zircon/system/ulib/c/test/default-stack-size-test.cc

// Copyright 2019 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include <lib/zircon-internal/default_stack_size.h>
#include <pthread.h>

#include <zxtest/zxtest.h>

namespace {

#ifdef STACK_TEST_EXPECTED_SIZE
constexpr size_t kExpectedSize = STACK_TEST_EXPECTED_SIZE;
static_assert(kExpectedSize != ZIRCON_DEFAULT_STACK_SIZE);
#else
constexpr size_t kExpectedSize = ZIRCON_DEFAULT_STACK_SIZE;
#endif

void FetchStackSize(pthread_t thread, size_t* out_size) {
  pthread_attr_t attr;
  ASSERT_EQ(0, pthread_getattr_np(thread, &attr));
  ASSERT_EQ(0, pthread_attr_getstacksize(&attr, out_size));
}

TEST(StackSizeTests, MainThreadStackSize) {
  size_t size;
  ASSERT_NO_FATAL_FAILURE(FetchStackSize(pthread_self(), &size),
                          "Cannot retrieve main thread's stack size");
  EXPECT_EQ(kExpectedSize, size);
}

// Simple RAII wrapper for pthread_mutex_t.
class PthreadLockGuard {
 public:
  explicit PthreadLockGuard(pthread_mutex_t* mtx) : mtx_(mtx) {
    ASSERT_EQ(pthread_mutex_lock(mtx_), 0);
  }
  ~PthreadLockGuard() { Reset(); }

  void Reset() {
    if (mtx_) {
      pthread_mutex_unlock(mtx_);
    }
    mtx_ = nullptr;
  }

 private:
  pthread_mutex_t* mtx_ = nullptr;
};

TEST(StackSizeTests, NewThreadStackSize) {
  pthread_mutex_t mtx = PTHREAD_MUTEX_INITIALIZER;
  PthreadLockGuard lock(&mtx);
  pthread_t th;
  ASSERT_EQ(0, pthread_create(
                   &th, nullptr,
                   [](void* arg) -> void* {
                     pthread_mutex_t* mtx = reinterpret_cast<pthread_mutex_t*>(arg);
                     PthreadLockGuard lock(mtx);
                     return nullptr;
                   },
                   &mtx));

  size_t size;
  ASSERT_NO_FATAL_FAILURE(FetchStackSize(th, &size), "Cannot retrieve new thread's stack size");
  EXPECT_EQ(kExpectedSize, size);
  lock.Reset();

  void* result = &result;
  EXPECT_EQ(0, pthread_join(th, &result));
  EXPECT_NULL(result);
}

}  // anonymous namespace