Merge "Speed up map creation." am: df3e89be94 am: 2bf9cbf233 am: bd048209b4 (672e4048) · Commits · e / os / android_system_core

libbacktrace/Android.bp

+14 −0

Original line number	Diff line number	Diff line
		@@ -244,3 +244,17 @@ cc_test {
		},
		},
		}

		cc_benchmark {
		name: "backtrace_benchmarks",
		defaults: ["libbacktrace_common"],

		srcs: [
		"backtrace_benchmarks.cpp",
		],

		shared_libs: [
		"libbacktrace",
		"libbase",
		],
		}

libbacktrace/backtrace_benchmarks.cpp

0 → 100644

+162 −0

Original line number	Diff line number	Diff line
		/*
		* Copyright (C) 2017 The Android Open Source Project
		*
		* 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 <errno.h>
		#include <fcntl.h>
		#include <stdio.h>
		#include <string.h>
		#include <sys/prctl.h>
		#include <sys/stat.h>
		#include <sys/types.h>
		#include <sys/wait.h>
		#include <unistd.h>

		#include <string>

		#include <android-base/file.h>

		#include <benchmark/benchmark.h>

		#include <backtrace/Backtrace.h>
		#include <backtrace/BacktraceMap.h>

		// Definitions of prctl arguments to set a vma name in Android kernels.
		#define ANDROID_PR_SET_VMA 0x53564d41
		#define ANDROID_PR_SET_VMA_ANON_NAME 0

		constexpr size_t kNumMaps = 2000;
		constexpr size_t kNumIterations = 1000;

		static bool CountMaps(pid_t pid, size_t* num_maps) {
		// Minimize the calls that might allocate memory. If too much memory
		// gets allocated, then this routine will add extra maps and the next
		// call will fail to get the same number of maps as before.
		int fd =
		open((std::string("/proc/") + std::to_string(pid) + "/maps").c_str(), O_RDONLY \| O_CLOEXEC);
		if (fd == -1) {
		fprintf(stderr, "Cannot open map file for pid %d: %s\n", pid, strerror(errno));
		return false;
		}
		*num_maps = 0;
		while (true) {
		char buffer[2048];
		ssize_t bytes = read(fd, buffer, sizeof(buffer));
		if (bytes <= 0) {
		break;
		}
		// Count the '\n'.
		for (size_t i = 0; i < static_cast<size_t>(bytes); i++) {
		if (buffer[i] == '\n') {
		++*num_maps;
		}
		}
		}

		close(fd);
		return true;
		}

		static void CreateMap(benchmark::State& state, BacktraceMap* (*map_func)(pid_t, bool)) {
		state.PauseTiming();
		// Create a remote process so that the map data is exactly the same.
		// Also, so that we can create a set number of maps.
		pid_t pid;
		if ((pid = fork()) == 0) {
		size_t num_maps;
		if (!CountMaps(getpid(), &num_maps)) {
		exit(1);
		}
		// Create uniquely named maps.
		std::vector<void*> maps;
		for (size_t i = num_maps; i < kNumMaps; i++) {
		int flags = PROT_READ \| PROT_WRITE;
		// Alternate page type to make sure a map entry is added for each call.
		if ((i % 2) == 0) {
		flags \|= PROT_EXEC;
		}
		void* memory = mmap(nullptr, PAGE_SIZE, flags, MAP_PRIVATE \| MAP_ANONYMOUS, -1, 0);
		if (memory == MAP_FAILED) {
		fprintf(stderr, "Failed to create map: %s\n", strerror(errno));
		exit(1);
		}
		memset(memory, 0x1, PAGE_SIZE);
		if (prctl(ANDROID_PR_SET_VMA, ANDROID_PR_SET_VMA_ANON_NAME, memory, PAGE_SIZE, "test_map") ==
		-1) {
		fprintf(stderr, "Failed: %s\n", strerror(errno));
		}
		maps.push_back(memory);
		}

		if (!CountMaps(getpid(), &num_maps)) {
		exit(1);
		}

		if (num_maps != kNumMaps) {
		fprintf(stderr, "Maps set incorrectly: %zu found, %zu expected.\n", num_maps, kNumMaps);
		std::string str;
		android::base::ReadFileToString("/proc/self/maps", &str);
		fprintf(stderr, "%s\n", str.c_str());
		exit(1);
		}

