73 lines
2.4 KiB
C++
73 lines
2.4 KiB
C++
/*
|
|
* Copyright (C) 2016 The Android Open Source Project
|
|
*
|
|
* 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
|
|
*
|
|
* http://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.
|
|
*/
|
|
|
|
#ifndef MEMORY_READER_H_
|
|
#define MEMORY_READER_H_
|
|
|
|
#include <cstdint>
|
|
#include <tuple>
|
|
|
|
#include "wifilogd/local_utils.h"
|
|
|
|
namespace android {
|
|
namespace wifilogd {
|
|
|
|
// A non-owning adapter, which helps with reading protocol messages out
|
|
// of a buffer. This is, essentially, the inverse of ByteBuffer.
|
|
//
|
|
// The user is responsible for ensuring that a MemoryReader does not
|
|
// outlive the underlying buffer.
|
|
class MemoryReader {
|
|
public:
|
|
MemoryReader(const void* buf, size_t buflen)
|
|
: head_(static_cast<const uint8_t*>(buf)), n_bytes_avail_(buflen) {}
|
|
|
|
explicit MemoryReader(std::tuple<const uint8_t*, size_t> buf)
|
|
: head_(std::get<0>(buf)), n_bytes_avail_(std::get<1>(buf)) {}
|
|
|
|
// Copies a |T| out of our referenced memory, aborting if sizeof(T) exceeds
|
|
// the number of bytes available. On success, updates the read position, and
|
|
// the number of bytes available.
|
|
template <typename T>
|
|
T CopyOutOrDie() {
|
|
CHECK(head_);
|
|
const T out{local_utils::CopyFromBufferOrDie<T>(head_, n_bytes_avail_)};
|
|
head_ += sizeof(T);
|
|
n_bytes_avail_ -= sizeof(T);
|
|
return out;
|
|
}
|
|
|
|
// Returns a pointer to the next bytes available for reading. Aborts if
|
|
// the number of available bytes is less than |n_bytes|. On success, updates
|
|
// the read position, and the number of bytes available.
|
|
RETURNS_NONNULL const uint8_t* GetBytesOrDie(size_t n_bytes);
|
|
|
|
// Returns true if the referenced memory is non-NULL, and has at least
|
|
// one byte available for reading.
|
|
explicit operator bool() const { return head_ && n_bytes_avail_; }
|
|
|
|
// Returns the number of bytes available for reading.
|
|
size_t size() const { return (head_ ? n_bytes_avail_ : 0); }
|
|
|
|
private:
|
|
const uint8_t* head_; // non-owned
|
|
size_t n_bytes_avail_;
|
|
};
|
|
|
|
} // namespace wifilogd
|
|
} // namespace android
|
|
|
|
#endif // MEMORY_READER_H_
|