inode.c

一个linux下NTFS文件格式源代码

	}
	/* terminating attribute */
	if(offset+8<size){
		NTFS_PUTU32(rec+offset,0xFFFFFFFF);
		offset+=4;
		NTFS_PUTU32(rec+offset,0);
		offset+=4;
	}else
		return E2BIG;
	NTFS_PUTU32(rec+0x18,offset);
	return 0;
}
  
int ntfs_update_inode(ntfs_inode *ino)
{
	int error;
	ntfs_disk_inode store;
	ntfs_io io;
	int i;

	store.count=store.size=0;
	store.records=0;
	error=layout_inode(ino,&store);
	if(error==E2BIG){
		error = ntfs_split_indexroot(ino);
		if(!error)
			error = layout_inode(ino,&store);
	}
	if(error == E2BIG){
		error = ntfs_attr_allnonresident(ino);
		if(!error)
			error = layout_inode(ino,&store);
	}
	if(error == E2BIG){
		/* should try:
		   introduce extension records
		   */
		ntfs_error("cannot handle saving inode %x\n",ino->i_number);
		deallocate_store(&store);
		return EOPNOTSUPP;
	}
	if(error){
		deallocate_store(&store);
		return error;
	}
	io.fn_get=ntfs_get;
	io.fn_put=0;
	for(i=0;i<store.count;i++){
		ntfs_insert_fixups(store.records[i].record,ino->vol->blocksize);
		io.param=store.records[i].record;
		io.size=ino->vol->mft_recordsize;
		/* FIXME: is this the right way? */
		error=ntfs_write_attr(
			ino->vol->mft_ino,ino->vol->at_data,0,
			store.records[i].recno*ino->vol->mft_recordsize,&io);
		if(error || io.size!=ino->vol->mft_recordsize){
			/* big trouble, partially written file */
			ntfs_error("Please unmount: write error in inode %x\n",ino->i_number);
			deallocate_store(&store);
			return error?error:EIO;
		}
	}
	return 0;
}	


void ntfs_decompress(unsigned char *dest, unsigned char *src, ntfs_size_t l)
{
	int head,comp;
	int copied=0;
	unsigned char *stop;
	int bits;
	int tag=0;
	int clear_pos;
	while(1)
	{
		head = NTFS_GETU16(src) & 0xFFF;
		/* high bit indicates that compression was performed */
		comp = NTFS_GETU16(src) & 0x8000;
		src += 2;
		stop = src+head;
		bits = 0;
		clear_pos=0;
		if(head==0)
			/* block is not used */
			return;/* FIXME: copied */
		if(!comp) /* uncompressible */
		{
			ntfs_memcpy(dest,src,0x1000);
			dest+=0x1000;
			copied+=0x1000;
			src+=0x1000;
			if(l==copied)
				return;
			continue;
		}
		while(src<=stop)
		{
			if(clear_pos>4096)
			{
				ntfs_error("Error 1 in decompress\n");
				return;
			}
			if(!bits){
				tag=NTFS_GETU8(src);
				bits=8;
				src++;
				if(src>stop)
					break;
			}
			if(tag & 1){
				int i,len,delta,code,lmask,dshift;
				code = NTFS_GETU16(src);
				src+=2;
				if(!clear_pos)
				{
					ntfs_error("Error 2 in decompress\n");
					return;
				}
				for(i=clear_pos-1,lmask=0xFFF,dshift=12;i>=0x10;i>>=1)
				{
					lmask >>= 1;
					dshift--;
				}
				delta = code >> dshift;
				len = (code & lmask) + 3;
				for(i=0; i<len; i++)
				{
					dest[clear_pos]=dest[clear_pos-delta-1];
					clear_pos++;
					copied++;
					if(copied==l)
						return;
				}
			}else{
				dest[clear_pos++]=NTFS_GETU8(src);
				src++;
				copied++;
				if(copied==l)
					return;
			}
			tag>>=1;
			bits--;
		}
		dest+=clear_pos;
	}
}

/* Caveat: No range checking in either ntfs_set_bit or ntfs_clear_bit */
void 
ntfs_set_bit (unsigned char *byte, int bit)
{
	byte += (bit >> 3);
	bit &= 7;
	*byte |= (1 << bit);
}

void 
ntfs_clear_bit (unsigned char *byte, int bit)
{
	byte += (bit >> 3);
	bit &= 7;
	*byte &= ~(1 << bit);
}

