snapshot/elf/elf_image_reader_test.cc - third_party/crashpad - Git at Google

 // Copyright 2017 The Crashpad Authors
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //     http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.

 #include "snapshot/elf/elf_image_reader.h"

 #include <dlfcn.h>
 #include <link.h>
 #include <unistd.h>

 #include "build/build_config.h"
 #include "gtest/gtest.h"
 #include "test/multiprocess_exec.h"
 #include "test/process_type.h"
 #include "test/scoped_module_handle.h"
 #include "test/test_paths.h"
 #include "util/file/file_io.h"
 #include "util/misc/address_types.h"
 #include "util/misc/elf_note_types.h"
 #include "util/misc/from_pointer_cast.h"
 #include "util/process/process_memory_native.h"

 #if BUILDFLAG(IS_FUCHSIA)
 #include <lib/zx/process.h>

 #include "base/fuchsia/fuchsia_logging.h"

 #elif BUILDFLAG(IS_LINUX) || BUILDFLAG(IS_CHROMEOS) || BUILDFLAG(IS_ANDROID)

 #include "test/linux/fake_ptrace_connection.h"
 #include "util/linux/auxiliary_vector.h"
 #include "util/linux/memory_map.h"

 #else

 #error Port.

 #endif  // BUILDFLAG(IS_FUCHSIA)

 extern "C" {
 __attribute__((visibility("default"))) void ElfImageReaderTestExportedSymbol() {
 }
 }  // extern "C"

 namespace crashpad {
 namespace test {
 namespace {

 #if BUILDFLAG(IS_FUCHSIA)

 void LocateExecutable(const ProcessType& process,
                       ProcessMemory* memory,
                       VMAddress* elf_address) {
   uintptr_t debug_address;
   zx_status_t status = process->get_property(
       ZX_PROP_PROCESS_DEBUG_ADDR, &debug_address, sizeof(debug_address));
   ASSERT_EQ(status, ZX_OK)
       << "zx_object_get_property: ZX_PROP_PROCESS_DEBUG_ADDR";
   // Can be 0 if requested before the loader has loaded anything.
   EXPECT_NE(debug_address, 0u);

   constexpr auto k_r_debug_map_offset = offsetof(r_debug, r_map);
   uintptr_t map;
   ASSERT_TRUE(
       memory->Read(debug_address + k_r_debug_map_offset, sizeof(map), &map))
       << "read link_map";

   constexpr auto k_link_map_addr_offset = offsetof(link_map, l_addr);
   uintptr_t base;
   ASSERT_TRUE(memory->Read(map + k_link_map_addr_offset, sizeof(base), &base))
       << "read base";

   *elf_address = base;
 }

 #elif BUILDFLAG(IS_LINUX) || BUILDFLAG(IS_CHROMEOS) || BUILDFLAG(IS_ANDROID)

 void LocateExecutable(PtraceConnection* connection,
                       ProcessMemory* memory,
                       VMAddress* elf_address) {
   AuxiliaryVector aux;
   ASSERT_TRUE(aux.Initialize(connection));

   VMAddress phdrs;
   ASSERT_TRUE(aux.GetValue(AT_PHDR, &phdrs));

   MemoryMap memory_map;
   ASSERT_TRUE(memory_map.Initialize(connection));
   const MemoryMap::Mapping* phdr_mapping = memory_map.FindMapping(phdrs);
   ASSERT_TRUE(phdr_mapping);
   auto possible_mappings = memory_map.FindFilePossibleMmapStarts(*phdr_mapping);
   ASSERT_EQ(possible_mappings->Count(), 1u);
   *elf_address = possible_mappings->Next()->range.Base();
 }

 #endif  // BUILDFLAG(IS_FUCHSIA)

 void ExpectSymbol(ElfImageReader* reader,
                   const std::string& symbol_name,
                   VMAddress expected_symbol_address) {
   VMAddress symbol_address;
   VMSize symbol_size;
   ASSERT_TRUE(
       reader->GetDynamicSymbol(symbol_name, &symbol_address, &symbol_size));
   EXPECT_EQ(symbol_address, expected_symbol_address);

