From e669a3f83d0f49b3c417fcb847490de4b553ed16 Mon Sep 17 00:00:00 2001
From: Vu Anh Phung <vu.phung@databricks.com>
Date: Tue, 29 Sep 2026 23:02:04 +0000
Subject: [PATCH] Validate required getFunctions functionName

Signed-off-by: Vu Anh Phung <vu.phung@databricks.com>
---
 lib/DBSQLSession.ts             | 10 +++++++++-
 tests/unit/DBSQLSession.test.ts | 30 ++++++++++++++++++++++++++++++
 2 files changed, 39 insertions(+), 1 deletion(-)

diff --git a/lib/DBSQLSession.ts b/lib/DBSQLSession.ts
index 1de9458d..18588ac3 100644
--- a/lib/DBSQLSession.ts
+++ b/lib/DBSQLSession.ts
@@ -22,6 +22,7 @@ import InfoValue from './dto/InfoValue';
 import CloseableCollection from './utils/CloseableCollection';
 import { LogLevel } from './contracts/IDBSQLLogger';
 import HiveDriverError from './errors/HiveDriverError';
+import ParameterError from './errors/ParameterError';
 import StagingError from './errors/StagingError';
 import IClientContext from './contracts/IClientContext';
 import ISessionBackend from './contracts/ISessionBackend';
@@ -293,7 +294,14 @@ export default class DBSQLSession implements IDBSQLSession {
    * @returns DBSQLOperation
    */
   public async getFunctions(request: FunctionsRequest): Promise<IOperation> {
-    return this.wrapOperation(await this.runBackend(() => this.backend.getFunctions(request)));
+    return this.wrapOperation(
+      await this.runBackend(() => {
+        if (typeof request?.functionName !== 'string') {
+          throw new ParameterError('functionName must be a string');
+        }
+        return this.backend.getFunctions(request);
+      }),
+    );
   }
 
   public async getPrimaryKeys(request: PrimaryKeysRequest): Promise<IOperation> {
diff --git a/tests/unit/DBSQLSession.test.ts b/tests/unit/DBSQLSession.test.ts
index 51b27133..59c19813 100644
--- a/tests/unit/DBSQLSession.test.ts
+++ b/tests/unit/DBSQLSession.test.ts
@@ -5,6 +5,8 @@ import DBSQLSession, { numberToInt64 } from '../../lib/DBSQLSession';
 import InfoValue from '../../lib/dto/InfoValue';
 import Status from '../../lib/dto/Status';
 import DBSQLOperation from '../../lib/DBSQLOperation';
+import ISessionBackend from '../../lib/contracts/ISessionBackend';
+import ParameterError from '../../lib/errors/ParameterError';
 import { TSessionHandle, TProtocolVersion } from '../../thrift/TCLIService_types';
 import ClientContextStub from './.stubs/ClientContextStub';
 import { createSessionForTest } from './.stubs/createSessionForTest';
@@ -450,6 +452,28 @@ describe('DBSQLSession', () => {
   });
 
   describe('getFunctions', () => {
+    it('rejects a missing or non-string functionName before calling the backend', async () => {
+      const getFunctions = sinon.stub();
+      const session = new DBSQLSession({
+        backend: { id: 'test', getFunctions } as unknown as ISessionBackend,
+        context: new ClientContextStub(),
+      });
+      const invalidRequests = [undefined, null, {}, { functionName: null }, { functionName: 123 }];
+
+      await Promise.all(
+        invalidRequests.map(async (request) => {
+          try {
+            await session.getFunctions(request as unknown as Parameters<DBSQLSession['getFunctions']>[0]);
+            expect.fail('Expected getFunctions to reject an invalid functionName');
+          } catch (error) {
+            expect(error).instanceOf(ParameterError);
+            expect((error as Error).message).equal('functionName must be a string');
+          }
+        }),
+      );
+      expect(getFunctions.called).false;
+    });
+
     it('should run operation', async () => {
       const session = createSessionForTest({ handle: sessionHandleStub, context: new ClientContextStub() });
       const result = await session.getFunctions({
@@ -460,6 +484,12 @@ describe('DBSQLSession', () => {
       expect(result).instanceOf(DBSQLOperation);
     });
 
+    it('accepts an empty functionName string', async () => {
+      const session = createSessionForTest({ handle: sessionHandleStub, context: new ClientContextStub() });
+      const result = await session.getFunctions({ functionName: '' });
+      expect(result).instanceOf(DBSQLOperation);
+    });
+
     it('should use direct results', async () => {
       const session = createSessionForTest({ handle: sessionHandleStub, context: new ClientContextStub() });
       const result = await session.getFunctions({