H5Dchunk_iter now passes offsets in units of dataset elements, fix HD…

…FGroup#1419 (HDFGroup#1969)

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

src/H5Dchunk.c

@@ -251,6 +251,7 @@ 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;
 
 /********************/
@@ -7681,7 +7682,14 @@ 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
 
@@ -7747,6 +7755,7 @@ 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)

src/H5Dpublic.h

@@ -226,10 +226,10 @@ typedef herr_t (*H5D_gather_func_t)(const void *dst_buf, size_t dst_buf_bytes_us
 /**
  * \brief Callback for H5Dchunk_iter()
  *
- * \param[in]     offset      Array of starting logical coordinates of chunk.
- * \param[in]     filter_mask Filter mask of chunk.
- * \param[in]     addr        Offset in file of chunk data.
- * \param[in]     nbytes      Size in bytes of chunk data in file.
+ * \param[in]     offset      Logical position of the chunk’s first element in units of dataset elements
+ * \param[in]     filter_mask Bitmask indicating the filters used when the chunk was written
+ * \param[in]     addr        Chunk address in the file
+ * \param[in]     size        Chunk size in bytes, 0 if the chunk does not exist
  * \param[in,out] op_data     Pointer to any user-defined data associated with
  *                            the operation.
  * \returns \li Zero (#H5_ITER_CONT) causes the iterator to continue, returning
@@ -647,7 +647,7 @@ H5_DLL herr_t H5Dget_chunk_info_by_coord(hid_t dset_id, const hsize_t *offset, u
  *
  * \return \herr_t
  *
- * \details H5Dget_chunk_iter iterates over all chunks in the dataset, calling the
+ * \details H5Dchunk_iter iterates over all chunks in the dataset, calling the
  *          user supplied callback with the details of the chunk and the supplied
  *          context \p op_data.
  *