   EXPECT_FALSE(
       reader->GetDynamicSymbol("notasymbol", &symbol_address, &symbol_size));
 }

 void ReadThisExecutableInTarget(ProcessType process,
                                 VMAddress exported_symbol_address) {
 #if defined(ARCH_CPU_64_BITS)
   constexpr bool am_64_bit = true;
 #else
   constexpr bool am_64_bit = false;
 #endif  // ARCH_CPU_64_BITS

   VMAddress elf_address;
 #if BUILDFLAG(IS_LINUX) || BUILDFLAG(IS_CHROMEOS) || BUILDFLAG(IS_ANDROID)
   FakePtraceConnection connection;
   ASSERT_TRUE(connection.Initialize(process));
   ProcessMemoryLinux memory(&connection);
   LocateExecutable(&connection, &memory, &elf_address);
 #elif BUILDFLAG(IS_FUCHSIA)
   ProcessMemoryFuchsia memory;
   ASSERT_TRUE(memory.Initialize(process));
   LocateExecutable(process, &memory, &elf_address);
 #endif
   ASSERT_NO_FATAL_FAILURE();

   ProcessMemoryRange range;
   ASSERT_TRUE(range.Initialize(&memory, am_64_bit));

   ElfImageReader reader;
   ASSERT_TRUE(reader.Initialize(range, elf_address));

   ExpectSymbol(
       &reader, "ElfImageReaderTestExportedSymbol", exported_symbol_address);

   ElfImageReader::NoteReader::Result result;
   std::string note_name;
   std::string note_desc;
   ElfImageReader::NoteReader::NoteType note_type;
   VMAddress desc_addr;

   std::unique_ptr<ElfImageReader::NoteReader> notes = reader.Notes(10000);
   while ((result = notes->NextNote(
               &note_name, &note_type, &note_desc, &desc_addr)) ==
          ElfImageReader::NoteReader::Result::kSuccess) {
   }
   EXPECT_EQ(result, ElfImageReader::NoteReader::Result::kNoMoreNotes);

   notes = reader.Notes(0);
   EXPECT_EQ(notes->NextNote(&note_name, &note_type, &note_desc, &desc_addr),
             ElfImageReader::NoteReader::Result::kNoMoreNotes);

   // Find the note defined in elf_image_reader_test_note.S.
   constexpr uint32_t kCrashpadNoteDesc = 42;
   notes = reader.NotesWithNameAndType(
       CRASHPAD_ELF_NOTE_NAME, CRASHPAD_ELF_NOTE_TYPE_SNAPSHOT_TEST, 10000);
   ASSERT_EQ(notes->NextNote(&note_name, &note_type, &note_desc, &desc_addr),
             ElfImageReader::NoteReader::Result::kSuccess);
   EXPECT_EQ(note_name, CRASHPAD_ELF_NOTE_NAME);
   EXPECT_EQ(note_type,
             implicit_cast<unsigned int>(CRASHPAD_ELF_NOTE_TYPE_SNAPSHOT_TEST));
   EXPECT_EQ(note_desc.size(), sizeof(kCrashpadNoteDesc));
   EXPECT_EQ(*reinterpret_cast<decltype(kCrashpadNoteDesc)*>(&note_desc[0]),
             kCrashpadNoteDesc);

   EXPECT_EQ(notes->NextNote(&note_name, &note_type, &note_desc, &desc_addr),
             ElfImageReader::NoteReader::Result::kNoMoreNotes);
 }

 void ReadLibcInTarget(ProcessType process,
                       VMAddress elf_address,
                       VMAddress getpid_address) {
 #if defined(ARCH_CPU_64_BITS)
   constexpr bool am_64_bit = true;
 #else
   constexpr bool am_64_bit = false;
 #endif  // ARCH_CPU_64_BITS

