[pve-devel] [PATCH proxmox 1/2] oci: fix rootfs extraction when paths already exist

[Filip Schauer]

Remove paths from previous layers that conflict with new layer entries
before unpacking. This aligns with the OCI spec. [0]

This fixes a rootfs extraction failure with docker.io/grafana/otel-lgtm,
which was reported in the Proxmox Forum [1].

[0] https://github.com/opencontainers/image-spec/blob/26647a49f642c7d22a1cd3aa0a48e4650a542269/layer.md#changeset-over-existing-files
[1] https://forum.proxmox.com/threads/otel-lgtm-oci-create-lxc-failed.176996/

Signed-off-by: Filip Schauer <f.schauer at proxmox.com>
---
 proxmox-oci/src/lib.rs | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/proxmox-oci/src/lib.rs b/proxmox-oci/src/lib.rs
index cf0e4271..cce68207 100644
--- a/proxmox-oci/src/lib.rs
+++ b/proxmox-oci/src/lib.rs
@@ -302,6 +302,16 @@ fn extract_archive<R: Read, P: AsRef<Path>>(reader: &mut R, target_path: P) -> s
             }
         }
 
+        // If a file or directory already exists at this path, remove it first.
+        let file_path_abs = target_path.as_ref().join(file.path()?);
+        if file_path_abs.exists() {
+            if file_path_abs.is_dir() {
+                remove_dir_all(file_path_abs)?;
+            } else {
+                remove_file(file_path_abs)?;
+            }
+        }
+
         file.unpack_in(&target_path)?;
     }
 
@@ -309,6 +319,16 @@ fn extract_archive<R: Read, P: AsRef<Path>>(reader: &mut R, target_path: P) -> s
     // to avoid failure on restrictive parent directory permissions.
     directories.sort_by(|a, b| b.path_bytes().cmp(&a.path_bytes()));
     for mut dir in directories {
+        let dir_path_abs = target_path.as_ref().join(dir.path()?);
+
+        // Remove the trailing slash
+        let dir_path_abs = dir_path_abs.components().as_path();
+
+        // If a file already exists at this path, remove it first.
+        if dir_path_abs.exists() && !dir_path_abs.is_dir() {
+            remove_file(dir_path_abs)?;
+        }
+
         dir.unpack_in(&target_path)?;
     }
 
-- 
2.47.3