1  /* Charset handling for GNU tar.
       2  
       3     Copyright 2004-2023 Free Software Foundation, Inc.
       4  
       5     This file is part of GNU tar.
       6  
       7     GNU tar is free software; you can redistribute it and/or modify
       8     it under the terms of the GNU General Public License as published by
       9     the Free Software Foundation; either version 3 of the License, or
      10     (at your option) any later version.
      11  
      12     GNU tar is distributed in the hope that it will be useful,
      13     but WITHOUT ANY WARRANTY; without even the implied warranty of
      14     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      15     GNU General Public License for more details.
      16  
      17     You should have received a copy of the GNU General Public License
      18     along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
      19  
      20  #include <system.h>
      21  #include <quotearg.h>
      22  #include <localcharset.h>
      23  #include "common.h"
      24  #ifdef HAVE_ICONV_H
      25  # include <iconv.h>
      26  #endif
      27  
      28  #ifndef ICONV_CONST
      29  # define ICONV_CONST
      30  #endif
      31  
      32  #ifndef HAVE_ICONV
      33  
      34  # undef iconv_open
      35  # define iconv_open(tocode, fromcode) ((iconv_t) -1)
      36  
      37  # undef iconv
      38  # define iconv(cd, inbuf, inbytesleft, outbuf, outbytesleft) (errno = ENOSYS, (size_t) -1)
      39  
      40  # undef iconv_close
      41  # define iconv_close(cd) 0
      42  
      43  # undef iconv_t
      44  # define iconv_t int
      45  
      46  #endif
      47  
      48  
      49  
      50  
      51  static iconv_t conv_desc[2] = { (iconv_t) -1, (iconv_t) -1 };
      52  
      53  static iconv_t
      54  utf8_init (bool to_utf)
      55  {
      56    if (conv_desc[(int) to_utf] == (iconv_t) -1)
      57      {
      58        if (to_utf)
      59  	conv_desc[(int) to_utf] = iconv_open ("UTF-8", locale_charset ());
      60        else
      61  	conv_desc[(int) to_utf] = iconv_open (locale_charset (), "UTF-8");
      62      }
      63    return conv_desc[(int) to_utf];
      64  }
      65  
      66  bool
      67  utf8_convert (bool to_utf, char const *input, char **output)
      68  {
      69    char ICONV_CONST *ib;
      70    char *ob, *ret;
      71    size_t inlen;
      72    size_t outlen;
      73    iconv_t cd = utf8_init (to_utf);
      74  
      75    if (cd == 0)
      76      {
      77        *output = xstrdup (input);
      78        return true;
      79      }
      80    else if (cd == (iconv_t)-1)
      81      return false;
      82  
      83    inlen = strlen (input) + 1;
      84    outlen = inlen * MB_LEN_MAX + 1;
      85    ob = ret = xmalloc (outlen);
      86    ib = (char ICONV_CONST *) input;
      87    /* According to POSIX, "if iconv() encounters a character in the input
      88       buffer that is valid, but for which an identical character does not
      89       exist in the target codeset, iconv() shall perform an
      90       implementation-defined conversion on this character." It will "update
      91       the variables pointed to by the arguments to reflect the extent of the
      92       conversion and return the number of non-identical conversions performed".
      93       On error, it returns -1. 
      94       In other words, non-zero return always indicates failure, either because
      95       the input was not fully converted, or because it was converted in a
      96       non-reversible way.
      97     */
      98    if (iconv (cd, &ib, &inlen, &ob, &outlen) != 0)
      99      {
     100        free (ret);
     101        return false;
     102      }
     103    *ob = 0;
     104    *output = ret;
     105    return true;
     106  }
     107  
     108  
     109  bool
     110  string_ascii_p (char const *p)
     111  {
     112    for (; *p; p++)
     113      if (*p & ~0x7f)
     114        return false;
     115    return true;
     116  }