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// This application reads FAT boot sectors from any drive and prints the results to the screen.
// Compatible with FAT, FAT12 and FAT16. Not compatible with FAT32 yet.
#include <stdlib.h>
#include <stdio.h>
#include <string.h>

// this struct contains the whole 512 bytes of the boot sector
typedef struct BPB
{
   unsigned char jumpCode[3];
   unsigned char oemName[8];
   unsigned short bytes_Sector;
   unsigned char sec_Cluster;
   unsigned short size_Sector_Reserved;
   unsigned char fatCount;
   unsigned short Max_Root_Entry;
   unsigned short Total_Sector_FS;
   unsigned char Media_Type;
   unsigned short sectors_per_fat;
   unsigned short sectors_per_track;
   unsigned short total_Head_Count;
   unsigned long no_Sectors_Before_Part;
   unsigned long no_Sector_FS32;
   unsigned char BIOS_13h_Drive_No;
   unsigned char reserved;
   unsigned char ext_Boot_Part_Signature;
   unsigned long vol_Serial_Number;
   unsigned char vol_Label_Name[11];
   unsigned char FS_Type[8];
   unsigned char boot_Code[448];
   unsigned short signature;
} __attribute__((__packed__)) BPB;


void printbpb(BPB bpb)
{
   printf("Disk Information: \n");
   printf("===========================\n");
   printf("Assembly Instruction to jump to Boot code: 0x%x\n",
          bpb.jumpCode);
   printf("OEM Name: \"%.8s\"\n", bpb.oemName); // this string may not be zero terminated!
   printf("Bytes per sector: %d\n", bpb.bytes_Sector);
   printf("Sector per cluster: %d\n", bpb.sec_Cluster);
   printf("Size in sector for reserved area(Boot Sector): %d\n", bpb.size_Sector_Reserved);
   printf("Number of FATs(File Allocation Table): %d\n", bpb.fatCount);
   printf("Number of files for root directory: %d\n", bpb.Max_Root_Entry);
   printf("Number of Sectors in File System: %d\n", bpb.Total_Sector_FS);
   printf("Media Type: 0x%x\n", bpb.Media_Type);
   printf("Number of Sectors for each FAT: %d\n", bpb.sectors_per_fat);
   printf("Sectors per track: %d\n", bpb.sectors_per_track);
   printf("Number of head in storage device: %d\n", bpb.total_Head_Count);
   printf("BIOS INT13h Drive number: 0x%x\n", bpb.BIOS_13h_Drive_No);
   printf("Number of large sectors: 0x%x\n", bpb.no_Sector_FS32);
   printf("Volume Serial Number: %d\n", bpb.vol_Serial_Number);
   printf("Volume label Name: \"%.11s\"\n", bpb.vol_Label_Name); // this string may not be zero terminated!
   printf("File system type: \"%.8s\"\n", bpb.FS_Type); // this string may not be zero terminated!
   printf("Boot Sector Signature: 0x%x\n", bpb.signature);

}

int main(int argc, char** argv)
{
	FILE*  drivefile;
	char bootsector[512];
	BPB bpb;
	
	if (argc < 2)
	{
		printf("The following error occurred: Application needs disk location.\n");
		return 1;
	}
	
	const char* drivename = argv[1]; // /dev/sdf1 on UNIX for example; A: on WINDOWS
	
	drivefile = fopen(drivename, "rb"); // force binary, for WINDOWS

	if (!drivefile)
	{
		perror ("The following error occurred");
		return 2;
	}
	
	// clear buffer
	memset(bootsector, 0, 512);

	// read bootsector
	fread(bootsector, 512, 1, drivefile);
	
	memcpy(&bpb, bootsector, 512);
	
	printbpb(bpb);
	
	fclose(drivefile);
	
	return 0;
}