gd/packet/parser/fields/scalar_field.cc - platform/system/bt - Git at Google

 /*
  * Copyright 2019 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.
  */

 #include "fields/scalar_field.h"

 #include "fields/fixed_scalar_field.h"
 #include "fields/size_field.h"
 #include "util.h"

 const std::string ScalarField::kFieldType = "ScalarField";

 ScalarField::ScalarField(std::string name, int size, ParseLocation loc) : PacketField(name, loc), size_(size) {
   if (size_ > 64 || size_ < 0) {
     ERROR(this) << "Not implemented for size_ = " << size_;
   }
 }

 const std::string& ScalarField::GetFieldType() const {
   return ScalarField::kFieldType;
 }

 Size ScalarField::GetSize() const {
   return size_;
 }

 std::string ScalarField::GetDataType() const {
   return util::GetTypeForSize(size_);
 }

 int GetShiftBits(int i) {
   int bits_past_byte_boundary = i % 8;
   if (bits_past_byte_boundary == 0) {
     return 0;
   } else {
     return 8 - bits_past_byte_boundary;
   }
 }

 int ScalarField::GenBounds(std::ostream& s, Size start_offset, Size end_offset, Size size) const {
   int num_leading_bits = 0;

   if (!start_offset.empty()) {
     // Default to start if available.
     num_leading_bits = start_offset.bits() % 8;
     s << "auto " << GetName() << "_it = to_bound + (" << start_offset << ") / 8;";
   } else if (!end_offset.empty()) {
     num_leading_bits = GetShiftBits(end_offset.bits() + size.bits());
     Size byte_offset = Size(num_leading_bits + size.bits()) + end_offset;
     s << "auto " << GetName() << "_it = to_bound + (to_bound.NumBytesRemaining() - (" << byte_offset << ") / 8);";
   } else {
     ERROR(this) << "Ambiguous offset for field.";
   }
   return num_leading_bits;
 }

 void ScalarField::GenExtractor(std::ostream& s, int num_leading_bits, bool) const {
   Size size = GetSize();
   // Extract the correct number of bytes. The return type could be different
   // from the extract type if an earlier field causes the beginning of the
   // current field to start in the middle of a byte.
   std::string extract_type = util::GetTypeForSize(size.bits() + num_leading_bits);
   s << "auto extracted_value = " << GetName() << "_it.extract<" << extract_type << ">();";

   // Right shift the result to remove leading bits.
   if (num_leading_bits != 0) {
     s << "extracted_value >>= " << num_leading_bits << ";";
   }
   // Mask the result if necessary.
   if (util::RoundSizeUp(size.bits()) != size.bits()) {
     uint64_t mask = 0;
     for (int i = 0; i < size.bits(); i++) {
       mask <<= 1;
       mask |= 1;
     }
     s << "extracted_value &= 0x" << std::hex << mask << std::dec << ";";
   }
   s << "*" << GetName() << "_ptr = static_cast<" << GetDataType() << ">(extracted_value);";
 }

 std::string ScalarField::GetGetterFunctionName() const {
   std::stringstream ss;
   ss << "Get" << util::UnderscoreToCamelCase(GetName());
   return ss.str();
 }

 void ScalarField::GenGetter(std::ostream& s, Size start_offset, Size end_offset) const {
   s << GetDataType() << " " << GetGetterFunctionName() << "() const {";
   s << "ASSERT(was_validated_);";
   s << "auto to_bound = begin();";
   int num_leading_bits = GenBounds(s, start_offset, end_offset, GetSize());
   s << GetDataType() << " " << GetName() << "_value{};";
   s << GetDataType() << "* " << GetName() << "_ptr = &" << GetName() << "_value;";
   GenExtractor(s, num_leading_bits, false);
   s << "return " << GetName() << "_value;";
   s << "}";
 }

 std::string ScalarField::GetBuilderParameterType() const {
   return GetDataType();
 }

 bool ScalarField::HasParameterValidator() const {
   return util::RoundSizeUp(GetSize().bits()) != GetSize().bits();
 }

 void ScalarField::GenParameterValidator(std::ostream& s) const {
   s << "ASSERT(" << GetName() << " < (static_cast<uint64_t>(1) << " << GetSize().bits() << "));";
 }

 void ScalarField::GenInserter(std::ostream& s) const {
   if (GetSize().bits() == 8) {
     s << "i.insert_byte(" << GetName() << "_);";
   } else {
     s << "insert(" << GetName() << "_, i," << GetSize().bits() << ");";
   }
 }

