GitSnapFS

GitSnapFS exposes snapshots of a Git repository as a read-only filesystem designed for safe inspection, automated audits, and tooling integration.

Highlights

• /commits/<full-hex-commit-id> presents the tree for an individual commit.
• branches/, tags/, and HEAD materialise as symlinks into the matching commit snapshot.
• Synthetic inodes are derived from Git object IDs so links remain stable across views.
• The filesystem is strictly read-only and answers requests lazily; updates in the underlying repo are surfaced without a pre-scan.
• Hot upgrades keep the mount active by duping the FUSE file descriptor across an exec.
• Directory listings leave . and .. to the kernel, letting path caches stay in userspace.
• We leverage the kernel’s zero-message open/opendir paths (NO_OPEN_SUPPORT, NO_OPENDIR_SUPPORT) for near-native performance once data is cached.

Requirements

• Linux with FUSE kernel support that advertises EXPORT_SUPPORT, ZERO_MESSAGE_OPEN, and ZERO_MESSAGE_OPENDIR.
• fusermount/fusermount3 (typically provided by fuse packages).
• Rust toolchain nightly or stable recent enough to build the dependency graph (cargo, rustc).

Quick Start

cargo run -- --repo path/to/.git --mountpoint /tmp/gitfs

The mount exposes the root layout (commits, branches, tags, HEAD). Unmount with:

fusermount -u /tmp/gitfs   # or fusermount3 -u

Or by just terminating the process.

Development

• Design notes live in codex_spec.md.

• Formatting and linting are enforced with the following commands:

  cargo fmt
  cargo clippy --all-targets --all-features -- -D clippy::pedantic -D clippy::style -D clippy::cargo

• The clippy.toml documents unavoidable duplicate crate versions coming from upstream dependencies.

• Please keep the filesystem read-only and avoid libfuse/libgit2 shims; all Git access goes through gix and FUSE plumbing through fuse-backend-rs.