Merge changes from topic "run_dex2oat_test" am: 8971b49161 am: 151a52e1eb am: 5b2b09cc04 (82a764be) · Commits · e / os / android_frameworks_native-old

cmds/installd/Android.bp

+28 −0

Original line number	Diff line number	Diff line
		@@ -17,7 +17,9 @@ cc_defaults {
		"InstalldNativeService.cpp",
		"QuotaUtils.cpp",
		"dexopt.cpp",
		"execv_helper.cpp",
		"globals.cpp",
		"run_dex2oat.cpp",
		"utils.cpp",
		"utils_default.cpp",
		"view_compiler.cpp",
		@@ -102,6 +104,30 @@ cc_library_headers {
		export_include_dirs: ["."],
		}

		//
		// Unit tests
		//

		cc_test_host {
		name: "run_dex2oat_test",
		test_suites: ["general-tests"],
		clang: true,
		srcs: [
		"run_dex2oat_test.cpp",
		"run_dex2oat.cpp",
		"execv_helper.cpp",
		],
		cflags: ["-Wall", "-Werror"],
		shared_libs: [
		"libbase",
		"server_configurable_flags",
		],
		static_libs: [
		//"libinstalld",
		],
		test_config: "run_dex2oat_test.xml",
		}

		//
		// Executable
		//
		@@ -205,9 +231,11 @@ cc_binary {

		srcs: [
		"dexopt.cpp",
		"execv_helper.cpp",
		"globals.cpp",
		"otapreopt.cpp",
		"otapreopt_utils.cpp",
		"run_dex2oat.cpp",
		"utils.cpp",
		"utils_default.cpp",
		"view_compiler.cpp",

cmds/installd/TEST_MAPPING

+3 −0

Original line number	Diff line number	Diff line
		@@ -15,6 +15,9 @@
		{
		"name": "installd_utils_test"
		},
		{
		"name": "run_dex2oat_test"
		},
		// AdoptableHostTest moves packages, part of which is handled by installd
		{
		"name": "AdoptableHostTest"

cmds/installd/dexopt.cpp

+27 −386

Original line number	Diff line number	Diff line
		@@ -50,11 +50,14 @@

		#include "dexopt.h"
		#include "dexopt_return_codes.h"
		#include "execv_helper.h"
		#include "globals.h"
		#include "installd_deps.h"
		#include "otapreopt_utils.h"
		#include "run_dex2oat.h"
		#include "utils.h"

		using android::base::Basename;
		using android::base::EndsWith;
		using android::base::GetBoolProperty;
		using android::base::GetProperty;
		@@ -67,16 +70,6 @@ using android::base::unique_fd;
		namespace android {
		namespace installd {

		// Should minidebug info be included in compiled artifacts? Even if this value is
		// "true," usage might still be conditional to other constraints, e.g., system
		// property overrides.
		static constexpr bool kEnableMinidebugInfo = true;

		static constexpr const char* kMinidebugInfoSystemProperty = "dalvik.vm.dex2oat-minidebuginfo";
		static constexpr bool kMinidebugInfoSystemPropertyDefault = false;
		static constexpr const char* kMinidebugDex2oatFlag = "--generate-mini-debug-info";
		static constexpr const char* kDisableCompactDexFlag = "--compact-dex-level=none";


		// Deleter using free() for use with std::unique_ptr<>. See also UniqueCPtr<> below.
		struct FreeDelete {
		@@ -186,93 +179,6 @@ bool clear_primary_current_profile(const std::string& package_name, const std::s
		return clear_current_profile(package_name, location, user, /is_secondary_dex/false);
		}

		static std::vector<std::string> SplitBySpaces(const std::string& str) {
		if (str.empty()) {
		return {};
		}
		return android::base::Split(str, " ");
		}

		static const char* get_location_from_path(const char* path) {
		static constexpr char kLocationSeparator = '/';
		const char *location = strrchr(path, kLocationSeparator);
		if (location == nullptr) {
		return path;
		} else {
		// Skip the separator character.
		return location + 1;
		}
		}