 #if BUILDFLAG(IS_ANDROID) || BUILDFLAG(IS_LINUX) || BUILDFLAG(IS_CHROMEOS)
   FakePtraceConnection connection;
   ASSERT_TRUE(connection.Initialize(process));
   ProcessMemoryLinux memory(&connection);
 #else
   ProcessMemoryNative memory;
   ASSERT_TRUE(memory.Initialize(process));
 #endif

   ProcessMemoryRange range;
   ASSERT_TRUE(range.Initialize(&memory, am_64_bit));

   ElfImageReader reader;
   ASSERT_TRUE(reader.Initialize(range, elf_address));

   ExpectSymbol(&reader, "getpid", getpid_address);
 }

 TEST(ElfImageReader, MainExecutableSelf) {
   ReadThisExecutableInTarget(
       GetSelfProcess(),
       FromPointerCast<VMAddress>(ElfImageReaderTestExportedSymbol));
 }

 CRASHPAD_CHILD_TEST_MAIN(ReadExecutableChild) {
   VMAddress exported_symbol_address =
       FromPointerCast<VMAddress>(ElfImageReaderTestExportedSymbol);
   CheckedWriteFile(StdioFileHandle(StdioStream::kStandardOutput),
                    &exported_symbol_address,
                    sizeof(exported_symbol_address));
   CheckedReadFileAtEOF(StdioFileHandle(StdioStream::kStandardInput));
   return 0;
 }

 class ReadExecutableChildTest : public MultiprocessExec {
  public:
   ReadExecutableChildTest() : MultiprocessExec() {}

  private:
   void MultiprocessParent() {
     // This read serves two purposes -- on Fuchsia, the loader may have not
     // filled in debug address as soon as the child process handle is valid, so
     // this causes a wait at least until the main() of the child, at which point
     // it will always be valid. Secondarily, the address of the symbol to be
     // looked up needs to be communicated.
     VMAddress exported_symbol_address;
     CheckedReadFileExactly(ReadPipeHandle(),
                            &exported_symbol_address,
                            sizeof(exported_symbol_address));
     ReadThisExecutableInTarget(ChildProcess(), exported_symbol_address);
   }
 };

 TEST(ElfImageReader, MainExecutableChild) {
   ReadExecutableChildTest test;
   test.SetChildTestMainFunction("ReadExecutableChild");
   test.Run();
 }

 TEST(ElfImageReader, OneModuleSelf) {
   Dl_info info;
   ASSERT_TRUE(dladdr(reinterpret_cast<void*>(getpid), &info)) << "dladdr:"
                                                               << dlerror();
   VMAddress elf_address = FromPointerCast<VMAddress>(info.dli_fbase);
   ReadLibcInTarget(
       GetSelfProcess(), elf_address, FromPointerCast<VMAddress>(getpid));
 }

 CRASHPAD_CHILD_TEST_MAIN(ReadLibcChild) {
   // Get the address of libc (by using getpid() as a representative member),
   // and also the address of getpid() itself, and write them to the parent, so
   // it can validate reading this information back out.
   Dl_info info;
   EXPECT_TRUE(dladdr(reinterpret_cast<void*>(getpid), &info))
       << "dladdr:" << dlerror();
   VMAddress elf_address = FromPointerCast<VMAddress>(info.dli_fbase);
   VMAddress getpid_address = FromPointerCast<VMAddress>(getpid);

