coreutils/catv.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * cat -v implementation for busybox
   4  *
   5  * Copyright (C) 2006 Rob Landley <rob@landley.net>
   6  *
   7  * Licensed under GPLv2 or later, see file LICENSE in this source tree.
   8  */
   9
  10 /* See "Cat -v considered harmful" at
  11  * http://cm.bell-labs.com/cm/cs/doc/84/kp.ps.gz */
  12
  13 //usage:#define catv_trivial_usage
  14 //usage:       "[-etv] [FILE]..."
  15 //usage:#define catv_full_usage "\n\n"
  16 //usage:       "Display nonprinting characters as ^x or M-x\n"
  17 //usage:     "\n        -e      End each line with $"
  18 //usage:     "\n        -t      Show tabs as ^I"
  19 //usage:     "\n        -v      Don't use ^x or M-x escapes"
  20
  21 #include "libbb.h"
  22
  23 int catv_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  24 int catv_main(int argc UNUSED_PARAM, char **argv)
  25 {
  26         int retval = EXIT_SUCCESS;
  27         int fd;
  28         unsigned flags;
  29
  30         flags = getopt32(argv, "etv");
  31 #define CATV_OPT_e (1<<0)
  32 #define CATV_OPT_t (1<<1)
  33 #define CATV_OPT_v (1<<2)
  34         flags ^= CATV_OPT_v;
  35         argv += optind;
  36
  37         /* Read from stdin if there's nothing else to do. */
  38         if (!argv[0])
  39                 *--argv = (char*)"-";
  40         do {
  41                 fd = open_or_warn_stdin(*argv);
  42                 if (fd < 0) {
  43                         retval = EXIT_FAILURE;
  44                         continue;
  45                 }
  46                 for (;;) {
  47                         int i, res;
  48
  49 #define read_buf bb_common_bufsiz1
  50                         res = read(fd, read_buf, COMMON_BUFSIZE);
  51                         if (res < 0)
  52                                 retval = EXIT_FAILURE;
  53                         if (res < 1)
  54                                 break;
  55                         for (i = 0; i < res; i++) {
  56                                 unsigned char c = read_buf[i];
  57
  58                                 if (c > 126 && (flags & CATV_OPT_v)) {
  59                                         if (c == 127) {
  60                                                 printf("^?");
  61                                                 continue;
  62                                         }
  63                                         printf("M-");
  64                                         c -= 128;
  65                                 }
  66                                 if (c < 32) {
  67                                         if (c == 10) {
  68                                                 if (flags & CATV_OPT_e)
  69                                                         bb_putchar('$');
  70                                         } else if (flags & (c==9 ? CATV_OPT_t : CATV_OPT_v)) {
  71                                                 printf("^%c", c+'@');
  72                                                 continue;
  73                                         }
  74                                 }
  75                                 bb_putchar(c);
  76                         }
  77                 }
  78                 if (ENABLE_FEATURE_CLEAN_UP && fd)
  79                         close(fd);
  80         } while (*++argv);
  81
  82         fflush_stdout_and_exit(retval);
  83 }