		// Wait for an hour at most.
		sleep(3600);
		exit(1);
		} else if (pid < 0) {
		fprintf(stderr, "Fork failed: %s\n", strerror(errno));
		return;
		}

		size_t num_maps = 0;
		for (size_t i = 0; i < 2000; i++) {
		if (CountMaps(pid, &num_maps) && num_maps == kNumMaps) {
		break;
		}
		usleep(1000);
		}
		if (num_maps != kNumMaps) {
		fprintf(stderr, "Timed out waiting for the number of maps available: %zu\n", num_maps);
		return;
		}

		state.ResumeTiming();
		while (state.KeepRunning()) {
		for (size_t i = 0; i < static_cast<size_t>(state.range(0)); i++) {
		BacktraceMap* map = map_func(pid, false);
		if (map == nullptr) {
		fprintf(stderr, "Failed to create map\n");
		return;
		}
		delete map;
		}
		}
		state.PauseTiming();

		kill(pid, SIGKILL);
		waitpid(pid, nullptr, 0);
		}

		static void BM_create_map(benchmark::State& state) {
		CreateMap(state, BacktraceMap::Create);
		}
		BENCHMARK(BM_create_map)->Arg(kNumIterations);

		static void BM_create_map_new(benchmark::State& state) {
		CreateMap(state, BacktraceMap::CreateNew);
		}
		BENCHMARK(BM_create_map_new)->Arg(kNumIterations);

		BENCHMARK_MAIN();

libunwindstack/Maps.cpp

+124 −35

Original line number	Diff line number	Diff line
		@@ -25,6 +25,7 @@

		#include <android-base/unique_fd.h>

		#include <cctype>
		#include <memory>
		#include <string>
		#include <vector>
		@@ -55,63 +56,151 @@ MapInfo* Maps::Find(uint64_t pc) {
		return nullptr;
		}

		bool Maps::ParseLine(const char* line, MapInfo* map_info) {
		char permissions[5];
		int name_pos;
		// Linux /proc/<pid>/maps lines:
		// Assumes that line does not end in '\n'.
		static bool InternalParseLine(const char* line, MapInfo* map_info) {
		// Do not use a sscanf implementation since it is not performant.

		// Example linux /proc/<pid>/maps lines:
		// 6f000000-6f01e000 rwxp 00000000 00:0c 16389419 /system/lib/libcomposer.so
		if (sscanf(line, "%" SCNx64 "-%" SCNx64 " %4s %" SCNx64 " %x:%x %*d %n", &map_info->start,
		&map_info->end, permissions, &map_info->offset, &name_pos) != 4) {
		char* str;
		const char* old_str = line;
		map_info->start = strtoul(old_str, &str, 16);
		if (old_str == str \|\| *str++ != '-') {
		return false;
		}

		old_str = str;
		map_info->end = strtoul(old_str, &str, 16);
		if (old_str == str \|\| !std::isspace(*str++)) {
		return false;
		}
		map_info->flags = PROT_NONE;
		if (permissions[0] == 'r') {

		while (std::isspace(*str)) {
		str++;
		}

		// Parse permissions data.
		if (*str == '\0') {
		return false;
		}
		map_info->flags = 0;
		if (*str == 'r') {
		map_info->flags \|= PROT_READ;
		} else if (*str != '-') {
		return false;
		}
		if (permissions[1] == 'w') {
		str++;
		if (*str == 'w') {
		map_info->flags \|= PROT_WRITE;
		} else if (*str != '-') {
		return false;
		}
		if (permissions[2] == 'x') {
		str++;
		if (*str == 'x') {
		map_info->flags \|= PROT_EXEC;
		} else if (*str != '-') {
		return false;
		}
		str++;
		if (str != 'p' && str != 's') {
		return false;
		}
		str++;

		if (!std::isspace(*str++)) {
		return false;
		}

		old_str = str;
		map_info->offset = strtoul(old_str, &str, 16);
		if (old_str == str \|\| !std::isspace(*str)) {
		return false;
		}

