mbr

#include <fstream>
#include <iostream>
#include <ostream>

namespace
{
	constexpr int BLOCK_SIZE = 512; // Not sure if MBR is aware of advanced format
	// https://en.wikipedia.org/wiki/Master_boot_record#Sector_layout
#pragma pack(1)
	struct PartitionRecord
	{
		uint8_t m_status;
		uint8_t m_chs[3];
		uint8_t m_type; //4
		uint8_t m_kakoe_to_govno[7];
		uint32_t m_sectors;

		uint64_t Megabytes() const
		{
			return (static_cast<uint64_t>(m_sectors) * BLOCK_SIZE) >> 20;
		}
	};

	void ReportPartitionRecord(const uint8_t* data)
	{
		const auto* p = reinterpret_cast<const PartitionRecord*>(data);
		switch (p->m_status)
		{
		case 0x80:
			std::cout << "Active";
			break;
		case 0x0:
			std::cout << "Inactive";
			break;
		default:
			std::cout << "Invalid";
			break;
		}
		// See type: https://en.wikipedia.org/wiki/Partition_type
		// 0 means "free"
		// 0xef is service efi etc
		std::cout << " type: " << std::hex << static_cast<int>(p->m_type);
		std::cout << " sectors: " << std::dec << static_cast<int>(p->m_sectors);
		std::cout << " megabytes: " << p->Megabytes();
	}


	void ReportMbr(const char* path)
	{
		std::cout << path << std::endl;
		uint8_t mbr[512];
		std::ifstream f(path, std::ios::in | std::ios::binary);
		f.read(reinterpret_cast<char*>(mbr), sizeof(mbr));
		// Must have 55:aa here, see https://en.wikipedia.org/wiki/Master_boot_record
		std::cout << "Signature: ";
		const auto* signature = reinterpret_cast<const uint16_t*>(&mbr[510]);
		std::cout << std::hex << *signature;
		if (*signature != 0xAA55)
		{
			std::cout << "Ne mbr, a govno";
			return;
		}


		std::cout << std::endl;
		for (unsigned int i = 0; i < 4; i++)
		{
			std::cout << "Partition " << i << ": ";
			// https://en.wikipedia.org/wiki/Master_boot_record
			// First Partition record starts at 446, and occupies 16 bytes.
			// There are 4 records
			ReportPartitionRecord(&mbr[446 + i * 16]);
			std::cout << std::endl;
		}
	}
}

int main()
{
	ReportMbr("\\\\.\\PhysicalDrive0");
	ReportMbr("c:\\temp\\CentOS-8.2.2004-x86_64-dvd1.iso");
	ReportMbr("c:\\temp\\slackware64-current-install-dvd.iso");
	ReportMbr("C:\\temp\\Windows 7 with SP1 U Russian\\ru_windows_7_professional_with_sp1_x64_dvd_u_677024.iso");
	return 0;
}