gix-commitgraph: ignore v1 bloom hashes

Signed-off-by: Vicent Marti <vmg@strn.cat>

Author: vmg

gix-commitgraph/src/file/init.rs

@@ -148,7 +148,7 @@ impl File {
                     bits_per_entry: from_be_u32(&data[data_range.start + 8..][..4]),
                 };
                 let bloom_data_payload_len = data_range.len() - BLOOM_FILTER_HEADER_SIZE;
-                if bloom_index_offsets_are_valid(&data[index_range.clone()], bloom_data_payload_len) {
+                if settings.is_supported() && bloom_index_offsets_are_valid(&data[index_range.clone()], bloom_data_payload_len) {
                     bloom_filter_settings = Some(settings);
                     bloom_filter_data_len = bloom_data_payload_len;
                     bloom_filter_data_offset = Some(data_range.start + BLOOM_FILTER_HEADER_SIZE);

gix-commitgraph/src/lib.rs

@@ -50,6 +50,16 @@ pub struct BloomFilterSettings {
     pub bits_per_entry: u32,
 }
 
+impl BloomFilterSettings {
+    pub(crate) fn is_supported(&self) -> bool {
+        match self.hash_version {
+            // Git's changed-path Bloom filter v1 hashes are deprecated, so we intentionally
+            // only support the current v2 format and fall back when older data is encountered.
+            2 => true,
+            _ => false,
+    }
+}
+
 /// A complete commit graph.
 ///
 /// The data in the commit graph may come from a monolithic `objects/info/commit-graph` file, or it

gix-commitgraph/tests/access/mod.rs

@@ -227,6 +227,22 @@ fn bloom_is_disabled_if_bidx_offsets_are_invalid() {
     );
 }
 
+#[test]
+fn bloom_is_disabled_if_hash_version_is_unsupported() {
+    let tmp = scripted_fixture_writable("changed_paths_v2.sh").expect("fixture available");
+    mutate_commit_graph(tmp.path(), |data| {
+        let entries = parse_chunk_table(data);
+        let bdat = find_chunk_index(&entries, *b"BDAT").expect("BDAT present in fixture");
+        let bdat_offset = entries[bdat].offset as usize;
+        data[bdat_offset..bdat_offset + 4].copy_from_slice(&1u32.to_be_bytes());
+    });
+    let graph = gix_commitgraph::Graph::from_info_dir(&info_dir(tmp.path())).expect("graph remains readable");
+    assert!(
+        graph.bloom_filter_settings().is_none(),
+        "unsupported hash versions disable Bloom so callers fall back safely"
+    );
+}
+
 #[derive(Clone, Copy)]
 struct ChunkTableEntry {
     id: [u8; 4],