		// Ignore the 00:00 values.
		old_str = str;
		(void)strtoul(old_str, &str, 16);
		if (old_str == str \|\| *str++ != ':') {
		return false;
		}
		if (std::isspace(*str)) {
		return false;
		}

		// Skip the inode.
		old_str = str;
		(void)strtoul(str, &str, 16);
		if (old_str == str \|\| !std::isspace(*str++)) {
		return false;
		}

		if (line[name_pos] != '\0') {
		map_info->name = &line[name_pos];
		size_t length = map_info->name.length() - 1;
		if (map_info->name[length] == '\n') {
		map_info->name.erase(length);
		// Skip decimal digit.
		old_str = str;
		(void)strtoul(old_str, &str, 10);
		if (old_str == str \|\| (!std::isspace(str) && str != '\0')) {
		return false;
		}

		while (std::isspace(*str)) {
		str++;
		}
		if (*str == '\0') {
		map_info->name = str;
		return true;
		}

		// Save the name data.
		map_info->name = str;

		// Mark a device map in /dev/ and not in /dev/ashmem/ specially.
		if (map_info->name.substr(0, 5) == "/dev/" && map_info->name.substr(5, 7) != "ashmem/") {
		map_info->flags \|= MAPS_FLAGS_DEVICE_MAP;
		}
		}

		return true;
		}

		bool Maps::Parse() {
		std::unique_ptr<FILE, decltype(&fclose)> fp(fopen(GetMapsFile().c_str(), "re"), fclose);
		if (!fp) {
		int fd = open(GetMapsFile().c_str(), O_RDONLY \| O_CLOEXEC);
		if (fd == -1) {
		return false;
		}

		bool valid = true;
		char* line = nullptr;
		size_t line_len;
		while (getline(&line, &line_len, fp.get()) > 0) {
		MapInfo map_info;
		if (!ParseLine(line, &map_info)) {
		valid = false;
		bool return_value = true;
		char buffer[2048];
		size_t leftover = 0;
		while (true) {
		ssize_t bytes = read(fd, &buffer[leftover], 2048 - leftover);
		if (bytes == -1) {
		return_value = false;
		break;
		}
		if (bytes == 0) {
		break;
		}
		bytes += leftover;
		char* line = buffer;
		while (bytes > 0) {
		char* newline = static_cast<char*>(memchr(line, '\n', bytes));
		if (newline == nullptr) {
		memmove(buffer, line, bytes);
		break;
		}
		*newline = '\0';

		maps_.push_back(map_info);
		MapInfo map_info;
		if (!InternalParseLine(line, &map_info)) {
		return_value = false;
		break;
		}
		free(line);
		maps_.push_back(map_info);

		return valid;
		bytes -= newline - line + 1;
		line = newline + 1;
		}
		leftover = bytes;
		}
		close(fd);
		return return_value;
		}

		Maps::~Maps() {
		@@ -129,12 +218,12 @@ bool BufferMaps::Parse() {
		if (end_of_line == nullptr) {
		line = start_of_line;
		} else {
		end_of_line++;
		line = std::string(start_of_line, end_of_line - start_of_line);
		end_of_line++;
		}

