Add image ls and image rm commands

src/registry.rs

@@ -1,8 +1,8 @@
 //! Registry: local storage of built VM artifacts under
 //! `$XDG_DATA_HOME/slim-rs/registry/<image>/`.
 
-use anyhow::{Context, Result, bail};
-use std::path::PathBuf;
+use anyhow::{Context, Result, anyhow, bail};
+use std::{fs, io, path::PathBuf};
 
 /// Validate a user-supplied image name before it is used in a registry path.
 ///
@@ -26,30 +26,25 @@ pub(crate) fn validate_image_name(name: &str) -> Result<()> {
     Ok(())
 }
 
+pub(crate) fn registry_base_dir() -> Result<PathBuf> {
+    let base = xdg::BaseDirectories::with_prefix("slim-rs");
+    base.create_data_directory("registry")
+        .context("Failed to create XDG_DATA_HOME subdirectory")
+}
+
 pub(crate) fn registry_dir(image: &str) -> Result<PathBuf> {
     validate_image_name(image)?;
-    let base = xdg::BaseDirectories::with_prefix("slim-rs");
-    let initrd_path = base
-        .place_data_file(format!("registry/{image}/initrd"))
-        .context("Failed to write to XDG_DATA_HOME")?;
-    let reg_dir = initrd_path
-        .parent()
-        .expect("data file has a parent")
-        .to_owned();
+    let base = registry_base_dir()?;
+
+    let reg_dir = base.join(image);
+    fs::create_dir(&reg_dir)
+        .or_else(|e| {
+            (e.kind() == io::ErrorKind::AlreadyExists)
+                .then_some(())
+                .ok_or(e)
+        })
+        .with_context(|| anyhow!("Failed to create {reg_dir:?}"))?;
 
-    // Defense in depth: the constructed path must stay inside the registry.
-    let registry_root = base
-        .place_data_file("registry/.root-check")
-        .context("Failed to write to XDG_DATA_HOME")?
-        .parent()
-        .expect("data file has a parent")
-        .to_owned();
-    if !reg_dir.starts_with(&registry_root) {
-        bail!(
-            "invalid image name '{image}': registry path escapes {}",
-            registry_root.display()
-        );
-    }
     Ok(reg_dir)
 }