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