   CheckedWriteFile(StdioFileHandle(StdioStream::kStandardOutput),
                    &elf_address,
                    sizeof(elf_address));
   CheckedWriteFile(StdioFileHandle(StdioStream::kStandardOutput),
                    &getpid_address,
                    sizeof(getpid_address));
   CheckedReadFileAtEOF(StdioFileHandle(StdioStream::kStandardInput));
   return 0;
 }

 class ReadLibcChildTest : public MultiprocessExec {
  public:
   ReadLibcChildTest() : MultiprocessExec() {}
   ~ReadLibcChildTest() {}

  private:
   void MultiprocessParent() {
     VMAddress elf_address, getpid_address;
     CheckedReadFileExactly(ReadPipeHandle(), &elf_address, sizeof(elf_address));
     CheckedReadFileExactly(
         ReadPipeHandle(), &getpid_address, sizeof(getpid_address));
     ReadLibcInTarget(ChildProcess(), elf_address, getpid_address);
   }
 };

 TEST(ElfImageReader, OneModuleChild) {
   ReadLibcChildTest test;
   test.SetChildTestMainFunction("ReadLibcChild");
   test.Run();
 }

 #if BUILDFLAG(IS_FUCHSIA)

 // crashpad_snapshot_test_both_dt_hash_styles is specially built and forced to
 // include both .hash and .gnu.hash sections. Linux, Android, and Fuchsia have
 // different defaults for which of these sections should be included; this test
 // confirms that we get the same count from both sections.
 //
 // TODO(scottmg): Investigation in https://crrev.com/c/876879 resulted in
 // realizing that ld.bfd does not emit a .gnu.hash that is very useful for this
 // purpose when there's 0 exported entries in the module. This is not likely to
 // be too important, as there's little need to look up non-exported symbols.
 // However, it makes this test not work on Linux, where the default build uses
 // ld.bfd. On Fuchsia, the only linker in use is lld, and it generates the
 // expected .gnu.hash. So, for now, this test is only run on Fuchsia, not Linux.
 //
 // TODO(scottmg): Separately, the location of the ELF on Android needs some
 // work, and then the test could also be enabled there.
 TEST(ElfImageReader, DtHashAndDtGnuHashMatch) {
   base::FilePath module_path =
       TestPaths::BuildArtifact(FILE_PATH_LITERAL("snapshot"),
                                FILE_PATH_LITERAL("both_dt_hash_styles"),
                                TestPaths::FileType::kLoadableModule);
   // TODO(scottmg): Remove this when upstream Fuchsia bug ZX-1619 is resolved.
   // See also explanation in build/run_tests.py for Fuchsia .so files.
   module_path = module_path.BaseName();
   ScopedModuleHandle module(
       dlopen(module_path.value().c_str(), RTLD_LAZY | RTLD_LOCAL));
   ASSERT_TRUE(module.valid()) << "dlopen " << module_path.value() << ": "
                               << dlerror();

 #if defined(ARCH_CPU_64_BITS)
   constexpr bool am_64_bit = true;
 #else
   constexpr bool am_64_bit = false;
 #endif  // ARCH_CPU_64_BITS

   ProcessMemoryNative memory;
   ASSERT_TRUE(memory.Initialize(GetSelfProcess()));
   ProcessMemoryRange range;
   ASSERT_TRUE(range.Initialize(&memory, am_64_bit));

   struct link_map* lm = reinterpret_cast<struct link_map*>(module.get());

   ElfImageReader reader;
   ASSERT_TRUE(reader.Initialize(range, lm->l_addr));

   VMSize from_dt_hash;
   ASSERT_TRUE(reader.GetNumberOfSymbolEntriesFromDtHash(&from_dt_hash));

   VMSize from_dt_gnu_hash;
   ASSERT_TRUE(reader.GetNumberOfSymbolEntriesFromDtGnuHash(&from_dt_gnu_hash));

   EXPECT_EQ(from_dt_hash, from_dt_gnu_hash);
 }

 #endif  // BUILDFLAG(IS_FUCHSIA)

 }  // namespace
 }  // namespace test
 }  // namespace crashpad
	// Copyright 2017 The Crashpad Authors
	//
	// Licensed under the Apache License, Version 2.0 (the "License");
	// you may not use this file except in compliance with the License.
	// You may obtain a copy of the License at
	//
	// http://www.apache.org/licenses/LICENSE-2.0
	//
	// Unless required by applicable law or agreed to in writing, software
	// distributed under the License is distributed on an "AS IS" BASIS,
	// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	// See the License for the specific language governing permissions and
	// limitations under the License.