		// ExecVHelper prepares and holds pointers to parsed command line arguments so that no allocations
		// need to be performed between the fork and exec.
		class ExecVHelper {
		public:
		// Store a placeholder for the binary name.
		ExecVHelper() : args_(1u, std::string()) {}

		void PrepareArgs(const std::string& bin) {
		CHECK(!args_.empty());
		CHECK(args_[0].empty());
		args_[0] = bin;
		// Write char* into array.
		for (const std::string& arg : args_) {
		argv_.push_back(arg.c_str());
		}
		argv_.push_back(nullptr); // Add null terminator.
		}

		[[ noreturn ]]
		void Exec(int exit_code) {
		execv(argv_[0], (char * const *)&argv_[0]);
		PLOG(ERROR) << "execv(" << argv_[0] << ") failed";
		exit(exit_code);
		}

		// Add an arg if it's not empty.
		void AddArg(const std::string& arg) {
		if (!arg.empty()) {
		args_.push_back(arg);
		}
		}

		// Add a runtime arg if it's not empty.
		void AddRuntimeArg(const std::string& arg) {
		if (!arg.empty()) {
		args_.push_back("--runtime-arg");
		args_.push_back(arg);
		}
		}

		protected:
		// Holder arrays for backing arg storage.
		std::vector<std::string> args_;

		// Argument poiners.
		std::vector<const char*> argv_;
		};

		static std::string MapPropertyToArg(const std::string& property,
		const std::string& format,
		const std::string& default_value = "") {
		std::string prop = GetProperty(property, default_value);
		if (!prop.empty()) {
		return StringPrintf(format.c_str(), prop.c_str());
		}
		return "";
		}

		static std::string MapPropertyToArgWithBackup(const std::string& property,
		const std::string& backupProperty,
		const std::string& format,
		const std::string& default_value = "") {
		std::string value = GetProperty(property, default_value);
		if (!value.empty()) {
		return StringPrintf(format.c_str(), value.c_str());
		}
		return MapPropertyToArg(backupProperty, format, default_value);
		}

		// Determines which binary we should use for execution (the debug or non-debug version).
		// e.g. dex2oatd vs dex2oat
		static const char* select_execution_binary(const char* binary, const char* debug_binary,
		@@ -311,9 +217,6 @@ const char* select_execution_binary(
		static const char* RUNTIME_NATIVE_BOOT_NAMESPACE = "runtime_native_boot";
		// Feature flag name for running the JIT in Zygote experiment, b/119800099.
		static const char* ENABLE_JITZYGOTE_IMAGE = "enable_apex_image";
		// Location of the JIT Zygote image.
		static const char* kJitZygoteImage =
		"boot.art:/nonx/boot-framework.art!/system/etc/boot-image.prof";

		// Phenotype property name for enabling profiling the boot class path.
		static const char* PROFILE_BOOT_CLASS_PATH = "profilebootclasspath";
		@@ -328,289 +231,6 @@ static bool IsBootClassPathProfilingEnable() {
		return profile_boot_class_path == "true";
		}

		class RunDex2Oat : public ExecVHelper {
		public:
		RunDex2Oat(int zip_fd,
		int oat_fd,
		int input_vdex_fd,
		int output_vdex_fd,
		int image_fd,
		const char* input_file_name,
		const char* output_file_name,
		int swap_fd,
		const char* instruction_set,
		const char* compiler_filter,
		bool debuggable,
		bool post_bootcomplete,
		bool for_restore,
		bool background_job_compile,
		int profile_fd,
		const char* class_loader_context,
		const std::string& class_loader_context_fds,
		int target_sdk_version,
		bool enable_hidden_api_checks,
		bool generate_compact_dex,
		int dex_metadata_fd,
		const char* compilation_reason) {
		// Get the relative path to the input file.
		const char* relative_input_file_name = get_location_from_path(input_file_name);

		std::string dex2oat_Xms_arg = MapPropertyToArg("dalvik.vm.dex2oat-Xms", "-Xms%s");
		std::string dex2oat_Xmx_arg = MapPropertyToArg("dalvik.vm.dex2oat-Xmx", "-Xmx%s");

