chromium/third_party/abseil-cpp/absl/debugging/internal/address_is_readable.cc

// Copyright 2017 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.

// base::AddressIsReadable() probes an address to see whether it is readable,
// without faulting.

#include "absl/debugging/internal/address_is_readable.h"

#if !defined(__linux__) || defined(__ANDROID__)

namespace absl {
ABSL_NAMESPACE_BEGIN
namespace debugging_internal {

// On platforms other than Linux, just return true.
bool AddressIsReadable(const void* /* addr */) { return true; }

}  // namespace debugging_internal
ABSL_NAMESPACE_END
}  // namespace absl

#else  // __linux__ && !__ANDROID__

#include <stdint.h>
#include <syscall.h>
#include <unistd.h>

#include "absl/base/internal/errno_saver.h"
#include "absl/base/internal/raw_logging.h"

namespace absl {
ABSL_NAMESPACE_BEGIN
namespace debugging_internal {

// NOTE: be extra careful about adding any interposable function calls here
// (such as open(), read(), etc.). These symbols may be interposed and will get
// invoked in contexts they don't expect.
//
// NOTE: any new system calls here may also require sandbox reconfiguration.
//
bool AddressIsReadable(const void *addr) { … }

}  // namespace debugging_internal
ABSL_NAMESPACE_END
}  // namespace absl

#endif  // __linux__ && !__ANDROID__