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 //config:config REV
   9 //config:       bool "rev (4.5 kb)"
  10 //config:       default y
  11 //config:       help
  12 //config:       Reverse lines of a file or files.
  13
  14 //applet:IF_REV(APPLET(rev, BB_DIR_BIN, BB_SUID_DROP))
  15
  16 //kbuild:lib-$(CONFIG_REV) += rev.o
  17
  18 //usage:#define rev_trivial_usage
  19 //usage:        "[FILE]..."
  20 //usage:#define rev_full_usage "\n\n"
  21 //usage:        "Reverse lines of FILE"
  22
  23 #include "libbb.h"
  24 #include "unicode.h"
  25
  26 #undef CHAR_T
  27 #if ENABLE_UNICODE_SUPPORT
  28 # define CHAR_T wchar_t
  29 #else
  30 # define CHAR_T char
  31 #endif
  32
  33 /* In-place invert */
  34 static void strrev(CHAR_T *s, int len)
  35 {
  36         int i;
  37
  38         if (len != 0) {
  39                 len--;
  40                 if (len != 0 && s[len] == '\n')
  41                         len--;
  42         }
  43
  44         for (i = 0; i < len; i++, len--) {
  45                 CHAR_T c = s[i];
  46                 s[i] = s[len];
  47                 s[len] = c;
  48         }
  49 }
  50
  51 int rev_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  52 int rev_main(int argc UNUSED_PARAM, char **argv)
  53 {
  54         int retval;
  55         size_t bufsize;
  56         char *buf;
  57
  58         init_unicode();
  59
  60         getopt32(argv, "");
  61         argv += optind;
  62         if (!argv[0])
  63                 argv = (char **)&bb_argv_dash;
  64
  65         retval = EXIT_SUCCESS;
  66         bufsize = 256;
  67         buf = xmalloc(bufsize);
  68         do {
  69                 size_t pos;
  70                 FILE *fp;
  71
  72                 fp = fopen_or_warn_stdin(*argv++);
  73                 if (!fp) {
  74                         retval = EXIT_FAILURE;
  75                         continue;
  76                 }
  77
  78                 pos = 0;
  79                 while (1) {
  80                         /* Read one line */
  81                         buf[bufsize - 1] = 1; /* not 0 */
  82                         if (!fgets(buf + pos, bufsize - pos, fp))
  83                                 break; /* EOF/error */
  84                         if (buf[bufsize - 1] == '\0' /* fgets filled entire buffer */
  85                          && buf[bufsize - 2] != '\n' /* and did not read '\n' */
  86                          && !feof(fp)
  87                         ) {
  88                                 /* Line is too long, extend buffer */
  89                                 pos = bufsize - 1;
  90                                 bufsize += 64 + bufsize / 8;
  91                                 buf = xrealloc(buf, bufsize);
  92                                 continue;
  93                         }
  94
  95                         /* Process and print it */
  96 #if ENABLE_UNICODE_SUPPORT
  97                         {
  98                                 wchar_t *tmp = xmalloc(bufsize * sizeof(wchar_t));
  99                                 /* Convert to wchar_t (might error out!) */
 100                                 int len  = mbstowcs(tmp, buf, bufsize);
 101                                 if (len >= 0) {
 102                                         strrev(tmp, len);
 103                                         /* Convert back to char */
 104                                         wcstombs(buf, tmp, bufsize);
 105                                 }
 106                                 free(tmp);
 107                         }
 108 #else
 109                         strrev(buf, strlen(buf));
 110 #endif
 111                         fputs(buf, stdout);
 112                 }
 113                 fclose(fp);
 114         } while (*argv);
 115
 116         if (ENABLE_FEATURE_CLEAN_UP)
 117                 free(buf);
 118
 119         fflush_stdout_and_exit(retval);
 120 }