/* We have to skip the 16 metafiles and the 8 reserved entries */
static int 
new_inode (ntfs_volume* vol,int* result)
{
	int byte,error;
	int bit;
	int size,length;
	unsigned char value;
	ntfs_u8 *buffer;
	ntfs_io io;
	ntfs_attribute *data;

	buffer=ntfs_malloc(2048);
	if(!buffer)return ENOMEM;
	io.fn_put=ntfs_put;
	io.fn_get=ntfs_get;
	io.param=buffer;
	/* FIXME: bitmaps larger than 2048 bytes */
	io.size=2048;
	error=ntfs_read_attr(vol->mft_ino,vol->at_bitmap,0,0,&io);
	if(error){
		ntfs_free(buffer);
		return error;
	}
	size=io.size;
	data=ntfs_find_attr(vol->mft_ino,vol->at_data,0);
	length=data->size/vol->mft_recordsize;

	/* SRD: start at byte 0: bits for system files _are_ already set in bitmap */
	for (byte = 0; 8*byte < length; byte++)
	{
		value = buffer[byte];
		if(value==0xFF)
			continue;
		for (bit = 0; (bit < 8) && (8*byte+bit<length); 
		     bit++, value >>= 1)
		{
			if (!(value & 1)){
				*result=byte*8+bit;
				return 0;
			}
		}
	}
	/* There is no free space.  We must first extend the MFT. */
	return ENOSPC;
}

static int 
add_mft_header (ntfs_inode *ino)
{
	unsigned char* mft;
	ntfs_volume *vol=ino->vol;
	mft=ino->attr;

	ntfs_bzero(mft, vol->mft_recordsize);
	ntfs_fill_mft_header(mft,vol->mft_recordsize,vol->blocksize,
			ino->sequence_number);
	return 0;
}

/* We need 0x48 bytes in total */
static int 
add_standard_information (ntfs_inode *ino)
{
	ntfs_time64_t now;
	char data[0x30];
	char *position=data;
	int error;
	ntfs_attribute *si;

	now = ntfs_now();
	NTFS_PUTU64(position + 0x00, now);		/* File creation */
	NTFS_PUTU64(position + 0x08, now);		/* Last modification */
	NTFS_PUTU64(position + 0x10, now);		/* Last mod for MFT */
	NTFS_PUTU64(position + 0x18, now);		/* Last access */

	NTFS_PUTU64(position + 0x20, 0x00);		/* MSDOS file perms */
	NTFS_PUTU64(position + 0x28, 0);               /* unknown */
	error=ntfs_create_attr(ino,ino->vol->at_standard_information,0,
			       data,sizeof(data),&si);

	return error;
}

static int 
add_filename (ntfs_inode* ino, ntfs_inode* dir, 
	      const unsigned char *filename, int length, ntfs_u32 flags)
{
	unsigned char   *position;
	unsigned int    size;
	ntfs_time64_t   now;
	int		count;
	int error;
	unsigned char* data;
	ntfs_attribute *fn;

	/* work out the size */
	size = 0x42 + 2 * length;
	data = ntfs_malloc(size);
	if( !data )
		return ENOMEM;
	ntfs_bzero(data,size);

	/* search for a position */
	position = data;

	NTFS_PUTINUM(position, dir);	/* Inode num of dir */

	now = ntfs_now();
	NTFS_PUTU64(position + 0x08, now);		/* File creation */
	NTFS_PUTU64(position + 0x10, now);		/* Last modification */
	NTFS_PUTU64(position + 0x18, now);		/* Last mod for MFT */
	NTFS_PUTU64(position + 0x20, now);		/* Last access */

	/* Don't know */
	NTFS_PUTU32(position+0x38, flags);