		MapInfo map_info;
		if (!ParseLine(line.c_str(), &map_info)) {
		if (!InternalParseLine(line.c_str(), &map_info)) {
		return false;
		}
		maps_.push_back(map_info);

libunwindstack/include/unwindstack/Maps.h

+5 −2

Original line number	Diff line number	Diff line
		@@ -38,8 +38,6 @@ class Maps {

		MapInfo* Find(uint64_t pc);

		bool ParseLine(const char* line, MapInfo* map_info);

		virtual bool Parse();

		virtual const std::string GetMapsFile() const { return ""; }
		@@ -54,6 +52,11 @@ class Maps {

		size_t Total() { return maps_.size(); }

		MapInfo* Get(size_t index) {
		if (index >= maps_.size()) return nullptr;
		return &maps_[index];
		}

		protected:
		std::vector<MapInfo> maps_;
		};

libunwindstack/tests/MapsTest.cpp

+285 −23

Original line number	Diff line number	Diff line
		@@ -14,9 +14,11 @@
		* limitations under the License.
		*/

		#include <inttypes.h>
		#include <sys/mman.h>

		#include <android-base/file.h>
		#include <android-base/stringprintf.h>
		#include <android-base/test_utils.h>
		#include <gtest/gtest.h>

		@@ -24,13 +26,116 @@

		namespace unwindstack {

		static void VerifyLine(std::string line, MapInfo* info) {
		BufferMaps maps(line.c_str());

		if (info == nullptr) {
		ASSERT_FALSE(maps.Parse()) << "Failed on: " + line;
		} else {
		ASSERT_TRUE(maps.Parse()) << "Failed on: " + line;
		MapInfo* element = maps.Get(0);
		ASSERT_TRUE(element != nullptr) << "Failed on: " + line;
		info = element;
		}
		}

		TEST(MapsTest, verify_parse_line) {
		MapInfo info;

		VerifyLine("01-02 rwxp 03 04:05 06\n", &info);
		EXPECT_EQ(1U, info.start);
		EXPECT_EQ(2U, info.end);
		EXPECT_EQ(PROT_READ \| PROT_WRITE \| PROT_EXEC, info.flags);
		EXPECT_EQ(3U, info.offset);
		EXPECT_EQ("", info.name);

		VerifyLine("0a-0b ---s 0c 0d:0e 06 /fake/name\n", &info);
		EXPECT_EQ(0xaU, info.start);
		EXPECT_EQ(0xbU, info.end);
		EXPECT_EQ(0U, info.flags);
		EXPECT_EQ(0xcU, info.offset);
		EXPECT_EQ("/fake/name", info.name);

		VerifyLine("01-02 rwxp 03 04:05 06 /fake/name/again\n", &info);
		EXPECT_EQ(1U, info.start);
		EXPECT_EQ(2U, info.end);
		EXPECT_EQ(PROT_READ \| PROT_WRITE \| PROT_EXEC, info.flags);
		EXPECT_EQ(3U, info.offset);
		EXPECT_EQ("/fake/name/again", info.name);