		std::string threads_format = "-j%s";
		std::string dex2oat_threads_arg = post_bootcomplete
		? (for_restore
		? MapPropertyToArgWithBackup(
		"dalvik.vm.restore-dex2oat-threads",
		"dalvik.vm.dex2oat-threads",
		threads_format)
		: MapPropertyToArg("dalvik.vm.dex2oat-threads", threads_format))
		: MapPropertyToArg("dalvik.vm.boot-dex2oat-threads", threads_format);
		std::string cpu_set_format = "--cpu-set=%s";
		std::string dex2oat_cpu_set_arg = post_bootcomplete
		? (for_restore
		? MapPropertyToArgWithBackup(
		"dalvik.vm.restore-dex2oat-cpu-set",
		"dalvik.vm.dex2oat-cpu-set",
		cpu_set_format)
		: MapPropertyToArg("dalvik.vm.dex2oat-cpu-set", cpu_set_format))
		: MapPropertyToArg("dalvik.vm.boot-dex2oat-cpu-set", cpu_set_format);

		std::string bootclasspath;
		char* dex2oat_bootclasspath = getenv("DEX2OATBOOTCLASSPATH");
		if (dex2oat_bootclasspath != nullptr) {
		bootclasspath = StringPrintf("-Xbootclasspath:%s", dex2oat_bootclasspath);
		}
		// If DEX2OATBOOTCLASSPATH is not in the environment, dex2oat is going to query
		// BOOTCLASSPATH.

		const std::string dex2oat_isa_features_key =
		StringPrintf("dalvik.vm.isa.%s.features", instruction_set);
		std::string instruction_set_features_arg =
		MapPropertyToArg(dex2oat_isa_features_key, "--instruction-set-features=%s");

		const std::string dex2oat_isa_variant_key =
		StringPrintf("dalvik.vm.isa.%s.variant", instruction_set);
		std::string instruction_set_variant_arg =
		MapPropertyToArg(dex2oat_isa_variant_key, "--instruction-set-variant=%s");

		const char* dex2oat_norelocation = "-Xnorelocate";

		const std::string dex2oat_flags = GetProperty("dalvik.vm.dex2oat-flags", "");
		std::vector<std::string> dex2oat_flags_args = SplitBySpaces(dex2oat_flags);
		ALOGV("dalvik.vm.dex2oat-flags=%s\n", dex2oat_flags.c_str());

		// If we are booting without the real /data, don't spend time compiling.
		std::string vold_decrypt = GetProperty("vold.decrypt", "");
		bool skip_compilation = vold_decrypt == "trigger_restart_min_framework" \|\|
		vold_decrypt == "1";

		std::string updatable_bcp_packages =
		MapPropertyToArg("dalvik.vm.dex2oat-updatable-bcp-packages-file",
		"--updatable-bcp-packages-file=%s");
		if (updatable_bcp_packages.empty()) {
		// Make dex2oat fail by providing non-existent file name.
		updatable_bcp_packages = "--updatable-bcp-packages-file=/nonx/updatable-bcp-packages.txt";
		}

		std::string resolve_startup_string_arg =
		MapPropertyToArg("persist.device_config.runtime.dex2oat_resolve_startup_strings",
		"--resolve-startup-const-strings=%s");
		if (resolve_startup_string_arg.empty()) {
		// If empty, fall back to system property.
		resolve_startup_string_arg =
		MapPropertyToArg("dalvik.vm.dex2oat-resolve-startup-strings",
		"--resolve-startup-const-strings=%s");
		}

		const std::string image_block_size_arg =
		MapPropertyToArg("dalvik.vm.dex2oat-max-image-block-size",
		"--max-image-block-size=%s");

		const bool generate_debug_info = GetBoolProperty("debug.generate-debug-info", false);

		std::string image_format_arg;
		if (image_fd >= 0) {
		image_format_arg = MapPropertyToArg("dalvik.vm.appimageformat", "--image-format=%s");
		}

		std::string dex2oat_large_app_threshold_arg =
		MapPropertyToArg("dalvik.vm.dex2oat-very-large", "--very-large-app-threshold=%s");



