本项目用C语言在linux下实现ext2文件系统的基本功能.zip

#include <stdio.h> #include <string.h> #include "init.h" static void update_super_block(void) //写超级块 { fp=fopen("./Ext2","r+"); fseek(fp,DISK_START,SEEK_SET); fwrite(sb_block,SB_SIZE,1,fp); fflush(fp); //立刻将缓冲区的内容输出，保证磁盘内存数据的一致性 } static void reload_super_block(void) //读超级块 { fseek(fp,DISK_START,SEEK_SET); fread(sb_block,SB_SIZE,1,fp);//读取内容到超级块缓冲区中 } static void update_group_desc(void) //写组描述符 { fp=fopen("./Ext2","r+"); fseek(fp,GDT_START,SEEK_SET); fwrite(gdt,GD_SIZE,1,fp); fflush(fp); } static void reload_group_desc(void) // 读组描述符 { fseek(fp,GDT_START,SEEK_SET); fread(gdt,GD_SIZE,1,fp); } static void update_inode_entry(unsigned short i) // 写第i个inode { fp=fopen("./Ext2","r+"); fseek(fp,INODE_TABLE+(i-1)*INODE_SIZE,SEEK_SET); fwrite(inode_area,INODE_SIZE,1,fp); fflush(fp); } static void reload_inode_entry(unsigned short i) // 读第i个inode { fseek(fp,INODE_TABLE+(i-1)*INODE_SIZE,SEEK_SET); fread(inode_area,INODE_SIZE,1,fp); } static void update_dir(unsigned short i) // 写第i个 数据块 { fp=fopen("./Ext2","r+"); fseek(fp,DATA_BLOCK+i*BLOCK_SIZE,SEEK_SET); fwrite(dir,BLOCK_SIZE,1,fp); fflush(fp); } static void reload_dir(unsigned short i) // 读第i个 数据块 { fseek(fp,DATA_BLOCK+i*BLOCK_SIZE,SEEK_SET); fread(dir,BLOCK_SIZE,1,fp); //fclose(fp); } static void update_block_bitmap(void) //写block位图 { fp=fopen("./Ext2","r+"); fseek(fp,BLOCK_BITMAP,SEEK_SET); fwrite(bitbuf,BLOCK_SIZE,1,fp); fflush(fp); } static void reload_block_bitmap(void) //读block位图 { fseek(fp,BLOCK_BITMAP,SEEK_SET); fread(bitbuf,BLOCK_SIZE,1,fp); } static void update_inode_bitmap(void) //写inode位图 { fp=fopen("./Ext2","r+"); fseek(fp,INODE_BITMAP,SEEK_SET); fwrite(ibuf,BLOCK_SIZE,1,fp); fflush(fp); } static void reload_inode_bitmap(void) // 读inode位图 { fseek(fp,INODE_BITMAP,SEEK_SET); fread(ibuf,BLOCK_SIZE,1,fp); } static void update_block(unsigned short i) // 写第i个数据块 { fp=fopen("./Ext2","r+"); fseek(fp,DATA_BLOCK+i*BLOCK_SIZE,SEEK_SET); //fseek(fp,0,SEEK_SET); fwrite(Buffer,BLOCK_SIZE,1,fp); fflush(fp); } static void reload_block(unsigned short i) // 读第i个数据块 { fseek(fp,DATA_BLOCK+i*BLOCK_SIZE,SEEK_SET); fread(Buffer,BLOCK_SIZE,1,fp); } static int alloc_block(void) // 分配一个数据块,返回数据块号 { //bitbuf共有512个字节，表示4096个数据块。根据last_alloc_block/8计算它在bitbuf的哪一个字节 unsigned short cur=last_alloc_block; //printf("cur: %d\n",cur); unsigned char con=128; // 1000 0000b int flag=0; if(gdt[0].bg_free_blocks_count==0) { printf("There is no block to be alloced!\n"); return(0); } reload_block_bitmap(); cur/=8; while(bitbuf[cur]==255)//该字节的8个bit都已有数据 { if(cur==511)cur=0; //最后一个字节也已经满，从头开始寻找 else cur++; } while(bitbuf[cur]&con) //在一个字节中找具体的某一个bit { con=con/2; flag++; } bitbuf[cur]=bitbuf[cur]+con; last_alloc_block=cur*8+flag; update_block_bitmap(); gdt[0].bg_free_blocks_count--; update_group_desc(); return last_alloc_block; } static int get_inode(void) // 分配一个inode { unsigned short cur=last_alloc_inode; unsigned char con=128; int flag=0; if(gdt[0].bg_free_inodes_count==0) { printf("There is no Inode to be alloced!