1*4bdff4beSrobert //===----------------------------------------------------------------------===//
2*4bdff4beSrobert //
3*4bdff4beSrobert // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4*4bdff4beSrobert // See https://llvm.org/LICENSE.txt for license information.
5*4bdff4beSrobert // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6*4bdff4beSrobert //
7*4bdff4beSrobert //===----------------------------------------------------------------------===//
8*4bdff4beSrobert
9*4bdff4beSrobert #include <cwchar> // mbstate_t
10*4bdff4beSrobert #include <limits.h> // MB_LEN_MAX
11*4bdff4beSrobert #include <stdlib.h> // MB_CUR_MAX, size_t
12*4bdff4beSrobert #include <string.h> // memcpy
13*4bdff4beSrobert
14*4bdff4beSrobert // Converts `max_source_chars` from the wide character buffer pointer to by *`src`,
15*4bdff4beSrobert // into the multi byte character sequence buffer stored at `dst`, which must be
16*4bdff4beSrobert // `dst_size_bytes` bytes in size. Returns the number of bytes in the sequence
17*4bdff4beSrobert // converted from *src, excluding the null terminator.
18*4bdff4beSrobert // Returns (size_t) -1 if an error occurs and sets errno.
19*4bdff4beSrobert // If `dst` is NULL, `dst_size_bytes` is ignored and no bytes are copied to `dst`.
20*4bdff4beSrobert _LIBCPP_FUNC_VIS
wcsnrtombs(char * __restrict dst,const wchar_t ** __restrict src,size_t max_source_chars,size_t dst_size_bytes,mbstate_t * __restrict ps)21*4bdff4beSrobert size_t wcsnrtombs(char *__restrict dst, const wchar_t **__restrict src,
22*4bdff4beSrobert size_t max_source_chars, size_t dst_size_bytes,
23*4bdff4beSrobert mbstate_t *__restrict ps) {
24*4bdff4beSrobert
25*4bdff4beSrobert const size_t invalid_wchar = static_cast<size_t>(-1);
26*4bdff4beSrobert
27*4bdff4beSrobert size_t source_converted;
28*4bdff4beSrobert size_t dest_converted;
29*4bdff4beSrobert size_t result = 0;
30*4bdff4beSrobert
31*4bdff4beSrobert // If `dst` is null then `dst_size_bytes` should be ignored according to the
32*4bdff4beSrobert // standard. Setting dst_size_bytes to a large value has this effect.
33*4bdff4beSrobert if (dst == nullptr)
34*4bdff4beSrobert dst_size_bytes = static_cast<size_t>(-1);
35*4bdff4beSrobert
36*4bdff4beSrobert for (dest_converted = source_converted = 0;
37*4bdff4beSrobert source_converted < max_source_chars && (!dst || dest_converted < dst_size_bytes);
38*4bdff4beSrobert ++source_converted, dest_converted += result) {
39*4bdff4beSrobert wchar_t c = (*src)[source_converted];
40*4bdff4beSrobert size_t dest_remaining = dst_size_bytes - dest_converted;
41*4bdff4beSrobert
42*4bdff4beSrobert if (dst == nullptr) {
43*4bdff4beSrobert result = wcrtomb(NULL, c, ps);
44*4bdff4beSrobert } else if (dest_remaining >= static_cast<size_t>(MB_CUR_MAX)) {
45*4bdff4beSrobert // dst has enough space to translate in-place.
46*4bdff4beSrobert result = wcrtomb(dst + dest_converted, c, ps);
47*4bdff4beSrobert } else {
48*4bdff4beSrobert /*
49*4bdff4beSrobert * dst may not have enough space, so use a temporary buffer.
50*4bdff4beSrobert *
51*4bdff4beSrobert * We need to save a copy of the conversion state
52*4bdff4beSrobert * here so we can restore it if the multibyte
53*4bdff4beSrobert * character is too long for the buffer.
54*4bdff4beSrobert */
55*4bdff4beSrobert char buff[MB_LEN_MAX];
56*4bdff4beSrobert mbstate_t mbstate_tmp;
57*4bdff4beSrobert
58*4bdff4beSrobert if (ps != nullptr)
59*4bdff4beSrobert mbstate_tmp = *ps;
60*4bdff4beSrobert result = wcrtomb(buff, c, ps);
61*4bdff4beSrobert
62*4bdff4beSrobert if (result > dest_remaining) {
63*4bdff4beSrobert // Multi-byte sequence for character won't fit.
64*4bdff4beSrobert if (ps != nullptr)
65*4bdff4beSrobert *ps = mbstate_tmp;
66*4bdff4beSrobert if (result != invalid_wchar)
67*4bdff4beSrobert break;
68*4bdff4beSrobert } else {
69*4bdff4beSrobert // The buffer was used, so we need copy the translation to dst.
70*4bdff4beSrobert memcpy(dst, buff, result);
71*4bdff4beSrobert }
72*4bdff4beSrobert }
73*4bdff4beSrobert
74*4bdff4beSrobert // result (char_size) contains the size of the multi-byte-sequence converted.
75*4bdff4beSrobert // Otherwise, result (char_size) is (size_t) -1 and wcrtomb() sets the errno.
76*4bdff4beSrobert if (result == invalid_wchar) {
77*4bdff4beSrobert if (dst)
78*4bdff4beSrobert *src = *src + source_converted;
79*4bdff4beSrobert return invalid_wchar;
80*4bdff4beSrobert }
81*4bdff4beSrobert
82*4bdff4beSrobert if (c == L'\0') {
83*4bdff4beSrobert if (dst)
84*4bdff4beSrobert *src = NULL;
85*4bdff4beSrobert return dest_converted;
86*4bdff4beSrobert }
87*4bdff4beSrobert }
88*4bdff4beSrobert
89*4bdff4beSrobert if (dst)
90*4bdff4beSrobert *src = *src + source_converted;
91*4bdff4beSrobert
92*4bdff4beSrobert return dest_converted;
93*4bdff4beSrobert }
94