release/src/router/busybox/coreutils/tac.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * tac implementation for busybox
   4  *
   5  * Copyright (C) 2003  Yang Xiaopeng  <yxp at hanwang.com.cn>
   6  * Copyright (C) 2007  Natanael Copa  <natanael.copa@gmail.com>
   7  * Copyright (C) 2007  Tito Ragusa    <farmatito@tiscali.it>
   8  *
   9  * Licensed under GPLv2, see file LICENSE in this source tree.
  10  *
  11  */
  12
  13 /* tac - concatenate and print files in reverse */
  14
  15 /* Based on Yang Xiaopeng's (yxp at hanwang.com.cn) patch
  16  * http://www.uclibc.org/lists/busybox/2003-July/008813.html
  17  */
  18
  19 #include "libbb.h"
  20
  21 /* This is a NOEXEC applet. Be very careful! */
  22
  23 struct lstring {
  24         int size;
  25         char buf[1];
  26 };
  27
  28 int tac_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  29 int tac_main(int argc UNUSED_PARAM, char **argv)
  30 {
  31         char **name;
  32         FILE *f;
  33         struct lstring *line = NULL;
  34         llist_t *list = NULL;
  35         int retval = EXIT_SUCCESS;
  36
  37 #if ENABLE_DESKTOP
  38 /* tac from coreutils 6.9 supports:
  39        -b, --before
  40               attach the separator before instead of after
  41        -r, --regex
  42               interpret the separator as a regular expression
  43        -s, --separator=STRING
  44               use STRING as the separator instead of newline
  45 We support none, but at least we will complain or handle "--":
  46 */
  47         getopt32(argv, "");
  48         argv += optind;
  49 #else
  50         argv++;
  51 #endif
  52         if (!*argv)
  53                 *--argv = (char *)"-";
  54         /* We will read from last file to first */
  55         name = argv;
  56         while (*name)
  57                 name++;
  58
  59         do {
  60                 int ch, i;
  61
  62                 name--;
  63                 f = fopen_or_warn_stdin(*name);
  64                 if (f == NULL) {
  65                         /* error message is printed by fopen_or_warn_stdin */
  66                         retval = EXIT_FAILURE;
  67                         continue;
  68                 }
  69
  70                 errno = i = 0;
  71                 do {
  72                         ch = fgetc(f);
  73                         if (ch != EOF) {
  74                                 if (!(i & 0x7f))
  75                                         /* Grow on every 128th char */
  76                                         line = xrealloc(line, i + 0x7f + sizeof(int) + 1);
  77                                 line->buf[i++] = ch;
  78                         }
  79                         if (ch == '\n' || (ch == EOF && i != 0)) {
  80                                 line = xrealloc(line, i + sizeof(int));
  81                                 line->size = i;
  82                                 llist_add_to(&list, line);
  83                                 line = NULL;
  84                                 i = 0;
  85                         }
  86                 } while (ch != EOF);
  87                 /* fgetc sets errno to ENOENT on EOF, we don't want
  88                  * to warn on this non-error! */
  89                 if (errno && errno != ENOENT) {
  90                         bb_simple_perror_msg(*name);
  91                         retval = EXIT_FAILURE;
  92                 }
  93         } while (name != argv);
  94
  95         while (list) {
  96                 line = (struct lstring *)list->data;
  97                 xwrite(STDOUT_FILENO, line->buf, line->size);
  98                 if (ENABLE_FEATURE_CLEAN_UP) {
  99                         free(llist_pop(&list));
 100                 } else {
 101                         list = list->link;
 102                 }
 103         }
 104
 105         return retval;
 106 }