6 uses of FILE_READABLE in Drupal 6

drupal_install_fix_file in includes/install.inc

Attempt to fix file permissions.

drupal_install_mkdir in includes/install.inc

Create a directory with specified permissions.

drupal_verify_install_file in includes/install.inc

Verify the state of the specified file.

install_check_requirements in ./install.php

Check installation requirements and report any errors.

install_tasks in ./install.php

Tasks performed after the database is initialized.

system_requirements in modules/system/system.install

Implementation of hook_requirements().