		VerifyLine("-00 rwxp 00 00:00 0\n", nullptr);
		VerifyLine("00- rwxp 00 00:00 0\n", nullptr);
		VerifyLine("00-00 rwxp 00 :00 0\n", nullptr);
		VerifyLine("00-00 rwxp 00 00:00 \n", nullptr);
		VerifyLine("x-00 rwxp 00 00:00 0\n", nullptr);
		VerifyLine("00 -00 rwxp 00 00:00 0\n", nullptr);
		VerifyLine("00-x rwxp 00 00:00 0\n", nullptr);
		VerifyLine("00-x rwxp 00 00:00 0\n", nullptr);
		VerifyLine("00-00x rwxp 00 00:00 0\n", nullptr);
		VerifyLine("00-00 rwxp0 00 00:00 0\n", nullptr);
		VerifyLine("00-00 rwxp0 00 00:00 0\n", nullptr);
		VerifyLine("00-00 rwp 00 00:00 0\n", nullptr);
		VerifyLine("00-00 rwxp 0000:00 0\n", nullptr);
		VerifyLine("00-00 rwxp 00 00 :00 0\n", nullptr);
		VerifyLine("00-00 rwxp 00 00: 00 0\n", nullptr);
		VerifyLine("00-00 rwxp 00 00:000\n", nullptr);
		VerifyLine("00-00 rwxp 00 00:00 0/fake\n", nullptr);
		VerifyLine("00-00 xxxx 00 00:00 0 /fake\n", nullptr);
		VerifyLine("00-00 ywxp 00 00:00 0 /fake\n", nullptr);
		VerifyLine("00-00 ryxp 00 00:00 0 /fake\n", nullptr);
		VerifyLine("00-00 rwyp 00 00:00 0 /fake\n", nullptr);
		VerifyLine("00-00 rwx- 00 00:00 0 /fake\n", nullptr);
		VerifyLine("0\n", nullptr);
		VerifyLine("00\n", nullptr);
		VerifyLine("00-\n", nullptr);
		VerifyLine("00-0\n", nullptr);
		VerifyLine("00-00\n", nullptr);
		VerifyLine("00-00 \n", nullptr);
		VerifyLine("00-00 -\n", nullptr);
		VerifyLine("00-00 r\n", nullptr);
		VerifyLine("00-00 --\n", nullptr);
		VerifyLine("00-00 rw\n", nullptr);
		VerifyLine("00-00 ---\n", nullptr);
		VerifyLine("00-00 rwx\n", nullptr);
		VerifyLine("00-00 ---s\n", nullptr);
		VerifyLine("00-00 ---p\n", nullptr);
		VerifyLine("00-00 ---s 0\n", nullptr);
		VerifyLine("00-00 ---p 0 \n", nullptr);
		VerifyLine("00-00 ---p 0 0\n", nullptr);
		VerifyLine("00-00 ---p 0 0:\n", nullptr);
		VerifyLine("00-00 ---p 0 0:0\n", nullptr);
		VerifyLine("00-00 ---p 0 0:0 \n", nullptr);

		// Line to verify that the parser will detect a completely malformed line
		// properly.
		VerifyLine("7ffff7dda000-7ffff7dfd7ffff7ff3000-7ffff7ff4000 ---p 0000f000 fc:02 44171565\n",
		nullptr);
		}

		TEST(MapsTest, verify_large_values) {
		MapInfo info;
		#if defined(__LP64__)
		VerifyLine("fabcdef012345678-f12345678abcdef8 rwxp f0b0d0f010305070 00:00 0\n", &info);
		EXPECT_EQ(0xfabcdef012345678UL, info.start);
		EXPECT_EQ(0xf12345678abcdef8UL, info.end);
		EXPECT_EQ(PROT_READ \| PROT_WRITE \| PROT_EXEC, info.flags);
		EXPECT_EQ(0xf0b0d0f010305070UL, info.offset);
		#else
		VerifyLine("f2345678-fabcdef8 rwxp f0305070 00:00 0\n", &info);
		EXPECT_EQ(0xf2345678UL, info.start);
		EXPECT_EQ(0xfabcdef8UL, info.end);
		EXPECT_EQ(PROT_READ \| PROT_WRITE \| PROT_EXEC, info.flags);
		EXPECT_EQ(0xf0305070UL, info.offset);
		#endif
		}

		TEST(MapsTest, parse_permissions) {
		BufferMaps maps(
		"1000-2000 ---- 00000000 00:00 0\n"
		"2000-3000 r--- 00000000 00:00 0\n"
		"3000-4000 -w-- 00000000 00:00 0\n"
		"4000-5000 --x- 00000000 00:00 0\n"
		"5000-6000 rwx- 00000000 00:00 0\n");
		"1000-2000 ---s 00000000 00:00 0\n"
		"2000-3000 r--s 00000000 00:00 0\n"
		"3000-4000 -w-s 00000000 00:00 0\n"
		"4000-5000 --xp 00000000 00:00 0\n"
		"5000-6000 rwxp 00000000 00:00 0\n");

		ASSERT_TRUE(maps.Parse());
		ASSERT_EQ(5U, maps.Total());
		@@ -70,28 +175,28 @@ TEST(MapsTest, parse_permissions) {