	#include "snapshot/elf/elf_image_reader.h"

	#include <dlfcn.h>
	#include <link.h>
	#include <unistd.h>

	#include "build/build_config.h"
	#include "gtest/gtest.h"
	#include "test/multiprocess_exec.h"
	#include "test/process_type.h"
	#include "test/scoped_module_handle.h"
	#include "test/test_paths.h"
	#include "util/file/file_io.h"
	#include "util/misc/address_types.h"
	#include "util/misc/elf_note_types.h"
	#include "util/misc/from_pointer_cast.h"
	#include "util/process/process_memory_native.h"

	#if BUILDFLAG(IS_FUCHSIA)
	#include <lib/zx/process.h>

	#include "base/fuchsia/fuchsia_logging.h"

	#elif BUILDFLAG(IS_LINUX) \|\| BUILDFLAG(IS_CHROMEOS) \|\| BUILDFLAG(IS_ANDROID)

	#include "test/linux/fake_ptrace_connection.h"
	#include "util/linux/auxiliary_vector.h"
	#include "util/linux/memory_map.h"

	#else

	#error Port.

	#endif // BUILDFLAG(IS_FUCHSIA)

	extern "C" {
	__attribute__((visibility("default"))) void ElfImageReaderTestExportedSymbol() {
	}
	} // extern "C"

	namespace crashpad {
	namespace test {
	namespace {

	#if BUILDFLAG(IS_FUCHSIA)

	void LocateExecutable(const ProcessType& process,
	ProcessMemory* memory,
	VMAddress* elf_address) {
	uintptr_t debug_address;
	zx_status_t status = process->get_property(
	ZX_PROP_PROCESS_DEBUG_ADDR, &debug_address, sizeof(debug_address));
	ASSERT_EQ(status, ZX_OK)
	<< "zx_object_get_property: ZX_PROP_PROCESS_DEBUG_ADDR";
	// Can be 0 if requested before the loader has loaded anything.
	EXPECT_NE(debug_address, 0u);

	constexpr auto k_r_debug_map_offset = offsetof(r_debug, r_map);
	uintptr_t map;
	ASSERT_TRUE(
	memory->Read(debug_address + k_r_debug_map_offset, sizeof(map), &map))
	<< "read link_map";

	constexpr auto k_link_map_addr_offset = offsetof(link_map, l_addr);
	uintptr_t base;
	ASSERT_TRUE(memory->Read(map + k_link_map_addr_offset, sizeof(base), &base))
	<< "read base";

	*elf_address = base;
	}

	#elif BUILDFLAG(IS_LINUX) \|\| BUILDFLAG(IS_CHROMEOS) \|\| BUILDFLAG(IS_ANDROID)

	void LocateExecutable(PtraceConnection* connection,
	ProcessMemory* memory,
	VMAddress* elf_address) {
	AuxiliaryVector aux;
	ASSERT_TRUE(aux.Initialize(connection));

	VMAddress phdrs;
	ASSERT_TRUE(aux.GetValue(AT_PHDR, &phdrs));

	MemoryMap memory_map;
	ASSERT_TRUE(memory_map.Initialize(connection));
	const MemoryMap::Mapping* phdr_mapping = memory_map.FindMapping(phdrs);
	ASSERT_TRUE(phdr_mapping);
	auto possible_mappings = memory_map.FindFilePossibleMmapStarts(*phdr_mapping);
	ASSERT_EQ(possible_mappings->Count(), 1u);
	*elf_address = possible_mappings->Next()->range.Base();
	}

