implement squashfs generation

hypha/src/image/mod.rs

@@ -0,0 +1,145 @@
+use crate::error::{HyphaError, Result};
+use backhand::{FilesystemWriter, NodeHeader};
+use log::{debug, trace};
+use oci_spec::image::MediaType;
+use ocipkg::distribution::Client;
+use ocipkg::error::Error;
+use ocipkg::{Digest, ImageName};
+use std::fs;
+use std::fs::File;
+use std::io::BufReader;
+use std::os::unix::fs::{FileTypeExt, MetadataExt, PermissionsExt};
+use std::path::PathBuf;
+use uuid::Uuid;
+use walkdir::WalkDir;
+
+pub struct ImageCompiler {}
+
+impl ImageCompiler {
+    pub fn new() -> Result<ImageCompiler> {
+        Ok(ImageCompiler {})
+    }
+
+    pub fn compile(&self, image: &ImageName) -> Result<String> {
+        debug!("ImageCompiler compile image={image}");
+        let mut tmp_dir = std::env::temp_dir().clone();
+        tmp_dir.push(format!("hypha-compile-{}", Uuid::new_v4()));
+        let mut image_dir = tmp_dir.clone();
+        image_dir.push("image");
+        fs::create_dir_all(&image_dir)?;
+        let mut squash_file = tmp_dir.clone();
+        squash_file.push("image.squashfs");
+        self.download(image, &image_dir)?;
+        self.squash(&image_dir, &squash_file)
+    }
+
+    fn download(&self, image: &ImageName, image_dir: &PathBuf) -> Result<()> {
+        debug!(
+            "ImageCompiler download image={image}, image_dir={}",
+            image_dir.to_str().unwrap()
+        );
+        let ImageName {
+            name, reference, ..
+        } = image;
+        let mut client = Client::new(image.registry_url()?, name.clone())?;
+        let manifest = client.get_manifest(reference)?;
+        for layer in manifest.layers() {
+            debug!(
+                "ImageCompiler download start digest={} size={}",
+                layer.digest(),
+                layer.size()
+            );
+            let blob = client.get_blob(&Digest::new(layer.digest())?)?;
+            match layer.media_type() {
+                MediaType::ImageLayerGzip => {}
+                MediaType::Other(ty) => {
+                    if !ty.ends_with("tar.gzip") {
+                        continue;
+                    }
+                }
+                _ => continue,
+            }
+            debug!(
+                "ImageCompiler download unpack digest={} size={}",
+                layer.digest(),
+                layer.size()
+            );
+            let buf = flate2::read::GzDecoder::new(blob.as_slice());
+            tar::Archive::new(buf).unpack(image_dir)?;
+            debug!(
+                "ImageCompiler download end digest={} size={}",
+                layer.digest(),
+                layer.size()
+            );
+            return Ok(());
+        }
+        Err(Error::MissingLayer.into())
+    }
+
+    fn squash(&self, image_dir: &PathBuf, squash_file: &PathBuf) -> Result<String> {
+        let mut writer = FilesystemWriter::default();
+        let walk = WalkDir::new(image_dir).follow_links(false);
+        for entry in walk {
+            let entry = entry?;
+            let rel = entry
+                .path()
+                .strip_prefix(image_dir)?
+                .to_str()
+                .ok_or_else(|| HyphaError::new("failed to strip prefix of tmpdir"))?;
+            let rel = format!("/{}", rel);
+            trace!("ImageCompiler squash write {}", rel);
+            let typ = entry.file_type();
+            let metadata = fs::symlink_metadata(entry.path())?;
+            let uid = metadata.uid();
+            let gid = metadata.gid();
+            let mode = metadata.permissions().mode();
+            let mtime = metadata.mtime();
+
+            if rel == "/" {
+                writer.set_root_uid(uid);
+                writer.set_root_gid(gid);
+                writer.set_root_mode(mode as u16);
+                continue;
+            }
+
+            let header = NodeHeader {
+                permissions: mode as u16,
+                uid,
+                gid,
+                mtime: mtime as u32,
+            };
+            if typ.is_symlink() {
+                let symlink = fs::read_link(entry.path())?;
+                let symlink = symlink
+                    .to_str()
+                    .ok_or_else(|| HyphaError::new("failed to read symlink"))?;
+                writer.push_symlink(symlink, rel, header)?;
+            } else if typ.is_dir() {
+                writer.push_dir(rel, header)?;
+            } else if typ.is_file() {
+                let reader = BufReader::new(File::open(entry.path())?);
+                writer.push_file(reader, rel, header)?;
+            } else if typ.is_block_device() {
+                let device = metadata.dev();
+                writer.push_block_device(device as u32, rel, header)?;
+            } else if typ.is_char_device() {
+                let device = metadata.dev();
+                writer.push_char_device(device as u32, rel, header)?;
+            } else {
+                return Err(HyphaError::new("invalid file type"));
+            }
+        }
+
+        fs::remove_dir_all(image_dir)?;
+
+        let squash_file_path = squash_file
+            .to_str()
+            .ok_or_else(|| HyphaError::new("failed to convert squashfs string"))?;
+
+        let mut out = File::create(squash_file)?;
+        trace!("ImageCompiler squash generateI : {}", squash_file_path);
+        writer.write(&mut out)?;
+
+        Ok(squash_file_path.to_string())
+    }
+}