操作系统实验文件系统设计

printf(\ return 0; } temp_buf=buf; off=sys_ofile[user[user_id].u_ofile[fd1]].f_off; if((off+size)>inode->di_size) size=inode->di_size-off; block_off=off%BLOCKSIZ; block=off/BLOCKSIZ; if(block_off+sizedi_addr[block]*BLOCKSIZ+block_off,SEEK_SET); fread(buf,1,size,fd); return size; } fseek(fd,DATASTART+inode->di_addr[block]*BLOCKSIZ+block_off,SEEK_SET); fread(temp_buf,1,BLOCKSIZ-block_off,fd); temp_buf+=BLOCKSIZ-block_off; j=(inode->di_size-off-block_off)/BLOCKSIZ; for(i=0;i<(size-block_off)/BLOCKSIZ; i++) { fseek(fd,DATASTART+inode->di_addr[j+i]*BLOCKSIZ,SEEK_SET); fread(temp_buf,1,BLOCKSIZ,fd); temp_buf+=BLOCKSIZ; } block_off=(size-block_off)%BLOCKSIZ; block=inode->di_addr[off+size/BLOCKSIZ+1]; fseek(fd,DATASTART+block*BLOCKSIZ,SEEK_SET); fread(temp_buf,1,block_off,fd); sys_ofile[user[user_id].u_ofile[fd1]].f_off+=size; return size; }

unsigned int write(fd1,buf,size) int fd1; char *buf;

unsigned int size; { unsigned long off; int block,block_off,i,j,k=0; struct inode *inode; char *temp_buf; inode=sys_ofile[user[user_id].u_ofile[fd1]].f_inode; temp_buf=buf; off=sys_ofile[user[user_id].u_ofile[fd1]].f_off; block_off=off%BLOCKSIZ; block=off/BLOCKSIZ; if(block_off+sizedi_addr[block]*BLOCKSIZ+block_off,SEEK_SET); fwrite(buf,1,size,fd); printf(\ return size; } if(sys_ofile[user[user_id].u_ofile[fd1]].f_flag==FAPPEND) { fseek(fd,DATASTART+inode->di_addr[block]*BLOCKSIZ+block_off,SEEK_SET); fwrite(temp_buf,1,BLOCKSIZ-block_off,fd); temp_buf+=BLOCKSIZ-block_off; k=1; } for(i=0;i<(size-k*(BLOCKSIZ-block_off)) { /BLOCKSIZ;i++) inode->di_addr[block+1+i]=balloc();

fseek(fd,DATASTART+inode->di_addr[block+k+i]*BLOCKSIZ,SEEK_SET); fwrite(temp_buf,1,BLOCKSIZ,fd); temp_buf+=BLOCKSIZ; } block_off=(size-k*(BLOCKSIZ-block_off))%BLOCKSIZ; block=inode->di_addr[block+k+i]=balloc(); fseek(fd,DATASTART+block*BLOCKSIZ,SEEK_SET); fwrite(temp_buf,1,block_off,fd); sys_ofile[user[user_id].u_ofile[fd1]].f_off+=size; inode->di_size=sys_ofile[user[user_id].u_ofile[fd1]].f_off; return size; }

18.注册和退出函数login()和logout()(文件名log.c) #include #include \int login(uid,passwd) //logn() unsigned short uid; char *passwd; { int i,j; for(i=0;i

int logout(uid) //logout() unsigned short uid; { int i,j,sys_no; struct inode *inode; for(i=0; i

for(j=0;j

19.打印输出函数dirlt()(文件名dirlt.c) #include #include \dirlt(j) int j; { int i; printf(\ for(i=0; i

<结果>

对上述makefiie文件进行编译后可得执行文件\。在Linux或UNIX系统V以上版本环境下,运行filsys,可对上述文件系统程序进行测试。其结果如下: $filsys〈CR> $format

$Do you want to format the disk?y

$Format will erase ail context on the disk.Are You Sure?y $install $dir

CURRENT DIRECTORY: . d xxx xxx xxx