init/firmware_handler.cpp - third_party/android/platform/system/core - Git at Google

 /*
  * 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 "firmware_handler.h"

 #include <fcntl.h>
 #include <fnmatch.h>
 #include <glob.h>
 #include <grp.h>
 #include <pwd.h>
 #include <signal.h>
 #include <stdlib.h>
 #include <string.h>
 #include <sys/sendfile.h>
 #include <sys/wait.h>
 #include <unistd.h>

 #include <thread>

 #include <android-base/chrono_utils.h>
 #include <android-base/file.h>
 #include <android-base/logging.h>
 #include <android-base/properties.h>
 #include <android-base/scopeguard.h>
 #include <android-base/strings.h>
 #include <android-base/unique_fd.h>

 using android::base::ReadFdToString;
 using android::base::Socketpair;
 using android::base::Split;
 using android::base::Timer;
 using android::base::Trim;
 using android::base::unique_fd;
 using android::base::WaitForProperty;
 using android::base::WriteFully;

 namespace android {
 namespace init {

 namespace {
 bool PrefixMatch(const std::string& pattern, const std::string& path) {
     return android::base::StartsWith(path, pattern);
 }

 bool FnMatch(const std::string& pattern, const std::string& path) {
     return fnmatch(pattern.c_str(), path.c_str(), 0) == 0;
 }

 bool EqualMatch(const std::string& pattern, const std::string& path) {
     return pattern == path;
 }
 }  // namespace

 static void LoadFirmware(const std::string& firmware, const std::string& root, int fw_fd,
                          size_t fw_size, int loading_fd, int data_fd) {
     // Start transfer.
     WriteFully(loading_fd, "1", 1);

     // Copy the firmware.
     int rc = sendfile(data_fd, fw_fd, nullptr, fw_size);
     if (rc == -1) {
         PLOG(ERROR) << "firmware: sendfile failed { '" << root << "', '" << firmware << "' }";
     }

     // Tell the firmware whether to abort or commit.
     const char* response = (rc != -1) ? "0" : "-1";
     WriteFully(loading_fd, response, strlen(response));
 }

 static bool IsBooting() {
     return access("/dev/.booting", F_OK) == 0;
 }

 static bool IsApexActivated() {
     static bool apex_activated = []() {
         // Wait for com.android.runtime.apex activation
         // Property name and value must be kept in sync with system/apexd/apex/apex_constants.h
         // 60s is the default firmware sysfs fallback timeout. (/sys/class/firmware/timeout)
         if (!WaitForProperty("apexd.status", "activated", 60s)) {
             LOG(ERROR) << "Apexd activation wait timeout";
             return false;
         }
         return true;
     }();

     return apex_activated;
 }

 static bool NeedsRerunExternalHandler() {
     static bool first = true;

     // Rerun external handler only on the first try and when apex is activated
     if (first) {
         first = false;
         return IsApexActivated();
     }

     return first;
 }

 ExternalFirmwareHandler::ExternalFirmwareHandler(std::string devpath, uid_t uid, gid_t gid,
                                                  std::string handler_path)
     : devpath(std::move(devpath)), uid(uid), gid(gid), handler_path(std::move(handler_path)) {
     auto wildcard_position = this->devpath.find('*');
     if (wildcard_position != std::string::npos) {
         if (wildcard_position == this->devpath.length() - 1) {
             this->devpath.pop_back();
             match = std::bind(PrefixMatch, this->devpath, std::placeholders::_1);
         } else {
             match = std::bind(FnMatch, this->devpath, std::placeholders::_1);
         }
     } else {
         match = std::bind(EqualMatch, this->devpath, std::placeholders::_1);
     }
 }

 ExternalFirmwareHandler::ExternalFirmwareHandler(std::string devpath, uid_t uid,
                                                  std::string handler_path)
     : ExternalFirmwareHandler(devpath, uid, 0, handler_path) {}

 FirmwareHandler::FirmwareHandler(std::vector<std::string> firmware_directories,
                                  std::vector<ExternalFirmwareHandler> external_firmware_handlers)
     : firmware_directories_(std::move(firmware_directories)),
       external_firmware_handlers_(std::move(external_firmware_handlers)) {}

