util-linux/rev.c

   1 /*
   2  * rev implementation for busybox
   3  *
   4  * Copyright (C) 2010 Marek Polacek <mmpolacek@gmail.com>
   5  *
   6  * Licensed under GPLv2, see file LICENSE in this source tree.
   7  */
   8
   9 //applet:IF_REV(APPLET(rev, BB_DIR_BIN, BB_SUID_DROP))
  10
  11 //kbuild:lib-$(CONFIG_REV) += rev.o
  12
  13 //config:config REV
  14 //config:       bool "rev"
  15 //config:       default y
  16 //config:       help
  17 //config:         Reverse lines of a file or files.
  18
  19 //usage:#define rev_trivial_usage
  20 //usage:        "[FILE]..."
  21 //usage:#define rev_full_usage "\n\n"
  22 //usage:        "Reverse lines of FILE"
  23
  24 #include "libbb.h"
  25 #include "unicode.h"
  26
  27 #undef CHAR_T
  28 #if ENABLE_UNICODE_SUPPORT
  29 # define CHAR_T wchar_t
  30 #else
  31 # define CHAR_T char
  32 #endif
  33
  34 /* In-place invert */
  35 static void strrev(CHAR_T *s, int len)
  36 {
  37         int i;
  38
  39         if (len != 0) {
  40                 len--;
  41                 if (len != 0 && s[len] == '\n')
  42                         len--;
  43         }
  44
  45         for (i = 0; i < len; i++, len--) {
  46                 CHAR_T c = s[i];
  47                 s[i] = s[len];
  48                 s[len] = c;
  49         }
  50 }
  51
  52 int rev_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  53 int rev_main(int argc UNUSED_PARAM, char **argv)
  54 {
  55         int retval;
  56         size_t bufsize;
  57         char *buf;
  58
  59         init_unicode();
  60
  61         getopt32(argv, "");
  62         argv += optind;
  63         if (!argv[0])
  64                 argv = (char **)&bb_argv_dash;
  65
  66         retval = EXIT_SUCCESS;
  67         bufsize = 256;
  68         buf = xmalloc(bufsize);
  69         do {
  70                 size_t pos;
  71                 FILE *fp;
  72
  73                 fp = fopen_or_warn_stdin(*argv++);
  74                 if (!fp) {
  75                         retval = EXIT_FAILURE;
  76                         continue;
  77                 }
  78
  79                 pos = 0;
  80                 while (1) {
  81                         /* Read one line */
  82                         buf[bufsize - 1] = 1; /* not 0 */
  83                         if (!fgets(buf + pos, bufsize - pos, fp))
  84                                 break; /* EOF/error */
  85                         if (buf[bufsize - 1] == '\0' /* fgets filled entire buffer */
  86                          && buf[bufsize - 2] != '\n' /* and did not read '\n' */
  87                          && !feof(fp)
  88                         ) {
  89                                 /* Line is too long, extend buffer */
  90                                 pos = bufsize - 1;
  91                                 bufsize += 64 + bufsize / 8;
  92                                 buf = xrealloc(buf, bufsize);
  93                                 continue;
  94                         }
  95
  96                         /* Process and print it */
  97 #if ENABLE_UNICODE_SUPPORT
  98                         {
  99                                 wchar_t *tmp = xmalloc(bufsize * sizeof(wchar_t));
 100                                 /* Convert to wchar_t (might error out!) */
 101                                 int len  = mbstowcs(tmp, buf, bufsize);
 102                                 if (len >= 0) {
 103                                         strrev(tmp, len);
 104                                         /* Convert back to char */
 105                                         wcstombs(buf, tmp, bufsize);
 106                                 }
 107                                 free(tmp);
 108                         }
 109 #else
 110                         strrev(buf, strlen(buf));
 111 #endif
 112                         fputs(buf, stdout);
 113                 }
 114                 fclose(fp);
 115         } while (*argv);
 116
 117         if (ENABLE_FEATURE_CLEAN_UP)
 118                 free(buf);
 119
 120         fflush_stdout_and_exit(retval);
 121 }