4. item

Module providing the Item class for files in the initramfs

Each file type of the initramfs has an Item subclass. Those classes provide methods used by Initramfs generation methods.

exception cmkinitramfs.item.MergeError[source]

Bases: Exception

Cannot merge an Item into another

class cmkinitramfs.item.Item[source]

Bases: abc.ABC

An object within the initramfs

Return type: None

__contains__(path)[source]

Check if this item is present at the given path in the initramfs

This method should be overriden by subclasses which add files to the initramfs.

Returns: True if path is part of this Item’s destination paths, False otherwise
Parameters: path (str) –
Return type: bool

__iter__()[source]

Get the paths of this item within the initramfs

This method should be overriden by subclasses which add files to the initramfs.

Returns: Iterator over this Item’s destination paths
Return type: Iterator[str]

static build_from_cpio_list(data)[source]

Build an Item from a string

This string should respect the format of gen_init_cpio.

Parameters: data (str) – String to parse
Returns: Item corresponding to data
Raises: ValueError – Invalid string
Return type: cmkinitramfs.item.Item

abstract build_to_cpio_list()[source]

String representing the item

The string is formatted to be compatible with the gen_init_cpio tool from the Linux kernel. This method has to be defined by subclasses.

Return type: str

abstract build_to_directory(base_dir)[source]

Add this item to a real filesystem

This will copy or create a file on a real filesystem. This method has to be defined by subclasses.

Parameters: base_dir (str) – Path to use as root directory (e.g. using /tmp/initramfs, /bin/ls will be copied to /tmp/initramfs/bin/ls)
Return type: None

is_mergeable(other)[source]

Check if two items can be merged together

By default, two items can only be merged if they are equal.

Parameters: other (cmkinitramfs.item.Item) – Item to merge into self
Returns: True if the items can be merged, False otherwise
Return type: bool

merge(other)[source]

Merge two items together

Default merge is just a no-op. Subclasses can override this as done by File to handle hardlink of identical files.

Parameters: other (cmkinitramfs.item.Item) – Item to merge into self
Raises: MergeError – Cannot merge the items
Return type: None

class cmkinitramfs.item.File(mode, user, group, dests, src, data_hash, chunk_size=65536)[source]

Bases: cmkinitramfs.item.Item

Normal file within the initramfs

Parameters

mode (int) – Permissions (e.g. 0o644)
user (int) – Owner user (UID)
group (int) – Owner group (GID)
dests (Set[str]) – Paths in the initramfs (hard-linked)
src (str) – Source file to copy (not unique to the file)
data_hash (bytes) – Hash of the file (can be obtained with hash_file())
chunk_size (int) – Chunk size to use when copying the file

Return type

None

class cmkinitramfs.item.Directory(mode, user, group, dest)[source]

Bases: cmkinitramfs.item.Item

Directory within the initramfs

Parameters

mode (int) – Permissions (e.g. 0o644)
user (int) – Owner user (UID)
group (int) – Owner group (GID)
dest (str) – Path in the initramfs

Return type

None

class cmkinitramfs.item.Node(mode, user, group, dest, nodetype, major, minor)[source]

Bases: cmkinitramfs.item.Item

Special file within the initramfs

Parameters

mode (int) – Permissions (e.g. 0o644)
user (int) – Owner user (UID)
group (int) – Owner group (GID)
dest (str) – Path in the initramfs
nodetype (cmkinitramfs.item.Node.NodeType) – Type of node (block, character)
major (int) – Major number of the node
minor (int) – Minor number of the node

Return type