| //===----------------------------------------------------------------------===// |
| // |
| // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| // See https://llvm.org/LICENSE.txt for license information. |
| // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include <cwchar> // mbstate_t |
| #include <limits.h> // MB_LEN_MAX |
| #include <stdlib.h> // MB_CUR_MAX, size_t |
| #include <string.h> // memcpy |
| |
| // Converts `max_source_chars` from the wide character buffer pointer to by *`src`, |
| // into the multi byte character sequence buffer stored at `dst`, which must be |
| // `dst_size_bytes` bytes in size. Returns the number of bytes in the sequence |
| // converted from *src, excluding the null terminator. |
| // Returns (size_t) -1 if an error occurs and sets errno. |
| // If `dst` is NULL, `dst_size_bytes` is ignored and no bytes are copied to `dst`. |
| _LIBCPP_FUNC_VIS |
| size_t wcsnrtombs(char *__restrict dst, const wchar_t **__restrict src, |
| size_t max_source_chars, size_t dst_size_bytes, |
| mbstate_t *__restrict ps) { |
| |
| const size_t invalid_wchar = static_cast<size_t>(-1); |
| |
| size_t source_converted; |
| size_t dest_converted; |
| size_t result = 0; |
| |
| // If `dst` is null then `dst_size_bytes` should be ignored according to the |
| // standard. Setting dst_size_bytes to a large value has this effect. |
| if (dst == nullptr) |
| dst_size_bytes = static_cast<size_t>(-1); |
| |
| for (dest_converted = source_converted = 0; |
| source_converted < max_source_chars && (!dst || dest_converted < dst_size_bytes); |
| ++source_converted, dest_converted += result) { |
| wchar_t c = (*src)[source_converted]; |
| size_t dest_remaining = dst_size_bytes - dest_converted; |
| |
| if (dst == nullptr) { |
| result = wcrtomb(NULL, c, ps); |
| } else if (dest_remaining >= static_cast<size_t>(MB_CUR_MAX)) { |
| // dst has enough space to translate in-place. |
| result = wcrtomb(dst + dest_converted, c, ps); |
| } else { |
| /* |
| * dst may not have enough space, so use a temporary buffer. |
| * |
| * We need to save a copy of the conversion state |
| * here so we can restore it if the multibyte |
| * character is too long for the buffer. |
| */ |
| char buff[MB_LEN_MAX]; |
| mbstate_t mbstate_tmp; |
| |
| if (ps != nullptr) |
| mbstate_tmp = *ps; |
| result = wcrtomb(buff, c, ps); |
| |
| if (result > dest_remaining) { |
| // Multi-byte sequence for character won't fit. |
| if (ps != nullptr) |
| *ps = mbstate_tmp; |
| if (result != invalid_wchar) |
| break; |
| } else { |
| // The buffer was used, so we need copy the translation to dst. |
| memcpy(dst, buff, result); |
| } |
| } |
| |
| // result (char_size) contains the size of the multi-byte-sequence converted. |
| // Otherwise, result (char_size) is (size_t) -1 and wcrtomb() sets the errno. |
| if (result == invalid_wchar) { |
| if (dst) |
| *src = *src + source_converted; |
| return invalid_wchar; |
| } |
| |
| if (c == L'\0') { |
| if (dst) |
| *src = NULL; |
| return dest_converted; |
| } |
| } |
| |
| if (dst) |
| *src = *src + source_converted; |
| |
| return dest_converted; |
| } |