refactor: copy files using coreutils cp (#595)

Author: plobsing

oci/private/image.sh

@@ -41,10 +41,10 @@ function base_from() {
       relative="$(coreutils realpath --relative-to="$OUTPUT/blobs/sha256" "$blob" --no-symlinks)"
       coreutils ln -s "$relative" "$OUTPUT/blobs/$relative_to_blobs"
     else
-      coreutils cat "$blob" > "$OUTPUT/blobs/$relative_to_blobs"
+      coreutils cp --no-preserve=mode "$blob" "$OUTPUT/blobs/$relative_to_blobs"
     fi
   done
-  coreutils cat "$path/oci-layout" >"$OUTPUT/oci-layout"
+  coreutils cp --no-preserve=mode "$path/oci-layout" "$OUTPUT/oci-layout"
   jq '.manifests[0].annotations["org.opencontainers.image.ref.name"] = "intermediate"' "$path/index.json" >"$OUTPUT/index.json"
 }
 
@@ -110,7 +110,7 @@ function add_layer() {
     relative=$(coreutils realpath --no-symlinks --canonicalize-missing --relative-to="$OUTPUT/blobs/sha256" "$path" )
     coreutils ln --force --symbolic "$relative" "$output_path"
   else
-    coreutils cat "$path" > "$output_path"
+    coreutils cp --no-preserve=mode "$path" "$output_path"
   fi
 }
 

oci/private/image_index.sh.tpl

@@ -26,7 +26,7 @@ function add_image() {
                 --argjson manifest "${manifest}" \
                 '.manifests |= [$manifest + {"platform": $platform}]'\
                 "${output_path}/manifest_list.json" > "${output_path}/manifest_list.new.json"
-        cat "${output_path}/manifest_list.new.json" > "${output_path}/manifest_list.json"
+        "${COREUTILS}" cp --no-preserve=mode "${output_path}/manifest_list.new.json" "${output_path}/manifest_list.json"
     done
 }
 
@@ -36,7 +36,7 @@ function copy_blob() {
     local blob_image_relative_path="$3"
     local dest_path="${output_path}/${blob_image_relative_path}"
     mkdirp "$(dirname "${dest_path}")"
-    "${COREUTILS}" cat "${image_path}/${blob_image_relative_path}" > "${dest_path}"
+    "${COREUTILS}" cp --no-preserve=mode "${image_path}/${blob_image_relative_path}" "${dest_path}"
 }
 
 function create_oci_layout() {