src: add internal erofs writer code

With this change, we create the erofs filesystem for ourselves, instead
of using the external mkcomposefs CLI.

This currently produces a different output than the output of
mkcomposefs.  We're planning to make changes here to make the output
more similar to mkcomposefs while pursuing changes in mkcomposefs to
make it more similar to our format.  This work is being tracked as an
issue in containers/composefs#198 and a first
pull request in containers/composefs#410 .

Closes containers#56

Signed-off-by: Allison Karlitskaya <[email protected]>

.github/workflows/examples.yml

@@ -27,7 +27,7 @@ jobs:
       run: sudo tune2fs -O verity $(findmnt -vno SOURCE /)
 
     - name: Install dependencies
-      run: sudo apt-get install -y meson mtools qemu-system systemd-boot-efi erofs-utils
+      run: sudo apt-get install -y meson mtools qemu-system systemd-boot-efi
 
     - name: Get a newer podman for heredoc support (from debian testing)
       run: |

Cargo.toml

@@ -16,8 +16,10 @@ anyhow = { version = "1.0.89", default-features = false }
 async-compression = { version = "0.4.17", default-features = false, features = ["tokio", "gzip"] }
 clap = { version = "4.5.19", default-features = false, features = ["std", "help", "usage", "derive"] }
 containers-image-proxy = "0.7.0"
+env_logger = "0.11.5"
 hex = "0.4.3"
 indicatif = { version = "0.17.8", features = ["tokio"] }
+log = "0.4.22"
 oci-spec = "0.7.0"
 regex-automata = { version = "0.4.8", default-features = false }
 rustix = { version = "0.38.37", features = ["fs", "mount", "process"] }
@@ -26,10 +28,12 @@ tar = { version = "0.4.42", default-features = false }
 tempfile = "3.13.0"
 thiserror = "2.0.4"
 tokio = "1.41.0"
-zerocopy = "0.8.13"
+xxhash-rust = { version = "0.8.12", features = ["xxh32"] }
+zerocopy = { version = "0.8.13", features = ["derive"] }
 zstd = "0.13.2"
 
 [dev-dependencies]
+insta = "1.42.0"
 similar-asserts = "1.6.0"
 test-with = { version = "0.14", default-features = false, features = ["executable"] }
 

src/bin/cfsctl.rs

@@ -97,6 +97,8 @@ enum Command {
 }
 
 fn main() -> Result<()> {
+    env_logger::init();
+
     let args = App::parse();
 
     let repo = (if let Some(path) = args.repo {

src/bin/erofs-debug.rs

@@ -0,0 +1,25 @@
+use std::{fs::File, io::Read, path::PathBuf};
+
+use clap::Parser;
+
+use composefs::erofs::debug::debug_img;
+
+/// Produce a detailed dump of an entire erofs image
+///
+/// The output is in a diff-friendly format, such that every distinct image produces a distinct
+/// output (ie: an injective mapping).  This is useful for determining the exact ways in which two
+/// different images are different.
+#[derive(Parser)]
+struct Args {
+    /// The path to the image file to dump
+    image: PathBuf,
+}
+
+fn main() {
+    let args = Args::parse();
+    let mut image = File::open(args.image).expect("Opening file");
+
+    let mut data = vec![];
+    image.read_to_end(&mut data).expect("read_to_end() failed");
+    debug_img(&mut std::io::stdout(), &data).unwrap();
+}