libcryfs/data/FixedSizeData.h

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#pragma once
#ifndef MESSMER_CPPUTILS_DATA_FIXEDSIZEDATA_H_
#define MESSMER_CPPUTILS_DATA_FIXEDSIZEDATA_H_
#include <cryptopp/cryptopp/hex.h>
#include <string>
#include <cstring>
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#include "../assert/assert.h"
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namespace cpputils {
template<size_t SIZE>
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class FixedSizeData final {
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public:
//Non-virtual destructor because we want objects to be small
~FixedSizeData() {}
static constexpr size_t BINARY_LENGTH = SIZE;
static constexpr size_t STRING_LENGTH = 2 * BINARY_LENGTH; // Hex encoding
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//TODO Test Null()
static FixedSizeData<SIZE> Null();
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static FixedSizeData<SIZE> FromString(const std::string &data);
std::string ToString() const;
static FixedSizeData<SIZE> FromBinary(const void *source);
void ToBinary(void *target) const;
const unsigned char *data() const;
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unsigned char *data();
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template<size_t size> FixedSizeData<size> take() const;
template<size_t size> FixedSizeData<SIZE-size> drop() const;
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private:
FixedSizeData() {}
template<size_t _SIZE> friend class FixedSizeData;
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unsigned char _data[BINARY_LENGTH];
};
template<size_t SIZE> bool operator==(const FixedSizeData<SIZE> &lhs, const FixedSizeData<SIZE> &rhs);
template<size_t SIZE> bool operator!=(const FixedSizeData<SIZE> &lhs, const FixedSizeData<SIZE> &rhs);
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// ----- Implementation -----
template<size_t SIZE> constexpr size_t FixedSizeData<SIZE>::BINARY_LENGTH;
template<size_t SIZE> constexpr size_t FixedSizeData<SIZE>::STRING_LENGTH;
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template<size_t SIZE>
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FixedSizeData<SIZE> FixedSizeData<SIZE>::Null() {
FixedSizeData<SIZE> result;
std::memset(result._data, 0, BINARY_LENGTH);
return result;
}
template<size_t SIZE>
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FixedSizeData<SIZE> FixedSizeData<SIZE>::FromString(const std::string &data) {
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ASSERT(data.size() == STRING_LENGTH, "Wrong string size for parsing FixedSizeData");
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FixedSizeData<SIZE> result;
CryptoPP::StringSource(data, true,
new CryptoPP::HexDecoder(
new CryptoPP::ArraySink(result._data, BINARY_LENGTH)
)
);
return result;
}
template<size_t SIZE>
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std::string FixedSizeData<SIZE>::ToString() const {
std::string result;
CryptoPP::ArraySource(_data, BINARY_LENGTH, true,
new CryptoPP::HexEncoder(
new CryptoPP::StringSink(result)
)
);
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ASSERT(result.size() == STRING_LENGTH, "Created wrongly sized string");
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return result;
}
template<size_t SIZE>
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const unsigned char *FixedSizeData<SIZE>::data() const {
return _data;
}
template<size_t SIZE>
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unsigned char *FixedSizeData<SIZE>::data() {
return const_cast<unsigned char*>(const_cast<const FixedSizeData<SIZE>*>(this)->data());
}
template<size_t SIZE>
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void FixedSizeData<SIZE>::ToBinary(void *target) const {
std::memcpy(target, _data, BINARY_LENGTH);
}
template<size_t SIZE>
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FixedSizeData<SIZE> FixedSizeData<SIZE>::FromBinary(const void *source) {
FixedSizeData<SIZE> result;
std::memcpy(result._data, source, BINARY_LENGTH);
return result;
}
template<size_t SIZE> template<size_t size>
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FixedSizeData<size> FixedSizeData<SIZE>::take() const {
static_assert(size <= SIZE, "Out of bounds");
FixedSizeData<size> result;
std::memcpy(result._data, _data, size);
return result;
}
template<size_t SIZE> template<size_t size>
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FixedSizeData<SIZE-size> FixedSizeData<SIZE>::drop() const {
static_assert(size <= SIZE, "Out of bounds");
FixedSizeData<SIZE-size> result;
std::memcpy(result._data, _data+size, SIZE-size);
return result;
}
template<size_t SIZE>
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bool operator==(const FixedSizeData<SIZE> &lhs, const FixedSizeData<SIZE> &rhs) {
return 0 == std::memcmp(lhs.data(), rhs.data(), FixedSizeData<SIZE>::BINARY_LENGTH);
}
template<size_t SIZE>
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bool operator!=(const FixedSizeData<SIZE> &lhs, const FixedSizeData<SIZE> &rhs) {
return !operator==(lhs, rhs);
}
}
#endif