		TEST(MapsTest, parse_name) {
		BufferMaps maps(
		"720b29b000-720b29e000 rw-p 00000000 00:00 0\n"
		"720b29e000-720b29f000 rw-p 00000000 00:00 0 /system/lib/fake.so\n"
		"720b29f000-720b2a0000 rw-p 00000000 00:00 0");
		"7b29b000-7b29e000 rw-p 00000000 00:00 0\n"
		"7b29e000-7b29f000 rw-p 00000000 00:00 0 /system/lib/fake.so\n"
		"7b29f000-7b2a0000 rw-p 00000000 00:00 0");

		ASSERT_TRUE(maps.Parse());
		ASSERT_EQ(3U, maps.Total());
		auto it = maps.begin();
		ASSERT_EQ("", it->name);
		ASSERT_EQ(0x720b29b000U, it->start);
		ASSERT_EQ(0x720b29e000U, it->end);
		ASSERT_EQ(0x7b29b000U, it->start);
		ASSERT_EQ(0x7b29e000U, it->end);
		ASSERT_EQ(0U, it->offset);
		ASSERT_EQ(PROT_READ \| PROT_WRITE, it->flags);
		++it;
		ASSERT_EQ("/system/lib/fake.so", it->name);
		ASSERT_EQ(0x720b29e000U, it->start);
		ASSERT_EQ(0x720b29f000U, it->end);
		ASSERT_EQ(0x7b29e000U, it->start);
		ASSERT_EQ(0x7b29f000U, it->end);
		ASSERT_EQ(0U, it->offset);
		ASSERT_EQ(PROT_READ \| PROT_WRITE, it->flags);
		++it;
		ASSERT_EQ("", it->name);
		ASSERT_EQ(0x720b29f000U, it->start);
		ASSERT_EQ(0x720b2a0000U, it->end);
		ASSERT_EQ(0x7b29f000U, it->start);
		ASSERT_EQ(0x7b2a0000U, it->end);
		ASSERT_EQ(0U, it->offset);
		ASSERT_EQ(PROT_READ \| PROT_WRITE, it->flags);
		++it;
		@@ -149,9 +254,9 @@ TEST(MapsTest, file_smoke) {
		ASSERT_TRUE(tf.fd != -1);

		ASSERT_TRUE(
		android::base::WriteStringToFile("720b29b000-720b29e000 r-xp a0000000 00:00 0 /fake.so\n"
		"720b2b0000-720b2e0000 r-xp b0000000 00:00 0 /fake2.so\n"
		"720b2e0000-720b2f0000 r-xp c0000000 00:00 0 /fake3.so\n",
		android::base::WriteStringToFile("7b29b000-7b29e000 r-xp a0000000 00:00 0 /fake.so\n"
		"7b2b0000-7b2e0000 r-xp b0000000 00:00 0 /fake2.so\n"
		"7b2e0000-7b2f0000 r-xp c0000000 00:00 0 /fake3.so\n",
		tf.path, 0660, getuid(), getgid()));

		FileMaps maps(tf.path);
		@@ -159,20 +264,20 @@ TEST(MapsTest, file_smoke) {
		ASSERT_TRUE(maps.Parse());
		ASSERT_EQ(3U, maps.Total());
		auto it = maps.begin();
		ASSERT_EQ(0x720b29b000U, it->start);
		ASSERT_EQ(0x720b29e000U, it->end);
		ASSERT_EQ(0x7b29b000U, it->start);
		ASSERT_EQ(0x7b29e000U, it->end);
		ASSERT_EQ(0xa0000000U, it->offset);
		ASSERT_EQ(PROT_READ \| PROT_EXEC, it->flags);
		ASSERT_EQ("/fake.so", it->name);
		++it;
		ASSERT_EQ(0x720b2b0000U, it->start);
		ASSERT_EQ(0x720b2e0000U, it->end);
		ASSERT_EQ(0x7b2b0000U, it->start);
		ASSERT_EQ(0x7b2e0000U, it->end);
		ASSERT_EQ(0xb0000000U, it->offset);
		ASSERT_EQ(PROT_READ \| PROT_EXEC, it->flags);
		ASSERT_EQ("/fake2.so", it->name);
		++it;
		ASSERT_EQ(0x720b2e0000U, it->start);
		ASSERT_EQ(0x720b2f0000U, it->end);
		ASSERT_EQ(0x7b2e0000U, it->start);
		ASSERT_EQ(0x7b2f0000U, it->end);
		ASSERT_EQ(0xc0000000U, it->offset);
		ASSERT_EQ(PROT_READ \| PROT_EXEC, it->flags);
		ASSERT_EQ("/fake3.so", it->name);
		@@ -180,6 +285,163 @@ TEST(MapsTest, file_smoke) {
		ASSERT_EQ(it, maps.end());
		}

