Ticket #31138: backup_package_functions.patch

../../../wp-includes/functions.php

@@ -4809 +4809 @@
 
         return (bool) $var;
 }
+
+/**
+ * Get the prefix of the backup name, compatible with transient names.
+ *
+ * The backup name is used for both a transient (which stores backup metadata) and a temporary directory (which
+ * stores backup files and directories).
+ *
+ * Plugin/theme names get truncated after 21 characters and it's possible (but quite improbable) that two different
+ * packages have exactly the same first 21 characters. In such a case there would be a prefix clash. However, to
+ * tell them apart, you can check the original plugin/theme directory name which is stored into the transient.
+ *
+ * Notice that many backups can potentially exist for each plugin/theme at the same time. The number of backups is at
+ * most the number of times the user updated to the latest version, which can occur many times in a row against one
+ * new version (due to user's retries) or many successive versions (due to frequent releases).
+ *
+ * Example for copying back in place user's customizations.
+ * <code>
+ * $plugin_dir = dirname(__FILE__);
+ * $prefix = backup_prefix($plugin_dir, 'plugin');
+ * $backups = get_transients_like("%$prefix%");
+ * if (count($backups)) {
+ *   $last = array_pop($backups);
+ *   copy_dir($last['backup_dir'] . '/custom_files', $plugin_dir . '/custom_files');
+ * }
+ * </code>
+ *
+ * @param string $package_dir Plugin/theme directory.
+ * @param string $type        Either 'plugin' or 'theme'.
+ *
+ * @return string The prefix.
+ */
+function backup_prefix( $package_dir, $type ) {
+        $package_name = basename($package_dir);
+        $package_type = '';
+        if ( $type == 'plugin' ) {
+                $package_type = '_p';
+        } elseif ( $type == 'theme' ) {
+                $package_type = '_t';
+        }
+        $transient_name_limit = 45;
+        $uniqid_length = 13;
+        $placeholder = '?';
+        $backup_name = 'backup' . $package_type . '_' . $placeholder . '_';
+        $cut_length = $transient_name_limit - (strlen($backup_name) + $uniqid_length - strlen($placeholder));   // 21 chars
+        $max_package_name = substr($package_name, 0, $cut_length);
+        $result = str_replace('?', $max_package_name, $backup_name);  // eg: 'backup_p_akismet_'
+        return $result;
+}