 Result<std::string> FirmwareHandler::RunExternalHandler(const std::string& handler, uid_t uid,
                                                         gid_t gid, const Uevent& uevent) const {
     unique_fd child_stdout;
     unique_fd parent_stdout;
     if (!Socketpair(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC, 0, &child_stdout, &parent_stdout)) {
         return ErrnoError() << "Socketpair() for stdout failed";
     }

     unique_fd child_stderr;
     unique_fd parent_stderr;
     if (!Socketpair(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC, 0, &child_stderr, &parent_stderr)) {
         return ErrnoError() << "Socketpair() for stderr failed";
     }

     signal(SIGCHLD, SIG_DFL);

     auto pid = fork();
     if (pid < 0) {
         return ErrnoError() << "fork() failed";
     }

     if (pid == 0) {
         setenv("FIRMWARE", uevent.firmware.c_str(), 1);
         setenv("DEVPATH", uevent.path.c_str(), 1);
         parent_stdout.reset();
         parent_stderr.reset();
         close(STDOUT_FILENO);
         close(STDERR_FILENO);
         dup2(child_stdout.get(), STDOUT_FILENO);
         dup2(child_stderr.get(), STDERR_FILENO);

         auto args = Split(handler, " ");
         std::vector<char*> c_args;
         for (auto& arg : args) {
             c_args.emplace_back(arg.data());
         }
         c_args.emplace_back(nullptr);

         if (gid != 0) {
             if (setgid(gid) != 0) {
                 fprintf(stderr, "setgid() failed: %s", strerror(errno));
                 _exit(EXIT_FAILURE);
             }
         }

         if (setuid(uid) != 0) {
             fprintf(stderr, "setuid() failed: %s", strerror(errno));
             _exit(EXIT_FAILURE);
         }

         execv(c_args[0], c_args.data());
         fprintf(stderr, "exec() failed: %s", strerror(errno));
         _exit(EXIT_FAILURE);
     }

     child_stdout.reset();
     child_stderr.reset();

     int status;
     pid_t waited_pid = TEMP_FAILURE_RETRY(waitpid(pid, &status, 0));
     if (waited_pid == -1) {
         return ErrnoError() << "waitpid() failed";
     }

     std::string stdout_content;
     if (!ReadFdToString(parent_stdout.get(), &stdout_content)) {
         return ErrnoError() << "ReadFdToString() for stdout failed";
     }

     std::string stderr_content;
     if (ReadFdToString(parent_stderr.get(), &stderr_content)) {
         auto messages = Split(stderr_content, "\n");
         for (const auto& message : messages) {
             if (!message.empty()) {
                 LOG(ERROR) << "External Firmware Handler: " << message;
             }
         }
     } else {
         LOG(ERROR) << "ReadFdToString() for stderr failed";
     }

     if (WIFEXITED(status)) {
         if (WEXITSTATUS(status) == EXIT_SUCCESS) {
             return Trim(stdout_content);
         } else {
             return Error() << "exited with status " << WEXITSTATUS(status);
         }
     } else if (WIFSIGNALED(status)) {
         return Error() << "killed by signal " << WTERMSIG(status);
     }

     return Error() << "unexpected exit status " << status;
 }

 std::string FirmwareHandler::GetFirmwarePath(const Uevent& uevent) const {
     for (const auto& external_handler : external_firmware_handlers_) {
         if (external_handler.match(uevent.path)) {
             LOG(INFO) << "Launching external firmware handler '" << external_handler.handler_path
                       << "' for devpath: '" << uevent.path << "' firmware: '" << uevent.firmware
                       << "'";

             auto result = RunExternalHandler(external_handler.handler_path, external_handler.uid,
                                              external_handler.gid, uevent);
             if (!result.ok() && NeedsRerunExternalHandler()) {
                 auto res = RunExternalHandler(external_handler.handler_path, external_handler.uid,
                                               external_handler.gid, uevent);
                 result = std::move(res);
             }
             if (!result.ok()) {
                 LOG(ERROR) << "Using default firmware; External firmware handler failed: "
                            << result.error();
                 return uevent.firmware;
             }
             if (result->find("..") != std::string::npos) {
                 LOG(ERROR) << "Using default firmware; External firmware handler provided an "
                               "invalid path, '"
                            << *result << "'";
                 return uevent.firmware;
             }
             LOG(INFO) << "Loading firmware '" << *result << "' in place of '" << uevent.firmware
                       << "'";
             return *result;
         }
     }
     LOG(INFO) << "firmware: loading '" << uevent.firmware << "' for '" << uevent.path << "'";
     return uevent.firmware;
 }

