424 lines
14 KiB
C++
424 lines
14 KiB
C++
// Copyright 2017 The Crashpad Authors. All rights reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#include "util/posix/scoped_mmap.h"
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#include <stdint.h>
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#include <sys/types.h>
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#include <unistd.h>
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#include <iterator>
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#include "base/numerics/safe_conversions.h"
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#include "base/rand_util.h"
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#include "base/strings/stringprintf.h"
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#include "gtest/gtest.h"
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#include "test/gtest_death.h"
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namespace crashpad {
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namespace test {
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namespace {
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bool ScopedMmapResetMmap(ScopedMmap* mapping, size_t len) {
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return mapping->ResetMmap(
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nullptr, len, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANON, -1, 0);
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}
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void* BareMmap(size_t len) {
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return mmap(
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nullptr, len, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANON, -1, 0);
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}
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// A weird class. This is used to test that memory-mapped regions are freed
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// as expected by calling munmap(). This is difficult to test well because once
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// a region has been unmapped, the address space it formerly occupied becomes
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// eligible for reuse.
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//
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// The strategy taken here is that a random 64-bit cookie value is written into
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// a mapped region by SetUp(). While the mapping is active, Check() should not
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// crash, or for a Google Test expectation, Expected() and Observed() should not
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// crash and should be equal. After the region is unmapped, Check() should
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// crash, either because the region has been unmapped and the address not
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// reused, the address has been reused but is protected against reading
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// (unlikely), or because the address has been reused but the cookie value is no
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// longer present there.
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class TestCookie {
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public:
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// A weird constructor for a weird class. The member variable initialization
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// assures that Check() won’t crash if called on an object that hasn’t had
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// SetUp() called on it.
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explicit TestCookie() : address_(&cookie_), cookie_(0) {}
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TestCookie(const TestCookie&) = delete;
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TestCookie& operator=(const TestCookie&) = delete;
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~TestCookie() {}
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void SetUp(uint64_t* address) {
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address_ = address, cookie_ = base::RandUint64();
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*address_ = cookie_;
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}
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uint64_t Expected() const { return cookie_; }
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uint64_t Observed() const { return *address_; }
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void Check() const {
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if (Observed() != Expected()) {
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__builtin_trap();
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}
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}
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private:
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uint64_t* address_;
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uint64_t cookie_;
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};
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TEST(ScopedMmap, Mmap) {
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TestCookie cookie;
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ScopedMmap mapping;
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EXPECT_FALSE(mapping.is_valid());
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EXPECT_EQ(mapping.addr(), MAP_FAILED);
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EXPECT_EQ(mapping.len(), 0u);
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ASSERT_TRUE(mapping.Reset());
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EXPECT_FALSE(mapping.is_valid());
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const size_t kPageSize = base::checked_cast<size_t>(getpagesize());
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ASSERT_TRUE(ScopedMmapResetMmap(&mapping, kPageSize));
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EXPECT_TRUE(mapping.is_valid());
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EXPECT_NE(mapping.addr(), MAP_FAILED);
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EXPECT_EQ(mapping.len(), kPageSize);
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cookie.SetUp(mapping.addr_as<uint64_t*>());
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EXPECT_EQ(cookie.Observed(), cookie.Expected());
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ASSERT_TRUE(mapping.Reset());
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EXPECT_FALSE(mapping.is_valid());
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}
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TEST(ScopedMmapDeathTest, Destructor) {
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TestCookie cookie;
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{
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ScopedMmap mapping;
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const size_t kPageSize = base::checked_cast<size_t>(getpagesize());
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ASSERT_TRUE(ScopedMmapResetMmap(&mapping, kPageSize));
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EXPECT_TRUE(mapping.is_valid());
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EXPECT_NE(mapping.addr(), MAP_FAILED);
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EXPECT_EQ(mapping.len(), kPageSize);
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cookie.SetUp(mapping.addr_as<uint64_t*>());
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}
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EXPECT_DEATH_CRASH(cookie.Check(), "");
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}
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TEST(ScopedMmapDeathTest, Reset) {
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ScopedMmap mapping;
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const size_t kPageSize = base::checked_cast<size_t>(getpagesize());
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ASSERT_TRUE(ScopedMmapResetMmap(&mapping, kPageSize));
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EXPECT_TRUE(mapping.is_valid());
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EXPECT_NE(mapping.addr(), MAP_FAILED);
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EXPECT_EQ(mapping.len(), kPageSize);
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TestCookie cookie;
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cookie.SetUp(mapping.addr_as<uint64_t*>());
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ASSERT_TRUE(mapping.Reset());
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EXPECT_DEATH_CRASH(cookie.Check(), "");
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}
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TEST(ScopedMmapDeathTest, ResetAddrLen_Shrink) {
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ScopedMmap mapping;
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// Start with three pages mapped.
