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// Copyright 2020 The Abseil Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include "absl/base/internal/strerror.h"
#include <array>
#include <cerrno>
#include <cstddef>
#include <cstdio>
#include <cstring>
#include <string>
#include <type_traits>
#include "absl/base/internal/errno_saver.h"
namespace absl {
ABSL_NAMESPACE_BEGIN
namespace base_internal {
namespace {
const char* StrErrorAdaptor(int errnum, char* buf, size_t buflen) {
#if defined(_WIN32)
int rc = strerror_s(buf, buflen, errnum);
buf[buflen - 1] = '\0'; // guarantee NUL termination
if (rc == 0 && strncmp(buf, "Unknown error", buflen) == 0) *buf = '\0';
return buf;
#else
// The type of `ret` is platform-specific; both of these branches must compile
// either way but only one will execute on any given platform:
auto ret = strerror_r(errnum, buf, buflen);
if (std::is_same<decltype(ret), int>::value) {
// XSI `strerror_r`; `ret` is `int`:
if (ret) *buf = '\0';
return buf;
} else {
// GNU `strerror_r`; `ret` is `char *`:
return reinterpret_cast<const char*>(ret);
}
#endif
}
std::string StrErrorInternal(int errnum) {
char buf[100];
const char* str = StrErrorAdaptor(errnum, buf, sizeof buf);
if (*str == '\0') {
snprintf(buf, sizeof buf, "Unknown error %d", errnum);
str = buf;
}
return str;
}
// kSysNerr is the number of errors from a recent glibc. `StrError()` falls back
// to `StrErrorAdaptor()` if the value is larger than this.
constexpr int kSysNerr = 135;
std::array<std::string, kSysNerr>* NewStrErrorTable() {
auto* table = new std::array<std::string, kSysNerr>;
for (size_t i = 0; i < table->size(); ++i) {
(*table)[i] = StrErrorInternal(static_cast<int>(i));
}
return table;
}
} // namespace
std::string StrError(int errnum) {
absl::base_internal::ErrnoSaver errno_saver;
static const auto* table = NewStrErrorTable();
if (errnum >= 0 && static_cast<size_t>(errnum) < table->size()) {
return (*table)[static_cast<size_t>(errnum)];
}
return StrErrorInternal(errnum);
}
} // namespace base_internal
ABSL_NAMESPACE_END
} // namespace absl
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