hypha: implement image cache

hypha/bin/controller.rs

@@ -1,6 +1,6 @@
 use clap::Parser;
 use hypha::ctl::Controller;
-use hypha::error::Result;
+use hypha::error::{HyphaError, Result};
 
 #[derive(Parser, Debug)]
 #[command(version, about)]
@@ -19,16 +19,38 @@ struct ControllerArgs {
 
     #[arg(short, long, default_value_t = 512)]
     mem: u64,
+
+    #[arg(short = 'C', long, default_value = "auto")]
+    cache: String,
 }
 
 fn main() -> Result<()> {
     env_logger::init();
 
     let args = ControllerArgs::parse();
-    let mut controller =
-        Controller::new(args.kernel, args.initrd, args.image, args.cpus, args.mem)?;
-    controller.compile()?;
+    let cache_path = if args.cache == "auto" {
+        default_cache_path()
+            .ok_or_else(|| HyphaError::new("unable to determine default cache path"))
+    } else {
+        Ok(args.cache)
+    }?;
+
+    let mut controller = Controller::new(
+        cache_path,
+        args.kernel,
+        args.initrd,
+        args.image,
+        args.cpus,
+        args.mem,
+    )?;
     let domid = controller.launch()?;
     println!("launched domain: {}", domid);
     Ok(())
 }
+
+fn default_cache_path() -> Option<String> {
+    let user_dirs = directories::UserDirs::new()?;
+    let mut path = user_dirs.home_dir().to_path_buf();
+    path.push(".hypha/cache");
+    Some(path.to_str()?.to_string())
+}