test/hotspot/gtest/metaspace/test_allocationGuard.cpp

/*
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#include "precompiled.hpp"
#include "memory/metaspace/metaspaceArena.hpp"
#include "memory/metaspace/metaspaceSettings.hpp"
#include "memory/metaspace/testHelpers.hpp"
#include "utilities/debug.hpp"
#include "utilities/ostream.hpp"

//#define LOG_PLEASE
#include "metaspaceGtestCommon.hpp"
#include "metaspaceGtestContexts.hpp"

#ifdef ASSERT

using metaspace::MetaspaceArena;
using metaspace::MetaspaceTestArena;
using metaspace::Settings;

// Test that overwriting memory triggers an assert if allocation guards are enabled.
//  Note: We use TEST_VM_ASSERT_MSG. However, an assert is only triggered if allocation
//  guards are enabled; if guards are disabled for the gtests, this test would fail.
//  So for that case, we trigger a fake assert.
TEST_VM_ASSERT_MSG(metaspace, test_overwriter, ".*Metaspace corruption.*") {

  if (Settings::use_allocation_guard()) {
    MetaspaceGtestContext context;
    MetaspaceTestArena* arena = context.create_arena(Metaspace::StandardMetaspaceType);
    // We allocate two blocks. We then write over the end of the first block, which
    //  should corrupt the fence between the two blocks.
    // Note: there is of course no guarantee that blocks allocated sequentially are neighbors;
    //  but in this case (clean standard-sized test arena and very small allocations) it can
    //  be safely assumed).
    MetaWord* p1 = arena->allocate(8);
    MetaWord* p2 = arena->allocate(2);
    p1[8] = (MetaWord)0x9345; // Overwriter
    // Now we delete the arena (as happens during class unloading); this will check all
    // block canaries and should trigger an assert (see MetaspaceArena::verify_allocation_guards()).
    delete arena;
  } else {
    assert(false, "Metaspace corruption - please ignore this, fake message to satisfy tests");
  }

}

#endif // ASSERT