+
+/* Copy string array value. */
+char **
+ocaml_guestfs_strings_val (guestfs_h *g, value sv)
+{
+ CAMLparam1 (sv);
+ char **r;
+ unsigned int i;
+
+ r = guestfs_safe_malloc (g, sizeof (char *) * (Wosize_val (sv) + 1));
+ for (i = 0; i < Wosize_val (sv); ++i)
+ r[i] = guestfs_safe_strdup (g, String_val (Field (sv, i)));
+ r[i] = NULL;
+
+ CAMLreturnT (char **, r);
+}
+
+/* Free array of strings. */
+void
+ocaml_guestfs_free_strings (char **argv)
+{
+ unsigned int i;
+
+ for (i = 0; argv[i] != NULL; ++i)
+ free (argv[i]);
+ free (argv);
+}
+
+#define PROGRESS_ROOT_KEY "_ocaml_progress_root"
+
+/* Guestfs.set_progress_callback */
+CAMLprim value
+ocaml_guestfs_set_progress_callback (value gv, value closure)
+{
+ CAMLparam2 (gv, closure);
+
+ guestfs_h *g = Guestfs_val (gv);
+ clear_progress_callback (g);
+
+ value *root = guestfs_safe_malloc (g, sizeof *root);
+ *root = closure;
+
+ /* XXX This global root is generational, but we cannot rely on every
+ * user having the OCaml 3.11 version which supports this.
+ */
+ caml_register_global_root (root);
+
+ guestfs_set_private (g, PROGRESS_ROOT_KEY, root);
+
+ guestfs_set_progress_callback (g, progress_callback, root);
+
+ CAMLreturn (Val_unit);
+}
+
+/* Guestfs.clear_progress_callback */
+CAMLprim value
+ocaml_guestfs_clear_progress_callback (value gv)
+{
+ CAMLparam1 (gv);
+
+ guestfs_h *g = Guestfs_val (gv);
+ clear_progress_callback (g);
+
+ CAMLreturn (Val_unit);
+}
+
+static void
+clear_progress_callback (guestfs_h *g)
+{
+ guestfs_set_progress_callback (g, NULL, NULL);
+
+ value *root = guestfs_get_private (g, PROGRESS_ROOT_KEY);
+ if (root) {
+ caml_remove_global_root (root);
+ free (root);
+ guestfs_set_private (g, PROGRESS_ROOT_KEY, NULL);
+ }
+}
+
+static void
+progress_callback (guestfs_h *g ATTRIBUTE_UNUSED, void *root,
+ int proc_nr, int serial, uint64_t position, uint64_t total)
+{
+ CAMLparam0 ();
+ CAMLlocal5 (proc_nrv, serialv, positionv, totalv, rv);
+
+ proc_nrv = Val_int (proc_nr);
+ serialv = Val_int (serial);
+ positionv = caml_copy_int64 (position);
+ totalv = caml_copy_int64 (total);
+
+ value args[4] = { proc_nrv, serialv, positionv, totalv };
+
+ caml_leave_blocking_section ();
+ rv = caml_callbackN_exn (*(value*)root, 4, args);
+ caml_enter_blocking_section ();
+
+ /* Callbacks shouldn't throw exceptions. There's not much we can do
+ * except to print it.
+ */
+ if (Is_exception_result (rv))
+ fprintf (stderr, "libguestfs: uncaught OCaml exception in progress callback: %s",
+ caml_format_exception (Extract_exception (rv)));
+
+ CAMLreturn0;
+}