 void FirmwareHandler::ProcessFirmwareEvent(const std::string& root,
                                            const std::string& firmware) const {
     std::string loading = root + "/loading";
     std::string data = root + "/data";

     unique_fd loading_fd(open(loading.c_str(), O_WRONLY | O_CLOEXEC));
     if (loading_fd == -1) {
         PLOG(ERROR) << "couldn't open firmware loading fd for " << firmware;
         return;
     }

     unique_fd data_fd(open(data.c_str(), O_WRONLY | O_CLOEXEC));
     if (data_fd == -1) {
         PLOG(ERROR) << "couldn't open firmware data fd for " << firmware;
         return;
     }

     std::vector<std::string> attempted_paths_and_errors;
     auto TryLoadFirmware = [&](const std::string& firmware_directory) {
         std::string file = firmware_directory + firmware;
         unique_fd fw_fd(open(file.c_str(), O_RDONLY | O_CLOEXEC));
         if (fw_fd == -1) {
             attempted_paths_and_errors.emplace_back("firmware: attempted " + file +
                                                     ", open failed: " + strerror(errno));
             return false;
         }
         struct stat sb;
         if (fstat(fw_fd.get(), &sb) == -1) {
             attempted_paths_and_errors.emplace_back("firmware: attempted " + file +
                                                     ", fstat failed: " + strerror(errno));
             return false;
         }
         LoadFirmware(firmware, root, fw_fd.get(), sb.st_size, loading_fd.get(), data_fd.get());
         return true;
     };

     int booting = IsBooting();
 try_loading_again:
     attempted_paths_and_errors.clear();
     if (ForEachFirmwareDirectory(TryLoadFirmware)) {
         return;
     }

     if (booting) {
         // If we're not fully booted, we may be missing
         // filesystems needed for firmware, wait and retry.
         std::this_thread::sleep_for(100ms);
         booting = IsBooting();
         goto try_loading_again;
     }

     LOG(ERROR) << "firmware: could not find firmware for " << firmware;
     for (const auto& message : attempted_paths_and_errors) {
         LOG(ERROR) << message;
     }

     // Write "-1" as our response to the kernel's firmware request, since we have nothing for it.
     write(loading_fd.get(), "-1", 2);
 }

 bool FirmwareHandler::ForEachFirmwareDirectory(
         std::function<bool(const std::string&)> handler) const {
     for (const std::string& firmware_directory : firmware_directories_) {
         if (std::invoke(handler, firmware_directory)) {
             return true;
         }
     }

     glob_t glob_result;
     glob("/apex/*/etc/firmware/", GLOB_MARK, nullptr, &glob_result);
     auto free_glob = android::base::make_scope_guard(std::bind(&globfree, &glob_result));
     for (size_t i = 0; i < glob_result.gl_pathc; i++) {
         char* apex_firmware_directory = glob_result.gl_pathv[i];
         // Filter-out /apex/<name>@<ver> paths. The paths are bind-mounted to
         // /apex/<name> paths, so unless we filter them out, we will look into the
         // same apex twice.
         if (strchr(apex_firmware_directory, '@')) {
             continue;
         }
         if (std::invoke(handler, apex_firmware_directory)) {
             return true;
         }
     }

     return false;
 }

 void FirmwareHandler::HandleUevent(const Uevent& uevent) {
     if (uevent.subsystem != "firmware" || uevent.action != "add") return;

     // Loading the firmware in a child means we can do that in parallel...
     auto pid = fork();
     if (pid == -1) {
         PLOG(ERROR) << "could not fork to process firmware event for " << uevent.firmware;
     }
     if (pid == 0) {
         Timer t;
         auto firmware = GetFirmwarePath(uevent);
         ProcessFirmwareEvent("/sys" + uevent.path, firmware);
         LOG(INFO) << "loading " << uevent.path << " took " << t;
         _exit(EXIT_SUCCESS);
     }
 }

