Use correct script paths when launching via autorun

The background script launching now checks where it's being run
from, rather than just assuming that DOCUMENT_ROOT will always
be available.
This stops `autorun.php` from attempting to start `/scripts/*`,
which doesn't exist.

Author: JasonTarka

src/Utils.php

@@ -108,6 +108,10 @@ public static function getFILES(): Map<string, array<string, mixed>> {
     return new Map($_FILES);
   }
 
+  public static function get_src_root() : string {
+    return preg_replace(':/src/.*$:', '/src', __DIR__);
+  }
+
   public static function redirect(string $location): void {
     header('Location: '.$location);
   }

src/models/Level.php

@@ -1284,7 +1284,7 @@ public static function getBasesResponses(
   // Bases processing and scoring.
   public static async function genBaseScoring(): Awaitable<void> {
     Utils::logMessage('Starting background script: bases');
-    $document_root = must_have_string(Utils::getSERVER(), 'DOCUMENT_ROOT');
+    $document_root = Utils::get_src_root();
     $cmd =
       'hhvm -vRepo.Central.Path=/var/run/hhvm/.hhvm.hhbc_bases '.
       $document_root.

src/models/Progressive.php

@@ -147,7 +147,7 @@ private static function progressiveFromRow(
   // Kick off the progressive scoreboard in the background.
   public static async function genRun(): Awaitable<void> {
     Utils::logMessage('Starting background script: progressive scoreboard');
-    $document_root = must_have_string(Utils::getSERVER(), 'DOCUMENT_ROOT');
+    $document_root = Utils::get_src_root();
     $cmd =
       'hhvm -vRepo.Central.Path=/var/run/hhvm/.hhvm.hhbc_progressive '.
       $document_root.