	NTFS_PUTU8(position + 0x40, length);	      /* Filename length */
	NTFS_PUTU8(position + 0x41, 0x0);	      /* only long name */

	position += 0x42;
	for (count = 0; count < length; count++)
	{
		NTFS_PUTU16(position + 2 * count, filename[count]);
	}

	error=ntfs_create_attr(ino,ino->vol->at_file_name,0,data,size,&fn);
	if(!error)
		error=ntfs_dir_add(dir,ino,fn);
	ntfs_free(data);
	return error;
}

int 
add_security (ntfs_inode* ino, ntfs_inode* dir)
{
	int error;
	char *buf;
	int size;
	ntfs_attribute* attr;
	ntfs_io io;
	ntfs_attribute *se;

	attr=ntfs_find_attr(dir,ino->vol->at_security_descriptor,0);
	if(!attr)
		return EOPNOTSUPP; /* need security in directory */
	size = attr->size;
	if(size>512)
		return EOPNOTSUPP;
	buf=ntfs_malloc(size);
	if(!buf)
		return ENOMEM;
	io.fn_get=ntfs_get;
	io.fn_put=ntfs_put;
	io.param=buf;
	io.size=size;
	error=ntfs_read_attr(dir,ino->vol->at_security_descriptor,0,0,&io);
	if(!error && io.size!=size)ntfs_error("wrong size in add_security");
	if(error){
		ntfs_free(buf);
		return error;
	}
	/* FIXME: consider ACL inheritance */
	error=ntfs_create_attr(ino,ino->vol->at_security_descriptor,
			       0,buf,size,&se);
	ntfs_free(buf);
	return error;
}

static int 
add_data (ntfs_inode* ino, unsigned char *data, int length)
{
	int error;
	ntfs_attribute *da;
	error=ntfs_create_attr(ino,ino->vol->at_data,0,data,length,&da);
	return error;
}

/* We _could_ use 'dir' to help optimise inode allocation */
int ntfs_alloc_inode (ntfs_inode *dir, ntfs_inode *result, 
		      const char *filename, int namelen, ntfs_u32 flags)
{
	ntfs_io io;
	int error;
	ntfs_u8 buffer[2];
	ntfs_volume* vol=dir->vol;
	int byte,bit;

	error=new_inode (vol,&(result->i_number));
	if(error==ENOSPC){
		error=ntfs_extend_mft(vol);
		if(error)return error;
		error=new_inode(vol,&(result->i_number));
	}
	if(error){
		ntfs_error ("ntfs_get_empty_inode: no free inodes\n");
		return error;
	}
	byte=result->i_number/8;
	bit=result->i_number & 7;

	io.fn_put = ntfs_put;
	io.fn_get = ntfs_get;
	io.param = buffer;
	io.size=1;
	/* set a single bit */
	error=ntfs_read_attr(vol->mft_ino,vol->at_bitmap,0,byte,&io);
	if(error)return error;
	if(io.size!=1)
		return EIO;
	ntfs_set_bit (buffer, bit);
	io.param = buffer;
	io.size = 1;
 	error = ntfs_write_attr (vol->mft_ino, vol->at_bitmap, 0, byte, &io);
	if(error)return error;
	if (io.size != 1)
		return EIO;
	/*FIXME: Should change MFT on disk
	  error=ntfs_update_inode(vol->mft_ino);
	  if(error)return error;
	  */
	/* get the sequence number */
	io.param = buffer;
	io.size = 2;
	error = ntfs_read_attr(vol->mft_ino, vol->at_data, 0, 
			       result->i_number*vol->mft_recordsize+0x10,&io);
	if(error)
		return error;
	result->sequence_number=NTFS_GETU16(buffer)+1;
	result->vol=vol;
	result->attr=ntfs_malloc(vol->mft_recordsize);
	if( !result->attr )
		return ENOMEM;
	result->attr_count=0;
	result->attrs=0;
	result->record_count=1;
	result->records=ntfs_malloc(8*sizeof(int));
	if( !result->records ) {
		ntfs_free( result->attr );
		result->attr = 0;
		return ENOMEM;
	}
	result->records[0]=result->i_number;
	error=add_mft_header(result);
	if(error)
		return error;
	error=add_standard_information(result);
	if(error)
		return error;
	error=add_filename(result,dir,filename,namelen,flags);
	if(error)
		return error;
	error=add_security(result,dir);
	/*FIXME: check error */
	return 0;
}

int
ntfs_alloc_file(ntfs_inode *dir, ntfs_inode *result, char *filename,
		int namelen)
{
	int error = ntfs_alloc_inode(dir,result,filename,namelen,0);
	if(error)
		return error;
	error = add_data(result,0,0);
	return error;
}

/*
 * Local variables:
 * c-file-style: "linux"
 * End:
 */