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const size_t kPageSize = base::checked_cast<size_t>(getpagesize());
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ASSERT_TRUE(ScopedMmapResetMmap(&mapping, 3 * kPageSize));
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EXPECT_TRUE(mapping.is_valid());
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EXPECT_NE(mapping.addr(), MAP_FAILED);
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EXPECT_EQ(mapping.len(), 3 * kPageSize);
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TestCookie cookies[3];
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for (size_t index = 0; index < std::size(cookies); ++index) {
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cookies[index].SetUp(reinterpret_cast<uint64_t*>(
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mapping.addr_as<uintptr_t>() + index * kPageSize));
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}
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// Reset to the second page. The first and third pages should be unmapped.
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void* const new_addr =
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reinterpret_cast<void*>(mapping.addr_as<uintptr_t>() + kPageSize);
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ASSERT_TRUE(mapping.ResetAddrLen(new_addr, kPageSize));
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EXPECT_TRUE(mapping.is_valid());
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EXPECT_EQ(mapping.addr(), new_addr);
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EXPECT_EQ(mapping.len(), kPageSize);
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EXPECT_EQ(cookies[1].Observed(), cookies[1].Expected());
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EXPECT_DEATH_CRASH(cookies[0].Check(), "");
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EXPECT_DEATH_CRASH(cookies[2].Check(), "");
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}
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TEST(ScopedMmap, ResetAddrLen_Grow) {
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// Start with three pages mapped, but ScopedMmap only aware of the the second
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// page.
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const size_t kPageSize = base::checked_cast<size_t>(getpagesize());
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void* pages = BareMmap(3 * kPageSize);
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ASSERT_NE(pages, MAP_FAILED);
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ScopedMmap mapping;
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void* const old_addr =
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reinterpret_cast<void*>(reinterpret_cast<uintptr_t>(pages) + kPageSize);
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ASSERT_TRUE(mapping.ResetAddrLen(old_addr, kPageSize));
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EXPECT_TRUE(mapping.is_valid());
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EXPECT_EQ(mapping.addr(), old_addr);
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EXPECT_EQ(mapping.len(), kPageSize);
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TestCookie cookies[3];
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for (size_t index = 0; index < std::size(cookies); ++index) {
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cookies[index].SetUp(reinterpret_cast<uint64_t*>(
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reinterpret_cast<uintptr_t>(pages) + index * kPageSize));
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}
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// Reset to all three pages. Nothing should be unmapped until destruction.
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ASSERT_TRUE(mapping.ResetAddrLen(pages, 3 * kPageSize));
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EXPECT_TRUE(mapping.is_valid());
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EXPECT_EQ(mapping.addr(), pages);
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EXPECT_EQ(mapping.len(), 3 * kPageSize);
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for (size_t index = 0; index < std::size(cookies); ++index) {
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SCOPED_TRACE(base::StringPrintf("index %zu", index));
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EXPECT_EQ(cookies[index].Observed(), cookies[index].Expected());
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}
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}
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TEST(ScopedMmapDeathTest, ResetAddrLen_MoveDownAndGrow) {
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// Start with three pages mapped, but ScopedMmap only aware of the third page.
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const size_t kPageSize = base::checked_cast<size_t>(getpagesize());
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void* pages = BareMmap(3 * kPageSize);
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ASSERT_NE(pages, MAP_FAILED);
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ScopedMmap mapping;
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void* const old_addr = reinterpret_cast<void*>(
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reinterpret_cast<uintptr_t>(pages) + 2 * kPageSize);
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ASSERT_TRUE(mapping.ResetAddrLen(old_addr, kPageSize));
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EXPECT_TRUE(mapping.is_valid());
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EXPECT_EQ(mapping.addr(), old_addr);
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EXPECT_EQ(mapping.len(), kPageSize);
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TestCookie cookies[3];
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for (size_t index = 0; index < std::size(cookies); ++index) {
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cookies[index].SetUp(reinterpret_cast<uint64_t*>(
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reinterpret_cast<uintptr_t>(pages) + index * kPageSize));
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}
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// Reset to the first two pages. The third page should be unmapped.
