105 lines
2.8 KiB
C++
105 lines
2.8 KiB
C++
/*
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* Copyright (c) Facebook, Inc. and its affiliates.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <folly/lang/CString.h>
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#include <algorithm>
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#include <cstring>
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#include <type_traits>
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#include <folly/CppAttributes.h>
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#include <folly/functional/Invoke.h>
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namespace {
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struct poison {};
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FOLLY_MAYBE_UNUSED FOLLY_ERASE void memrchr(poison) noexcept {}
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} // namespace
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namespace folly {
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namespace detail {
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void* memrchr_fallback(void* s, int c, std::size_t len) noexcept {
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return const_cast<void*>(
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memrchr_fallback(const_cast<void const*>(s), c, len));
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}
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void const* memrchr_fallback(void const* s, int c, std::size_t len) noexcept {
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auto const ss = static_cast<unsigned char const*>(s);
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for (auto it = ss + len - 1; it >= ss; --it) {
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if (*it == static_cast<unsigned char>(c)) {
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return it;
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}
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}
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return nullptr;
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}
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} // namespace detail
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namespace c_string_detail {
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struct invoke_fallback_memrchr_fn {
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template <typename... A>
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FOLLY_MAYBE_UNUSED FOLLY_ERASE auto operator()(A... a) const noexcept
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-> decltype(detail::memrchr_fallback(a...)) {
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return detail::memrchr_fallback(a...);
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}
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};
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struct invoke_primary_memrchr_fn {
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template <typename... A>
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FOLLY_MAYBE_UNUSED FOLLY_ERASE auto operator()(A... a) const noexcept
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-> decltype(::memrchr(a...)) {
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return ::memrchr(a...);
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}
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};
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} // namespace c_string_detail
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namespace {
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template <typename... A>
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using invoke_memrchr_fn = conditional_t<
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is_invocable_v<c_string_detail::invoke_primary_memrchr_fn, A...>,
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c_string_detail::invoke_primary_memrchr_fn,
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c_string_detail::invoke_fallback_memrchr_fn>;
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template <typename... A>
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constexpr invoke_memrchr_fn<A...> invoke_memrchr{};
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} // namespace
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void* memrchr(void* s, int c, std::size_t len) noexcept {
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return invoke_memrchr<void*, int, std::size_t>(s, c, len);
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}
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void const* memrchr(void const* s, int c, std::size_t len) noexcept {
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return invoke_memrchr<void const*, int, std::size_t>(s, c, len);
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}
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std::size_t strlcpy(
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char* const dest, char const* const src, std::size_t const size) {
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std::size_t const len = std::strlen(src);
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if (size != 0) {
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std::size_t const n = std::min(len, size - 1); // always null terminate!
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std::memcpy(dest, src, n);
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dest[n] = '\0';
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}
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return len;
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}
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} // namespace folly
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