[wp-trac] [WordPress Trac] #51011: Empty string comparison on home option during DB upgrades is invalid

[WordPress Trac]

#51011: Empty string comparison on home option during DB upgrades is invalid
-----------------------------+-----------------------------
 Reporter:  fjarrett         |      Owner:  (none)
     Type:  defect (bug)     |     Status:  new
 Priority:  normal           |  Milestone:  Awaiting Review
Component:  Upgrade/Install  |    Version:  5.5
 Severity:  minor            |   Keywords:
  Focuses:                   |
-----------------------------+-----------------------------
 The private `__get_option()` function used during database upgrades was
 recently changed in WordPress 5.5 to use a strict comparison operator to
 check whether the `home` option value is empty string. However,
 `wpdb::get_var` returns `NULL` if the option is empty, so this condition
 never actually exists.

 https://github.com/WordPress/WordPress/blob/537fd931bc02e6e934a2d774422b897871aa87ad
 /wp-admin/includes/upgrade.php#L2570

 This was discovered because of an oddity that manifested when using WP-CLI
 to run database upgrades on sites that has an empty `home` option, and it
 was only reproducible with WordPress 5.5. Full discussion can be found in
 the #cli Slack.

 https://wordpress.slack.com/archives/C02RP4T41/p1597352867393200

 Some possible solutions are:

 1. Correct the strict comparison to use `null === $option`
 2. Use a more generous empty comparison like `! $option`
 3. Refactor `__get_option()` to use `wpdb::get_col` like its
 `get_option()` cousin

 ---

 The WP-CLI oddity is fairly easy to reproduce:

 1. Empty the `home` option value in the WordPress database:

 {{{
 $ wp db query "UPDATE wp_options SET option_value = '' WHERE option_name =
 'home';"
 }}}

  ''Note: `wp option update home ''` won't work because the core fallback
 to `siteurl` prevents it.''

 2. Set the `db_version` option to anything less than 48748:

 {{{
 $ wp option update db_version 47018
 Success: Updated 'db_version' option.
 }}}

 3. Execute the database update:

 {{{
 $ wp core update-db
 Success: WordPress database upgraded successfully from db version 47018 to
 48748.
 }}}

 4. Check the option value:

 {{{
 $ wp option get home
 http://http://example.com
 }}}

-- 
Ticket URL: <https://core.trac.wordpress.org/ticket/51011>
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