hypha: config as a block device

hypha/src/ctl/cfgblk.rs

@@ -0,0 +1,49 @@
+use crate::error::Result;
+use crate::image::ImageInfo;
+use backhand::{FilesystemWriter, NodeHeader};
+use std::fs;
+use std::fs::File;
+use std::path::PathBuf;
+use uuid::Uuid;
+
+pub struct ConfigBlock<'a> {
+    pub image_info: &'a ImageInfo,
+    pub file: PathBuf,
+}
+
+impl ConfigBlock<'_> {
+    pub fn new<'a>(uuid: &Uuid, image_info: &'a ImageInfo) -> Result<ConfigBlock<'a>> {
+        let mut file = std::env::temp_dir().clone();
+        file.push(format!("hypha-cfg-{}", uuid));
+        fs::create_dir_all(&file)?;
+        file.push("config.squashfs");
+        Ok(ConfigBlock { image_info, file })
+    }
+
+    pub fn build(&self) -> Result<()> {
+        let manifest = self.image_info.config.to_string()?;
+        let mut writer = FilesystemWriter::default();
+        writer.push_dir(
+            "/image",
+            NodeHeader {
+                permissions: 384,
+                uid: 0,
+                gid: 0,
+                mtime: 0,
+            },
+        )?;
+        writer.push_file(
+            manifest.as_bytes(),
+            "/image/config.json",
+            NodeHeader {
+                permissions: 384,
+                uid: 0,
+                gid: 0,
+                mtime: 0,
+            },
+        )?;
+        let mut file = File::create(&self.file)?;
+        writer.write(&mut file)?;
+        Ok(())
+    }
+}