Check for file image callbacks

src/api/helpers.jl

@@ -817,6 +817,10 @@ end
 Retrieve a file image of the appropriate size in a `Vector{UInt8}`.
 """
 function h5p_get_file_image(fapl_id)::Vector{UInt8}
+    cb = h5p_get_file_image_callbacks(fapl_id)
+    if cb.image_free != C_NULL
+        error("File image callback image_free is not C_NULL. Use the three argument method of h5p_get_file_image when setting file image callbacks.")
+    end
     buf_ptr_ref = Ref{Ptr{Nothing}}()
     buf_len_ref = Ref{Csize_t}(0)
     h5p_get_file_image(fapl_id, buf_ptr_ref, buf_len_ref)
@@ -832,6 +836,26 @@ function h5p_set_file_image(fapl_id, image::Vector{UInt8})
     h5p_set_file_image(fapl_id, image, length(image))
 end
 
+"""
+    h5p_get_file_image_callbacks(fapl_id)
+
+Retrieve the file image callbacks for memory operations
+"""
+function h5p_get_file_image_callbacks(fapl_id)
+    cb = H5FD_file_image_callbacks_t(
+        C_NULL,
+        C_NULL,
+        C_NULL,
+        C_NULL,
+        C_NULL,
+        C_NULL,
+        C_NULL)
+    r = Ref(cb)
+    h5p_get_file_image_callbacks(fapl_id, r)
+    return r[]
+end
+
+
 # Note: The following function(s) implement direct ccalls because the binding generator
 # cannot (yet) do the string wrapping and memory freeing.