Crate squib_snapshot 

squib-snapshot — bitcode state file, sparse memory file, dirty-page tracking.

Implements Phase 5 of the squib roadmap. The crate is split into:

• error — wire-stable SnapshotError (I-RC-8 in 11 § 7).
• state — MicrovmState and child structs (vCPU, GIC, MMDS, devices).
• envelope — Snapshot<T> outer container with bitcode + CRC64 trailer.
• atomic — D25 temp-file + fsync + rename writer with cross-FS pre-flight check.
• memory — Full / sparse-of-dirty memory-file writer.
• dirty — Box<[AtomicU64]> dirty bitmap + adaptive heuristic (D11 + D21).
• save / load — high-level orchestrators that tie the pieces together.

Cross-references: 16-snapshots.md, 10-data-model.md § 5–6, 11-runtime-core. md § 6, 99-key-decisions.md § D5, D11, D21, D25.

Quality bar

#![forbid(unsafe_code)] — every public surface is safe Rust. The Mach-exception pager that backs --mem-backend=Uffd lives in the sibling squib-host crate where the unsafe is bounded and reviewed.

Re-exports

pub use atomic::AtomicWriter;

pub use atomic::TEMP_SUFFIX;

pub use atomic::UnlinkOnDrop;

pub use atomic::check_same_filesystem;

pub use atomic::derive_temp_path;

pub use dirty::ADAPTIVE_WINDOW;

pub use dirty::AdaptiveController;

pub use dirty::DEFAULT_STEP_DOWN_THRESHOLD;

pub use dirty::DirtyBitmap;

pub use dirty::TrackedRegion;

pub use dirty::TrackingGranule;

pub use envelope::Crc64Writer;

pub use envelope::SNAPSHOT_DESERIALIZATION_BYTES_LIMIT;

pub use envelope::SNAPSHOT_MAGIC_AARCH64;

pub use envelope::SNAPSHOT_VERSION;

pub use envelope::Snapshot;

pub use envelope::SnapshotHdr;

pub use envelope::arch_magic;

pub use error::Result;

pub use error::SnapshotError;

pub use load::LoadedSnapshot;

pub use load::SnapshotDescription;

pub use load::describe;

pub use load::load;

pub use memory::MemorySnapshotKind;

pub use memory::MemoryWriter;

pub use memory::PageReader;

pub use memory::VecPageReader;

pub use save::SaveReport;

pub use save::SaveRequest;

pub use save::SnapshotKind;

pub use save::save;

pub use state::DeviceState;

pub use state::DeviceStates;

pub use state::FpSimdRegs;

pub use state::GicState;

pub use state::GpRegs;

pub use state::MicrovmState;

pub use state::MmdsState;

pub use state::PsciVcpuState;

pub use state::VcpuState;

pub use state::VmInfo;

pub use vcpu_save::GicRestoreTarget;

pub use vcpu_save::GicSnapshotSource;

pub use vcpu_save::MmdsRestoreTarget;

pub use vcpu_save::MmdsSnapshotSource;

pub use vcpu_save::VcpuRestoreTarget;

pub use vcpu_save::VcpuSnapshotSource;

pub use vcpu_save::capture_vcpu_state;

pub use vcpu_save::normalized_psci_state;

pub use vcpu_save::restore_vcpu_state;

Modules

atomic

Atomic temp-file + fsync + rename pattern (D25).

dirty

Dirty page tracking — Box<[AtomicU64]> shadow bitmap, adaptive heuristic.

envelope

Snapshot<Data> envelope, header, and CRC64 framing.

error

SnapshotError — wire-stable error variants for the snapshot subsystem.

load

High-level load orchestrator.

memory

Memory file writer / reader — Full dump and sparse-of-dirty.

save

High-level save / load orchestrator.

state

MicrovmState and child types — the snapshot state blob.

vcpu_save

vCPU + GIC capture/restore helpers — the host-portable surface.