 }  // namespace init
 }  // namespace android
	/*
	* 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 "firmware_handler.h"

	#include <fcntl.h>
	#include <fnmatch.h>
	#include <glob.h>
	#include <grp.h>
	#include <pwd.h>
	#include <signal.h>
	#include <stdlib.h>
	#include <string.h>
	#include <sys/sendfile.h>
	#include <sys/wait.h>
	#include <unistd.h>

	#include <thread>

	#include <android-base/chrono_utils.h>
	#include <android-base/file.h>
	#include <android-base/logging.h>
	#include <android-base/properties.h>
	#include <android-base/scopeguard.h>
	#include <android-base/strings.h>
	#include <android-base/unique_fd.h>

	using android::base::ReadFdToString;
	using android::base::Socketpair;
	using android::base::Split;
	using android::base::Timer;
	using android::base::Trim;
	using android::base::unique_fd;
	using android::base::WaitForProperty;
	using android::base::WriteFully;

	namespace android {
	namespace init {

	namespace {
	bool PrefixMatch(const std::string& pattern, const std::string& path) {
	return android::base::StartsWith(path, pattern);
	}

	bool FnMatch(const std::string& pattern, const std::string& path) {
	return fnmatch(pattern.c_str(), path.c_str(), 0) == 0;
	}

	bool EqualMatch(const std::string& pattern, const std::string& path) {
	return pattern == path;
	}
	} // namespace

	static void LoadFirmware(const std::string& firmware, const std::string& root, int fw_fd,
	size_t fw_size, int loading_fd, int data_fd) {
	// Start transfer.
	WriteFully(loading_fd, "1", 1);

	// Copy the firmware.
	int rc = sendfile(data_fd, fw_fd, nullptr, fw_size);
	if (rc == -1) {
	PLOG(ERROR) << "firmware: sendfile failed { '" << root << "', '" << firmware << "' }";
	}

	// Tell the firmware whether to abort or commit.
	const char* response = (rc != -1) ? "0" : "-1";
	WriteFully(loading_fd, response, strlen(response));
	}

	static bool IsBooting() {
	return access("/dev/.booting", F_OK) == 0;
	}

	static bool IsApexActivated() {
	static bool apex_activated = []() {
	// Wait for com.android.runtime.apex activation
	// Property name and value must be kept in sync with system/apexd/apex/apex_constants.h
	// 60s is the default firmware sysfs fallback timeout. (/sys/class/firmware/timeout)
	if (!WaitForProperty("apexd.status", "activated", 60s)) {
	LOG(ERROR) << "Apexd activation wait timeout";
	return false;
	}
	return true;
	}();

	return apex_activated;
	}

	static bool NeedsRerunExternalHandler() {
	static bool first = true;

	// Rerun external handler only on the first try and when apex is activated
	if (first) {
	first = false;
	return IsApexActivated();
	}

	return first;
	}

	ExternalFirmwareHandler::ExternalFirmwareHandler(std::string devpath, uid_t uid, gid_t gid,
	std::string handler_path)
	: devpath(std::move(devpath)), uid(uid), gid(gid), handler_path(std::move(handler_path)) {
	auto wildcard_position = this->devpath.find('*');
	if (wildcard_position != std::string::npos) {
	if (wildcard_position == this->devpath.length() - 1) {
	this->devpath.pop_back();
	match = std::bind(PrefixMatch, this->devpath, std::placeholders::_1);
	} else {
	match = std::bind(FnMatch, this->devpath, std::placeholders::_1);
	}
	} else {
	match = std::bind(EqualMatch, this->devpath, std::placeholders::_1);
	}
	}

	ExternalFirmwareHandler::ExternalFirmwareHandler(std::string devpath, uid_t uid,
	std::string handler_path)
	: ExternalFirmwareHandler(devpath, uid, 0, handler_path) {}

	FirmwareHandler::FirmwareHandler(std::vector<std::string> firmware_directories,
	std::vector<ExternalFirmwareHandler> external_firmware_handlers)
	: firmware_directories_(std::move(firmware_directories)),
	external_firmware_handlers_(std::move(external_firmware_handlers)) {}