\n"); return 0; } reload_inode_bitmap(); cur=(cur-1)/8; //第一个标号是1，但是存储是从0开始的 //printf("%s",) while(ibuf[cur]==255) //先看该字节的8个位是否已经填满 { if(cur==511)cur=0; else cur++; } while(ibuf[cur]&con) //再看某个字节的具体哪一位没有被占用 { con=con/2; flag++; } ibuf[cur]=ibuf[cur]+con; last_alloc_inode=cur*8+flag+1; update_inode_bitmap(); gdt[0].bg_free_inodes_count--; update_group_desc(); //printf("%d\n",last_alloc_inode); return last_alloc_inode; } //当前目录中查找文件或目录为tmp，并得到该文件的 inode 号，它在上级目录中的数据块号以及数据块中目录的项号 static unsigned short reserch_file(char tmp[9],int file_type,unsigned short *inode_num, unsigned short *block_num,unsigned short *dir_num) { unsigned short j,k; reload_inode_entry(current_dir); //进入当前目录 j=0; while(j<inode_area[0].i_blocks) { reload_dir(inode_area[0].i_block[j]); k=0; while(k<32) { if(!dir[k].inode||dir[k].file_type!=file_type||strcmp(dir[k].name,tmp)) { k++; } else { *inode_num=dir[k].inode; *block_num=j; *dir_num=k; return 1; } } j++; } return 0; } /*为新增目录或文件分配 dir_entry 对于新增文件，只需分配一个inode号 对于新增目录，除了inode号外，还需要分配数据区存储.和..两个目录项*/ static void dir_prepare(unsigned short tmp,unsigned short len,int type) { reload_inode_entry(tmp); if(type==2) // 目录 { inode_area[0].i_size=32; inode_area[0].i_blocks=1; inode_area[0].i_block[0]=alloc_block(); //printf("alloc %d\n",inode_area[0].i_block[0]); dir[0].inode=tmp; dir[1].inode=current_dir; dir[0].name_len=len; dir[1].name_len=current_dirlen; dir[0].file_type=dir[1].file_type=2; for(type=2;type<32;type++) dir[type].inode=0; strcpy(dir[0].name,"."); strcpy(dir[1].name,".."); update_dir(inode_area[0].i_block[0]); inode_area[0].i_mode=01006; } else { inode_area[0].i_size=0; inode_area[0].i_blocks=0; inode_area[0].i_mode=0407; } update_inode_entry(tmp); } //删除一个块号 static void remove_block(unsigned short del_num) { unsigned short tmp; tmp=del_num/8; reload_block_bitmap(); switch(del_num%8) // 更新block位图 将具体的位置为0 { case 0:bitbuf[tmp]=bitbuf[tmp]&127;break; // bitbuf[tmp] & 0111 1111b case 1:bitbuf[tmp]=bitbuf[tmp]&191;break; //bitbuf[tmp] & 1011 1111b case 2:bitbuf[tmp]=bitbuf[tmp]&223;break; //bitbuf[tmp] & 1101 1111b case 3:bitbuf[tmp]=bitbuf[tmp]&239;break; //bitbbuf[tmp] & 1110 1111b case 4:bitbuf[tmp]=bitbuf[tmp]&247;break; //bitbuf[tmp] & 1111 0111b case 5:bitbuf[tmp]=bitbuf[tmp]&251;break; //bitbuf[tmp] & 1111 1011b case 6:bitbuf[tmp]=bitbuf[tmp]&253;break; //bitbuf[tmp] & 1111 1101b case 7:bitbuf[tmp]=bitbuf[tmp]&254;break; // bitbuf[tmp] & 1111 1110b } update_block_bitmap(); gdt[0].bg_free_blocks_count++; update_group_desc(); } //删除一个inode 号 static void remove_inode(unsigned short del_num) { unsigned short tmp; tmp=(del_num-1)/8; reload_inode_bitmap(); switch((del_num-1)%8)//更改block位图 { case 0:bitbuf[tmp]=bitbuf[tmp]&127;break; case 1:bitbuf[tmp]=bitbuf[tmp]&191;break; case 2:bitbuf[tmp]=bitbuf[tmp]&223;break; case 3:bitbuf[tmp]=bitbuf[tmp]&239;break; case 4:bitbuf[tmp]=bitbuf[tmp]&247;break; case 5:bitbuf[tmp]=bitbuf[tmp]&251;break; case 6:bitbuf[tmp]=bitbuf[tmp]&253;break; case 7:bitbuf[tmp]=bitbuf[tmp]&254;break; } update_inode_bitmap(); gdt[0].bg_free_inodes_count++; update_group_desc(); } //在打开文件表中查找是否已打开文件 static unsigned short search_file(unsigned short Inode) { unsigned short fopen_table_point=0; while(fopen_table_point<16&&fopen_table[fopen_table_point++]!=Inode); if(fopen_table_point==16) { return 0; } return 1; } void initialize_disk(void) //初始化磁盘 { int i=0; printf("Creating the ext2 file system\n"); printf("Please wait "); while(i<1) { printf("... "); ++i;