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crcunwrap.cpp
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crcunwrap.cpp
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/*
* Harpocrates Paper Backup & Restore Tool
*
* Copyright 2019 Hartle & Klug Consulting GmbH
*
* 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 <array>
#include <cstddef>
#include <cstdlib>
#include <cstdio>
#include <cstring>
#include <iostream>
#include <CRCpp/CRC.h>
#include <tclap/CmdLine.h>
int main(int argc, char** argv)
{
try
{
TCLAP::CmdLine cmd("crcunwrap checks and removes continuous CRC16-ARC checksums from binary data previously wrapped with crcwrap.", ' ', "1.0");
TCLAP::ValueArg<std::string> inputArg("i", "input", "File to read from, \"-\" is used by default for stdin", false, "-", "string");
TCLAP::ValueArg<std::string> outputArg("o", "output", "File to write to, use \"-\" for stdout", true, "-", "string");
cmd.add(outputArg);
cmd.add(inputArg);
// Parse command line
cmd.parse(argc, argv);
std::string inputFile = inputArg.getValue();
std::FILE* inputStream = nullptr;
std::string outputFile = outputArg.getValue();
std::FILE* outputStream = nullptr;
// Handle stdin as input
if(inputFile == "-")
{
inputStream = stdin;
std::freopen(nullptr, "rb", inputStream);
}
else
{
inputStream = std::fopen(inputFile.data(), "rb");
if(inputStream == nullptr)
{
std::cerr << "Failed to open " << inputFile << " for reading." << std::endl;
return -1;
}
}
if(std::ferror(inputStream))
{
throw std::runtime_error(std::strerror(errno));
}
// Handle stdout as input
if (outputFile == "-")
{
outputStream = stdout;
std::freopen(nullptr, "wb", outputStream);
}
else
{
outputStream = std::fopen(outputFile.data(), "wb");
if(outputStream == nullptr)
{
std::cerr << "Failed to open " << outputFile << " for writing." << std::endl;
return -1;
}
}
if(std::ferror(outputStream))
{
throw std::runtime_error(std::strerror(errno));
}
std::size_t i;
std::size_t len;
std::array<char, 16> input_buffer;
std::array<char, 14> output_buffer;
std::uint16_t old_crc = 0;
std::uint16_t *parsed_crc = nullptr;
int row = 0;
// use std::fread and remember to only use as many bytes as are returned
// according to len
while((len = std::fread(input_buffer.data(), sizeof(input_buffer[0]), input_buffer.size(), inputStream)) > 0)
{
// Handle stdin EOF and errors
if(std::ferror(stdin) && !std::feof(stdin))
{
throw std::runtime_error(std::strerror(errno));
}
// Compute a continuous CRC for the new block
std::uint16_t crc = CRC::Calculate(input_buffer.data() + 2, len - 2, CRC::CRC_16_ARC(), old_crc);
old_crc = crc;
parsed_crc = (std::uint16_t *)input_buffer.data();
if(*parsed_crc != crc)
{
std::ostringstream errorMessage;
errorMessage << "CRC error in row " << (row + 1) << " (address " << std::setfill('0') << std::setw(4) << std::hex << (row * 16) << "); read CRC " << std::hex << std::setfill('0') << std::setw(2) << (*parsed_crc & 0xFF) << ((*parsed_crc >> 8) & 0xFF) << ", but data yields CRC " << std::hex << std::setfill('0') << std::setw(2) << (crc & 0xFF) << ((crc >> 8) & 0xFF) << ".";
throw std::runtime_error(errorMessage.str());
}
// Write block
std::fwrite(input_buffer.data() + 2, 1, len - 2, outputStream);
row++;
}
if(inputStream != stdin)
{
std::fclose(inputStream);
}
if(outputStream != stdout)
{
std::fclose(outputStream);
}
}
catch(std::exception const& e)
{
std::cerr << e.what() << '\n';
return EXIT_FAILURE;
}
}