From e95b44cf61de3244e9042f71753310d010a4d67c Mon Sep 17 00:00:00 2001
From: Edwin Wu <edwinwu@google.com>
Date: Thu, 7 Aug 2025 17:06:17 -0700
Subject: [PATCH] Fixes a potential crash when shutting down a `BleMedium`.

PiperOrigin-RevId: 792365629
---
 .../apple/Mediums/BLEv2/GNCBLEMedium.h             |  5 +++++
 .../apple/Mediums/BLEv2/GNCBLEMedium.m             | 14 ++++++++++++--
 .../implementation/apple/Tests/GNCPlatformTest.mm  |  6 ++++++
 .../platform/implementation/apple/ble_medium.h     |  2 +-
 .../platform/implementation/apple/ble_medium.mm    |  3 +++
 5 files changed, 27 insertions(+), 3 deletions(-)

diff --git a/internal/platform/implementation/apple/Mediums/BLEv2/GNCBLEMedium.h b/internal/platform/implementation/apple/Mediums/BLEv2/GNCBLEMedium.h
index b95790a9..65a8e633 100644
--- a/internal/platform/implementation/apple/Mediums/BLEv2/GNCBLEMedium.h
+++ b/internal/platform/implementation/apple/Mediums/BLEv2/GNCBLEMedium.h
@@ -238,6 +238,11 @@ typedef void (^GNCGATTConnectionCompletionHandler)(GNCBLEGATTClient *_Nullable c
                      peripheral:(id<GNCPeripheral>)remotePeripheral
               completionHandler:(nullable GNCOpenL2CAPStreamCompletionHandler)completionHandler;
 
+/**
+ * Stops all BLE operations.
+ */
+- (void)stop;
+
 @end
 
 NS_ASSUME_NONNULL_END
diff --git a/internal/platform/implementation/apple/Mediums/BLEv2/GNCBLEMedium.m b/internal/platform/implementation/apple/Mediums/BLEv2/GNCBLEMedium.m
index 283620d2..0e14d94b 100644
--- a/internal/platform/implementation/apple/Mediums/BLEv2/GNCBLEMedium.m
+++ b/internal/platform/implementation/apple/Mediums/BLEv2/GNCBLEMedium.m
@@ -34,6 +34,7 @@ NS_ASSUME_NONNULL_BEGIN
 static char *const kBLEMediumQueueLabel = "com.nearby.GNCBLEMedium";
 // TODO: b/762454867 - Make this a flag.
 static const NSTimeInterval kPeripheralConnectTimeout = 10.0;  // 10 seconds timeout
+static const NSTimeInterval kStopTimeout = 5.0;
 
 static NSError *AlreadyScanningError() {
   return [NSError errorWithDomain:GNCBLEErrorDomain code:GNCBLEErrorAlreadyScanning userInfo:nil];
@@ -122,8 +123,17 @@ static GNCBLEL2CAPServer *_Nonnull CreateL2CapServer(
   return self;
 }
 
-- (void)dealloc {
-  [self cancelConnectionTimeout];
+- (void)stop {
+  dispatch_semaphore_t semaphore = dispatch_semaphore_create(0);
+  dispatch_async(_queue, ^{
+    [self cancelConnectionTimeout];
+    dispatch_semaphore_signal(semaphore);
+  });
+  dispatch_time_t timeout =
+      dispatch_time(DISPATCH_TIME_NOW, kStopTimeout * NSEC_PER_SEC);  // 5 seconds timeout
+  if (dispatch_semaphore_wait(semaphore, timeout) != 0) {
+    GNCLoggerError(@"GNCBLEMedium stop timeout.");
+  }
 }
 
 - (BOOL)supportsExtendedAdvertisements {
diff --git a/internal/platform/implementation/apple/Tests/GNCPlatformTest.mm b/internal/platform/implementation/apple/Tests/GNCPlatformTest.mm
index 322d0725..72467db7 100644
--- a/internal/platform/implementation/apple/Tests/GNCPlatformTest.mm
+++ b/internal/platform/implementation/apple/Tests/GNCPlatformTest.mm
@@ -80,4 +80,10 @@ void GNCEnsureFileAtPath(std::string path) {
   XCTAssertEqualObjects(@(actual.c_str()), expected);
 }
 
+- (void)testCreateBleV2Medium {
+  auto bluetooth_adapter = nearby::api::ImplementationPlatform::CreateBluetoothAdapter();
+  auto ble_medium = nearby::api::ImplementationPlatform::CreateBleV2Medium(*bluetooth_adapter);
+  XCTAssertNotEqual(ble_medium.get(), nullptr);
+}
+
 @end
diff --git a/internal/platform/implementation/apple/ble_medium.h b/internal/platform/implementation/apple/ble_medium.h
index 6520221e..bc86ebcd 100644
--- a/internal/platform/implementation/apple/ble_medium.h
+++ b/internal/platform/implementation/apple/ble_medium.h
@@ -47,7 +47,7 @@ namespace apple {
 class BleMedium : public api::ble_v2::BleMedium {
  public:
   BleMedium();
-  ~BleMedium() override = default;
+  ~BleMedium() override;
 
   // Async interface for StartAdvertising.
   //
diff --git a/internal/platform/implementation/apple/ble_medium.mm b/internal/platform/implementation/apple/ble_medium.mm
index 96071ed8..1c9277b2 100644
--- a/internal/platform/implementation/apple/ble_medium.mm
+++ b/internal/platform/implementation/apple/ble_medium.mm
@@ -82,6 +82,9 @@ NSString *ConvertDataToHexString(NSData *data) {
 
 BleMedium::BleMedium() : medium_([[GNCBLEMedium alloc] init]) {}
 
+// ble_medium.mm
+BleMedium::~BleMedium() { [medium_ stop]; }
+
 std::unique_ptr<api::ble_v2::BleMedium::AdvertisingSession> BleMedium::StartAdvertising(
     const api::ble_v2::BleAdvertisementData &advertising_data,
     api::ble_v2::AdvertiseParameters advertise_set_parameters,