500: allow longer usernames in frontend

[johnpink]

Fixes issue #500

[johnpink]

When trying to add a new member with username length greater than 14, the GUI won't let you because of a hard-coded values.

For more context, you can already allow a longer username in the back-end by simply altering the name column to set it to varchar(64) instead of varchar(16) and then bumping up the sql_max_username_length value in the variable table. This allows you to insert longer usernames, but only through SQL. The changes here are to allow longer usernames through the front-end / GUI.

[kienanstewart]

I don't think sql_max_username_length is the appropriate variable to use here. There's a very specific reason the default of 14 was chosen, so that it would be 2 less than sql_max_username_length. This allows databases to be created with uses in the following pattern:

• username
• username_[a-z0-9]

Since the limit has a purpose is distinct from sql_max_username_length, I would like to propose the following changes:

1. Use a max_login_length variable, defaulting at 14 as it is now.
2. Remove the input maxlength attribute for the login from bureau/admin/adm_add.php: the UX of http input's maxlength is quite bad and results in the longer strings being silently truncated by the client
3. In bureau/m_admin.php::add_mem, validate that the length of the login is >= 1 and <= variable_get('max_login_length', 14, "The maximum length of login names")
4. Implement hook_variable_set in bureau/m_admin.php to ensure that the new setting is sane. For max_login_length, the bounds might be something like:

• >= 1
• <= variable_get("sql_max_username_length") - 2
• <= 128 (the size of the login column)

If the new setting is outside those bounds, I would expect the old value to be saved back and an warning or error shown to the user.

There could be further considerations for the login length, such as:

• the maximum length of user names for ftp accounts (64, by default and limited by the ftpusers name column) - 2, in the same way that sql usernames affects the length limit.