In all cases changes have been kept to a minimum while not making
the code completely horrible. For example, there are many instances
where it would probably be better to rewrite a query entirely, but
I have not done that (in order to reduce the risk of changes).

The function must be static and actually has to do what it is supposed to. It also breaks PHP 8.0

This reverts commit 522e4c6c.

The DB calls are not redundant and have an impact in a number of edge
cases.

Switch the order of operations performed when collating list of paths
from which a user can include attachments.

First collect all normalised/absolute paths then filter empty entries,
which fixes an issue where $CFG->localrequestdir could be defined but
not exist. This would lead to an empty string being passed to strpos
which triggered a PHP warning.

Co-authored-by: Peter Burnett <peterburnett@catalyst-au.net>

Rather than using the provided path, the `realpath` must be used to
ensure that the use of symlinks in paths is normalised.

Co-authored-by: Paul Holden <paulh@moodle.com>

Brendan Heywood authored Oct 28, 2020 and Eloy Lafuente committed Nov 01, 2020

Also, ensure that remove_dir() only processes directories,
because sometimes it was being called by shutdown managers
with files, leading to PHP warnings.

Co-authored-by: Eloy Lafuente (stronk7) <stronk7@moodle.org>
Co-authored-by: Jun Pataleta <jun@moodle.com>

The remove_course_contents function did not delete data from
course_module_completion table in most cases, resulting in large
quantities of orphaned data.

Changes:
- The client can now be instantiated with the new mode enabled.
- A user refresh token will be stored if returned as part of the
authorization_code grant but only if the user is authenticated and only
if the mode is enabled.
- If the mode permits it, attempt to exchange a stored refresh token for
a new access token during login checks, allowing access to continue
across sessions without the need to re-grant consent every time.
- Purge all refresh tokens for a given user, issuer and scope on client
log out. This makes sure logout persists across logins.

When we want to delete all of the activities in a course we should
mark them as having a deletion in progress, as this makes them
unavailable to users immediately.

This should make it much less likely that a request to get a context
that does not exist should be made when a user accesses a page.

When deleting a course (especially one containing a large amount of
data) the course mod info cache could contain entries for deleted
activities for a signifcant amount of time making it possible that
users could see errors in Moodle.

Implemented with moodle_read_slave_trait

Functionality is triggered by supplying config dboption['readonly'].
See config-dist.php for more info on supported dboptions.

pgsql and mysqli drivers are using this feature. Also added support for
connection timeout for these two drivers.

Or when a course category is moved/deleted