oci: make create-image actually create the image

Also add a new create-dumpfile which does what create-image used to do.
This is really useful for debugging purposes.

Also adjust the hardlink output format to match the stricter validation
requirements of new versions of mkcomposefs.

Closes #6

src/bin/cfsctl.rs

@@ -40,7 +40,11 @@ enum OciCommand {
         /// the name of the stream
         name: String,
     },
+    CreateDumpfile {
+        layers: Vec<String>,
+    },
     CreateImage {
+        name: String,
         layers: Vec<String>,
     },
 }
@@ -120,8 +124,12 @@ fn main() -> Result<()> {
             OciCommand::LsLayer { name } => {
                 oci::ls_layer(&repo, &name)?;
             },
-            OciCommand::CreateImage { layers } => {
-                oci::image::create_image(&repo, &layers)?;
+            OciCommand::CreateDumpfile { layers } => {
+                oci::image::create_dumpfile(&repo, &layers)?;
+            },
+            OciCommand::CreateImage { name, layers } => {
+                let image_id = oci::image::create_image(&repo, &name, &layers)?;
+                println!("{}", hex::encode(image_id));
             },
         }
         Command::Mount { name, mountpoint } => {

src/dumpfile.rs

@@ -127,28 +127,29 @@ fn write_entry(
 }
 
 pub fn write_directory(writer: &mut impl fmt::Write, path: &Path, stat: &Stat, nlink: usize) -> fmt::Result {
-    write_entry(writer, path, stat, FileType::Directory, 0, nlink, 0, &"", &[], None)
+    write_entry(writer, path, stat, FileType::Directory, 0, nlink, 0, "", &[], None)
 }
 
 pub fn write_leaf(writer: &mut impl fmt::Write, path: &Path, stat: &Stat, content: &LeafContent, nlink: usize) -> fmt::Result {
     match content {
         LeafContent::InlineFile(ref data) => write_entry(
-            writer, path, stat, FileType::RegularFile, data.len() as u64, nlink, 0, &"", data, None
+            writer, path, stat, FileType::RegularFile, data.len() as u64, nlink, 0, "", data, None
         ),
         LeafContent::ExternalFile(id, size) => write_entry(
-            writer, path, stat, FileType::RegularFile, *size, nlink, 0, &"", &[], Some(id)
+            writer, path, stat, FileType::RegularFile, *size, nlink, 0,
+            format!("{:02x}/{}", id[0], hex::encode(&id[1..])), &[], Some(id)
         ),
         LeafContent::BlockDevice(rdev) => write_entry(
-            writer, path, stat, FileType::BlockDevice, 0, nlink, *rdev, &"", &[], None
+            writer, path, stat, FileType::BlockDevice, 0, nlink, *rdev, "", &[], None
         ),
         LeafContent::CharacterDevice(rdev) => write_entry(
-            writer, path, stat, FileType::CharacterDevice, 0, nlink, *rdev, &"", &[], None
+            writer, path, stat, FileType::CharacterDevice, 0, nlink, *rdev, "", &[], None
         ),
         LeafContent::Fifo => write_entry(
-            writer, path, stat, FileType::Fifo, 0, nlink, 0, &"", &[], None
+            writer, path, stat, FileType::Fifo, 0, nlink, 0, "", &[], None
         ),
         LeafContent::Socket => write_entry(
-            writer, path, stat, FileType::Socket, 0, nlink, 0, &"", &[], None
+            writer, path, stat, FileType::Socket, 0, nlink, 0, "", &[], None
         ),
         LeafContent::Symlink(ref target) => write_entry(
             writer, path, stat, FileType::Symlink, target.as_bytes().len() as u64, nlink, 0, target, &[], None
@@ -158,9 +159,9 @@ pub fn write_leaf(writer: &mut impl fmt::Write, path: &Path, stat: &Stat, conten
 
 pub fn write_hardlink(writer: &mut impl fmt::Write, path: &Path, target: &OsStr) -> fmt::Result {
     write_escaped(writer, path.as_os_str().as_bytes())?;
-    write!(writer, " - @0 - - - - - ")?;
+    write!(writer, " 0 @120000 - - - - 0.0 ")?;
     write_escaped(writer, target.as_bytes())?;
-    writeln!(writer, " - -")?;
+    write!(writer, " - -")?;
     Ok(())
 }
 
@@ -226,5 +227,5 @@ impl<'a, W: Write> DumpfileWriter<'a, W> {
 }
 
 pub fn write_dumpfile<W: Write>(writer: &mut W, fs: &FileSystem) -> Result<()> {
-    Ok(DumpfileWriter::new(writer).write_dir(Path::new("/"), &fs.root)?)
+    DumpfileWriter::new(writer).write_dir(Path::new("/"), &fs.root)
 }

src/oci/image.rs

@@ -1,6 +1,11 @@
 use std::{
     ffi::OsStr,
+    io::Read,
     os::unix::ffi::OsStrExt,
+    process::{
+        Command,
+        Stdio
+    },
 };
 
 use anyhow::{
@@ -9,6 +14,7 @@ use anyhow::{
 };
 use crate::{
     dumpfile::write_dumpfile,
+    fsverity::Sha256HashValue,
     image::{
         FileSystem,
         Leaf,
@@ -50,7 +56,7 @@ pub fn process_entry(filesystem: &mut FileSystem, entry: oci::tar::TarEntry) ->
     Ok(())
 }
 