 void ScalarField::GenValidator(std::ostream&) const {
   // Do nothing
 }

 void ScalarField::GenStringRepresentation(std::ostream& s, std::string accessor) const {
   s << "+" << accessor;
 }

 std::string ScalarField::GetRustDataType() const {
   return util::GetRustTypeForSize(size_);
 }

 std::string ScalarField::GetRustParseDataType() const {
   return util::GetRustTypeForSize(size_);
 }

 int ScalarField::GetRustBitOffset(
     std::ostream&, Size start_offset, Size end_offset, Size size) const {
   int num_leading_bits = 0;

   if (!start_offset.empty()) {
     // Default to start if available.
     num_leading_bits = start_offset.bits() % 8;
   } else if (!end_offset.empty()) {
     num_leading_bits = GetShiftBits(end_offset.bits() + size.bits());
     Size byte_offset = Size(num_leading_bits + size.bits()) + end_offset;
   } else {
     ERROR(this) << "Ambiguous offset for field.";
   }
   return num_leading_bits;
 }

 void ScalarField::GenRustGetter(std::ostream& s, Size start_offset, Size end_offset) const {
   Size size = GetSize();

   int num_leading_bits = GetRustBitOffset(s, start_offset, end_offset, GetSize());

   s << "let " << GetName() << " = ";
   auto offset = num_leading_bits == 0 ? 0 : -1;
   s << GetRustParseDataType() << "::from_le_bytes([";
   int total_bytes;
   if (size_ <= 8) {
     total_bytes = 1;
   } else if (size_ <= 16) {
     total_bytes = 2;
   } else if (size_ <= 32) {
     total_bytes = 4;
   } else {
     total_bytes = 8;
   }
   for (int i = 0; i < total_bytes; i++) {
     if (i > 0) {
       s << ",";
     }
     if (i < size.bytes()) {
       s << "bytes[" << start_offset.bytes() + i + offset << "]";
     } else {
       s << 0;
     }
   }
   s << "]);";

   if (num_leading_bits != 0) {
     s << "let " << GetName() << " = " << GetName() << " >> " << num_leading_bits << ";";
   }

   if (util::RoundSizeUp(size.bits()) != size.bits()) {
     uint64_t mask = 0;
     for (int i = 0; i < size.bits(); i++) {
       mask <<= 1;
       mask |= 1;
     }
     s << "let " << GetName() << " = ";
     s << GetName() << " & 0x" << std::hex << mask << std::dec << ";";
   }

   // needs casting from primitive
   if (GetRustParseDataType() != GetRustDataType()) {
     s << "let " << GetName() << " = ";
     s << GetRustDataType() << "::from_" << GetRustParseDataType() << "(" << GetName() << ").unwrap();";
   }
 }

 void ScalarField::GenRustWriter(std::ostream& s, Size start_offset, Size end_offset) const {
   Size size = GetSize();
   int num_leading_bits = GetRustBitOffset(s, start_offset, end_offset, GetSize());

   if (GetFieldType() == SizeField::kFieldType || GetFieldType() == FixedScalarField::kFieldType) {
     // Do nothing, the field access has already happened
   } else if (GetRustParseDataType() != GetRustDataType()) {
     // needs casting to primitive
     s << "let " << GetName() << " = self." << GetName() << ".to_" << GetRustParseDataType() << "().unwrap();";
   } else {
     s << "let " << GetName() << " = self." << GetName() << ";";
   }
   if (util::RoundSizeUp(size.bits()) != size.bits()) {
     uint64_t mask = 0;
     for (int i = 0; i < size.bits(); i++) {
       mask <<= 1;
       mask |= 1;
     }
     s << "let " << GetName() << " = ";
     s << GetName() << " & 0x" << std::hex << mask << std::dec << ";";
   }

   int access_offset = 0;
   if (num_leading_bits != 0) {
     access_offset = -1;
     uint64_t mask = 0;
     for (int i = 0; i < num_leading_bits; i++) {
       mask <<= 1;
       mask |= 1;
     }
     s << "let " << GetName() << " = (" << GetName() << " << " << num_leading_bits << ") | ("
       << "(buffer[" << start_offset.bytes() + access_offset << "] as " << GetRustParseDataType() << ") & 0x" << std::hex
       << mask << std::dec << ");";
   }

   s << "buffer[" << start_offset.bytes() + access_offset << ".."
     << start_offset.bytes() + GetSize().bytes() + access_offset << "].copy_from_slice(&" << GetName()
     << ".to_le_bytes()[0.." << size.bytes() << "]);";
 }
	/*
	* Copyright 2019 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.
	*/

