?? unix文件模擬系統.cpp
字號:
{
printf( "Can't creat file\n" );
return 0;
}
// 找空閑用戶打開表項
for( j = 0; j < NOFILE; j++ )
{
if( user[user_id].u_ofile[j] == SYSOPENFILE + 1 )
break;
}
if( j == NOFILE )
{
printf( "Can't creat file\n" );
return 0;
}
// 寫系統打開表項信息
user[user_id].u_ofile[j] = i;
sys_ofile[i].f_flag = mode;
sys_ofile[i].f_count = 1;
sys_ofile[i].f_off = 0;
sys_ofile[i].f_inode = inode;
return j; // 返回文件描述符
}
return 0;
}
// 刪除文件
void _delete( char * filename )
{
unsigned int dinodeid;
struct inode * inode;
struct dir tempdir;
int i;
dinodeid = namei( filename );
if(( dinodeid == NULL ) || ( dinodeid == -1 )) // 找不到該文件
{
printf( "rm: %s: No such file\n", filename );
return;
}
inode = iget( dinodeid );
if( !( inode->i_mode & DIREG )) // 不是文件
{
printf( "rm: %s: Not a file\n", filename );
iput( inode );
return;
}
if( !( access( inode ) & WRITE)) // 沒有權限
{
printf( "bash: %s: Permission denied\n", filename );
iput( inode );
return;
}
if( pre_dinodeid == cur_path_inode->i_ino )
{
for( i = 0; i < dir.size; i++ )
{
if( dir.direct[i].d_ino == dinodeid )
break;
}
for( ; i < dir.size - 1; i++ )
{
dir.direct[i].d_ino=dir.direct[i + 1].d_ino;
strcpy(dir.direct[i].d_name, dir.direct[i + 1].d_name);
}
dir.direct[i].d_ino = 0;
strcpy( dir.direct[i].d_name, " " );
dir.size--;
}
else
{
tempdir = getdir( pre_dinodeid, " " );
for( i = 0; i < tempdir.size; i++ )
{
if( tempdir.direct[i].d_ino == dinodeid )
break;
}
for( ; i < tempdir.size - 1; i++ )
{
tempdir.direct[i].d_ino=tempdir.direct[i + 1].d_ino;
strcpy(tempdir.direct[i].d_name,tempdir.direct[i + 1].d_name);
}
tempdir.direct[i].d_ino = 0;
strcpy( tempdir.direct[i].d_name, " " );
tempdir.size--;
putdir( pre_dinodeid, tempdir );
}
inode->i_number--;
iput( inode );
}
// 打開文件
int open( char * filename, unsigned short openmode )
{
unsigned int dinodeid;
struct inode * inode;
int i, j;
// 檢索目錄
dinodeid = namei( filename );
if( dinodeid == -1 )
{
printf( "No such directory\n" );
return -1;
}
if( dinodeid == NULL )
{
if( openmode & O_CREAT )
return creat( filename, openmode & ( ~ O_CREAT ));
printf( "File does not existed\n" );
return -1;
}
// 分配內存i節點
inode = iget( dinodeid );
if( !access( inode ))
{
printf( "File open has not access\n" );
iput( inode );
return -1;
}
// 分配文件表項
for( i = 0; i < SYSOPENFILE; i++ )
{
if( sys_ofile[i].f_count == 0 )
break;
}
if( i == SYSOPENFILE )
{
printf( "System open file too much\n" );
iput( inode );
return -1;
}
// 分配用戶文件描述表項
for( j = 0; j < NOFILE; j++ )
if( user[user_id].u_ofile[j] == SYSOPENFILE + 1 )
break;
if( j == NOFILE )
{
printf( "user open file too much\n" );
iput( inode );
return -1;
}
sys_ofile[i].f_inode = inode;
sys_ofile[i].f_flag = openmode;
sys_ofile[i].f_count++;
