file.c

学习有关Linux文件管理程序如何组织的知识

#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

#define DEVNAME "/dev/fd0H1440"

#define BYTES_PER_SECTOR 512

void ReadBootSector(unsigned char *buf)
{
  int i;

  printf("--------------- Boot -----------------\n");
  for (i = 0; i < 32; i++)
    printf("%2d ",i);

  for (i = 0; i < 256; i++) {
    if (i % 32 == 0) 
      printf("\n");
    printf("%2x ",buf[i]);
  }
  printf("\n\n");
}

void ReadCluster(unsigned char *buf,int addr)
{
  int i;

  printf("---------------Data %x-----------------\n",addr);
  for (i = 0; i < 32; i++)
    printf("%2d ",i);

  for (i = 0; i < 256; i++) {
    if (i % 32 == 0) 
      printf("\n");
    printf("%2x ",buf[i]);
  }
  printf("\n\n");
}

void ReadFAT(unsigned char *buf)
{
  int i;

  printf("----------------FAT-----------------\n");
  for (i = 0; i < 32; i++)
    printf("%2d ",i);

  for (i = 0; i < 256; i++) {
    if (i % 32 == 0) 
      printf("\n");
    printf("%2x ",buf[i]);
  }
  printf("\n\n");
}

void ReadDirectory(unsigned char *buf)
{
  int i;

  printf("--------------ROOTDIR---------------\n");
  for (i = 0; i < 32; i++)
    printf("%2d ",i);

  for (i = 0; i < 256; i++) {
    if (i % 32 == 0) 
      printf("\n");
    printf("%2x ",buf[i]);
  }
  printf("\n\n");
}

int main()
{
  int fd,count;
  int ret;
  unsigned char buf[256];	 /* Attention to type  */
	
  if ((fd = open(DEVNAME,O_RDWR)) < 0)
    perror("open failed");
	
  if ((count = read(fd,buf,256)) < 0)
    perror("read failed");

  ReadBootSector(buf);

  if ((ret = lseek(fd,0x2600,SEEK_SET)) < 0)
    perror("seek failed\n");

  if ((count = read(fd,buf,256)) < 0)
    perror("read failed\n");

  ReadDirectory(buf);

  if ((ret = lseek(fd,0x200,SEEK_SET)) < 0)
    perror("seek failed\n");

  if ((count = read(fd,buf,256)) < 0)
    perror("read failed\n");

  ReadFAT(buf);

  if ((ret = lseek(fd,0x4200,SEEK_SET)) < 0)
    perror("seek failed\n");

  if ((count = read(fd,buf,256)) < 0)
    perror("read failed\n");

  ReadCluster(buf,0x4200);

  close(fd);
  return 0;
}