)
 199                                 reverse(fp, fn, style, off, &sb);
 200                         else
 201                                 forward(fp, fn, style, off, &sb);
 202                 }
 203         } else {
 204                 fn = "stdin";
 205
 206                 if (fstat(fileno(stdin), &sb)) {
 207                         ierr(fn);
 208                         exit(1);
 209                 }
 210
 211                 /*
 212                  * Determine if input is a pipe.  4.4BSD will set the SOCKET
 213                  * bit in the st_mode field for pipes.  Fix this then.
 214                  */
 215                 if (lseek(fileno(stdin), (off_t)0, SEEK_CUR) == -1 &&
 216                     errno == ESPIPE) {
 217                         errno = 0;
 218                         fflag = 0;              /* POSIX.2 requires this. */
 219                 }
 220
 221                 if (rflag)
 222                         reverse(stdin, fn, style, off, &sb);
 223                 else
 224                         forward(stdin, fn, style, off, &sb);
 225         }
 226         exit(rval);
 227 }
 228
 229 /*
 230  * Convert the obsolete argument form into something that getopt can handle.
 231  * This means that anything of the form [+-][0-9][0-9]*[lbc][Ffr] that isn't
 232  * the option argument for a -b, -c or -n option gets converted.
 233  */
 234 static void
 235 obsolete(char *argv[])
 236 {
 237         char *ap, *p, *t;
 238         size_t len;
 239         char *start;
 240
 241         while ((ap = *++argv)) {
 242                 /* Return if "--" or not an option of any form. */
 243                 if (ap[0] != '-') {
 244                         if (ap[0] != '+')
 245                                 return;
 246                 } else if (ap[1] == '-')
 247                         return;
 248
 249                 switch (*++ap) {
 250                 /* Old-style option. */
 251                 case '0': case '1': case '2': case '3': case '4':
 252                 case '5': case '6': case '7': case '8': case '9':
 253
 254                         /* Malloc space for dash, new option and argument. */
 255                         len = strlen(*argv);
 256                         if ((start = p = malloc(len + 3)) == NULL)
 257                                 err(1, "malloc");
 258                         *p++ = '-';
 259
 260                         /*
 261                          * Go to the end of the option argument.  Save off any
 262                          * trailing options (-3lf) and translate any trailing
 263                          * output style characters.
 264                          */
 265                         t = *argv + len - 1;
 266                         if (*t == 'F' || *t == 'f' || *t == 'r') {
 267                                 *p++ = *t;
 268                                 *t-- = '\0';
 269                         }
 270                         switch (*t) {
 271                         case 'b':
 272                                 *p++ = 'b';
 273                                 *t = '\0';
 274                                 break;
 275                         case 'c':
 276                                 *p++ = 'c';
 277                                 *t = '\0';
 278                                 break;
 279                         case 'l':
 280                                 *t = '\0';
 281                                 /* FALLTHROUGH */
 282                         case '0': case '1': case '2': case '3': case '4':
 283                         case '5': case '6': case '7': case '8': case '9':
 284                                 *p++ = 'n';
 285                                 break;
 286                         default:
 287                                 errx(1, "illegal option -- %s", *argv);
 288                         }
 289                         *p++ = *argv[0];
 290                         (void) strcpy(p, ap);
 291                         *argv = start;
 292                         continue;
 293
 294                 /*
 295                  * Legacy Solaris tail supports "+c" "-c", "+l", "-l",
 296                  * "+b", and "-b" with an default number of 10.  Map
 297                  * these arguments to an explicit +/-10 for FreeBSD.
 298                  * New argument will be of the form -[bcn][+-]10
 299                  */
 300                 case 'b':
 301                 case 'c':
 302                 case 'l':
 303                         if ((start = p = malloc(6)) == NULL)
 304                                 err(1, "malloc");
 305                         *p++ = '-';
 306                         switch (ap[0]) {
 307                         case 'c':
 308                                 *p++ = ap[0];
 309                                 break;
 310                         case 'b':
 311                                 *p++ = ap[0];
 312                                 break;
 313                         case 'l':
 314                                 *p++ = 'n';
 315                                 break;
 316                         }
 317                         (void) snprintf(p, 6, "%c10", *argv[0]);
 318                         *argv = start;
 319
 320                         continue;
 321                 /*
 322                  * Options w/ arguments, skip the argument and continue
 323                  * with the next option.
 324                  */
 325                 case 'n':
 326                         if (!ap[1])
 327                                 ++argv;
 328                         /* FALLTHROUGH */
 329                 /* Options w/o arguments, continue with the next option. */
 330                 case 'F':
 331                 case 'f':
 332                 case 'r':
 333                         continue;
 334
 335                 /* Illegal option, return and let getopt handle it. */
 336                 default:
 337                         return;
 338                 }
 339         }
 340 }
 341
 342 static void
 343 usage(void)
 344 {
 345         (void) fprintf(stderr,
 346             "usage: tail [-F | -f | -r] [-q] [-b # | -c # | -n #]"
 347             " [file ...]\n");
 348         exit(1);
 349 }