-pub fn create_image(repo: &Repository, layers: &Vec<String>) -> Result<()> {
+pub fn compose_filesystem(repo: &Repository, layers: &[String]) -> Result<FileSystem> {
     let mut filesystem = FileSystem::new();
 
     for layer in layers {
@@ -61,8 +67,45 @@ pub fn create_image(repo: &Repository, layers: &Vec<String>) -> Result<()> {
         }
     }
 
+    Ok(filesystem)
+}
+
+pub fn create_dumpfile(repo: &Repository, layers: &[String]) -> Result<()> {
+    let filesystem = compose_filesystem(repo, layers)?;
     let mut stdout = std::io::stdout();
     write_dumpfile(&mut stdout, &filesystem)?;
-
     Ok(())
 }
+
+pub fn create_image(repo: &Repository, name: &str, layers: &Vec<String>) -> Result<Sha256HashValue> {
+    let mut filesystem = FileSystem::new();
+
+    for layer in layers {
+        let mut split_stream = repo.open_stream(layer)?;
+        let mut reader = SplitStreamReader::new(&mut split_stream);
+        while let Some(entry) = oci::tar::get_entry(&mut reader)? {
+           process_entry(&mut filesystem, entry)?;
+        }
+    }
+
+    let mut mkcomposefs = Command::new("mkcomposefs")
+        .args(["--from-file", "-", "-"])
+        .stdin(Stdio::piped())
+        .stdout(Stdio::piped())
+        .spawn()?;
+
+    let mut stdin = mkcomposefs.stdin.take().unwrap();
+    write_dumpfile(&mut stdin, &filesystem)?;
+    drop(stdin);
+
+    let mut stdout = mkcomposefs.stdout.take().unwrap();
+    let mut image = vec![];
+    stdout.read_to_end(&mut image)?;
+    drop(stdout);
+
+    if !mkcomposefs.wait()?.success() {
+        bail!("mkcomposefs failed");
+    };
+
+    repo.write_image(name, &image)
+}

src/repository.rs

@@ -284,12 +284,17 @@ impl Repository {
         Ok(())
     }
 
+    /// this function is not safe for untrusted users
+    pub fn write_image(&self, name: &str, data: &[u8]) -> Result<Sha256HashValue> {
+        let object_id = self.ensure_object(data)?;
+        self.link_ref(name, "images", object_id)
+    }
+
     /// this function is not safe for untrusted users
     pub fn import_image<R: Read>(&self, name: &str, image: &mut R) -> Result<Sha256HashValue> {
         let mut data = vec![];
         image.read_to_end(&mut data)?;
-        let object_id = self.ensure_object(&data)?;
-        self.link_ref(name, "images", object_id)
+        self.write_image(name, &data)
     }
 
     pub fn mount(self, name: &str, mountpoint: &str) -> Result<()> {
@@ -305,8 +310,8 @@ impl Repository {
         let category_path = format!("{}/{}", category, hex::encode(object_id));
         let ref_path = format!("{}/refs/{}", category, name);
 
+        self.ensure_symlink(&category_path, &object_path)?;
         self.symlink(&ref_path, &category_path)?;
-        self.symlink(&category_path, &object_path)?;
         Ok(object_id)
     }
 

tests/repo.rs

@@ -61,9 +61,9 @@ fn test_layer() -> Result<()> {
     }
     assert_eq!(dump, "\
 /file0 0 100700 1 0 0 0 0.0 - - -
-/file4095 4095 100700 1 0 0 0 0.0 - - 5372beb83c78537c8970c8361e3254119fafdf1763854ecd57d3f0fe2da7c719
-/file4096 4096 100700 1 0 0 0 0.0 - - babc284ee4ffe7f449377fbf6692715b43aec7bc39c094a95878904d34bac97e
-/file4097 4097 100700 1 0 0 0 0.0 - - 093756e4ea9683329106d4a16982682ed182c14bf076463a9e7f97305cbac743
+/file4095 4095 100700 1 0 0 0 0.0 53/72beb83c78537c8970c8361e3254119fafdf1763854ecd57d3f0fe2da7c719 - 5372beb83c78537c8970c8361e3254119fafdf1763854ecd57d3f0fe2da7c719
+/file4096 4096 100700 1 0 0 0 0.0 ba/bc284ee4ffe7f449377fbf6692715b43aec7bc39c094a95878904d34bac97e - babc284ee4ffe7f449377fbf6692715b43aec7bc39c094a95878904d34bac97e
+/file4097 4097 100700 1 0 0 0 0.0 09/3756e4ea9683329106d4a16982682ed182c14bf076463a9e7f97305cbac743 - 093756e4ea9683329106d4a16982682ed182c14bf076463a9e7f97305cbac743
 ");
     Ok(())
 }