Re: [PATCH v1 proxmox-backup 2/3] datastore: check that .i.bad files from S3 actually match that pattern

[Christian Ebner <c.ebner@proxmox.com>]

only one small nit inline, with that addressed:

Reviewed-by: Christian Ebner <c.ebner@proxmox.com>

On 7/13/26 3:24 PM, Robert Obkircher wrote:
> Compare the characters, not just the length, and introduce a helper
> that can be tested in isolation.
> 
> Signed-off-by: Robert Obkircher <r.obkircher@proxmox.com>
> ---
>   pbs-datastore/src/chunk_store.rs | 21 ++++++++++++++-------
>   pbs-datastore/src/datastore.rs   |  7 +++----
>   2 files changed, 17 insertions(+), 11 deletions(-)
> 
> diff --git a/pbs-datastore/src/chunk_store.rs b/pbs-datastore/src/chunk_store.rs
> index a936f5034..f40c58f7e 100644
> --- a/pbs-datastore/src/chunk_store.rs
> +++ b/pbs-datastore/src/chunk_store.rs
> @@ -360,13 +360,7 @@ impl ChunkStore {
>                               }
>   
>                               // i-th bad chunk
> -                            if bytes.len() == 64 + ".i.bad".len()
> -                                && bytes[64] == b'.'
> -                                && bytes[65] >= b'0'
> -                                && bytes[65] <= b'9'
> -                                && bytes[66] == b'.'
> -                                && bytes.ends_with(b"bad")
> -                            {
> +                            if is_bad_chunk_suffix(&bytes[64..]) {
>                                   return Some((Ok(entry), percentage, ChunkExt::Bad));
>                               }
>   
> @@ -1028,6 +1022,19 @@ impl ChunkExt {
>       }
>   }
>   
> +pub fn is_bad_chunk_suffix(s: &[u8]) -> bool {

nit: this should be pub(crate) only, no callers from outside.

> +    s.len() == ".i.bad".len() && s[0] == b'.' && s[1].is_ascii_digit() && &s[2..] == b".bad"
> +}
> +
> +#[test]
> +fn test_is_bad_chunk_suffix() {
> +    assert!(is_bad_chunk_suffix(".0.bad".as_bytes()));
> +    assert!(is_bad_chunk_suffix(".9.bad".as_bytes()));
> +    for s in [".10.bad", ".a.bad", ".bad", "0.bad", ""] {
> +        assert!(!is_bad_chunk_suffix(s.as_bytes()));
> +    }
> +}
> +

thanks a lot for the additional tests!

>   #[test]
>   fn test_chunk_store1() {
>       use tempfile::TempDir;
> diff --git a/pbs-datastore/src/datastore.rs b/pbs-datastore/src/datastore.rs
> index 3079fe833..bac5ce3b4 100644
> --- a/pbs-datastore/src/datastore.rs
> +++ b/pbs-datastore/src/datastore.rs
> @@ -43,7 +43,7 @@ use proxmox_section_config::SectionConfigData;
>   use crate::backup_info::{
>       BackupDir, BackupGroup, BackupInfo, OLD_LOCKING, PROTECTED_MARKER_FILENAME,
>   };
> -use crate::chunk_store::ChunkStore;
> +use crate::chunk_store::{ChunkStore, is_bad_chunk_suffix};
>   use crate::dynamic_index::{DynamicIndexReader, DynamicIndexWriter};
>   use crate::fixed_index::{FixedIndexReader, FixedIndexWriter};
>   use crate::hierarchy::{ListGroups, ListGroupsType, ListNamespaces, ListNamespacesRecursive};
> @@ -2680,13 +2680,12 @@ impl DataStore {
>           // file_name() should always be Some, as objects will have a filename
>           let file_name = path.file_name()?;
>           let bytes = file_name.as_bytes();
> -        let bad_ext_len = ".0.bad".len();
> -        let bad_chunk = if bytes.len() == 64 + bad_ext_len {
> +        let bad_chunk = if is_bad_chunk_suffix(&bytes[64..]) {
>               true
>           } else if bytes.len() == 64 {
>               false
>           } else {
> -            return None;
> +            return None; // unexpected suffix
>           };
>           if !bytes.iter().take(64).all(u8::is_ascii_hexdigit) {
>               return None;