Enum ComposefsCmdline 

pub enum ComposefsCmdline<ObjectID: FsVerityHashValue> {
    V2 {
        digest: ObjectID,
        insecure: bool,
    },
    V1 {
        digest: ObjectID,
        insecure: bool,
    },
}

A composefs kernel argument identifying which EROFS image to mount at boot.

Two variants exist to distinguish EROFS format versions:

• ComposefsCmdline::V2: V2 EROFS — either composefs=<digest> (legacy shorthand) or composefs.digest=v2-<hash>-<lg>:<digest> (explicit form)
• ComposefsCmdline::V1: V1 EROFS — composefs.digest=v1-<hash>-<lg>:<digest>

The initramfs checks for composefs.digest= first (accepting both v1 and v2 descriptors), then falls back to the legacy composefs= shorthand. Multiple composefs.digest= entries may appear on the cmdline (different format/algorithm combinations); the initramfs tries each in order, mounting the first image that exists.

NOTE: The equivalent parsing logic in bootc’s crates/initramfs/src/lib.rs must be kept in sync with this file manually, since bootc does not yet depend on composefs-boot directly.

Variants

V2

V2 EROFS image: embedded as composefs=<hex-digest> in the UKI cmdline.

The insecure flag, when true, means the digest is prefixed with ? (e.g. composefs=?<hex>), making fs-verity verification optional.

Fields

digest: ObjectID

The fs-verity hash of the EROFS image.

insecure: bool

If true, a ? prefix is added to the digest, making fs-verity verification optional at boot.

V1

V1 EROFS image: embedded as composefs.digest=v1-<hash>-<lg>:<hex-digest> in the UKI cmdline.

The value encodes the algorithm, e.g. composefs.digest=v1-sha256-12:<hex> or composefs.digest=v1-sha512-12:<hex>.

The insecure flag, when true, means the value is prefixed with ? (e.g. composefs.digest=?v1-sha512-12:<hex>), making fs-verity verification optional.

Fields

digest: ObjectID

The fs-verity hash of the EROFS image.

insecure: bool

If true, a ? prefix is added before the format descriptor in the value, making fs-verity verification optional at boot.

Implementations

impl<ObjectID: FsVerityHashValue> ComposefsCmdline<ObjectID>

pub fn digest(&self) -> &ObjectID

Returns a reference to the hex digest, regardless of variant.

Useful for looking up the image in composefs/images/<digest>.

pub fn validate_digest<'a>( &self, acceptable: impl IntoIterator<Item = &'a ObjectID>, ) -> Result<&ObjectID>

where ObjectID: 'a,

Validates that this UKI cmdline’s digest matches one of the acceptable boot image digests.

With dual V1+V2 EROFS, a single composefs image is stored as two boot EROFS serializations with distinct digests; a UKI is sealed carrying exactly one of them. This accepts the UKI if its digest matches ANY of acceptable. Returns the matched (UKI’s own) digest on success.

pub fn is_insecure(&self) -> bool

Returns whether this karg is in insecure mode (fs-verity verification skipped).

pub fn new_v2(digest: ObjectID, insecure: bool) -> Self

Constructs a V2 cmdline value (composefs=<hex>).

pub fn new_v1(digest: ObjectID, insecure: bool) -> Self

Constructs a V1 cmdline value (composefs.digest=v1-<hash>-<lg>:<hex>).

pub fn from_cmdline(cmdline: &str) -> Result<Option<Self>>

Parses a ComposefsCmdline from a kernel command line string.

Scans for composefs.digest= tokens first (→ ComposefsCmdline::V1). Multiple such tokens may appear on the cmdline (different algorithms); the first one whose format descriptor matches the ObjectID algorithm is returned. Then falls back to composefs= (→ ComposefsCmdline::V2). Returns None if no matching token is present.

Errors

Returns an error if a matching karg is found but the hex digest cannot be parsed for the given ObjectID type.

pub fn to_cmdline_arg(&self) -> String

Renders this value as a kernel command line fragment.

• ComposefsCmdline::V1 (secure) → "composefs.digest=v1-<hash>-<lg>:<hex>"
• ComposefsCmdline::V1 (insecure) → "composefs.digest=?v1-<hash>-<lg>:<hex>"
• ComposefsCmdline::V2 (secure) → "composefs=<hex>"
• ComposefsCmdline::V2 (insecure) → "composefs=?<hex>"

Trait Implementations

impl<ObjectID: Clone + FsVerityHashValue> Clone for ComposefsCmdline<ObjectID>

fn clone(&self) -> ComposefsCmdline<ObjectID>

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<ObjectID: Debug + FsVerityHashValue> Debug for ComposefsCmdline<ObjectID>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<ObjectID: Eq + FsVerityHashValue> Eq for ComposefsCmdline<ObjectID>

impl<ObjectID: PartialEq + FsVerityHashValue> PartialEq for ComposefsCmdline<ObjectID>

fn eq(&self, other: &ComposefsCmdline<ObjectID>) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<ObjectID: PartialEq + FsVerityHashValue> StructuralPartialEq for ComposefsCmdline<ObjectID>