Trim cookie paths

[Kevin Brent]

I had just migrated a WP website that was very old. I encountered an issue that took several hours to debug.

The site was on PHP 5.6 and I updated everything to use PHP 7.3. At PHP 5.6 this was not an issue, but was at PHP 7.3.

The site seemed to be loading fine. No errors in the PHP error logs. However, I was not able to login to the WP Admin. After I defined error logging true. I get this:

After several hours of debugging I found this:

I was able to fix this in the DB. But, feel that WP could simply trim

spaces from cookie paths since they are not allowed by PHP.

There are 3 constants that require this attention.

COOKIEPATH

SITECOOKIEPATH

PLUGINS_COOKIE_PATH

This PR ensures that cookie path constants are trimmed so that accidental leading or trailing whitespace in home, siteurl, or plugin URLs cannot create invalid cookie paths.

Affected constants: COOKIEPATH, SITECOOKIEPATH, PLUGINS_COOKIE_PATH (defined in default-constants.php)

Code used for testing:

update_option( 'home', ' http://example.org/ ' );
update_option( 'siteurl', ' http://example.org/ ' );

Trac ticket: https://core.trac.wordpress.org/ticket/49633