		TEST(MapsTest, file_no_map_name) {
		TemporaryFile tf;
		ASSERT_TRUE(tf.fd != -1);

		ASSERT_TRUE(
		android::base::WriteStringToFile("7b29b000-7b29e000 r-xp a0000000 00:00 0\n"
		"7b2b0000-7b2e0000 r-xp b0000000 00:00 0 /fake2.so\n"
		"7b2e0000-7b2f0000 r-xp c0000000 00:00 0 \n",
		tf.path, 0660, getuid(), getgid()));

		FileMaps maps(tf.path);

		ASSERT_TRUE(maps.Parse());
		ASSERT_EQ(3U, maps.Total());
		auto it = maps.begin();
		ASSERT_EQ(0x7b29b000U, it->start);
		ASSERT_EQ(0x7b29e000U, it->end);
		ASSERT_EQ(0xa0000000U, it->offset);
		ASSERT_EQ(PROT_READ \| PROT_EXEC, it->flags);
		ASSERT_EQ("", it->name);
		++it;
		ASSERT_EQ(0x7b2b0000U, it->start);
		ASSERT_EQ(0x7b2e0000U, it->end);
		ASSERT_EQ(0xb0000000U, it->offset);
		ASSERT_EQ(PROT_READ \| PROT_EXEC, it->flags);
		ASSERT_EQ("/fake2.so", it->name);
		++it;
		ASSERT_EQ(0x7b2e0000U, it->start);
		ASSERT_EQ(0x7b2f0000U, it->end);
		ASSERT_EQ(0xc0000000U, it->offset);
		ASSERT_EQ(PROT_READ \| PROT_EXEC, it->flags);
		ASSERT_EQ("", it->name);
		++it;
		ASSERT_EQ(it, maps.end());
		}

		// Verify that a file that crosses a buffer is parsed correctly.
		static std::string CreateEntry(size_t index) {
		return android::base::StringPrintf("%08zx-%08zx rwxp 0000 00:00 0\n", index * 4096,
		(index + 1) * 4096);
		}

		TEST(MapsTest, file_buffer_cross) {
		constexpr size_t kBufferSize = 2048;
		TemporaryFile tf;
		ASSERT_TRUE(tf.fd != -1);

		// Compute how many to add in the first buffer.
		size_t entry_len = CreateEntry(0).size();
		size_t index;
		std::string file_data;
		for (index = 0; index < kBufferSize / entry_len; index++) {
		file_data += CreateEntry(index);
		}
		// Add a long name to make sure that the first buffer does not contain a
		// complete line.
		// Remove the last newline.
		size_t extra = 0;
		size_t leftover = kBufferSize % entry_len;
		size_t overlap1_index = 0;
		std::string overlap1_name;
		if (leftover == 0) {
		// Exact match, add a long name to cross over the value.
		overlap1_name = "/fake/name/is/long/on/purpose";
		file_data.erase(file_data.size() - 1);
		file_data += ' ' + overlap1_name + '\n';
		extra = entry_len + overlap1_name.size() + 1;
		overlap1_index = index;
		}