		// Decide whether to use dex2oat64.
		bool use_dex2oat64 = false;
		// Check whether the device even supports 64-bit ABIs.
		if (!GetProperty("ro.product.cpu.abilist64", "").empty()) {
		use_dex2oat64 = GetBoolProperty("dalvik.vm.dex2oat64.enabled", false);
		}
		const char* dex2oat_bin = select_execution_binary(
		(use_dex2oat64 ? kDex2oat64Path : kDex2oat32Path),
		(use_dex2oat64 ? kDex2oatDebug64Path : kDex2oatDebug32Path),
		background_job_compile);

		bool generate_minidebug_info = kEnableMinidebugInfo &&
		GetBoolProperty(kMinidebugInfoSystemProperty, kMinidebugInfoSystemPropertyDefault);

		std::string boot_image;
		std::string use_jitzygote_image =
		server_configurable_flags::GetServerConfigurableFlag(RUNTIME_NATIVE_BOOT_NAMESPACE,
		ENABLE_JITZYGOTE_IMAGE,
		/default_value=/ "");

		if (use_jitzygote_image == "true" \|\| IsBootClassPathProfilingEnable()) {
		boot_image = StringPrintf("--boot-image=%s", kJitZygoteImage);
		} else {
		boot_image = MapPropertyToArg("dalvik.vm.boot-image", "--boot-image=%s");
		}

		// clang FORTIFY doesn't let us use strlen in constant array bounds, so we
		// use arraysize instead.
		std::string zip_fd_arg = StringPrintf("--zip-fd=%d", zip_fd);
		std::string zip_location_arg = StringPrintf("--zip-location=%s", relative_input_file_name);
		std::string input_vdex_fd_arg = StringPrintf("--input-vdex-fd=%d", input_vdex_fd);
		std::string output_vdex_fd_arg = StringPrintf("--output-vdex-fd=%d", output_vdex_fd);
		std::string oat_fd_arg = StringPrintf("--oat-fd=%d", oat_fd);
		std::string oat_location_arg = StringPrintf("--oat-location=%s", output_file_name);
		std::string instruction_set_arg = StringPrintf("--instruction-set=%s", instruction_set);
		std::string dex2oat_compiler_filter_arg;
		std::string dex2oat_swap_fd;
		std::string dex2oat_image_fd;
		std::string target_sdk_version_arg;
		if (target_sdk_version != 0) {
		target_sdk_version_arg = StringPrintf("-Xtarget-sdk-version:%d", target_sdk_version);
		}
		std::string class_loader_context_arg;
		std::string class_loader_context_fds_arg;
		if (class_loader_context != nullptr) {
		class_loader_context_arg = StringPrintf("--class-loader-context=%s",
		class_loader_context);
		if (!class_loader_context_fds.empty()) {
		class_loader_context_fds_arg = StringPrintf("--class-loader-context-fds=%s",
		class_loader_context_fds.c_str());
		}
		}

		if (swap_fd >= 0) {
		dex2oat_swap_fd = StringPrintf("--swap-fd=%d", swap_fd);
		}
		if (image_fd >= 0) {
		dex2oat_image_fd = StringPrintf("--app-image-fd=%d", image_fd);
		}

		// Compute compiler filter.
		bool have_dex2oat_relocation_skip_flag = false;
		if (skip_compilation) {
		dex2oat_compiler_filter_arg = "--compiler-filter=extract";
		have_dex2oat_relocation_skip_flag = true;
		} else if (compiler_filter != nullptr) {
		dex2oat_compiler_filter_arg = StringPrintf("--compiler-filter=%s", compiler_filter);
		}

		if (dex2oat_compiler_filter_arg.empty()) {
		dex2oat_compiler_filter_arg = MapPropertyToArg("dalvik.vm.dex2oat-filter",
		"--compiler-filter=%s");
		}

		// Check whether all apps should be compiled debuggable.
		if (!debuggable) {
		debuggable = GetProperty("dalvik.vm.always_debuggable", "") == "1";
		}
		std::string profile_arg;
		if (profile_fd != -1) {
		profile_arg = StringPrintf("--profile-file-fd=%d", profile_fd);
		}

		// Get the directory of the apk to pass as a base classpath directory.
		std::string base_dir;
		std::string apk_dir(input_file_name);
		unsigned long dir_index = apk_dir.rfind('/');
		bool has_base_dir = dir_index != std::string::npos;
		if (has_base_dir) {
		apk_dir = apk_dir.substr(0, dir_index);
		base_dir = StringPrintf("--classpath-dir=%s", apk_dir.c_str());
		}

		std::string dex_metadata_fd_arg = "--dm-fd=" + std::to_string(dex_metadata_fd);

		std::string compilation_reason_arg = compilation_reason == nullptr
		? ""
		: std::string("--compilation-reason=") + compilation_reason;

