1/* Multibyte to UTF-8 conversion.
2 Copyright (C) 2022-2023 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <https://www.gnu.org/licenses/>. */
18
19#include <assert.h>
20#include <dlfcn.h>
21#include <errno.h>
22#include <gconv.h>
23#include <uchar.h>
24#include <wcsmbsload.h>
25
26#ifndef EILSEQ
27# define EILSEQ EINVAL
28#endif
29
30
31/* This is the private state used if PS is NULL. */
32static mbstate_t state;
33
34size_t
35mbrtoc8 (char8_t *pc8, const char *s, size_t n, mbstate_t *ps)
36{
37 /* This implementation depends on the converter invoked by mbrtowc not
38 needing to retain state in either the top most bit of ps->__count or
39 in ps->__value between invocations. This implementation uses the
40 top most bit of ps->__count to indicate that trailing code units are
41 yet to be written and uses ps->__value to store those code units. */
42
43 if (ps == NULL)
44 ps = &state;
45
46 /* If state indicates that trailing code units are yet to be written, write
47 those first regardless of whether 's' is a null pointer. */
48 if (ps->__count & 0x80000000)
49 {
50 /* ps->__value.__wchb[3] stores the index of the next code unit to
51 write. Code units are stored in reverse order. */
52 size_t i = ps->__value.__wchb[3];
53 if (pc8 != NULL)
54 {
55 *pc8 = ps->__value.__wchb[i];
56 }
57 if (i == 0)
58 {
59 ps->__count &= 0x7fffffff;
60 ps->__value.__wch = 0;
61 }
62 else
63 --ps->__value.__wchb[3];
64 return -3;
65 }
66
67 if (s == NULL)
68 {
69 /* if 's' is a null pointer, behave as if a null pointer was passed for
70 'pc8', an empty string was passed for 's', and 1 passed for 'n'. */
71 pc8 = NULL;
72 s = "";
73 n = 1;
74 }
75
76 wchar_t wc;
77 size_t result;
78
79 result = mbrtowc (&wc, s, n, ps);
80 if (result <= n)
81 {
82 if (wc <= 0x7F)
83 {
84 if (pc8 != NULL)
85 *pc8 = wc;
86 }
87 else if (wc <= 0x7FF)
88 {
89 if (pc8 != NULL)
90 *pc8 = 0xC0 + ((wc >> 6) & 0x1F);
91 ps->__value.__wchb[0] = 0x80 + (wc & 0x3F);
92 ps->__value.__wchb[3] = 0;
93 ps->__count |= 0x80000000;
94 }
95 else if (wc <= 0xFFFF)
96 {
97 if (pc8 != NULL)
98 *pc8 = 0xE0 + ((wc >> 12) & 0x0F);
99 ps->__value.__wchb[1] = 0x80 + ((wc >> 6) & 0x3F);
100 ps->__value.__wchb[0] = 0x80 + (wc & 0x3F);
101 ps->__value.__wchb[3] = 1;
102 ps->__count |= 0x80000000;
103 }
104 else if (wc <= 0x10FFFF)
105 {
106 if (pc8 != NULL)
107 *pc8 = 0xF0 + ((wc >> 18) & 0x07);
108 ps->__value.__wchb[2] = 0x80 + ((wc >> 12) & 0x3F);
109 ps->__value.__wchb[1] = 0x80 + ((wc >> 6) & 0x3F);
110 ps->__value.__wchb[0] = 0x80 + (wc & 0x3F);
111 ps->__value.__wchb[3] = 2;
112 ps->__count |= 0x80000000;
113 }
114 }
115 if (result == 0 && wc != 0)
116 {
117 /* mbrtowc() never returns -3. When a MB sequence converts to multiple
118 WCs, no input is consumed when writing the subsequent WCs resulting
119 in a result of 0 even if a null character wasn't written. */
120 result = -3;
121 }
122
123 return result;
124}
125