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 size_t wcsnrtombs( 21 char* __restrict dst, 22 const wchar_t** __restrict src, 23 size_t max_source_chars, 24 size_t dst_size_bytes, 25 mbstate_t* __restrict ps) { 26 const size_t invalid_wchar = static_cast<size_t>(-1); 27 28 size_t source_converted; 29 size_t dest_converted; 30 size_t result = 0; 31 32 // If `dst` is null then `dst_size_bytes` should be ignored according to the 33 // standard. Setting dst_size_bytes to a large value has this effect. 34 if (dst == nullptr) 35 dst_size_bytes = static_cast<size_t>(-1); 36 37 for (dest_converted = source_converted = 0; 38 source_converted < max_source_chars && (!dst || dest_converted < dst_size_bytes); 39 ++source_converted, dest_converted += result) { 40 wchar_t c = (*src)[source_converted]; 41 size_t dest_remaining = dst_size_bytes - dest_converted; 42 43 if (dst == nullptr) { 44 result = wcrtomb(NULL, c, ps); 45 } else if (dest_remaining >= static_cast<size_t>(MB_CUR_MAX)) { 46 // dst has enough space to translate in-place. 47 result = wcrtomb(dst + dest_converted, c, ps); 48 } else { 49 /* 50 * dst may not have enough space, so use a temporary buffer. 51 * 52 * We need to save a copy of the conversion state 53 * here so we can restore it if the multibyte 54 * character is too long for the buffer. 55 */ 56 char buff[MB_LEN_MAX]; 57 mbstate_t mbstate_tmp; 58 59 if (ps != nullptr) 60 mbstate_tmp = *ps; 61 result = wcrtomb(buff, c, ps); 62 63 if (result > dest_remaining) { 64 // Multi-byte sequence for character won't fit. 65 if (ps != nullptr) 66 *ps = mbstate_tmp; 67 if (result != invalid_wchar) 68 break; 69 } else { 70 // The buffer was used, so we need copy the translation to dst. 71 memcpy(dst, buff, result); 72 } 73 } 74 75 // result (char_size) contains the size of the multi-byte-sequence converted. 76 // Otherwise, result (char_size) is (size_t) -1 and wcrtomb() sets the errno. 77 if (result == invalid_wchar) { 78 if (dst) 79 *src = *src + source_converted; 80 return invalid_wchar; 81 } 82 83 if (c == L'\0') { 84 if (dst) 85 *src = NULL; 86 return dest_converted; 87 } 88 } 89 90 if (dst) 91 *src = *src + source_converted; 92 93 return dest_converted; 94 } 95