// 讀/寫指針置位
if( openmode & O_APPEND )
sys_ofile[i].f_off = inode->i_size; // 讀/寫指針置于文件尾
else
sys_ofile[i].f_off = 0; // 讀/寫指針置于文件開始位置
user[user_id].u_ofile[j] = i;
// 將原來存在的文件清空
if( openmode & O_TRUNC )
{
for( i = 0; i < inode->i_size / BLOCKSIZ + 1; i++ )
bfree( inode->i_addr[i] );
inode->i_size = 0;
}
return j;
}
void close( int cfd )
{
int sys_ip;
// 獲得指向文件表項的指針sys_ip
sys_ip = user[user_id].u_ofile[cfd];
// 釋放內存i節點
iput( sys_ofile[sys_ip].f_inode );
// 文件表項引用計數減1
sys_ofile[sys_ip].f_count--;
// 清空用戶打開表
user[user_id].u_ofile[cfd] = SYSOPENFILE + 1;
}
// 讀文件
int read( int fh, char * buf, unsigned int nbyte )
{
unsigned long off;
unsigned int block, block_off, i, sys_ip;
struct inode * inode;
sys_ip = user[user_id].u_ofile[fh];
inode = sys_ofile[sys_ip].f_inode;
if( !( sys_ofile[sys_ip].f_flag & O_RDONLY ))
{
printf( "The file is not opened for read\n" );
return -1;
}
off = sys_ofile[sys_ip].f_off;
block = off / BLOCKSIZ; // 從inode->i_addr[block]號盤塊讀起
block_off = off % BLOCKSIZ; // block_off是在block號盤塊中的偏移量
// 讀寫指針在文件末尾，讀出字數為0
if( off == inode->i_size )
return 0;
// 讀文件不用跨越盤塊，即在一盤塊中就可讀出nbyte字
if( block_off + nbyte < BLOCKSIZ )
{
fseek( fd,
DATASTART + inode->i_addr[block] * BLOCKSIZ + block_off,
SEEK_SET );
fread( buf, 1, nbyte, fd );
return nbyte;
}
// 讀文件跨越盤塊，即所讀的文件有多個盤塊
// 先讀block盤塊
fseek( fd,
DATASTART + inode->i_addr[block] * BLOCKSIZ + block_off,
SEEK_SET );
fread( buf, 1, BLOCKSIZ - block_off, fd );
buf += BLOCKSIZ - block_off;
block++;
// 所讀的文件沒有到末尾
if( nbyte + off < inode->i_size )
{for(i=0;i<(nbyte-block_off)/BLOCKSIZ;i++)
{
fseek( fd, DATASTART + inode->i_addr[i+block] * BLOCKSIZ + block_off, SEEK_SET );
fwrite( buf, 1, BLOCKSIZ, fd );
buf += BLOCKSIZ;
}
fseek( fd, DATASTART + inode->i_addr[i + block] * BLOCKSIZ, SEEK_SET );
fread( buf, 1, ( nbyte - block_off ) % BLOCKSIZ, fd );
// 置文件讀/寫指針位置
sys_ofile[sys_ip].f_off += nbyte;
return nbyte;
}
// 所讀的文件到末尾
for( i = block; i < inode->i_size / BLOCKSIZ; i++ )
{
fseek( fd,
DATASTART + inode->i_addr[i] * BLOCKSIZ,
SEEK_SET );
fread( buf, 1, BLOCKSIZ, fd );
buf += BLOCKSIZ;
}
fseek( fd, DATASTART + inode->i_addr[i] * BLOCKSIZ, SEEK_SET );
fread( buf, 1, inode->i_size % BLOCKSIZ, fd );
sys_ofile[sys_ip].f_off = inode->i_size;
return ( inode->i_size - off );
}
// 寫文件
int write( int fh, char * buf, unsigned int nbyte )
{unsigned long off;
unsigned short block, block_off, i, sys_ip;
struct inode * inode;
sys_ip = user[user_id].u_ofile[fh];
inode = sys_ofile[sys_ip].f_inode;
if( !( sys_ofile[sys_ip].f_flag & O_WRONLY ))
{
printf( "The file is not opened for write\n" );
return -1;
}
off = sys_ofile[sys_ip].f_off;
block = off / BLOCKSIZ; // 從inode->i_addr[block]號盤塊起開始寫