		ALOGV("Running %s in=%s out=%s\n", dex2oat_bin, relative_input_file_name, output_file_name);

		// Disable cdex if update input vdex is true since this combination of options is not
		// supported.
		const bool disable_cdex = !generate_compact_dex \|\| (input_vdex_fd == output_vdex_fd);

		AddArg(zip_fd_arg);
		AddArg(zip_location_arg);
		AddArg(input_vdex_fd_arg);
		AddArg(output_vdex_fd_arg);
		AddArg(oat_fd_arg);
		AddArg(oat_location_arg);
		AddArg(instruction_set_arg);

		AddArg(instruction_set_variant_arg);
		AddArg(instruction_set_features_arg);

		AddArg(boot_image);

		AddRuntimeArg(bootclasspath);
		AddRuntimeArg(dex2oat_Xms_arg);
		AddRuntimeArg(dex2oat_Xmx_arg);

		AddArg(updatable_bcp_packages);
		AddArg(resolve_startup_string_arg);
		AddArg(image_block_size_arg);
		AddArg(dex2oat_compiler_filter_arg);
		AddArg(dex2oat_threads_arg);
		AddArg(dex2oat_cpu_set_arg);
		AddArg(dex2oat_swap_fd);
		AddArg(dex2oat_image_fd);

		if (generate_debug_info) {
		AddArg("--generate-debug-info");
		}
		if (debuggable) {
		AddArg("--debuggable");
		}
		AddArg(image_format_arg);
		AddArg(dex2oat_large_app_threshold_arg);

		if (have_dex2oat_relocation_skip_flag) {
		AddRuntimeArg(dex2oat_norelocation);
		}
		AddArg(profile_arg);
		AddArg(base_dir);
		AddArg(class_loader_context_arg);
		AddArg(class_loader_context_fds_arg);
		if (generate_minidebug_info) {
		AddArg(kMinidebugDex2oatFlag);
		}
		if (disable_cdex) {
		AddArg(kDisableCompactDexFlag);
		}
		AddRuntimeArg(target_sdk_version_arg);
		if (enable_hidden_api_checks) {
		AddRuntimeArg("-Xhidden-api-policy:enabled");
		}

		if (dex_metadata_fd > -1) {
		AddArg(dex_metadata_fd_arg);
		}

		AddArg(compilation_reason_arg);

		// Do not add args after dex2oat_flags, they should override others for debugging.
		args_.insert(args_.end(), dex2oat_flags_args.begin(), dex2oat_flags_args.end());

		PrepareArgs(dex2oat_bin);
		}
		};

		/*
		* Whether dexopt should use a swap file when compiling an APK.
		*
		@@ -868,6 +488,7 @@ class RunProfman : public ExecVHelper {
		/for_boot_image/false);
		}

		using ExecVHelper::Exec; // To suppress -Wno-overloaded-virtual
		void Exec() {
		ExecVHelper::Exec(DexoptReturnCodes::kProfmanExec);
		}
		@@ -1022,7 +643,7 @@ bool dump_profiles(int32_t uid, const std::string& pkgname, const std::string& p
		PLOG(ERROR) << "installd cannot open " << code_path.c_str();
		return false;
		}
		dex_locations.push_back(get_location_from_path(code_path.c_str()));
		dex_locations.push_back(Basename(code_path));
		apk_fds.push_back(std::move(apk_fd));


		@@ -2220,9 +1841,29 @@ int dexopt(const char* dex_path, uid_t uid, const char* pkgname, const char* ins
		}
		}

		std::string jitzygote_flag = server_configurable_flags::GetServerConfigurableFlag(
		RUNTIME_NATIVE_BOOT_NAMESPACE,
		ENABLE_JITZYGOTE_IMAGE,
		/default_value=/ "");
		bool use_jitzygote_image = jitzygote_flag == "true" \|\| IsBootClassPathProfilingEnable();

