How to alter block configuration form in Drupal 7?

How can I alter block configurations in Drupal 7?

There are some hooks like hook_block_info_alter() and hook_block_view_alter() but it seems there is not anything name开发者_运维知识库d "hook_block_configure_alter".

Is hook_form_alter() the only solution?

Yes, you should use hook_form_alter() or hook_form_FORM_ID_alter(). If you are making changes specific to a single form, the latter should be used. A good description of the two hooks can be found HERE.