	Result<std::string> FirmwareHandler::RunExternalHandler(const std::string& handler, uid_t uid,
	gid_t gid, const Uevent& uevent) const {
	unique_fd child_stdout;
	unique_fd parent_stdout;
	if (!Socketpair(AF_UNIX, SOCK_STREAM \| SOCK_CLOEXEC, 0, &child_stdout, &parent_stdout)) {
	return ErrnoError() << "Socketpair() for stdout failed";
	}

	unique_fd child_stderr;
	unique_fd parent_stderr;
	if (!Socketpair(AF_UNIX, SOCK_STREAM \| SOCK_CLOEXEC, 0, &child_stderr, &parent_stderr)) {
	return ErrnoError() << "Socketpair() for stderr failed";
	}

	signal(SIGCHLD, SIG_DFL);

	auto pid = fork();
	if (pid < 0) {
	return ErrnoError() << "fork() failed";
	}

	if (pid == 0) {
	setenv("FIRMWARE", uevent.firmware.c_str(), 1);
	setenv("DEVPATH", uevent.path.c_str(), 1);
	parent_stdout.reset();
	parent_stderr.reset();
	close(STDOUT_FILENO);
	close(STDERR_FILENO);
	dup2(child_stdout.get(), STDOUT_FILENO);
	dup2(child_stderr.get(), STDERR_FILENO);

	auto args = Split(handler, " ");
	std::vector<char*> c_args;
	for (auto& arg : args) {
	c_args.emplace_back(arg.data());
	}
	c_args.emplace_back(nullptr);

	if (gid != 0) {
	if (setgid(gid) != 0) {
	fprintf(stderr, "setgid() failed: %s", strerror(errno));
	_exit(EXIT_FAILURE);
	}
	}

	if (setuid(uid) != 0) {
	fprintf(stderr, "setuid() failed: %s", strerror(errno));
	_exit(EXIT_FAILURE);
	}

	execv(c_args[0], c_args.data());
	fprintf(stderr, "exec() failed: %s", strerror(errno));
	_exit(EXIT_FAILURE);
	}

	child_stdout.reset();
	child_stderr.reset();

	int status;
	pid_t waited_pid = TEMP_FAILURE_RETRY(waitpid(pid, &status, 0));
	if (waited_pid == -1) {
	return ErrnoError() << "waitpid() failed";
	}

	std::string stdout_content;
	if (!ReadFdToString(parent_stdout.get(), &stdout_content)) {
	return ErrnoError() << "ReadFdToString() for stdout failed";
	}

	std::string stderr_content;
	if (ReadFdToString(parent_stderr.get(), &stderr_content)) {
	auto messages = Split(stderr_content, "\n");
	for (const auto& message : messages) {
	if (!message.empty()) {
	LOG(ERROR) << "External Firmware Handler: " << message;
	}
	}
	} else {
	LOG(ERROR) << "ReadFdToString() for stderr failed";
	}

	if (WIFEXITED(status)) {
	if (WEXITSTATUS(status) == EXIT_SUCCESS) {
	return Trim(stdout_content);
	} else {
	return Error() << "exited with status " << WEXITSTATUS(status);
	}
	} else if (WIFSIGNALED(status)) {
	return Error() << "killed by signal " << WTERMSIG(status);
	}

	return Error() << "unexpected exit status " << status;
	}

	std::string FirmwareHandler::GetFirmwarePath(const Uevent& uevent) const {
	for (const auto& external_handler : external_firmware_handlers_) {
	if (external_handler.match(uevent.path)) {
	LOG(INFO) << "Launching external firmware handler '" << external_handler.handler_path
	<< "' for devpath: '" << uevent.path << "' firmware: '" << uevent.firmware
	<< "'";

	auto result = RunExternalHandler(external_handler.handler_path, external_handler.uid,
	external_handler.gid, uevent);
	if (!result.ok() && NeedsRerunExternalHandler()) {
	auto res = RunExternalHandler(external_handler.handler_path, external_handler.uid,
	external_handler.gid, uevent);
	result = std::move(res);
	}
	if (!result.ok()) {
	LOG(ERROR) << "Using default firmware; External firmware handler failed: "
	<< result.error();
	return uevent.firmware;
	}
	if (result->find("..") != std::string::npos) {
	LOG(ERROR) << "Using default firmware; External firmware handler provided an "
	"invalid path, '"
	<< *result << "'";
	return uevent.firmware;
	}
	LOG(INFO) << "Loading firmware '" << *result << "' in place of '" << uevent.firmware
	<< "'";
	return *result;
	}
	}
	LOG(INFO) << "firmware: loading '" << uevent.firmware << "' for '" << uevent.path << "'";
	return uevent.firmware;
	}

