[pbs-devel] [PATCH v3 proxmox-backup] client: catalog shell: avoid navigating below archive root

[Christian Ebner]

Avoid to underflow the catalogs shell position stack by navigating
below the archives root directory into the catalog root. Otherwise
the shell will panic, as the root entry is always expected to be
present.

This threats the archive root directory as being it's own parent
directory, mimicking the behaviour of most common shells.

Signed-off-by: Christian Ebner <c.ebner at proxmox.com>
---
Encountered while implementing the catalog shell for the split pxar
archive case.

Without this additional check, underflowing the pxar archive root of
the catalog shell will panic.

changes since version 2, thanks @Wolfgang for catching this:
- also handle cases where the current working directory is not the root
  directory

changes since version 1:
- use `is_empty` to check if vector is empty
- extend commit message and comment to clarify that archive root acts as
  its own parent directory

 pbs-client/src/catalog_shell.rs | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/pbs-client/src/catalog_shell.rs b/pbs-client/src/catalog_shell.rs
index 349bb7cbc..f687e7e14 100644
--- a/pbs-client/src/catalog_shell.rs
+++ b/pbs-client/src/catalog_shell.rs
@@ -720,6 +720,14 @@ impl Shell {
                     &mut None,
                 )
                 .await?;
+
+                if new_position.is_empty() {
+                    // Avoid moving below archive root into catalog root, thereby treating
+                    // the archive root as its own parent directory.
+                    self.position.truncate(1);
+                    return Ok(());
+                }
+
                 if !new_position.last().unwrap().catalog.is_directory() {
                     bail!("not a directory");
                 }
-- 
2.39.2