Note: this list is generated by pattern matching, so it may include some functions that are not actually implementations of this hook.

config_file_download in core/modules/config/config.module
Implements hook_file_download().
file_file_download in core/modules/file/file.module
Implements hook_file_download().
file_module_test_file_download in core/modules/file/tests/file_module_test/file_module_test.module
Implements hook_file_download().
file_test_file_download in core/modules/simpletest/tests/file_test.module
Implements hook_file_download().
image_file_download in core/modules/image/image.module
Implements hook_file_download().
image_module_test_file_download in core/modules/image/tests/image_module_test/image_module_test.module
user_file_download in core/modules/user/user.module
Implements hook_file_download().