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ASSERT_TRUE(mapping.ResetAddrLen(pages, 2 * kPageSize));
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EXPECT_TRUE(mapping.is_valid());
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EXPECT_EQ(mapping.addr(), pages);
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EXPECT_EQ(mapping.len(), 2 * kPageSize);
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EXPECT_EQ(cookies[0].Observed(), cookies[0].Expected());
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EXPECT_EQ(cookies[1].Observed(), cookies[1].Expected());
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EXPECT_DEATH_CRASH(cookies[2].Check(), "");
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}
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TEST(ScopedMmapDeathTest, ResetAddrLen_MoveUpAndShrink) {
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// Start with three pages mapped, but ScopedMmap only aware of the first two
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// pages.
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const size_t kPageSize = base::checked_cast<size_t>(getpagesize());
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void* pages = BareMmap(3 * kPageSize);
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ASSERT_NE(pages, MAP_FAILED);
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ScopedMmap mapping;
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ASSERT_TRUE(mapping.ResetAddrLen(pages, 2 * kPageSize));
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EXPECT_TRUE(mapping.is_valid());
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EXPECT_EQ(mapping.addr(), pages);
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EXPECT_EQ(mapping.len(), 2 * kPageSize);
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TestCookie cookies[3];
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for (size_t index = 0; index < std::size(cookies); ++index) {
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cookies[index].SetUp(reinterpret_cast<uint64_t*>(
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reinterpret_cast<uintptr_t>(pages) + index * kPageSize));
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}
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// Reset to the third page. The first two pages should be unmapped.
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void* const new_addr =
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reinterpret_cast<void*>(mapping.addr_as<uintptr_t>() + 2 * kPageSize);
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ASSERT_TRUE(mapping.ResetAddrLen(new_addr, kPageSize));
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EXPECT_TRUE(mapping.is_valid());
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EXPECT_EQ(mapping.addr(), new_addr);
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EXPECT_EQ(mapping.len(), kPageSize);
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EXPECT_EQ(cookies[2].Observed(), cookies[2].Expected());
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EXPECT_DEATH_CRASH(cookies[0].Check(), "");
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EXPECT_DEATH_CRASH(cookies[1].Check(), "");
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}
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TEST(ScopedMmapDeathTest, ResetMmap) {
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ScopedMmap mapping;
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// Calling ScopedMmap::ResetMmap() frees the existing mapping before
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// establishing the new one, so the new one may wind up at the same address as
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// the old. In fact, this is likely. Create a two-page mapping and replace it
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// with a single-page mapping, so that the test can assure that the second
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// page isn’t mapped after establishing the second mapping.
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const size_t kPageSize = base::checked_cast<size_t>(getpagesize());
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ASSERT_TRUE(ScopedMmapResetMmap(&mapping, 2 * kPageSize));
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EXPECT_TRUE(mapping.is_valid());
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EXPECT_NE(mapping.addr(), MAP_FAILED);
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EXPECT_EQ(mapping.len(), 2 * kPageSize);
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TestCookie cookie;
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cookie.SetUp(
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reinterpret_cast<uint64_t*>(mapping.addr_as<char*>() + kPageSize));
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ASSERT_TRUE(ScopedMmapResetMmap(&mapping, kPageSize));
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EXPECT_TRUE(mapping.is_valid());
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EXPECT_NE(mapping.addr(), MAP_FAILED);
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EXPECT_EQ(mapping.len(), kPageSize);
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EXPECT_DEATH_CRASH(cookie.Check(), "");
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}
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TEST(ScopedMmapDeathTest, NotIntegralNumberOfPages) {
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ScopedMmap mapping;
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EXPECT_FALSE(mapping.is_valid());
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EXPECT_EQ(mapping.addr(), MAP_FAILED);
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EXPECT_EQ(mapping.len(), 0u);
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ASSERT_TRUE(mapping.Reset());
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EXPECT_FALSE(mapping.is_valid());
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// Establishing a half-page mapping actually establishes a single page.
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const size_t kPageSize = base::checked_cast<size_t>(getpagesize());
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const size_t kHalfPageSize = kPageSize / 2;
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ASSERT_TRUE(ScopedMmapResetMmap(&mapping, kHalfPageSize));
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EXPECT_TRUE(mapping.is_valid());
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EXPECT_NE(mapping.addr(), MAP_FAILED);
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EXPECT_EQ(mapping.len(), kHalfPageSize);
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TestCookie cookie;
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cookie.SetUp(mapping.addr_as<uint64_t*>());
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// Shrinking a one-page mapping to a half page is a no-op.
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void* orig_addr = mapping.addr();
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ASSERT_TRUE(mapping.ResetAddrLen(orig_addr, kHalfPageSize));
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EXPECT_TRUE(mapping.is_valid());
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EXPECT_EQ(mapping.addr(), orig_addr);
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EXPECT_EQ(mapping.len(), kHalfPageSize);
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EXPECT_EQ(cookie.Observed(), cookie.Expected());
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// Same thing shrinking it to a single byte, or one byte less than a whole
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// page.
