Re: [PATCH proxmox-backup v2] fix #5247: relative paths in exclude patterns.

[Wolfgang Bumiller <w.bumiller@proxmox.com>]

On Mon, 30 Mar 2026 10:11:10 +0200, Manuel Federanko <m.federanko@proxmox.com> wrote:
> Patterns which start with ./ or for that matter contain /../ or similar
> constructs will never match, since they get compared to sanitized paths
> from directory traversal, sanitize those patterns too. Implement this
> for both .pxarexclude files and the --exclude command line option.
> Log a warning if a path was sanitized that was provided via --exclude.

In the `.pxarexclude` case, logging may make sense as well IMO.

As for `--exclude`, I wonder we should just *bail* instead?

Although that might "break" some automated
otherwise-working-but-probably-too-big backups, so we can't... (although
for `foo/../bar` it's *really* tempting...)

>
>
> diff --git a/pbs-client/src/pxar/tools.rs b/pbs-client/src/pxar/tools.rs
> index 475c08ad3..7ad4009fe 100644
> --- a/pbs-client/src/pxar/tools.rs
> +++ b/pbs-client/src/pxar/tools.rs
> @@ -76,6 +76,37 @@ fn assert_single_path_component_do(path: &Path) -> Result<(), Error> {
>      Ok(())
>  }
>  
> +pub fn normalize_lexically<S: AsRef<OsStr> + ?Sized>(path: &S) -> PathBuf {

(Note: the monomorphization from v1 was actually fine, but if the `_do`
variant is only used by this one function it could live *inside* here.)

> +    // FIXME: Once std::path::normalize_lexically is stabilized we can
> +    // switch to that
> +    use std::path::Component;
> +
> +    let path = Path::new(path);
> +    let has_trailing_slash = path
> +        .as_os_str()
> +        .as_encoded_bytes()
> +        .last()
> +        .copied()
> +        .is_some_and(|c: u8| c == std::path::MAIN_SEPARATOR_STR.bytes().last().unwrap());

Could just use

    .as_encoded_bytes()
    .ends_with(MAIN_SEPARATOR_STR.as_bytes())

--