Move docker .tar.gz handling to unencapsulate.rs

To handle this is a different location

Signed-off-by: Eric Curtin <eric.curtin@docker.com>

Author: ericcurtin

crates/ostree-ext/src/container/unencapsulate.rs

@@ -203,7 +203,7 @@ pub(crate) async fn fetch_layer<'a>(
     tracing::debug!("fetching {}", layer.digest());
     let layer_index = manifest.layers().iter().position(|x| x == layer).unwrap();
     let (blob, driver, size);
-    let media_type: oci_image::MediaType;
+    let mut media_type: oci_image::MediaType;
     match transport_src {
         // Both containers-storage and docker-daemon store layers uncompressed in their
         // local storage, even though the manifest may indicate they are compressed.
@@ -218,6 +218,19 @@ pub(crate) async fn fetch_layer<'a>(
             })?;
             size = layer_blob.size;
             media_type = layer_blob.media_type.clone();
+
+            // docker-daemon stores layers uncompressed even when the media type
+            // indicates gzip compression. Translate to the uncompressed variant.
+            if transport_src == Transport::DockerDaemon {
+                if let oci_image::MediaType::Other(t) = &media_type {
+                    if t.as_str() == "application/vnd.docker.image.rootfs.diff.tar.gzip" {
+                        media_type = oci_image::MediaType::Other(
+                            "application/vnd.docker.image.rootfs.diff.tar".to_string(),
+                        );
+                    }
+                }
+            }
+
             (blob, driver) = proxy.get_blob(img, &layer_blob.digest, size).await?;
         }
         _ => {

crates/ostree-ext/src/generic_decompress.rs

@@ -22,11 +22,6 @@ use crate::oci_spec::image as oci_image;
 /// TODO: change the skopeo code to shield us from this correctly
 const DOCKER_TYPE_LAYER_TAR: &str = "application/vnd.docker.image.rootfs.diff.tar";
 
-/// The Docker MIME type for gzipped layers when stored in docker-daemon.
-/// Even though this indicates gzip compression, docker-daemon actually stores
-/// the layers uncompressed, so we need to treat this as uncompressed.
-const DOCKER_TYPE_LAYER_TAR_GZIP: &str = "application/vnd.docker.image.rootfs.diff.tar.gzip";
-
 /// Extends the `Read` trait with another method to get mutable access to the inner reader
 trait ReadWithGetInnerMut: Read + Send + 'static {
     fn get_inner_mut(&mut self) -> &mut dyn Read;
@@ -130,9 +125,6 @@ impl Decompressor {
             oci_image::MediaType::Other(t) if t.as_str() == DOCKER_TYPE_LAYER_TAR => {
                 Box::new(TransparentDecompressor(src))
             }
-            oci_image::MediaType::Other(t) if t.as_str() == DOCKER_TYPE_LAYER_TAR_GZIP => {
-                Box::new(TransparentDecompressor(src))
-            }
             o => anyhow::bail!("Unhandled layer type: {}", o),
         };
         Ok(Self {
@@ -236,17 +228,4 @@ mod tests {
         assert_eq!(e.to_string(), "Unknown frame descriptor".to_string());
         drop(d)
     }
-
-    #[test]
-    fn test_docker_tar_gzip_media_type_uses_transparent_decompressor() {
-        // Test that the docker-daemon gzip media type is treated as uncompressed
-        let data = b"test data";
-        let media_type = oci_image::MediaType::Other(DOCKER_TYPE_LAYER_TAR_GZIP.to_string());
-        let mut d = Decompressor::new(&media_type, &data[..]).unwrap();
-        let mut buf = [0u8; 32];
-        let n = d.read(&mut buf).unwrap();
-        assert_eq!(n, data.len());
-        assert_eq!(&buf[..n], data);
-        drop(d)
-    }
 }