coreutils/tac.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * tac implementation for busybox
   4  * tac - concatenate and print files in reverse
   5  *
   6  * Copyright (C) 2003  Yang Xiaopeng  <yxp at hanwang.com.cn>
   7  * Copyright (C) 2007  Natanael Copa  <natanael.copa@gmail.com>
   8  * Copyright (C) 2007  Tito Ragusa    <farmatito@tiscali.it>
   9  *
  10  * Licensed under GPLv2, see file LICENSE in this source tree.
  11  */
  12 /* Based on Yang Xiaopeng's (yxp at hanwang.com.cn) patch
  13  * http://www.uclibc.org/lists/busybox/2003-July/008813.html
  14  */
  15 //config:config TAC
  16 //config:       bool "tac (4.1 kb)"
  17 //config:       default y
  18 //config:       help
  19 //config:       tac is used to concatenate and print files in reverse.
  20
  21 //applet:IF_TAC(APPLET_NOEXEC(tac, tac, BB_DIR_USR_BIN, BB_SUID_DROP, tac))
  22
  23 //kbuild:lib-$(CONFIG_TAC) += tac.o
  24
  25 //usage:#define tac_trivial_usage
  26 //usage:        "[FILE]..."
  27 //usage:#define tac_full_usage "\n\n"
  28 //usage:        "Concatenate FILEs and print them in reverse"
  29
  30 #include "libbb.h"
  31
  32 /* This is a NOEXEC applet. Be very careful! */
  33
  34 struct lstring {
  35         int size;
  36         char buf[1];
  37 };
  38
  39 int tac_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  40 int tac_main(int argc UNUSED_PARAM, char **argv)
  41 {
  42         char **name;
  43         FILE *f;
  44         struct lstring *line = NULL;
  45         llist_t *list = NULL;
  46         int retval = EXIT_SUCCESS;
  47
  48 #if ENABLE_DESKTOP
  49 /* tac from coreutils 6.9 supports:
  50        -b, --before
  51               attach the separator before instead of after
  52        -r, --regex
  53               interpret the separator as a regular expression
  54        -s, --separator=STRING
  55               use STRING as the separator instead of newline
  56 We support none, but at least we will complain or handle "--":
  57 */
  58         getopt32(argv, "");
  59         argv += optind;
  60 #else
  61         argv++;
  62 #endif
  63         if (!*argv)
  64                 *--argv = (char *)"-";
  65         /* We will read from last file to first */
  66         name = argv;
  67         while (*name)
  68                 name++;
  69
  70         do {
  71                 int ch, i;
  72
  73                 name--;
  74                 f = fopen_or_warn_stdin(*name);
  75                 if (f == NULL) {
  76                         /* error message is printed by fopen_or_warn_stdin */
  77                         retval = EXIT_FAILURE;
  78                         continue;
  79                 }
  80
  81                 errno = i = 0;
  82                 do {
  83                         ch = fgetc(f);
  84                         if (ch != EOF) {
  85                                 if (!(i & 0x7f))
  86                                         /* Grow on every 128th char */
  87                                         line = xrealloc(line, i + 0x7f + sizeof(int) + 1);
  88                                 line->buf[i++] = ch;
  89                         }
  90                         if (ch == '\n' || (ch == EOF && i != 0)) {
  91                                 line = xrealloc(line, i + sizeof(int));
  92                                 line->size = i;
  93                                 llist_add_to(&list, line);
  94                                 line = NULL;
  95                                 i = 0;
  96                         }
  97                 } while (ch != EOF);
  98                 /* fgetc sets errno to ENOENT on EOF, we don't want
  99                  * to warn on this non-error! */
 100                 if (errno && errno != ENOENT) {
 101                         bb_simple_perror_msg(*name);
 102                         retval = EXIT_FAILURE;
 103                 }
 104         } while (name != argv);
 105
 106         while (list) {
 107                 line = (struct lstring *)list->data;
 108                 xwrite(STDOUT_FILENO, line->buf, line->size);
 109                 if (ENABLE_FEATURE_CLEAN_UP) {
 110                         free(llist_pop(&list));
 111                 } else {
 112                         list = list->link;
 113                 }
 114         }
 115
 116         return retval;
 117 }