root/maint/gnulib/lib/unistr/u16-to-u8.c

/* */

DEFINITIONS

1. FUNC

   1 /* Convert UTF-16 string to UTF-8 string.
   2    Copyright (C) 2002, 2006-2007, 2009-2021 Free Software Foundation, Inc.
   3    Written by Bruno Haible <bruno@clisp.org>, 2002.
   4 
   5    This file is free software.
   6    It is dual-licensed under "the GNU LGPLv3+ or the GNU GPLv2+".
   7    You can redistribute it and/or modify it under either
   8      - the terms of the GNU Lesser General Public License as published
   9        by the Free Software Foundation; either version 3, or (at your
  10        option) any later version, or
  11      - the terms of the GNU General Public License as published by the
  12        Free Software Foundation; either version 2, or (at your option)
  13        any later version, or
  14      - the same dual license "the GNU LGPLv3+ or the GNU GPLv2+".
  15 
  16    This file is distributed in the hope that it will be useful,
  17    but WITHOUT ANY WARRANTY; without even the implied warranty of
  18    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  19    Lesser General Public License and the GNU General Public License
  20    for more details.
  21 
  22    You should have received a copy of the GNU Lesser General Public
  23    License and of the GNU General Public License along with this
  24    program.  If not, see <https://www.gnu.org/licenses/>.  */
  25 
  26 #include <config.h>
  27 
  28 /* Specification.  */
  29 #include "unistr.h"
  30 
  31 #define FUNC u16_to_u8
  32 #define SRC_UNIT uint16_t
  33 #define DST_UNIT uint8_t
  34 
  35 #include <errno.h>
  36 #include <stdlib.h>
  37 #include <string.h>
  38 
  39 DST_UNIT *
  40 FUNC (const SRC_UNIT *s, size_t n, DST_UNIT *resultbuf, size_t *lengthp)
     /*  */
  41 {
  42   const SRC_UNIT *s_end = s + n;
  43   /* Output string accumulator.  */
  44   DST_UNIT *result;
  45   size_t allocated;
  46   size_t length;
  47 
  48   if (resultbuf != NULL)
  49     {
  50       result = resultbuf;
  51       allocated = *lengthp;
  52     }
  53   else
  54     {
  55       result = NULL;
  56       allocated = 0;
  57     }
  58   length = 0;
  59   /* Invariants:
  60      result is either == resultbuf or == NULL or malloc-allocated.
  61      If length > 0, then result != NULL.  */
  62 
  63   while (s < s_end)
  64     {
  65       ucs4_t uc;
  66       int count;
  67 
  68       /* Fetch a Unicode character from the input string.  */
  69       count = u16_mbtoucr (&uc, s, s_end - s);
  70       if (count < 0)
  71         {
  72           if (!(result == resultbuf || result == NULL))
  73             free (result);
  74           errno = EILSEQ;
  75           return NULL;
  76         }
  77       s += count;
  78 
  79       /* Store it in the output string.  */
  80       count = u8_uctomb (result + length, uc, allocated - length);
  81       if (count == -1)
  82         {
  83           if (!(result == resultbuf || result == NULL))
  84             free (result);
  85           errno = EILSEQ;
  86           return NULL;
  87         }
  88       if (count == -2)
  89         {
  90           DST_UNIT *memory;
  91 
  92           allocated = (allocated > 0 ? 2 * allocated : 12);
  93           if (length + 6 > allocated)
  94             allocated = length + 6;
  95           if (result == resultbuf || result == NULL)
  96             memory = (DST_UNIT *) malloc (allocated * sizeof (DST_UNIT));
  97           else
  98             memory =
  99               (DST_UNIT *) realloc (result, allocated * sizeof (DST_UNIT));
 100 
 101           if (memory == NULL)
 102             {
 103               if (!(result == resultbuf || result == NULL))
 104                 free (result);
 105               errno = ENOMEM;
 106               return NULL;
 107             }
 108           if (result == resultbuf && length > 0)
 109             memcpy ((char *) memory, (char *) result,
 110                     length * sizeof (DST_UNIT));
 111           result = memory;
 112           count = u8_uctomb (result + length, uc, allocated - length);
 113           if (count < 0)
 114             abort ();
 115         }
 116       length += count;
 117     }
 118 
 119   if (length == 0)
 120     {
 121       if (result == NULL)
 122         {
 123           /* Return a non-NULL value.  NULL means error.  */
 124           result = (DST_UNIT *) malloc (1);
 125           if (result == NULL)
 126             {
 127               errno = ENOMEM;
 128               return NULL;
 129             }
 130         }
 131     }
 132   else if (result != resultbuf && length < allocated)
 133     {
 134       /* Shrink the allocated memory if possible.  */
 135       DST_UNIT *memory;
 136 
 137       memory = (DST_UNIT *) realloc (result, length * sizeof (DST_UNIT));
 138       if (memory != NULL)
 139         result = memory;
 140     }
 141 
 142   *lengthp = length;
 143   return result;
 144 }

/* */