		// Compute how many need to go in to hit the buffer boundary exactly.
		size_t bytes_left_in_buffer = kBufferSize - extra;
		size_t entries_to_add = bytes_left_in_buffer / entry_len + index;
		for (; index < entries_to_add; index++) {
		file_data += CreateEntry(index);
		}

		// Now figure out how many bytes to add to get exactly to the buffer boundary.
		leftover = bytes_left_in_buffer % entry_len;
		std::string overlap2_name;
		size_t overlap2_index = 0;
		if (leftover != 0) {
		file_data.erase(file_data.size() - 1);
		file_data += ' ';
		overlap2_name = std::string(leftover - 1, 'x');
		file_data += overlap2_name + '\n';
		overlap2_index = index - 1;
		}

		// Now add a few entries on the next page.
		for (size_t start = index; index < start + 10; index++) {
		file_data += CreateEntry(index);
		}

		ASSERT_TRUE(android::base::WriteStringToFile(file_data, tf.path, 0660, getuid(), getgid()));

		FileMaps maps(tf.path);
		ASSERT_TRUE(maps.Parse());
		EXPECT_EQ(index, maps.Total());
		// Verify all of the maps.
		for (size_t i = 0; i < index; i++) {
		MapInfo* info = maps.Get(i);
		ASSERT_TRUE(info != nullptr) << "Failed verifying index " + std::to_string(i);
		EXPECT_EQ(i * 4096, info->start) << "Failed verifying index " + std::to_string(i);
		EXPECT_EQ((i + 1) * 4096, info->end) << "Failed verifying index " + std::to_string(i);
		EXPECT_EQ(0U, info->offset) << "Failed verifying index " + std::to_string(i);
		if (overlap1_index != 0 && i == overlap1_index) {
		EXPECT_EQ(overlap1_name, info->name) << "Failed verifying overlap1 name " + std::to_string(i);
		} else if (overlap2_index != 0 && i == overlap2_index) {
		EXPECT_EQ(overlap2_name, info->name) << "Failed verifying overlap2 name " + std::to_string(i);
		} else {
		EXPECT_EQ("", info->name) << "Failed verifying index " + std::to_string(i);
		}
		}
		}

		TEST(MapsTest, file_should_fail) {
		TemporaryFile tf;
		ASSERT_TRUE(tf.fd != -1);

		ASSERT_TRUE(android::base::WriteStringToFile(
		"7ffff7dda000-7ffff7dfd7ffff7ff3000-7ffff7ff4000 ---p 0000f000 fc:02 44171565\n", tf.path,
		0660, getuid(), getgid()));

		FileMaps maps(tf.path);

		ASSERT_FALSE(maps.Parse());
		}

		// Create a maps file that is extremely large.
		TEST(MapsTest, large_file) {
		TemporaryFile tf;
		ASSERT_TRUE(tf.fd != -1);

		std::string file_data;
		uint64_t start = 0x700000;
		for (size_t i = 0; i < 5000; i++) {
		file_data +=
		android::base::StringPrintf("%" PRIx64 "-%" PRIx64 " r-xp 1000 00:0 0 /fake%zu.so\n",
		start + i * 4096, start + (i + 1) * 4096, i);
		}

		ASSERT_TRUE(android::base::WriteStringToFile(file_data, tf.path, 0660, getuid(), getgid()));

		FileMaps maps(tf.path);

		ASSERT_TRUE(maps.Parse());
		ASSERT_EQ(5000U, maps.Total());
		for (size_t i = 0; i < 5000; i++) {
		MapInfo* info = maps.Get(i);
		ASSERT_EQ(start + i * 4096, info->start) << "Failed at map " + std::to_string(i);
		ASSERT_EQ(start + (i + 1) * 4096, info->end) << "Failed at map " + std::to_string(i);
		std::string name = "/fake" + std::to_string(i) + ".so";
		ASSERT_EQ(name, info->name) << "Failed at map " + std::to_string(i);
		}
		}

		TEST(MapsTest, find) {
		BufferMaps maps(
		"1000-2000 r--p 00000010 00:00 0 /system/lib/fake1.so\n"