From cfd30ce4b20d89f09830b7856cbf058163b3280a Mon Sep 17 00:00:00 2001 From: Harrison Booth <73434116+Harrison-Booth@users.noreply.github.com> Date: Wed, 28 Oct 2026 17:49:33 -0500 Subject: [PATCH] M1.2: deduplicate font collection offsets early --- crates/fonts/src/fontdb.rs | 16 +++++++++------- 1 file changed, 9 insertions(+), 7 deletions(-) diff --git a/crates/fonts/src/fontdb.rs b/crates/fonts/src/fontdb.rs index 1b04e0f3..f355e762 100644 --- a/crates/fonts/src/fontdb.rs +++ b/crates/fonts/src/fontdb.rs @@ -611,11 +611,11 @@ const MAX_COLLECTION_ENTRIES_SCANNED: u32 = 16_384; /// Maximum named instances read from a single face. const MAX_NAMED_INSTANCES_PER_FACE: usize = 1024; -fn distinct_face_indices(entries: impl IntoIterator) -> Vec { - let mut directories = std::collections::HashSet::new(); +fn distinct_face_indices(entries: impl IntoIterator) -> Vec { + let mut offsets = std::collections::HashSet::new(); let mut indices = Vec::with_capacity(MAX_COLLECTION_FACES as usize); - for (index, directory) in entries.into_iter().take(MAX_COLLECTION_ENTRIES_SCANNED as usize) { - if directories.insert(directory) { + for (index, offset) in entries.into_iter().take(MAX_COLLECTION_ENTRIES_SCANNED as usize) { + if offsets.insert(offset) { indices.push(index); if indices.len() == MAX_COLLECTION_FACES as usize { break; @@ -636,8 +636,10 @@ fn enumerate_faces(data: &[u8]) -> Vec { Ok(FileRef::Font(_)) => vec![0], Ok(FileRef::Collection(c)) => { let entries = (0..c.len().min(MAX_COLLECTION_ENTRIES_SCANNED)).filter_map(|i| { - let f = skrifa::FontRef::from_index(data, i).ok()?; - Some((i, f.table_directory().table_records().as_ptr() as usize)) + let start = 12usize.checked_add((i as usize).checked_mul(4)?)?; + let end = start.checked_add(4)?; + let offset = u32::from_be_bytes(data.get(start..end)?.try_into().ok()?); + Some((i, offset)) }); distinct_face_indices(entries) } @@ -1470,7 +1472,7 @@ mod font_dir_tests { #[test] fn duplicate_collection_offsets_do_not_consume_face_cap() { let mut entries = vec![(0, 7); MAX_COLLECTION_FACES as usize]; - entries.extend((0..MAX_COLLECTION_FACES).map(|i| (i + MAX_COLLECTION_FACES, i as usize + 8))); + entries.extend((0..MAX_COLLECTION_FACES).map(|i| (i + MAX_COLLECTION_FACES, i + 8))); let faces = distinct_face_indices(entries); assert_eq!(faces.len(), MAX_COLLECTION_FACES as usize); assert_eq!(faces.first(), Some(&0));