Initial support for compressed data blobs with zstd compression

[ariel-miculas]

Fixes #14

[hallyn]

hm, not sure if this is a result of this patch, but i see that when I create a new fs, the index.json has:

      "fs_verity_digest": [
        72,
        188,
        196,
        180,
        57,
        215,
        11,
        70,
        53,
        77,
        131,
        29,
        3,
        28,
        195,
        163,
        219,
        236,
        102,
        26,
        128,
        244,
        122,
        78,
        89,
        196,
        91,
        58,
        145,
        162,
        138,
        32
      ],

instead of all one string like

      "annotations": {
        "io.stackeroci.stacker.squashfs_verity_root_hash": "6fb77b2e33699df89e7df475944aa5d2eeb356e8070e05fd4db273773ac460b4"
      }

[hallyn]

Other than that it looks good. It won't auto-merge, so I'll hit approve.

[ariel-miculas]

That's definitely not intended behavior, fs_verity shouldn't appear in index.json

[ariel-miculas]

Diff:

diff --git a/builder/src/lib.rs b/builder/src/lib.rs
index d3b6d11..70323a6 100644
--- a/builder/src/lib.rs
+++ b/builder/src/lib.rs
@@ -95,12 +95,13 @@ fn process_chunks<C: for<'a> Compression<'a> + Any>(
         let chunk = result.unwrap();
         let mut chunk_used: u64 = 0;
 
-        let desc = oci.put_blob::<C, media_types::Chunk>(&chunk.data)?;
+        let (desc, fs_verity_digest, compressed) =
+            oci.put_blob::<C, media_types::Chunk>(&chunk.data)?;
         let blob_kind = BlobRefKind::Other {
             digest: desc.digest.underlying(),
         };
 
-        let verity_hash = desc.fs_verity_digest;
+        let verity_hash = fs_verity_digest;
         verity_data.insert(desc.digest.underlying(), verity_hash);
 
         while chunk_used < chunk.length as u64 {
@@ -112,7 +113,7 @@ fn process_chunks<C: for<'a> Compression<'a> + Any>(
             let blob = BlobRef {
                 offset: chunk_used,
                 kind: blob_kind,
-                compressed: desc.compressed,
+                compressed,
             };
 
             file.as_mut()
@@ -455,7 +456,7 @@ fn build_delta<C: for<'a> Compression<'a> + Any>(
     md_buf.append(&mut files_buf);
     md_buf.append(&mut others_buf);
 
-    let desc = oci.put_blob::<compression::Noop, media_types::Inodes>(md_buf.as_slice())?;
+    let (desc, ..) = oci.put_blob::<compression::Noop, media_types::Inodes>(md_buf.as_slice())?;
     let verity_hash = get_fs_verity_digest(md_buf.as_slice())?;
     verity_data.insert(desc.digest.underlying(), verity_hash);
 
@@ -486,7 +487,9 @@ pub fn build_initial_rootfs<C: for<'a> Compression<'a> + Any>(
             manifest_version: PUZZLEFS_IMAGE_MANIFEST_VERSION,
         },
     )?;
-    oci.put_blob::<compression::Noop, media_types::Rootfs>(rootfs_buf.as_slice())
+    Ok(oci
+        .put_blob::<compression::Noop, media_types::Rootfs>(rootfs_buf.as_slice())?
+        .0)
 }
 
 // add_rootfs_delta adds whatever the delta between the current rootfs and the puzzlefs
@@ -524,7 +527,8 @@ pub fn add_rootfs_delta<C: for<'a> Compression<'a> + Any>(
     let mut rootfs_buf = Vec::new();
     serde_cbor::to_writer(&mut rootfs_buf, &rootfs)?;
     Ok((
-        oci.put_blob::<compression::Noop, media_types::Rootfs>(rootfs_buf.as_slice())?,
+        oci.put_blob::<compression::Noop, media_types::Rootfs>(rootfs_buf.as_slice())?
+            .0,
         oci,
     ))
 }
diff --git a/oci/src/descriptor.rs b/oci/src/descriptor.rs
index 7f80f42..91940b8 100644
--- a/oci/src/descriptor.rs
+++ b/oci/src/descriptor.rs
@@ -11,25 +11,15 @@ pub struct Descriptor {
     pub size: u64,
     pub media_type: String,
     pub annotations: HashMap<String, String>,
-    pub fs_verity_digest: [u8; SHA256_BLOCK_SIZE],
-    pub compressed: bool,
 }
 