	#endif // BUILDFLAG(IS_FUCHSIA)

	void ExpectSymbol(ElfImageReader* reader,
	const std::string& symbol_name,
	VMAddress expected_symbol_address) {
	VMAddress symbol_address;
	VMSize symbol_size;
	ASSERT_TRUE(
	reader->GetDynamicSymbol(symbol_name, &symbol_address, &symbol_size));
	EXPECT_EQ(symbol_address, expected_symbol_address);

	EXPECT_FALSE(
	reader->GetDynamicSymbol("notasymbol", &symbol_address, &symbol_size));
	}

	void ReadThisExecutableInTarget(ProcessType process,
	VMAddress exported_symbol_address) {
	#if defined(ARCH_CPU_64_BITS)
	constexpr bool am_64_bit = true;
	#else
	constexpr bool am_64_bit = false;
	#endif // ARCH_CPU_64_BITS

	VMAddress elf_address;
	#if BUILDFLAG(IS_LINUX) \|\| BUILDFLAG(IS_CHROMEOS) \|\| BUILDFLAG(IS_ANDROID)
	FakePtraceConnection connection;
	ASSERT_TRUE(connection.Initialize(process));
	ProcessMemoryLinux memory(&connection);
	LocateExecutable(&connection, &memory, &elf_address);
	#elif BUILDFLAG(IS_FUCHSIA)
	ProcessMemoryFuchsia memory;
	ASSERT_TRUE(memory.Initialize(process));
	LocateExecutable(process, &memory, &elf_address);
	#endif
	ASSERT_NO_FATAL_FAILURE();

	ProcessMemoryRange range;
	ASSERT_TRUE(range.Initialize(&memory, am_64_bit));

	ElfImageReader reader;
	ASSERT_TRUE(reader.Initialize(range, elf_address));

	ExpectSymbol(
	&reader, "ElfImageReaderTestExportedSymbol", exported_symbol_address);

	ElfImageReader::NoteReader::Result result;
	std::string note_name;
	std::string note_desc;
	ElfImageReader::NoteReader::NoteType note_type;
	VMAddress desc_addr;

	std::unique_ptr<ElfImageReader::NoteReader> notes = reader.Notes(10000);
	while ((result = notes->NextNote(
	&note_name, &note_type, &note_desc, &desc_addr)) ==
	ElfImageReader::NoteReader::Result::kSuccess) {
	}
	EXPECT_EQ(result, ElfImageReader::NoteReader::Result::kNoMoreNotes);

	notes = reader.Notes(0);
	EXPECT_EQ(notes->NextNote(&note_name, &note_type, &note_desc, &desc_addr),
	ElfImageReader::NoteReader::Result::kNoMoreNotes);

	// Find the note defined in elf_image_reader_test_note.S.
	constexpr uint32_t kCrashpadNoteDesc = 42;
	notes = reader.NotesWithNameAndType(
	CRASHPAD_ELF_NOTE_NAME, CRASHPAD_ELF_NOTE_TYPE_SNAPSHOT_TEST, 10000);
	ASSERT_EQ(notes->NextNote(&note_name, &note_type, &note_desc, &desc_addr),
	ElfImageReader::NoteReader::Result::kSuccess);
	EXPECT_EQ(note_name, CRASHPAD_ELF_NOTE_NAME);
	EXPECT_EQ(note_type,
	implicit_cast<unsigned int>(CRASHPAD_ELF_NOTE_TYPE_SNAPSHOT_TEST));
	EXPECT_EQ(note_desc.size(), sizeof(kCrashpadNoteDesc));
	EXPECT_EQ(reinterpret_cast<decltype(kCrashpadNoteDesc)>(&note_desc[0]),
	kCrashpadNoteDesc);

