FILE_READABLE

drupal_install_fix_file in core/includes/install.inc

Attempts to fix file permissions.

drupal_install_mkdir in core/includes/install.inc

Creates a directory with the specified permissions.

drupal_verify_install_file in core/includes/install.inc

Verifies the state of the specified file.

install_check_requirements in core/includes/install.core.inc

Checks installation requirements and reports any errors.

simpletest_requirements in core/modules/simpletest/simpletest.install

Implements hook_requirements().

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