1 /*
2 * Copyright (c) Facebook, Inc. and its affiliates.
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #include <folly/lang/CString.h>
18
19 #include <algorithm>
20 #include <cstring>
21 #include <type_traits>
22
23 #include <folly/CppAttributes.h>
24 #include <folly/functional/Invoke.h>
25
26 namespace {
27
28 struct poison {};
29
memrchr(poison)30 FOLLY_MAYBE_UNUSED FOLLY_ERASE void memrchr(poison) noexcept {}
31
32 } // namespace
33
34 namespace folly {
35
36 namespace detail {
37
memrchr_fallback(void * s,int c,std::size_t len)38 void* memrchr_fallback(void* s, int c, std::size_t len) noexcept {
39 return const_cast<void*>(
40 memrchr_fallback(const_cast<void const*>(s), c, len));
41 }
42
memrchr_fallback(void const * s,int c,std::size_t len)43 void const* memrchr_fallback(void const* s, int c, std::size_t len) noexcept {
44 auto const ss = static_cast<unsigned char const*>(s);
45 for (auto it = ss + len - 1; it >= ss; --it) {
46 if (*it == static_cast<unsigned char>(c)) {
47 return it;
48 }
49 }
50 return nullptr;
51 }
52
53 } // namespace detail
54
55 namespace c_string_detail {
56
57 struct invoke_fallback_memrchr_fn {
58 template <typename... A>
operator ()folly::c_string_detail::invoke_fallback_memrchr_fn59 FOLLY_MAYBE_UNUSED FOLLY_ERASE auto operator()(A... a) const noexcept
60 -> decltype(detail::memrchr_fallback(a...)) {
61 return detail::memrchr_fallback(a...);
62 }
63 };
64 struct invoke_primary_memrchr_fn {
65 template <typename... A>
operator ()folly::c_string_detail::invoke_primary_memrchr_fn66 FOLLY_MAYBE_UNUSED FOLLY_ERASE auto operator()(A... a) const noexcept
67 -> decltype(::memrchr(a...)) {
68 return ::memrchr(a...);
69 }
70 };
71
72 } // namespace c_string_detail
73
74 namespace {
75
76 template <typename... A>
77 using invoke_memrchr_fn = conditional_t<
78 is_invocable_v<c_string_detail::invoke_primary_memrchr_fn, A...>,
79 c_string_detail::invoke_primary_memrchr_fn,
80 c_string_detail::invoke_fallback_memrchr_fn>;
81 template <typename... A>
82 constexpr invoke_memrchr_fn<A...> invoke_memrchr{};
83
84 } // namespace
85
memrchr(void * s,int c,std::size_t len)86 void* memrchr(void* s, int c, std::size_t len) noexcept {
87 return invoke_memrchr<void*, int, std::size_t>(s, c, len);
88 }
memrchr(void const * s,int c,std::size_t len)89 void const* memrchr(void const* s, int c, std::size_t len) noexcept {
90 return invoke_memrchr<void const*, int, std::size_t>(s, c, len);
91 }
92
strlcpy(char * const dest,char const * const src,std::size_t const size)93 std::size_t strlcpy(
94 char* const dest, char const* const src, std::size_t const size) {
95 std::size_t const len = std::strlen(src);
96 if (size != 0) {
97 std::size_t const n = std::min(len, size - 1); // always null terminate!
98 std::memcpy(dest, src, n);
99 dest[n] = '\0';
100 }
101 return len;
102 }
103
104 } // namespace folly
105