	void FirmwareHandler::ProcessFirmwareEvent(const std::string& root,
	const std::string& firmware) const {
	std::string loading = root + "/loading";
	std::string data = root + "/data";

	unique_fd loading_fd(open(loading.c_str(), O_WRONLY \| O_CLOEXEC));
	if (loading_fd == -1) {
	PLOG(ERROR) << "couldn't open firmware loading fd for " << firmware;
	return;
	}

	unique_fd data_fd(open(data.c_str(), O_WRONLY \| O_CLOEXEC));
	if (data_fd == -1) {
	PLOG(ERROR) << "couldn't open firmware data fd for " << firmware;
	return;
	}

	std::vector<std::string> attempted_paths_and_errors;
	auto TryLoadFirmware = [&](const std::string& firmware_directory) {
	std::string file = firmware_directory + firmware;
	unique_fd fw_fd(open(file.c_str(), O_RDONLY \| O_CLOEXEC));
	if (fw_fd == -1) {
	attempted_paths_and_errors.emplace_back("firmware: attempted " + file +
	", open failed: " + strerror(errno));
	return false;
	}
	struct stat sb;
	if (fstat(fw_fd.get(), &sb) == -1) {
	attempted_paths_and_errors.emplace_back("firmware: attempted " + file +
	", fstat failed: " + strerror(errno));
	return false;
	}
	LoadFirmware(firmware, root, fw_fd.get(), sb.st_size, loading_fd.get(), data_fd.get());
	return true;
	};

	int booting = IsBooting();
	try_loading_again:
	attempted_paths_and_errors.clear();
	if (ForEachFirmwareDirectory(TryLoadFirmware)) {
	return;
	}

	if (booting) {
	// If we're not fully booted, we may be missing
	// filesystems needed for firmware, wait and retry.
	std::this_thread::sleep_for(100ms);
	booting = IsBooting();
	goto try_loading_again;
	}

	LOG(ERROR) << "firmware: could not find firmware for " << firmware;
	for (const auto& message : attempted_paths_and_errors) {
	LOG(ERROR) << message;
	}

	// Write "-1" as our response to the kernel's firmware request, since we have nothing for it.
	write(loading_fd.get(), "-1", 2);
	}

	bool FirmwareHandler::ForEachFirmwareDirectory(
	std::function<bool(const std::string&)> handler) const {
	for (const std::string& firmware_directory : firmware_directories_) {
	if (std::invoke(handler, firmware_directory)) {
	return true;
	}
	}

	glob_t glob_result;
	glob("/apex/*/etc/firmware/", GLOB_MARK, nullptr, &glob_result);
	auto free_glob = android::base::make_scope_guard(std::bind(&globfree, &glob_result));
	for (size_t i = 0; i < glob_result.gl_pathc; i++) {
	char* apex_firmware_directory = glob_result.gl_pathv[i];
	// Filter-out /apex/<name>@<ver> paths. The paths are bind-mounted to
	// /apex/<name> paths, so unless we filter them out, we will look into the
	// same apex twice.
	if (strchr(apex_firmware_directory, '@')) {
	continue;
	}
	if (std::invoke(handler, apex_firmware_directory)) {
	return true;
	}
	}

	return false;
	}

	void FirmwareHandler::HandleUevent(const Uevent& uevent) {
	if (uevent.subsystem != "firmware" \|\| uevent.action != "add") return;

	// Loading the firmware in a child means we can do that in parallel...
	auto pid = fork();
	if (pid == -1) {
	PLOG(ERROR) << "could not fork to process firmware event for " << uevent.firmware;
	}
	if (pid == 0) {
	Timer t;
	auto firmware = GetFirmwarePath(uevent);
	ProcessFirmwareEvent("/sys" + uevent.path, firmware);
	LOG(INFO) << "loading " << uevent.path << " took " << t;
	_exit(EXIT_SUCCESS);
	}
	}

	} // namespace init
	} // namespace android