LXR 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 tarball for details.
  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
  23struct lstring {
  24        int size;
  25        char buf[1];
  26};
  27
  28int tac_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  29int 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
  45We 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}
 107