mojo/public/tests/bindings/buffer_unittest.cc

// Copyright 2013 The Chromium 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 "mojo/public/bindings/lib/bindings_serialization.h"
#include "mojo/public/bindings/lib/buffer.h"
#include "mojo/public/environment/environment.h"
#include "testing/gtest/include/gtest/gtest.h"

namespace mojo {
namespace test {

bool IsZero(void* p_buf, size_t size) {
  char* buf = reinterpret_cast<char*>(p_buf);
  for (size_t i = 0; i < size; ++i) {
    if (buf[i] != 0)
      return false;
  }
  return true;
}

// Tests small and large allocations in ScratchBuffer.
TEST(ScratchBufferTest, Basic) {
  Environment env;

  // Test that a small allocation is placed on the stack.
  internal::ScratchBuffer buf;
  void* small = buf.Allocate(10);
  EXPECT_TRUE(small >= &buf && small < (&buf + sizeof(buf)));
  EXPECT_TRUE(IsZero(small, 10));

  // Large allocations won't be on the stack.
  void* large = buf.Allocate(100*1024);
  EXPECT_TRUE(IsZero(large, 100*1024));
  EXPECT_FALSE(large >= &buf && large < (&buf + sizeof(buf)));

  // But another small allocation should be back on the stack.
  small = buf.Allocate(10);
  EXPECT_TRUE(IsZero(small, 10));
  EXPECT_TRUE(small >= &buf && small < (&buf + sizeof(buf)));
}

// Tests that Buffer::current() returns the correct value.
TEST(ScratchBufferTest, Stacked) {
  Environment env;

  EXPECT_FALSE(Buffer::current());

  {
    internal::ScratchBuffer a;
    EXPECT_EQ(&a, Buffer::current());

    {
      internal::ScratchBuffer b;
      EXPECT_EQ(&b, Buffer::current());
    }
  }

  EXPECT_FALSE(Buffer::current());
}

// Tests that FixedBuffer allocates memory aligned to 8 byte boundaries.
TEST(FixedBufferTest, Alignment) {
  Environment env;

  internal::FixedBuffer buf(internal::Align(10) * 2);
  ASSERT_EQ(buf.size(), 16u * 2);

  void* a = buf.Allocate(10);
  ASSERT_TRUE(a);
  EXPECT_TRUE(IsZero(a, 10));
  EXPECT_EQ(0, reinterpret_cast<ptrdiff_t>(a) % 8);

  void* b = buf.Allocate(10);
  ASSERT_TRUE(b);
  EXPECT_TRUE(IsZero(b, 10));
  EXPECT_EQ(0, reinterpret_cast<ptrdiff_t>(b) % 8);

  // Any more allocations would result in an assert, but we can't test that.
}

// Tests that FixedBuffer::Leak passes ownership to the caller.
TEST(FixedBufferTest, Leak) {
  Environment env;

  void* ptr = NULL;
  void* buf_ptr = NULL;
  {
    internal::FixedBuffer buf(8);
    ASSERT_EQ(8u, buf.size());

    ptr = buf.Allocate(8);
    ASSERT_TRUE(ptr);
    void* buf_ptr = buf.Leak();

    // The buffer should point to the first element allocated.
    // TODO(mpcomplete): Is this a reasonable expectation?
    EXPECT_EQ(ptr, buf_ptr);

    // The FixedBuffer should be empty now.
    EXPECT_EQ(0u, buf.size());
    EXPECT_FALSE(buf.Leak());
  }

  // Since we called Leak, ptr is still writable after FixedBuffer went out of
  // scope.
  memset(ptr, 1, 8);
  free(buf_ptr);
}

}  // namespace test
}  // namespace mojo