file.c~

模拟linux的ext3文件系统。采用位图法。用一个文件模拟硬盘。实现创建、删除目录、文件。读、写文件

#define MAIN
#include "structure.h"

//function create()

u16 create(u8 *path,u8 *name)
{
 u16 block,parent_inode_num,inode_num,offset;
 struct ext2_inode parent_inode;
 tag='1';
 if((strlen(path))){
      if(!(parent_inode_num=get_dir(path))) {
             printf("invalid pathname!\n");
             return 0;
      }
 }
 else parent_inode_num=current_dir;
 if(!(strlen(name))){
        printf("miss parameter!\n");
        return 0;
 }
 load_inode_entry(&parent_inode,parent_inode_num);
 if((block=search_name(&parent_inode,name,&offset)))    {
          printf("file already exist\n");
          return 0;
 }
 if(!(inode_num=create_dir_entry(&parent_inode,name))){
          printf("cannot create file\n");
          return 0;
 }
 return 1;
}

//function delete()

u16 delete(u8 *path,u8 *name)
{
 u16 oldi,block,parent_inode_num,offset;
 struct ext2_inode parent_inode,inode;
 u8 buffer[512];
 if((strlen(path))){
      if(!(parent_inode_num=get_dir(path))) {
             printf("invalid pathname!\n");
             return 0;
      }
 }
 else parent_inode_num=current_dir;
 if(!(strlen(name))){
        printf("miss parameter\n");
        return 0;
 }
 
 load_inode_entry(&parent_inode,parent_inode_num);
 if(!(block=search_name(&parent_inode,name,&offset))){ 
	 printf("The file is not existing!\n");
	 return 0;
 }
 load_block_entry(buffer,block);
 oldi=buffer[offset]+buffer[offset+1]*0x100;
 load_inode_entry(&inode,oldi);
 free_blocks(&inode);
 free_inode(oldi);
 buffer[offset]=buffer[offset+1]=0;
 update_block_entry(buffer,block);
 return 1;
}
//function open()

u16* open(u8 *path,u8 *name)
{
 u16 block,i;
 u16 inode_num,parent_inode_num;
 u16 offset;
 u8 buffer[512];
 struct ext2_inode parent_inode;
 if((strlen(path))){
      if(!(parent_inode_num=get_dir(path))) {
             printf("wrong pathname!\n");
             return 0;
      }
 }
 else parent_inode_num=current_dir;
 if(!(strlen(name))){
        printf("miss parameter\n");
        return 0;
 }
 load_inode_entry(&parent_inode,parent_inode_num);
 if(!(block=search_name(&parent_inode,name,&offset))) {
	 printf("cannot open file\n");
	 return 0;
 }
 load_block_entry(buffer,block);
 inode_num=buffer[offset]+buffer[offset+1];
 for(i=0;i<MAX_OPEN_FILE;i++){
         if(file_open_table[i]==0||file_open_table[i]==inode_num){
                 file_open_table[i]=inode_num;
                 return file_open_table+i*sizeof(u16);
	 }
 }
  return NULL;
}

//function close()

void close(u16 *fd)
{
 *fd=0;

 
}
//function  read()

u16 read(u16 *fd)
{
 u16 inode_num;
 struct ext2_inode inode;
 if(!fd) {
	 printf("You must open file before operation!\n");
	 return 0;
 }
 inode_num=*fd;
 load_inode_entry(&inode,inode_num);
 print(&inode);
 return 1;
}

//function write()

u16 write(u16 *fd,u8 *string,u8 *string2 )
{
 u16 inode_num;
 u16 start=0;
 strcat(string,string2);
 u16 end=strlen(string);
 struct ext2_inode inode;
 if(!fd) {
	 printf("You must open file before operation!\n");
	 return 0;
 }
 inode_num=*fd;
 load_inode_entry(&inode,inode_num);
 free_blocks(&inode);
 store(&inode,string,&start,&end);
 update_inode_entry(&inode,inode_num);
 return 1;
}