Read Master Boot Record(MBR) from the disk (USB, Hard Drive, SSD, SD card)

read_mbr.c

//Check img whether there is partition in MBR locates at 0x1BE of 1st sector
#include <stdio.h>
#include <stdlib.h>

int main() {
    FILE * in = fopen("test.img", "rb");  //change img to your img
    // FILE * in = fopen("usb.img", "rb");
    unsigned int i, start_sector, length_sectors;
    
    fseek(in, 0x1BE, SEEK_SET); // go to partition table start
    
    for(i=0; i<4; i++) { // read all four entries
        printf("Partition entry %d: First byte %02X\n", i, fgetc(in));
        printf("  Partition start in CHS: %02X:%02X:%02X\n", fgetc(in), fgetc(in), fgetc(in));
        printf("  Partition type 0x%02X\n", fgetc(in));
        printf("  Partition end in CHS: %02X:%02X:%02X\n", fgetc(in), fgetc(in), fgetc(in));
        
        fread(&start_sector, 4, 1, in);
        fread(&length_sectors, 4, 1, in);
        printf("  Relative LBA address 0x%08X, %d sectors long\n", start_sector, length_sectors);
    }
    
    fclose(in);
    return 0;
}

~/Ctest/k_r/kernel_hi11Bulk$ gcc read_mbr.c -o read_mbr
~/Ctest/k_r/kernel_hi11Bulk$ sudo ./read_mbr
Partition entry 0: First byte 00
Partition start in CHS: 00:04:02
Partition type 0x06
Partition end in CHS: C9:E4:04
Relative LBA address 0x00000081, 1953663 sectors long
Partition entry 1: First byte 00
Partition start in CHS: 00:00:00
Partition type 0x00
Partition end in CHS: 00:00:00
Relative LBA address 0x00000000, 0 sectors long
Partition entry 2: First byte 00
Partition start in CHS: 00:00:00
Partition type 0x00
Partition end in CHS: 00:00:00
Relative LBA address 0x00000000, 0 sectors long
Partition entry 3: First byte 00
Partition start in CHS: 00:00:00
Partition type 0x00
Partition end in CHS: 00:00:00
Relative LBA address 0x00000000, 0 sectors long
~/Ctest/k_r/kernel_hi11Bulk$