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ASSERT_TRUE(mapping.ResetAddrLen(orig_addr, 1));
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EXPECT_TRUE(mapping.is_valid());
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EXPECT_EQ(mapping.addr(), orig_addr);
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EXPECT_EQ(mapping.len(), 1u);
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EXPECT_EQ(cookie.Observed(), cookie.Expected());
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ASSERT_TRUE(mapping.ResetAddrLen(orig_addr, kPageSize - 1));
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EXPECT_TRUE(mapping.is_valid());
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EXPECT_EQ(mapping.addr(), orig_addr);
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EXPECT_EQ(mapping.len(), kPageSize - 1);
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EXPECT_EQ(cookie.Observed(), cookie.Expected());
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// Shrinking a two-page mapping to a half page frees the second page but
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// leaves the first alone.
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ASSERT_TRUE(ScopedMmapResetMmap(&mapping, 2 * kPageSize));
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EXPECT_TRUE(mapping.is_valid());
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EXPECT_NE(mapping.addr(), MAP_FAILED);
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EXPECT_EQ(mapping.len(), 2 * kPageSize);
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TestCookie two_cookies[2];
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for (size_t index = 0; index < std::size(two_cookies); ++index) {
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two_cookies[index].SetUp(reinterpret_cast<uint64_t*>(
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mapping.addr_as<uintptr_t>() + index * kPageSize));
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}
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orig_addr = mapping.addr();
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ASSERT_TRUE(mapping.ResetAddrLen(orig_addr, kHalfPageSize));
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EXPECT_TRUE(mapping.is_valid());
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EXPECT_EQ(mapping.addr(), orig_addr);
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EXPECT_EQ(mapping.len(), kHalfPageSize);
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EXPECT_EQ(two_cookies[0].Observed(), two_cookies[0].Expected());
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EXPECT_DEATH_CRASH(two_cookies[1].Check(), "");
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// Shrinking a two-page mapping to a page and a half is a no-op.
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ASSERT_TRUE(ScopedMmapResetMmap(&mapping, 2 * kPageSize));
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EXPECT_TRUE(mapping.is_valid());
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EXPECT_NE(mapping.addr(), MAP_FAILED);
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EXPECT_EQ(mapping.len(), 2 * kPageSize);
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for (size_t index = 0; index < std::size(two_cookies); ++index) {
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two_cookies[index].SetUp(reinterpret_cast<uint64_t*>(
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mapping.addr_as<uintptr_t>() + index * kPageSize));
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}
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orig_addr = mapping.addr();
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ASSERT_TRUE(mapping.ResetAddrLen(orig_addr, kPageSize + kHalfPageSize));
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EXPECT_TRUE(mapping.is_valid());
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EXPECT_EQ(mapping.addr(), orig_addr);
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EXPECT_EQ(mapping.len(), kPageSize + kHalfPageSize);
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EXPECT_EQ(two_cookies[0].Observed(), two_cookies[0].Expected());
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EXPECT_EQ(two_cookies[1].Observed(), two_cookies[1].Expected());
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}
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TEST(ScopedMmapDeathTest, Mprotect) {
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ScopedMmap mapping;
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const size_t kPageSize = base::checked_cast<size_t>(getpagesize());
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ASSERT_TRUE(ScopedMmapResetMmap(&mapping, kPageSize));
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EXPECT_TRUE(mapping.is_valid());
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EXPECT_NE(mapping.addr(), MAP_FAILED);
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EXPECT_EQ(mapping.len(), kPageSize);
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char* addr = mapping.addr_as<char*>();
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*addr = 1;
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ASSERT_TRUE(mapping.Mprotect(PROT_READ));
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EXPECT_DEATH_CRASH(*addr = 0, "");
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ASSERT_TRUE(mapping.Mprotect(PROT_READ | PROT_WRITE));
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EXPECT_EQ(*addr, 1);
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*addr = 2;
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}
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TEST(ScopedMmapTest, Release) {
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ScopedMmap mapping;
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const size_t kPageSize = base::checked_cast<size_t>(getpagesize());
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ASSERT_TRUE(ScopedMmapResetMmap(&mapping, kPageSize));
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ASSERT_TRUE(mapping.is_valid());
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ScopedMmap mapping2;
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ASSERT_TRUE(mapping2.ResetAddrLen(mapping.release(), kPageSize));
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EXPECT_TRUE(mapping2.is_valid());
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EXPECT_FALSE(mapping.is_valid());
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}
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} // namespace
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} // namespace test
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} // namespace crashpad
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