	EXPECT_EQ(notes->NextNote(&note_name, &note_type, &note_desc, &desc_addr),
	ElfImageReader::NoteReader::Result::kNoMoreNotes);
	}

	void ReadLibcInTarget(ProcessType process,
	VMAddress elf_address,
	VMAddress getpid_address) {
	#if defined(ARCH_CPU_64_BITS)
	constexpr bool am_64_bit = true;
	#else
	constexpr bool am_64_bit = false;
	#endif // ARCH_CPU_64_BITS

	#if BUILDFLAG(IS_ANDROID) \|\| BUILDFLAG(IS_LINUX) \|\| BUILDFLAG(IS_CHROMEOS)
	FakePtraceConnection connection;
	ASSERT_TRUE(connection.Initialize(process));
	ProcessMemoryLinux memory(&connection);
	#else
	ProcessMemoryNative memory;
	ASSERT_TRUE(memory.Initialize(process));
	#endif

	ProcessMemoryRange range;
	ASSERT_TRUE(range.Initialize(&memory, am_64_bit));

	ElfImageReader reader;
	ASSERT_TRUE(reader.Initialize(range, elf_address));

	ExpectSymbol(&reader, "getpid", getpid_address);
	}

	TEST(ElfImageReader, MainExecutableSelf) {
	ReadThisExecutableInTarget(
	GetSelfProcess(),
	FromPointerCast<VMAddress>(ElfImageReaderTestExportedSymbol));
	}

	CRASHPAD_CHILD_TEST_MAIN(ReadExecutableChild) {
	VMAddress exported_symbol_address =
	FromPointerCast<VMAddress>(ElfImageReaderTestExportedSymbol);
	CheckedWriteFile(StdioFileHandle(StdioStream::kStandardOutput),
	&exported_symbol_address,
	sizeof(exported_symbol_address));
	CheckedReadFileAtEOF(StdioFileHandle(StdioStream::kStandardInput));
	return 0;
	}

	class ReadExecutableChildTest : public MultiprocessExec {
	public:
	ReadExecutableChildTest() : MultiprocessExec() {}

	private:
	void MultiprocessParent() {
	// This read serves two purposes -- on Fuchsia, the loader may have not
	// filled in debug address as soon as the child process handle is valid, so
	// this causes a wait at least until the main() of the child, at which point
	// it will always be valid. Secondarily, the address of the symbol to be
	// looked up needs to be communicated.
	VMAddress exported_symbol_address;
	CheckedReadFileExactly(ReadPipeHandle(),
	&exported_symbol_address,
	sizeof(exported_symbol_address));
	ReadThisExecutableInTarget(ChildProcess(), exported_symbol_address);
	}
	};

	TEST(ElfImageReader, MainExecutableChild) {
	ReadExecutableChildTest test;
	test.SetChildTestMainFunction("ReadExecutableChild");
	test.Run();
	}

	TEST(ElfImageReader, OneModuleSelf) {
	Dl_info info;
	ASSERT_TRUE(dladdr(reinterpret_cast<void*>(getpid), &info)) << "dladdr:"
	<< dlerror();
	VMAddress elf_address = FromPointerCast<VMAddress>(info.dli_fbase);
	ReadLibcInTarget(
	GetSelfProcess(), elf_address, FromPointerCast<VMAddress>(getpid));
	}

	CRASHPAD_CHILD_TEST_MAIN(ReadLibcChild) {
	// Get the address of libc (by using getpid() as a representative member),
	// and also the address of getpid() itself, and write them to the parent, so
	// it can validate reading this information back out.
	Dl_info info;
	EXPECT_TRUE(dladdr(reinterpret_cast<void*>(getpid), &info))
	<< "dladdr:" << dlerror();
	VMAddress elf_address = FromPointerCast<VMAddress>(info.dli_fbase);
	VMAddress getpid_address = FromPointerCast<VMAddress>(getpid);

