H5Dchunk_iter now passes offsets in units of dataset elements, fix #1419 (#1969)

* H5Dchunk_iter now passes chunk dimension scaled offsets, fix #1419

* Update docs for H5Dchunk_iter, H5Dget_chunk_info*

Modified description for `H5Dchunk_iter`, `H5Dget_chunk_info`, and `H5Dget_chunk_info_by_coord` to the following

 * offset          Logical position of the chunk’s first element in units of dataset elements
 * filter_mask  Bitmask indicating the filters used when the chunk was written
 * size             Chunk size in bytes, 0 if the chunk does not exist

1 files changed, 11 insertions, 2 deletions

diff --git a/src/H5Dchunk.c b/src/H5Dchunk.c
index 4f628a7..925bf58 100644
--- a/src/H5Dchunk.c
+++ b/src/H5Dchunk.c
@@ -254,6 +254,7 @@ typedef struct H5D_chunk_coll_fill_info_t {
 typedef struct H5D_chunk_iter_ud_t {
     H5D_chunk_iter_op_t op;      /* User defined callback */
     void               *op_data; /* User data for user defined callback */
+    H5O_layout_chunk_t *chunk;   /* Chunk layout */
 } H5D_chunk_iter_ud_t;
 
 /********************/
@@ -8066,13 +8067,20 @@ static int
 H5D__chunk_iter_cb(const H5D_chunk_rec_t *chunk_rec, void *udata)
 {
     const H5D_chunk_iter_ud_t *data      = (H5D_chunk_iter_ud_t *)udata;
+    const H5O_layout_chunk_t  *chunk     = data->chunk;
     int                        ret_value = H5_ITER_CONT;
+    hsize_t                    offset[H5O_LAYOUT_NDIMS];
+    unsigned                   ii; /* Match H5O_layout_chunk_t.ndims */
+
+    /* Similar to H5D__get_chunk_info */
+    for (ii = 0; ii < chunk->ndims; ii++)
+        offset[ii] = chunk_rec->scaled[ii] * chunk->dim[ii];
 
     FUNC_ENTER_PACKAGE_NOERR
 
     /* Check for callback failure and pass along return value */
-    if ((ret_value = (data->op)(chunk_rec->scaled, chunk_rec->filter_mask, chunk_rec->chunk_addr,
-                                chunk_rec->nbytes, data->op_data)) < 0)
+    if ((ret_value = (data->op)(offset, chunk_rec->filter_mask, chunk_rec->chunk_addr, chunk_rec->nbytes,
+                                data->op_data)) < 0)
         HERROR(H5E_DATASET, H5E_CANTNEXT, "iteration operator failed");
 
     FUNC_LEAVE_NOAPI(ret_value)
@@ -8132,6 +8140,7 @@ H5D__chunk_iter(H5D_t *dset, H5D_chunk_iter_op_t op, void *op_data)
         /* Set up info for iteration callback */
         ud.op      = op;
         ud.op_data = op_data;
+        ud.chunk   = &dset->shared->layout.u.chunk;
 
         /* Iterate over the allocated chunks calling the iterator callback */
         if ((ret_value = (layout->storage.u.chunk.ops->iterate)(&idx_info, H5D__chunk_iter_cb, &ud)) < 0)