	#include "fields/scalar_field.h"

	#include "fields/fixed_scalar_field.h"
	#include "fields/size_field.h"
	#include "util.h"

	const std::string ScalarField::kFieldType = "ScalarField";

	ScalarField::ScalarField(std::string name, int size, ParseLocation loc) : PacketField(name, loc), size_(size) {
	if (size_ > 64 \|\| size_ < 0) {
	ERROR(this) << "Not implemented for size_ = " << size_;
	}
	}

	const std::string& ScalarField::GetFieldType() const {
	return ScalarField::kFieldType;
	}

	Size ScalarField::GetSize() const {
	return size_;
	}

	std::string ScalarField::GetDataType() const {
	return util::GetTypeForSize(size_);
	}

	int GetShiftBits(int i) {
	int bits_past_byte_boundary = i % 8;
	if (bits_past_byte_boundary == 0) {
	return 0;
	} else {
	return 8 - bits_past_byte_boundary;
	}
	}

	int ScalarField::GenBounds(std::ostream& s, Size start_offset, Size end_offset, Size size) const {
	int num_leading_bits = 0;

	if (!start_offset.empty()) {
	// Default to start if available.
	num_leading_bits = start_offset.bits() % 8;
	s << "auto " << GetName() << "_it = to_bound + (" << start_offset << ") / 8;";
	} else if (!end_offset.empty()) {
	num_leading_bits = GetShiftBits(end_offset.bits() + size.bits());
	Size byte_offset = Size(num_leading_bits + size.bits()) + end_offset;
	s << "auto " << GetName() << "_it = to_bound + (to_bound.NumBytesRemaining() - (" << byte_offset << ") / 8);";
	} else {
	ERROR(this) << "Ambiguous offset for field.";
	}
	return num_leading_bits;
	}

	void ScalarField::GenExtractor(std::ostream& s, int num_leading_bits, bool) const {
	Size size = GetSize();
	// Extract the correct number of bytes. The return type could be different
	// from the extract type if an earlier field causes the beginning of the
	// current field to start in the middle of a byte.
	std::string extract_type = util::GetTypeForSize(size.bits() + num_leading_bits);
	s << "auto extracted_value = " << GetName() << "_it.extract<" << extract_type << ">();";

	// Right shift the result to remove leading bits.
	if (num_leading_bits != 0) {
	s << "extracted_value >>= " << num_leading_bits << ";";
	}
	// Mask the result if necessary.
	if (util::RoundSizeUp(size.bits()) != size.bits()) {
	uint64_t mask = 0;
	for (int i = 0; i < size.bits(); i++) {
	mask <<= 1;
	mask \|= 1;
	}
	s << "extracted_value &= 0x" << std::hex << mask << std::dec << ";";
	}
	s << "*" << GetName() << "_ptr = static_cast<" << GetDataType() << ">(extracted_value);";
	}

	std::string ScalarField::GetGetterFunctionName() const {
	std::stringstream ss;
	ss << "Get" << util::UnderscoreToCamelCase(GetName());
	return ss.str();
	}

	void ScalarField::GenGetter(std::ostream& s, Size start_offset, Size end_offset) const {
	s << GetDataType() << " " << GetGetterFunctionName() << "() const {";
	s << "ASSERT(was_validated_);";
	s << "auto to_bound = begin();";
	int num_leading_bits = GenBounds(s, start_offset, end_offset, GetSize());
	s << GetDataType() << " " << GetName() << "_value{};";
	s << GetDataType() << "* " << GetName() << "_ptr = &" << GetName() << "_value;";
	GenExtractor(s, num_leading_bits, false);
	s << "return " << GetName() << "_value;";
	s << "}";
	}

	std::string ScalarField::GetBuilderParameterType() const {
	return GetDataType();
	}

	bool ScalarField::HasParameterValidator() const {
	return util::RoundSizeUp(GetSize().bits()) != GetSize().bits();
	}

	void ScalarField::GenParameterValidator(std::ostream& s) const {
	s << "ASSERT(" << GetName() << " < (static_cast<uint64_t>(1) << " << GetSize().bits() << "));";
	}

	void ScalarField::GenInserter(std::ostream& s) const {
	if (GetSize().bits() == 8) {
	s << "i.insert_byte(" << GetName() << "_);";
	} else {
	s << "insert(" << GetName() << "_, i," << GetSize().bits() << ");";
	}
	}