	CheckedWriteFile(StdioFileHandle(StdioStream::kStandardOutput),
	&elf_address,
	sizeof(elf_address));
	CheckedWriteFile(StdioFileHandle(StdioStream::kStandardOutput),
	&getpid_address,
	sizeof(getpid_address));
	CheckedReadFileAtEOF(StdioFileHandle(StdioStream::kStandardInput));
	return 0;
	}

	class ReadLibcChildTest : public MultiprocessExec {
	public:
	ReadLibcChildTest() : MultiprocessExec() {}
	~ReadLibcChildTest() {}

	private:
	void MultiprocessParent() {
	VMAddress elf_address, getpid_address;
	CheckedReadFileExactly(ReadPipeHandle(), &elf_address, sizeof(elf_address));
	CheckedReadFileExactly(
	ReadPipeHandle(), &getpid_address, sizeof(getpid_address));
	ReadLibcInTarget(ChildProcess(), elf_address, getpid_address);
	}
	};

	TEST(ElfImageReader, OneModuleChild) {
	ReadLibcChildTest test;
	test.SetChildTestMainFunction("ReadLibcChild");
	test.Run();
	}

	#if BUILDFLAG(IS_FUCHSIA)

	// crashpad_snapshot_test_both_dt_hash_styles is specially built and forced to
	// include both .hash and .gnu.hash sections. Linux, Android, and Fuchsia have
	// different defaults for which of these sections should be included; this test
	// confirms that we get the same count from both sections.
	//
	// TODO(scottmg): Investigation in https://crrev.com/c/876879 resulted in
	// realizing that ld.bfd does not emit a .gnu.hash that is very useful for this
	// purpose when there's 0 exported entries in the module. This is not likely to
	// be too important, as there's little need to look up non-exported symbols.
	// However, it makes this test not work on Linux, where the default build uses
	// ld.bfd. On Fuchsia, the only linker in use is lld, and it generates the
	// expected .gnu.hash. So, for now, this test is only run on Fuchsia, not Linux.
	//
	// TODO(scottmg): Separately, the location of the ELF on Android needs some
	// work, and then the test could also be enabled there.
	TEST(ElfImageReader, DtHashAndDtGnuHashMatch) {
	base::FilePath module_path =
	TestPaths::BuildArtifact(FILE_PATH_LITERAL("snapshot"),
	FILE_PATH_LITERAL("both_dt_hash_styles"),
	TestPaths::FileType::kLoadableModule);
	// TODO(scottmg): Remove this when upstream Fuchsia bug ZX-1619 is resolved.
	// See also explanation in build/run_tests.py for Fuchsia .so files.
	module_path = module_path.BaseName();
	ScopedModuleHandle module(
	dlopen(module_path.value().c_str(), RTLD_LAZY \| RTLD_LOCAL));
	ASSERT_TRUE(module.valid()) << "dlopen " << module_path.value() << ": "
	<< dlerror();

	#if defined(ARCH_CPU_64_BITS)
	constexpr bool am_64_bit = true;
	#else
	constexpr bool am_64_bit = false;
	#endif // ARCH_CPU_64_BITS

	ProcessMemoryNative memory;
	ASSERT_TRUE(memory.Initialize(GetSelfProcess()));
	ProcessMemoryRange range;
	ASSERT_TRUE(range.Initialize(&memory, am_64_bit));

	struct link_map* lm = reinterpret_cast<struct link_map*>(module.get());

	ElfImageReader reader;
	ASSERT_TRUE(reader.Initialize(range, lm->l_addr));

	VMSize from_dt_hash;
	ASSERT_TRUE(reader.GetNumberOfSymbolEntriesFromDtHash(&from_dt_hash));

	VMSize from_dt_gnu_hash;
	ASSERT_TRUE(reader.GetNumberOfSymbolEntriesFromDtGnuHash(&from_dt_gnu_hash));

	EXPECT_EQ(from_dt_hash, from_dt_gnu_hash);
	}

	#endif // BUILDFLAG(IS_FUCHSIA)

	} // namespace
	} // namespace test
	} // namespace crashpad