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156ab87500
See: * https://discourse.llvm.org/t/rfc-freezing-c-03-headers-in-libc/77319 * https://discourse.llvm.org/t/rfc-project-hand-in-hand-llvm-libc-libc-code-sharing/77701 We're dropping support for C++03 for Zig due to the first change; it would be insane to ship 1018 duplicate header files just for this outdated use case. As a result of the second change, I had to bring in a subset of the headers from llvm-libc since libc++ now depends on these. Hopefully we can continue to get away with not copying the entirety of llvm-libc.
94 lines
3.2 KiB
C++
Vendored
94 lines
3.2 KiB
C++
Vendored
//===----------------------------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include <cwchar> // mbstate_t
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#include <limits.h> // MB_LEN_MAX
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#include <stdlib.h> // MB_CUR_MAX, size_t
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#include <string.h> // memcpy
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// Converts `max_source_chars` from the wide character buffer pointer to by *`src`,
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// into the multi byte character sequence buffer stored at `dst`, which must be
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// `dst_size_bytes` bytes in size. Returns the number of bytes in the sequence
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// converted from *src, excluding the null terminator.
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// Returns (size_t) -1 if an error occurs and sets errno.
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// If `dst` is NULL, `dst_size_bytes` is ignored and no bytes are copied to `dst`.
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_LIBCPP_EXPORTED_FROM_ABI size_t wcsnrtombs(
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char* __restrict dst,
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const wchar_t** __restrict src,
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size_t max_source_chars,
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size_t dst_size_bytes,
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mbstate_t* __restrict ps) {
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const size_t invalid_wchar = static_cast<size_t>(-1);
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size_t source_converted;
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size_t dest_converted;
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size_t result = 0;
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// If `dst` is null then `dst_size_bytes` should be ignored according to the
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// standard. Setting dst_size_bytes to a large value has this effect.
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if (dst == nullptr)
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dst_size_bytes = static_cast<size_t>(-1);
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for (dest_converted = source_converted = 0;
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source_converted < max_source_chars && (!dst || dest_converted < dst_size_bytes);
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++source_converted, dest_converted += result) {
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wchar_t c = (*src)[source_converted];
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size_t dest_remaining = dst_size_bytes - dest_converted;
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if (dst == nullptr) {
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result = wcrtomb(nullptr, c, ps);
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} else if (dest_remaining >= static_cast<size_t>(MB_CUR_MAX)) {
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// dst has enough space to translate in-place.
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result = wcrtomb(dst + dest_converted, c, ps);
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} else {
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/*
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* dst may not have enough space, so use a temporary buffer.
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*
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* We need to save a copy of the conversion state
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* here so we can restore it if the multibyte
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* character is too long for the buffer.
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*/
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char buff[MB_LEN_MAX];
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mbstate_t mbstate_tmp;
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if (ps != nullptr)
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mbstate_tmp = *ps;
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result = wcrtomb(buff, c, ps);
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if (result > dest_remaining) {
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// Multi-byte sequence for character won't fit.
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if (ps != nullptr)
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*ps = mbstate_tmp;
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if (result != invalid_wchar)
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break;
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} else {
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// The buffer was used, so we need copy the translation to dst.
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memcpy(dst, buff, result);
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}
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}
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// result (char_size) contains the size of the multi-byte-sequence converted.
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// Otherwise, result (char_size) is (size_t) -1 and wcrtomb() sets the errno.
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if (result == invalid_wchar) {
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if (dst)
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*src = *src + source_converted;
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return invalid_wchar;
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}
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if (c == L'\0') {
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if (dst)
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*src = nullptr;
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return dest_converted;
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}
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}
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if (dst)
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*src = *src + source_converted;
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return dest_converted;
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}
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