Merge branch 'feat/p3-python-remote-edit' into feat/p3-wasm-swmr-python

# Conflicts:
#	CHANGELOG.md
#	docs/design/range-reads.md
#	docs/known-issues.md

crates/clawhdf5-format/src/chunk_grid.rs

@@ -135,6 +135,12 @@ impl ChunkGrid {
         let mut rem = index;
         for p in 0..rank {
             let d = self.order[p];
+            // A zero stride: a later dimension has no chunks (its maximum,
+            // or with none recorded its current extent, is 0), so no slot of
+            // the index is a chunk of the dataset.
+            if self.down[p] == 0 {
+                return None;
+            }
             let scaled = rem / self.down[p];
             rem %= self.down[p];
             if scaled >= self.cur_chunks[d] {
@@ -193,6 +199,28 @@ mod tests {
         assert_eq!(g.offsets(11), Some(vec![2, 3]));
     }
 
+    #[test]
+    fn zero_extent_has_no_chunks() {
+        // No maximum recorded and a zero current dimension: every stride
+        // before it is 0 (this divided by zero).
+        let g = ChunkGrid::fixed_array(&[1, 0], None, &[6, 6]).unwrap();
+        for i in 0..16 {
+            assert_eq!(g.offsets(i), None);
+        }
+        let g = ChunkGrid::fixed_array(&[0, 0, 3], Some(&[4, 0, 3]), &[2, 2, 3]).unwrap();
+        for i in 0..16 {
+            assert_eq!(g.offsets(i), None);
+        }
+        let g = ChunkGrid::extensible_array(&[0, 5], Some(&[u64::MAX, 0]), &[2, 2]).unwrap();
+        for i in 0..16 {
+            assert_eq!(g.offsets(i), None);
+        }
+        // A zero last dimension leaves the other strides alone.
+        let g = ChunkGrid::fixed_array(&[4, 0], Some(&[4, 6]), &[2, 3]).unwrap();
+        assert_eq!(g.offsets(0), None);
+        assert_eq!(g.linear_index(&[1, 1]), 3);
+    }
+
     #[test]
     fn rejects_two_unlimited_dims_after_the_first() {
         assert!(ChunkGrid::fixed_array(&[4, 6], Some(&[u64::MAX, u64::MAX]), &[2, 3]).is_err());

crates/clawhdf5-format/src/file_writer.rs

@@ -130,6 +130,22 @@ pub(crate) fn build_chunked_dataset_oh(
     fill_message: &[u8],
     refcount: u32,
 ) -> Result<Vec<u8>, FormatError> {
+    // libhdf5 records every simple dataspace's maximum dimensions (the
+    // dimensions themselves when none are given, `H5S_set_extent_simple`).
+    // Without them libhdf5 takes the maximum to be the current dimensions,
+    // so a resize by libhdf5 (h5py's `Dataset.resize`) would also change
+    // the maximum a Fixed Array chunk index is laid out by, and move every
+    // chunk already written.
+    let recorded;
+    let ds = if ds.space_type == DataspaceType::Simple && ds.max_dimensions.is_none() {
+        recorded = Dataspace {
+            max_dimensions: Some(ds.dimensions.clone()),
+            ..ds.clone()
+        };
+        &recorded
+    } else {
+        ds
+    };
     let mut w = ObjectHeaderWriter::new();
     w.add_message_with_flags(MessageType::Datatype, dt.serialize(), 0x01);
     w.add_message(MessageType::Dataspace, ds.serialize(LENGTH_SIZE));