add exec_wrapper function

src/codeql.ts

@@ -12,6 +12,7 @@ import uuidV4 from 'uuid/v4';
 
 import * as api from './api-client';
 import * as defaults from './defaults.json'; // Referenced from codeql-action-sync-tool!
+import { exec_wrapper } from './exec_wrapper';
 import { Language } from './languages';
 import * as util from './util';
 
@@ -390,7 +391,7 @@ function getCodeQLForCmd(cmd: string): CodeQL {
       ]);
     },
     finalizeDatabase: async function(databasePath: string) {
-      await exec.exec(cmd, [
+      await exec_wrapper(cmd, [
         'database',
         'finalize',
         ...getExtraOptionsFromEnv(['database', 'finalize']),

src/exec_wrapper.ts

@@ -0,0 +1,39 @@
+import * as exec from '@actions/exec';
+import * as im from '@actions/exec/lib/interfaces';
+
+export async function exec_wrapper(commandLine: string, args?: string[], options?: im.ExecOptions): Promise<number> {
+
+  const originalListener = options?.listeners;
+
+  let stdout = '';
+  let stderr = '';
+
+  let listeners = {
+    stdout: (data: Buffer) => {
+      stdout += data.toString();
+      // NB change behaviour to only write to stdout/err if no listener passed
+      process.stdout.write(data);
+      originalListener?.stdout?.(data);
+    },
+    stderr: (data: Buffer) => {
+      stderr += data.toString();
+      process.stderr.write(data);
+      originalListener?.stderr?.(data);
+    }
+  };
+
+  const returnCode = await exec.exec(
+    commandLine,
+    args,
+    {
+      listeners: listeners,
+      ...options
+    });
+
+  if (stderr === stdout ) {
+    console.log('foo bar');
+  }
+
+  return returnCode;
+
+}