89 lines
2.6 KiB
C++
89 lines
2.6 KiB
C++
// Copyright 2020 The Abseil Authors.
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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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// https://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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#include "absl/base/internal/strerror.h"
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#include <array>
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#include <cerrno>
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#include <cstddef>
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#include <cstdio>
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#include <cstring>
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#include <string>
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#include <type_traits>
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#include "absl/base/internal/errno_saver.h"
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namespace absl {
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ABSL_NAMESPACE_BEGIN
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namespace base_internal {
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namespace {
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const char* StrErrorAdaptor(int errnum, char* buf, size_t buflen) {
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#if defined(_WIN32)
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int rc = strerror_s(buf, buflen, errnum);
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buf[buflen - 1] = '\0'; // guarantee NUL termination
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if (rc == 0 && strncmp(buf, "Unknown error", buflen) == 0) *buf = '\0';
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return buf;
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#else
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// The type of `ret` is platform-specific; both of these branches must compile
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// either way but only one will execute on any given platform:
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auto ret = strerror_r(errnum, buf, buflen);
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if (std::is_same<decltype(ret), int>::value) {
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// XSI `strerror_r`; `ret` is `int`:
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if (ret) *buf = '\0';
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return buf;
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} else {
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// GNU `strerror_r`; `ret` is `char *`:
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return reinterpret_cast<const char*>(ret);
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}
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#endif
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}
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std::string StrErrorInternal(int errnum) {
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char buf[100];
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const char* str = StrErrorAdaptor(errnum, buf, sizeof buf);
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if (*str == '\0') {
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snprintf(buf, sizeof buf, "Unknown error %d", errnum);
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str = buf;
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}
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return str;
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}
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// kSysNerr is the number of errors from a recent glibc. `StrError()` falls back
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// to `StrErrorAdaptor()` if the value is larger than this.
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constexpr int kSysNerr = 135;
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std::array<std::string, kSysNerr>* NewStrErrorTable() {
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auto* table = new std::array<std::string, kSysNerr>;
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for (int i = 0; i < static_cast<int>(table->size()); ++i) {
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(*table)[i] = StrErrorInternal(i);
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}
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return table;
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}
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} // namespace
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std::string StrError(int errnum) {
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absl::base_internal::ErrnoSaver errno_saver;
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static const auto* table = NewStrErrorTable();
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if (errnum >= 0 && errnum < static_cast<int>(table->size())) {
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return (*table)[errnum];
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}
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return StrErrorInternal(errnum);
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}
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} // namespace base_internal
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ABSL_NAMESPACE_END
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} // namespace absl
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