 impl Descriptor {
-    pub fn new(
-        digest: [u8; 32],
-        size: u64,
-        media_type: String,
-        fs_verity_digest: [u8; SHA256_BLOCK_SIZE],
-        compressed: bool,
-    ) -> Descriptor {
+    pub fn new(digest: [u8; 32], size: u64, media_type: String) -> Descriptor {
         Descriptor {
             digest: Digest::new(&digest),
             size,
             media_type,
             annotations: HashMap::new(),
-            fs_verity_digest,
-            compressed,
         }
     }
 
diff --git a/oci/src/lib.rs b/oci/src/lib.rs
index 6b70b4a..01cb619 100644
--- a/oci/src/lib.rs
+++ b/oci/src/lib.rs
@@ -15,7 +15,7 @@ use sha2::{Digest as Sha2Digest, Sha256};
 use tempfile::NamedTempFile;
 
 use compression::{Compression, Decompressor};
-use format::{MetadataBlob, Result, Rootfs, VerityData, WireFormatError};
+use format::{MetadataBlob, Result, Rootfs, VerityData, WireFormatError, SHA256_BLOCK_SIZE};
 use openat::Dir;
 use std::io::{Error, ErrorKind};
 
@@ -89,7 +89,7 @@ impl Image {
     pub fn put_blob<C: for<'a> Compression<'a> + Any, MT: media_types::MediaType>(
         &self,
         buf: &[u8],
-    ) -> Result<Descriptor> {
+    ) -> Result<(Descriptor, [u8; SHA256_BLOCK_SIZE], bool)> {
         let mut compressed_data = Cursor::new(Vec::<u8>::new());
         let mut compressed = C::compress(&mut compressed_data)?;
         let mut hasher = Sha256::new();
@@ -117,13 +117,8 @@ impl Image {
         hasher.update(final_data);
         let digest = hasher.finalize();
         let media_type = C::append_extension(MT::name());
-        let descriptor = Descriptor::new(
-            digest.into(),
-            uncompressed_size,
-            media_type,
-            get_fs_verity_digest(final_data)?,
-            compressed_blob,
-        );
+        let descriptor = Descriptor::new(digest.into(), uncompressed_size, media_type);
+        let fs_verity_digest = get_fs_verity_digest(&compressed_data.get_ref()[..])?;
         let path = self.blob_path().join(descriptor.digest.to_string());
 
         // avoid replacing the data blob so we don't drop fsverity data
@@ -145,7 +140,7 @@ impl Image {
             tmp.write_all(final_data)?;
             tmp.persist(path).map_err(|e| e.error)?;
         }
-        Ok(descriptor)
+        Ok((descriptor, fs_verity_digest, compressed_blob))
     }
 
     fn open_raw_blob(&self, digest: &Digest, verity: Option<&[u8]>) -> io::Result<fs::File> {
@@ -269,7 +264,7 @@ mod tests {
     fn test_put_blob_correct_hash() {
         let dir = tempdir().unwrap();
         let image: Image = Image::new(dir.path()).unwrap();
-        let desc = image
+        let (desc, ..) = image
             .put_blob::<compression::Noop, media_types::Chunk>("meshuggah rocks".as_bytes())
             .unwrap();
 
@@ -291,7 +286,7 @@ mod tests {
     fn test_put_get_index() {
         let dir = tempdir().unwrap();
         let image = Image::new(dir.path()).unwrap();
-        let mut desc = image
+        let (mut desc, ..) = image
             .put_blob::<DefaultCompression, media_types::Chunk>("meshuggah rocks".as_bytes())
             .unwrap();
         desc.set_name("foo");