		// Decide whether to use dex2oat64.
		bool use_dex2oat64 = false;
		// Check whether the device even supports 64-bit ABIs.
		if (!GetProperty("ro.product.cpu.abilist64", "").empty()) {
		use_dex2oat64 = GetBoolProperty("dalvik.vm.dex2oat64.enabled", false);
		}
		const char* dex2oat_bin = select_execution_binary(
		(use_dex2oat64 ? kDex2oat64Path : kDex2oat32Path),
		(use_dex2oat64 ? kDex2oatDebug64Path : kDex2oatDebug32Path),
		background_job_compile);

		auto execv_helper = std::make_unique<ExecVHelper>();

		LOG(VERBOSE) << "DexInv: --- BEGIN '" << dex_path << "' ---";

		RunDex2Oat runner(input_fd.get(),
		RunDex2Oat runner(dex2oat_bin, execv_helper.get());
		runner.Initialize(input_fd.get(),
		out_oat_fd.get(),
		in_vdex_fd.get(),
		out_vdex_fd.get(),
		@@ -2235,7 +1876,6 @@ int dexopt(const char* dex_path, uid_t uid, const char* pkgname, const char* ins
		debuggable,
		boot_complete,
		for_restore,
		background_job_compile,
		reference_profile_fd.get(),
		class_loader_context,
		join_fds(context_input_fds),
		@@ -2243,6 +1883,7 @@ int dexopt(const char* dex_path, uid_t uid, const char* pkgname, const char* ins
		enable_hidden_api_checks,
		generate_compact_dex,
		dex_metadata_fd.get(),
		use_jitzygote_image,
		compilation_reason);

		pid_t pid = fork();

cmds/installd/execv_helper.cpp

0 → 100644

+67 −0

Original line number	Diff line number	Diff line
		/*
		* Copyright (C) 2020 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.
		*/
		#define LOG_TAG "installd"

		#include "execv_helper.h"

		#include <stdlib.h>
		#include <unistd.h>

		#include <string>

		#include <android-base/logging.h>
		#include <android-base/properties.h>

		namespace android {
		namespace installd {

		// Store a placeholder for the binary name.
		ExecVHelper::ExecVHelper() : args_(1u, std::string()) {}

		ExecVHelper::~ExecVHelper() {}

		void ExecVHelper::PrepareArgs(const std::string& bin) {
		CHECK(!args_.empty());
		CHECK(args_[0].empty());
		args_[0] = bin;
		// Write char* into array.
		for (const std::string& arg : args_) {
		argv_.push_back(arg.c_str());
		}
		argv_.push_back(nullptr); // Add null terminator.
		}

		void ExecVHelper::Exec(int exit_code) {
		execv(argv_[0], (char * const *)&argv_[0]);
		PLOG(ERROR) << "execv(" << argv_[0] << ") failed";
		exit(exit_code);
		}

		void ExecVHelper::AddArg(const std::string& arg) {
		if (!arg.empty()) {
		args_.push_back(arg);
		}
		}

		void ExecVHelper::AddRuntimeArg(const std::string& arg) {
		if (!arg.empty()) {
		args_.push_back("--runtime-arg");
		args_.push_back(arg);
		}
		}

		} // namespace installd
		} // namespace android

cmds/installd/execv_helper.h

0 → 100644

+55 −0

Original line number	Diff line number	Diff line
		/*
		* Copyright (C) 2020 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.
		*/

		#ifndef ANDROID_INSTALLD_EXECV_HELPER_H
		#define ANDROID_INSTALLD_EXECV_HELPER_H

		#include <string>
		#include <vector>

		namespace android {
		namespace installd {

		// ExecVHelper prepares and holds pointers to parsed command line arguments so that no allocations
		// need to be performed between the fork and exec.
		class ExecVHelper {
		public:
		ExecVHelper();
		virtual ~ExecVHelper();

		[[ noreturn ]]
		virtual void Exec(int exit_code);

		void PrepareArgs(const std::string& bin);

		// Add an arg if it's not empty.
		void AddArg(const std::string& arg);

		// Add a runtime arg if it's not empty.
		void AddRuntimeArg(const std::string& arg);

		protected:
		// Holder arrays for backing arg storage.
		std::vector<std::string> args_;

		// Argument poiners.
		std::vector<const char*> argv_;
		};

		} // namespace installd
		} // namespace android

		#endif // ANDROID_INSTALLD_EXECV_HELPER_H