Support overlay modes for "codeql database init"

Author: cklin

lib/codeql.js

@@ -1,3 +1,4 @@
+import assert from "assert";
 import * as fs from "fs";
 import * as path from "path";
 
@@ -585,6 +586,18 @@ export async function getCodeQLForCmd(
         extraArgs.push(`--qlconfig-file=${qlconfigFile}`);
       }
 
+      let dbLocation = config.dbLocation;
+      const overlayDatabaseEnv = process.env["CODEQL_OVERLAY_DATABASE_INIT"];
+      if (overlayDatabaseEnv === "overlay") {
+        assert(config.buildMode === BuildMode.None);
+        extraArgs.push("--overlay");
+        assert(config.languages.length === 1);
+        dbLocation = path.join(dbLocation, config.languages[0]);
+      } else if (overlayDatabaseEnv === "overlay-base") {
+        assert(config.buildMode === BuildMode.None);
+        extraArgs.push("--overlay-base");
+      }
+
       const overwriteFlag = isSupportedToolsFeature(
         await this.getVersion(),
         ToolsFeature.ForceOverwrite,
@@ -599,7 +612,7 @@ export async function getCodeQLForCmd(
           "init",
           overwriteFlag,
           "--db-cluster",
-          config.dbLocation,
+          dbLocation,
           `--source-root=${sourceRoot}`,
           "--calculate-language-specific-baseline",
           "--extractor-include-aliases",

lib/codeql.js.map

@@ -163,6 +163,11 @@ export function cleanupDatabaseClusterDirectory(
   // for testing.
   rmSync = fs.rmSync,
 ): void {
+  const overlayDatabaseEnv = process.env["CODEQL_OVERLAY_DATABASE_INIT"];
+  if (overlayDatabaseEnv === "overlay") {
+    return;
+  }
+
   if (
     fs.existsSync(config.dbLocation) &&
     (fs.statSync(config.dbLocation).isFile() ||