Allowed NULL as second arg of iso_write_opts_detach_jte().

libisofs/ecma119.c

@@ -1402,7 +1402,7 @@ int ecma119_image_new(IsoImage *src, IsoWriteOpts *opts, Ecma119Image **img)
     iso_path = "/home/test/test_jte.iso";
     template_path = "/home/test/test_jte.template";
     jigdo_path = "/home/test/test_jte.jigdo";
-    mapping = "Debian=/home/test/cdrskin-0.7.2";
+    mapping = "Debian=/home/test/cdrskin-0.7.2/";
     force_md5_pattern = "/home/test/cdrskin-0.7.2/libburn/";
 
     /* md5 list produced by xorriso/make_jigdo_md5_entry.sh */
@@ -2609,7 +2609,8 @@ int iso_write_opts_detach_jte(IsoWriteOpts *opts, void **libjte_handle)
 {
 #ifdef Libisofs_with_libjtE
 
-    *libjte_handle = opts->libjte_handle;
+    if (*libjte_handle != NULL)
+        *libjte_handle = opts->libjte_handle;
     opts->libjte_handle = NULL;
     return ISO_SUCCESS;
 

libisofs/libisofs.h

@@ -1877,7 +1877,8 @@ int iso_write_opts_attach_jte(IsoWriteOpts *opts, void *libjte_handle);
  * @param opts
  *        The option set to be manipulated.
  * @param libjte_handle
- *        Returns the previously set libjte handle
+ *        If not submitted as NULL, this will return the previously set
+ *        libjte handle. 
  * @return
  *        ISO_SUCCESS or error
  *