block_off = off % BLOCKSIZ; // block_off是在block號盤塊中的偏移量
// 寫文件不用跨越盤塊，即在一盤塊中就可寫入nbyte字
if( block_off + nbyte < BLOCKSIZ )
{
fseek( fd, DATASTART + inode->i_addr[block] * BLOCKSIZ + block_off, SEEK_SET );
fwrite( buf, 1, nbyte, fd );
if( inode->i_size < nbyte )
inode->i_size = nbyte;
return nbyte;
}
// 寫文件跨越盤塊，即所寫的文件有多個盤塊
// 先往block盤塊寫入
fseek( fd, DATASTART + inode->i_addr[block] * BLOCKSIZ + block_off, SEEK_SET );
fwrite(buf, 1, BLOCKSIZ - block_off, fd );
buf += BLOCKSIZ - block_off;
// 所寫的文件沒有到末尾
if(nbyte + off < inode->i_size )
{
for(i=0;i<(nbyte-block_off)/BLOCKSIZ;i++)
{
inode->i_addr[block+i] = balloc();
fseek( fd, DATASTART + inode->i_addr[block] * BLOCKSIZ + block_off, SEEK_SET );
fwrite( buf, 1, BLOCKSIZ, fd );
buf += BLOCKSIZ;
}
}
fseek( fd, DATASTART + inode->i_addr[i + block] * BLOCKSIZ, SEEK_SET );
fwrite( buf, 1, ( nbyte - block_off ) % BLOCKSIZ, fd );
// 置文件讀/寫指針位置
sys_ofile[sys_ip].f_off += nbyte;
if( inode->i_size < nbyte )
{inode->i_size = nbyte;
return nbyte;
}
// 所讀的文件到末尾
// 寫到文件尾
for( i = block; i < inode->i_size / BLOCKSIZ; i++ )
{
fseek( fd, DATASTART + inode->i_addr[i] * BLOCKSIZ, SEEK_SET );
fwrite( buf, 1, BLOCKSIZ, fd );
buf += BLOCKSIZ;
}
// 申請空間再寫
for(i=0;i<(nbyte-block_off)/BLOCKSIZ;i++)
{ inode->i_addr[block+i] = balloc();
fseek( fd, DATASTART + inode->i_addr[i] * BLOCKSIZ, SEEK_SET );
fwrite( buf, 1, BLOCKSIZ, fd );
buf += BLOCKSIZ;
}
fseek(fd, DATASTART + inode->i_addr[i] * BLOCKSIZ, SEEK_SET );
fwrite( buf, 1, ( nbyte + off ) % BLOCKSIZ, fd );
inode->i_size = nbyte + off;
sys_ofile[sys_ip].f_off = inode->i_size;
if( inode->i_size < nbyte )
inode->i_size = nbyte;
return nbyte;
}
// 改變文件或目錄權限
void chmod( char * pathname, char * modename )
{
struct inode * inode;
int dinodeid;
dinodeid = namei( pathname );
if(( dinodeid == -1 ) || ( dinodeid == NULL ))
{
printf( "chmod: '%s': No such file or directory\n", pathname );
return;
}
inode = iget( dinodeid );
if( inode->i_uid - 1 != user_id ) // 該用戶不是文件主
{
iput( inode );
printf( "chmod: '%s': Permission denied\n", pathname );
return;
}
if(( modename[0] == '+' ) ||( modename[0] == '=' ))
{
switch( modename[2] )
{
case 'u': // 文件主權限
{
switch( modename[1] )
{
case 'r': inode->i_mode = inode->i_mode | UREAD; break;
case 'w': inode->i_mode = inode->i_mode | UWRITE; break;
case 'x': inode->i_mode = inode->i_mode | UEXE; break;
default: printf( "chmod: '%s': No such option\n", pathname );
}
break;
}
case 'g': // 同組用戶權限
{
switch( modename[1] )
{
case 'r': inode->i_mode = inode->i_mode | GREAD; break;
case 'w': inode->i_mode = inode->i_mode | GWRITE; break;
case 'x': inode->i_mode = inode->i_mode | GEXE; break;
default: printf( "chmod: '%s': No such option\n", pathname );
}
break;
}
case 'o': // 其它用戶權限
