feat: oci compliance work (#85)

* chore: rework oci crate to be more composable

* feat: image pull is now internally explicit

* feat: utilize vfs for assembling oci images

* feat: rework oci to preserve permissions via a vfs

crates/ctl/src/cli/pull.rs

@@ -0,0 +1,42 @@
+use anyhow::Result;
+use clap::{Parser, ValueEnum};
+use krata::v1::{
+    common::GuestOciImageFormat,
+    control::{control_service_client::ControlServiceClient, PullImageRequest},
+};
+
+use tonic::transport::Channel;
+
+use crate::pull::pull_interactive_progress;
+
+#[derive(ValueEnum, Clone, Debug, PartialEq, Eq)]
+pub enum PullImageFormat {
+    Squashfs,
+    Erofs,
+}
+
+#[derive(Parser)]
+#[command(about = "Pull an image into the cache")]
+pub struct PullCommand {
+    #[arg(help = "Image name")]
+    image: String,
+    #[arg(short = 's', long, default_value = "squashfs", help = "Image format")]
+    image_format: PullImageFormat,
+}
+
+impl PullCommand {
+    pub async fn run(self, mut client: ControlServiceClient<Channel>) -> Result<()> {
+        let response = client
+            .pull_image(PullImageRequest {
+                image: self.image.clone(),
+                format: match self.image_format {
+                    PullImageFormat::Squashfs => GuestOciImageFormat::Squashfs.into(),
+                    PullImageFormat::Erofs => GuestOciImageFormat::Erofs.into(),
+                },
+            })
+            .await?;
+        let reply = pull_interactive_progress(response.into_inner()).await?;
+        println!("{}", reply.digest);
+        Ok(())
+    }
+}