	void ScalarField::GenValidator(std::ostream&) const {
	// Do nothing
	}

	void ScalarField::GenStringRepresentation(std::ostream& s, std::string accessor) const {
	s << "+" << accessor;
	}

	std::string ScalarField::GetRustDataType() const {
	return util::GetRustTypeForSize(size_);
	}

	std::string ScalarField::GetRustParseDataType() const {
	return util::GetRustTypeForSize(size_);
	}

	int ScalarField::GetRustBitOffset(
	std::ostream&, Size start_offset, Size end_offset, Size size) const {
	int num_leading_bits = 0;

	if (!start_offset.empty()) {
	// Default to start if available.
	num_leading_bits = start_offset.bits() % 8;
	} else if (!end_offset.empty()) {
	num_leading_bits = GetShiftBits(end_offset.bits() + size.bits());
	Size byte_offset = Size(num_leading_bits + size.bits()) + end_offset;
	} else {
	ERROR(this) << "Ambiguous offset for field.";
	}
	return num_leading_bits;
	}

	void ScalarField::GenRustGetter(std::ostream& s, Size start_offset, Size end_offset) const {
	Size size = GetSize();

	int num_leading_bits = GetRustBitOffset(s, start_offset, end_offset, GetSize());

	s << "let " << GetName() << " = ";
	auto offset = num_leading_bits == 0 ? 0 : -1;
	s << GetRustParseDataType() << "::from_le_bytes([";
	int total_bytes;
	if (size_ <= 8) {
	total_bytes = 1;
	} else if (size_ <= 16) {
	total_bytes = 2;
	} else if (size_ <= 32) {
	total_bytes = 4;
	} else {
	total_bytes = 8;
	}
	for (int i = 0; i < total_bytes; i++) {
	if (i > 0) {
	s << ",";
	}
	if (i < size.bytes()) {
	s << "bytes[" << start_offset.bytes() + i + offset << "]";
	} else {
	s << 0;
	}
	}
	s << "]);";

	if (num_leading_bits != 0) {
	s << "let " << GetName() << " = " << GetName() << " >> " << num_leading_bits << ";";
	}

	if (util::RoundSizeUp(size.bits()) != size.bits()) {
	uint64_t mask = 0;
	for (int i = 0; i < size.bits(); i++) {
	mask <<= 1;
	mask \|= 1;
	}
	s << "let " << GetName() << " = ";
	s << GetName() << " & 0x" << std::hex << mask << std::dec << ";";
	}

	// needs casting from primitive
	if (GetRustParseDataType() != GetRustDataType()) {
	s << "let " << GetName() << " = ";
	s << GetRustDataType() << "::from_" << GetRustParseDataType() << "(" << GetName() << ").unwrap();";
	}
	}

	void ScalarField::GenRustWriter(std::ostream& s, Size start_offset, Size end_offset) const {
	Size size = GetSize();
	int num_leading_bits = GetRustBitOffset(s, start_offset, end_offset, GetSize());

	if (GetFieldType() == SizeField::kFieldType \|\| GetFieldType() == FixedScalarField::kFieldType) {
	// Do nothing, the field access has already happened
	} else if (GetRustParseDataType() != GetRustDataType()) {
	// needs casting to primitive
	s << "let " << GetName() << " = self." << GetName() << ".to_" << GetRustParseDataType() << "().unwrap();";
	} else {
	s << "let " << GetName() << " = self." << GetName() << ";";
	}
	if (util::RoundSizeUp(size.bits()) != size.bits()) {
	uint64_t mask = 0;
	for (int i = 0; i < size.bits(); i++) {
	mask <<= 1;
	mask \|= 1;
	}
	s << "let " << GetName() << " = ";
	s << GetName() << " & 0x" << std::hex << mask << std::dec << ";";
	}

	int access_offset = 0;
	if (num_leading_bits != 0) {
	access_offset = -1;
	uint64_t mask = 0;
	for (int i = 0; i < num_leading_bits; i++) {
	mask <<= 1;
	mask \|= 1;
	}
	s << "let " << GetName() << " = (" << GetName() << " << " << num_leading_bits << ") \| ("
	<< "(buffer[" << start_offset.bytes() + access_offset << "] as " << GetRustParseDataType() << ") & 0x" << std::hex
	<< mask << std::dec << ");";
	}

	s << "buffer[" << start_offset.bytes() + access_offset << ".."
	<< start_offset.bytes() + GetSize().bytes() + access_offset << "].copy_from_slice(&" << GetName()
	<< ".to_le_bytes()[0.." << size.bytes() << "]);";
	}