file_add_form_submit in core/modules/file/file.pages.inc

Submit handler for the add file form.

file_add_upload_step_scheme in core/modules/file/file.pages.inc

Generate form fields for the third step in the add file wizard.

file_field_settings_form in core/modules/file/file.field.inc

Implements hook_field_settings_form().

file_get_stream_wrappers in core/includes/file.inc

Provides Backdrop stream wrapper registry.

file_is_writeable in core/modules/file/file.module

Check if a file entity is considered writeable or not.

file_manage_form in core/modules/file/file.pages.inc

Page callback: Form constructor for the file manage form.

filter_editor_file_upload_settings_form in core/modules/filter/filter.admin.inc

Subform constructor to configure the text editor's file upload settings.

filter_editor_image_upload_settings_form in core/modules/filter/filter.admin.inc

Subform constructor to configure the text editor's image upload settings.

image_field_settings_form in core/modules/image/image.field.inc

Implements hook_field_settings_form().

image_style_flush in core/modules/image/image.module

Flush cached media for a style.

stream_wrappers.inc in core/includes/stream_wrappers.inc

Backdrop stream wrapper interface.

system_file_system_settings in core/modules/system/system.admin.inc

Form builder; Configure the site file handling.