读取bochs硬盘分区信息的C程序

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>

#define OFFSET 446

struct boot_info
{
  unsigned char bootind;
  unsigned char start_head;
  unsigned char start_sec;
  unsigned char start_cyl;

  unsigned char sysind;
  unsigned char last_head;
  unsigned char last_sec;
  unsigned char last_cyl;

  unsigned int lowsec;
  unsigned int size;
} record;

void print()
{
  printf("bootind\t\t%u\t0x%x\n", record.bootind, record.bootind);
  printf("start_head\t%u\t0x%x\n", record.start_head, record.start_head);
  printf("start_sec\t%u\t0x%x\n", record.start_sec, record.start_sec);
  printf("start_cyl\t%u\t0x%x\n", record.start_cyl, record.start_cyl);
  printf("sysind\t\t%u\t0x%x\n", record.sysind, record.sysind);
  printf("last_head\t%u\t0x%x\n", record.last_head, record.last_head);
  printf("last_sec\t%u\t0x%x\n", record.last_sec, record.last_sec);
  printf("last_cyl\t%u\t0x%x\n", record.last_cyl, record.last_cyl);
  printf("lowsec\t\t%u\t0x%x\n", record.lowsec, record.lowsec);
  printf("size\t\t%u\t0x%x\n", record.size, record.size);
}

int main(int argc, char *argv[])
{
  int i, fd;

  fd = open(argv[1], O_RDWR);
  lseek(fd, OFFSET, SEEK_SET);
 
  for (i = 0; i < 4; i ++) {
    read(fd, &record, sizeof(record));
    print();
    if (i != 3)
      printf("\n");
  }
 
  close(fd);

  return EXIT_SUCCESS;
}

mishuang@msh:~/setup/bochs> read_mbr ./c.img
bootind         128     0x80
start_head      1       0x1
start_sec       1       0x1
start_cyl       0       0x0
sysind          129     0x81
last_head       15      0xf
last_sec        63      0x3f
last_cyl        121     0x79
lowsec          63      0x3f
size            122913  0x1e021

bootind         0       0x0
start_head      0       0x0
start_sec       1       0x1
start_cyl       122     0x7a
sysind          129     0x81
last_head       15      0xf
last_sec        63      0x3f
last_cyl        243     0xf3
lowsec          122976  0x1e060
size            122976  0x1e060

bootind         0       0x0
start_head      0       0x0
start_sec       1       0x1
start_cyl       244     0xf4
sysind          5       0x5
last_head       15      0xf
last_sec        127     0x7f
last_cyl        108     0x6c
lowsec          245952  0x3c0c0
size            121968  0x1dc70

bootind         0       0x0
start_head      0       0x0
start_sec       0       0x0
start_cyl       0       0x0
sysind          0       0x0
last_head       0       0x0
last_sec        0       0x0
last_cyl        0       0x0
lowsec          0       0x0
size            0       0x0