4.2. lf.win.ole.cfb — OLE structured storage (compound file binary)

This package provides support to work with OLE structured storage files. More information about this file format can be found at: http://msdn.microsoft.com/en-us/library/dd942138(PROT.10).aspx

class lf.win.ole.cfb.CompoundFile(stream, offset=None)

Represents an OLE structured storage file (compound file binary).

Parameters:

• stream (IStream) – A stream covering the contents of the compound file.
• offset (int) – The start of the compound file in the stream.

header

A Header object containing information from the compound file header.

sect_size

The number of bytes in a sector.

mini_sect_size

The number of bytes in a mini sector.

mini_stream_cutoff

The maximum size of a file (in bytes) in the mini stream.

ver_major

The major version number. (from the header)

ver_minor

The minor version number. (from the header)

di_fat

A list of entries from the double indirect FAT.

fat

A list of entries from the FAT.

mini_fat

A list of entries from the mini FAT.

mini_stream

A stream covering the contents of the mini stream. None if there is no mini stream.

dir_stream

A stream covering the contents of the directory stream. None if there is no directory stream.

root_dir_entry

A DirEntry object for the root directory entry. None if there is no root directory.

dir_entries

A dictionary of directory entries, found by traversing the RB tree.

cfb_stream

A stream covering the contents of the file.

byte_offset(sect_num)

Calculates the byte offset of a sector number.

Parameter:sect_num (int) – The sector number. Return type:int Returns:The byte offset in the file of the sector.

mini_byte_offset(mini_sect_num)

Calculates the byte offset of a mini sector number.

Parameter:mini_sect_num (int) – The mini sector number. Return type:int Returns:The byte offset in the mini stream of the mini sector number.

get_fat_chain(first_sect)

Retrieves a chain from the FAT.

Parameter:first_sect (int) – The sector number of the first sector in the chain. Raises IndexError:  If first_sect is beyond the size of the file. Return type:list Returns:The sector chain from the FAT.

get_mini_fat_chain(first_mini_sect)

Retrieves a chain from the mini FAT.

Parameter:first_mini_sect (int) – The sector number of the first sector in the chain. Raises IndexError:  If first_mini_sect is beyond the size of the mini FAT. Return type:list Returns:The sector chain from the mini FAT.

get_dir_entry(sid)

Retrieves a directory entry

Parameter:sid (int) – The stream identifier of the directory entry. Raises IndexError:  If sid is out of range. Return type:DirEntry Returns:The directory entry.

classmethod is_valid_dir_entry(entry)

Determines if a DirEntry object is valid.

If entry matches any of the following tests, it is considered invalid:

• if entry.name is empty
• if entry.name contains invalid characters
• if entry.type is not 0x0, 0x1, 0x2, or 0x5
• if entry.color is not 0x0 or 0x1
• if entry.left_sid, entry.right_sid, or entry.child_sid is not between STREAM_ID_MIN and STREAM_ID_MAX, and is not STREAM_ID_NONE

Parameter:entry (DirEntry) – The DirEntry object to examine Return type:bool Returns:True if entry is a valid directory entry.

get_stream(sid, slack=False)

Retrieves the contents of a stream.

Parameters:

• sid (int) – The stream identifier for the directory entry associated with the stream.
• slack (bool) – If True, the contents of the entire stream are returned. Otherwise the stream is truncated at the size specified by the associated directory entry.

Raises IndexError:  

If sid is out of range.

Return type:

IStream

Returns:

An IStream covering the contents of the stream.

class lf.win.ole.cfb.Header

Represents the header from a compound file binary.

sig

The signature value.

clsid

The class ID value.

ver_minor

The minor version number.

ver_major

The major version number.

byte_order

The byte order mark value.

sect_shift

The size of a sector, as a power of 2.

mini_sect_shift

The size of a sector in the mini stream, as a power of 2.

rsvd

The reserved value.

dir_sect_count

The number of sectors that contain directory entries.

fat_sect_count

The number of sectors that contain FAT entries.

dir_sect_offset

The sector offset of the first directory entry.

trans_num

The transaction signature number.

mini_stream_cutoff

The maximum size of a user-defined data stream that can be allocated in the mini FAT.

mini_fat_sect_offset

The sector offset of the first mini FAT entry.

mini_fat_sect_count

The number of sectors in the mini FAT.

di_fat_sect_offset

The sector offset of the first DIFAT entry (beyond the header).

di_fat_sect_count

The number of sectors in the DIFAT.

di_fat

The first 109 DIFAT entries.

classmethod from_stream(stream, offset=None)

Creates a Header object from a stream.

Parameters:

• stream (IStream) – A stream that contains the compound file header.
• offset (int) – The start of the header in stream.

Return type:

Header

Returns:

The corresponding Header object.

class lf.win.ole.cfb.DirEntry

Represents a directory entry in a compound file.

name

The name of the directory entry.

name_size

The length of the name field (in bytes).

type

The type of directory entry.

color

The color of the directory entry.

left_sid

The stream identifier of the left sibling directory entry.

right_sid

The stream identifier of the right sibling directory entry.

child_sid

The stream identifier of the child directory entry.

clsid

The CLSID of the directory entry.

state

The user defined state bits.

btime

The creation time of the directory entry.

mtime

The last modification time of the directory entry.

stream_sect_offset

The first sector of the stream.

stream_size

The size in bytes of the stream.

Note

Per the spec. if ver_major is 0x3, the high 4 bytes of this value may be invalid, and must be ignored. This is a responsibility of the calling function.

classmethod from_stream(stream, offset=None)

Creates a DirEntry object from a stream.

Parameters:

• stream (IStream) – A stream that contains the directory entry.
• offset (int) – The start of the directory entry in stream.

Return type:

DirEntry

Returns:

The corresponding DirEntry object.