{
switch( modename[1] )
{
case 'r': inode->i_mode = inode->i_mode | OREAD ; break;
case 'w': inode->i_mode = inode->i_mode | OWRITE; break;
case 'x': inode->i_mode = inode->i_mode | OEXE; break;
default: printf( "chmod: '%s': No such option\n", pathname );
}
break;
}
case 'a': // 所有用戶權限
{
switch( modename[1] )
{
case 'r': inode->i_mode = inode->i_mode | UREAD | GREAD | OREAD; break;
case 'w': inode->i_mode = inode->i_mode | UWRITE | GWRITE | OWRITE; break;
case 'x': inode->i_mode = inode->i_mode | UEXE | GEXE | OEXE; break;
default: printf( "chmod: '%s': No such option\n", pathname );
}
break;
}
}
}
else if( modename[0] == '-' )
{
switch( modename[2] )
{
case 'u':
{
switch( modename[1] )
{
case 'r': inode->i_mode = inode->i_mode & ( ~ UREAD ); break;
case 'w': inode->i_mode = inode->i_mode & ( ~ UWRITE ); break;
case 'x': inode->i_mode = inode->i_mode & ( ~ UEXE ); break;
default: printf( "chmod: '%s': No such option\n", pathname );
}
break;
}
case 'g':
{
switch( modename[1] )
{
case 'r': inode->i_mode = inode->i_mode & ( ~ GREAD ); break;
case 'w': inode->i_mode = inode->i_mode & ( ~ GWRITE ); break;
case 'x': inode->i_mode = inode->i_mode & ( ~ GEXE ); break;
default: printf( "chmod: '%s': No such option\n", pathname );
}
break;
}
case 'o':
{
switch( modename[1] )
{
case 'r': inode->i_mode = inode->i_mode & ( ~ OREAD ); break;
case 'w': inode->i_mode = inode->i_mode & ( ~ OWRITE ); break;
case 'x': inode->i_mode = inode->i_mode & ( ~ OEXE ); break;
default: printf( "chmod: '%s': No such option\n", pathname );
}
break;
}
case 'a':
{
switch( modename[1] )
{
case 'r': inode->i_mode = inode->i_mode & ( ~ ( UREAD | GREAD | OREAD )); break;
case 'w': inode->i_mode = inode->i_mode & ( ~ ( UWRITE | GWRITE | OWRITE )); break;
case 'x': inode->i_mode = inode->i_mode & ( ~ ( UEXE | GEXE | OEXE )); break;
default: printf( "chmod: '%s': No such option\n", pathname );
}
break;
}
default: printf( "chmod: '%s': No such option\n", pathname );
}
}
iput( inode );
}
// 文件編輯器
void edlin( char * filename )
{ char buf[BLOCKSIZ];
int i, fh;
if(( fh = open(filename, DEFAULTMODE | O_CREAT )) == -1)
printf( "Can't creat file %s\n", filename );
printf( "輸入一行字符串到文件中\n\n" );
cin>>buf;
i=strlen(buf);
buf[i] = '\0';
write(fh, buf, strlen(buf)+1);
close( fh );
}
// 顯示文件內容
void list( char * filename )
{
struct inode * inode;
char * buf;
int fh, dinodeid;
dinodeid = namei( filename );
inode = iget( dinodeid );
buf = ( char * )malloc( inode->i_size );
if(( fh = open( filename, O_RDONLY )) != -1 )
{
read( fh, buf, inode->i_size );
printf( "%s\n", buf );
close( fh );
}
}
?? 快捷鍵說明
復制代碼
Ctrl + C
搜索代碼
Ctrl + F
全屏模式
F11
切換主題
Ctrl + Shift + D
顯示快捷鍵
?
增大字號
Ctrl + =
減小字號
Ctrl + -