summaryrefslogtreecommitdiff
path: root/lib/unistr/u32-to-u8.c
blob: dc45b5ce8547159730eea628f8450e604b506bb5 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
/* Convert UTF-32 string to UTF-8 string.
   Copyright (C) 2002, 2006-2007, 2009-2018 Free Software Foundation, Inc.
   Written by Bruno Haible <bruno@clisp.org>, 2002.

   This program is free software: you can redistribute it and/or
   modify it under the terms of either:

     * the GNU Lesser General Public License as published by the Free
       Software Foundation; either version 3 of the License, or (at your
       option) any later version.

   or

     * the GNU General Public License as published by the Free
       Software Foundation; either version 2 of the License, or (at your
       option) any later version.

   or both in parallel, as here.
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public License
   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */

#include <config.h>

/* Specification.  */
#include "unistr.h"

#define FUNC u32_to_u8
#define SRC_UNIT uint32_t
#define DST_UNIT uint8_t

#include <errno.h>
#include <stdlib.h>
#include <string.h>

DST_UNIT *
FUNC (const SRC_UNIT *s, size_t n, DST_UNIT *resultbuf, size_t *lengthp)
{
  const SRC_UNIT *s_end = s + n;
  /* Output string accumulator.  */
  DST_UNIT *result;
  size_t allocated;
  size_t length;

  if (resultbuf != NULL)
    {
      result = resultbuf;
      allocated = *lengthp;
    }
  else
    {
      result = NULL;
      allocated = 0;
    }
  length = 0;
  /* Invariants:
     result is either == resultbuf or == NULL or malloc-allocated.
     If length > 0, then result != NULL.  */

  while (s < s_end)
    {
      ucs4_t uc;
      int count;

      /* Fetch a Unicode character from the input string.  */
      uc = *s++;
      /* No need to call the safe variant u32_mbtouc, because
         u8_uctomb will verify uc anyway.  */

      /* Store it in the output string.  */
      count = u8_uctomb (result + length, uc, allocated - length);
      if (count == -1)
        {
          if (!(result == resultbuf || result == NULL))
            free (result);
          errno = EILSEQ;
          return NULL;
        }
      if (count == -2)
        {
          DST_UNIT *memory;

          allocated = (allocated > 0 ? 2 * allocated : 12);
          if (length + 6 > allocated)
            allocated = length + 6;
          if (result == resultbuf || result == NULL)
            memory = (DST_UNIT *) malloc (allocated * sizeof (DST_UNIT));
          else
            memory =
              (DST_UNIT *) realloc (result, allocated * sizeof (DST_UNIT));

          if (memory == NULL)
            {
              if (!(result == resultbuf || result == NULL))
                free (result);
              errno = ENOMEM;
              return NULL;
            }
          if (result == resultbuf && length > 0)
            memcpy ((char *) memory, (char *) result,
                    length * sizeof (DST_UNIT));
          result = memory;
          count = u8_uctomb (result + length, uc, allocated - length);
          if (count < 0)
            abort ();
        }
      length += count;
    }

  if (length == 0)
    {
      if (result == NULL)
        {
          /* Return a non-NULL value.  NULL means error.  */
          result = (DST_UNIT *) malloc (1);
          if (result == NULL)
            {
              errno = ENOMEM;
              return NULL;
            }
        }
    }
  else if (result != resultbuf && length < allocated)
    {
      /* Shrink the allocated memory if possible.  */
      DST_UNIT *memory;

      memory = (DST_UNIT *) realloc (result, length * sizeof (DST_UNIT));
      if (memory != NULL)
        result = memory;
    }

  *lengthp = length;
  return result;
}