subprocess.cc - SHIFTPHONES/android_system_update_engine - Gitiles

 //
 // Copyright (C) 2012 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 "update_engine/subprocess.h"

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

 #include <memory>
 #include <string>
 #include <vector>

 #include <base/bind.h>
 #include <base/logging.h>
 #include <base/posix/eintr_wrapper.h>
 #include <base/strings/string_util.h>
 #include <base/strings/stringprintf.h>
 #include <chromeos/process.h>
 #include <chromeos/secure_blob.h>

 using chromeos::MessageLoop;
 using std::string;
 using std::unique_ptr;
 using std::vector;

 namespace chromeos_update_engine {

 namespace {

 bool SetupChild(const std::map<string, string>& env, uint32_t flags) {
   // Setup the environment variables.
   clearenv();
   for (const auto& key_value : env) {
     setenv(key_value.first.c_str(), key_value.second.c_str(), 0);
   }

   if ((flags & Subprocess::kRedirectStderrToStdout) != 0) {
     if (HANDLE_EINTR(dup2(STDOUT_FILENO, STDERR_FILENO)) != STDERR_FILENO)
       return false;
   }

   int fd = HANDLE_EINTR(open("/dev/null", O_RDONLY));
   if (fd < 0)
     return false;
   if (HANDLE_EINTR(dup2(fd, STDIN_FILENO)) != STDIN_FILENO)
     return false;
   IGNORE_EINTR(close(fd));

   return true;
 }

 // Helper function to launch a process with the given Subprocess::Flags.
 // This function only sets up and starts the process according to the |flags|.
 // The caller is responsible for watching the termination of the subprocess.
 // Return whether the process was successfully launched and fills in the |proc|
 // Process.
 bool LaunchProcess(const vector<string>& cmd,
                    uint32_t flags,
                    chromeos::Process* proc) {
   for (const string& arg : cmd)
     proc->AddArg(arg);
   proc->SetSearchPath((flags & Subprocess::kSearchPath) != 0);

   // Create an environment for the child process with just the required PATHs.
   std::map<string, string> env;
   for (const char* key : {"LD_LIBRARY_PATH", "PATH"}) {
     const char* value = getenv(key);
     if (value)
       env.emplace(key, value);
   }

   proc->RedirectUsingPipe(STDOUT_FILENO, false);
   proc->SetPreExecCallback(base::Bind(&SetupChild, env, flags));

   return proc->Start();
 }

 }  // namespace

 void Subprocess::Init(
       chromeos::AsynchronousSignalHandlerInterface* async_signal_handler) {
   if (subprocess_singleton_ == this)
     return;
   CHECK(subprocess_singleton_ == nullptr);
   subprocess_singleton_ = this;

   process_reaper_.Register(async_signal_handler);
 }

 Subprocess::~Subprocess() {
   if (subprocess_singleton_ == this)
     subprocess_singleton_ = nullptr;
 }

 void Subprocess::OnStdoutReady(SubprocessRecord* record) {
   char buf[1024];
   ssize_t rc = 0;
   do {
     rc = HANDLE_EINTR(read(record->stdout_fd, buf, arraysize(buf)));
     if (rc < 0) {
       // EAGAIN and EWOULDBLOCK are normal return values when there's no more
       // input as we are in non-blocking mode.
       if (errno != EWOULDBLOCK && errno != EAGAIN) {
         PLOG(ERROR) << "Error reading fd " << record->stdout_fd;
         MessageLoop::current()->CancelTask(record->stdout_task_id);
         record->stdout_task_id = MessageLoop::kTaskIdNull;
       }
     } else if (rc == 0) {
       // A value of 0 means that the child closed its end of the pipe and there
       // is nothing else to read from stdout.
       MessageLoop::current()->CancelTask(record->stdout_task_id);
       record->stdout_task_id = MessageLoop::kTaskIdNull;
     } else {
       record->stdout.append(buf, rc);
     }
   } while (rc > 0);
 }

 void Subprocess::ChildExitedCallback(const siginfo_t& info) {
   auto pid_record = subprocess_records_.find(info.si_pid);
   if (pid_record == subprocess_records_.end())
     return;
   SubprocessRecord* record = pid_record->second.get();

   // Make sure we read any remaining process output and then close the pipe.
   OnStdoutReady(record);

   MessageLoop::current()->CancelTask(record->stdout_task_id);
   record->stdout_task_id = MessageLoop::kTaskIdNull;

   // Release and close all the pipes now.
   record->proc.Release();
   record->proc.Reset(0);

   // Don't print any log if the subprocess exited with exit code 0.
   if (info.si_code != CLD_EXITED) {
     LOG(INFO) << "Subprocess terminated with si_code " << info.si_code;
   } else if (info.si_status != 0) {
     LOG(INFO) << "Subprocess exited with si_status: " << info.si_status;
   }

   if (!record->stdout.empty()) {
     LOG(INFO) << "Subprocess output:\n" << record->stdout;
   }
   if (!record->callback.is_null()) {
     record->callback.Run(info.si_status, record->stdout);
   }
   subprocess_records_.erase(pid_record);
 }

 pid_t Subprocess::Exec(const vector<string>& cmd,
                        const ExecCallback& callback) {
   return ExecFlags(cmd, kRedirectStderrToStdout, callback);
 }

 pid_t Subprocess::ExecFlags(const vector<string>& cmd,
                             uint32_t flags,
                             const ExecCallback& callback) {
   unique_ptr<SubprocessRecord> record(new SubprocessRecord(callback));

   if (!LaunchProcess(cmd, flags, &record->proc)) {
     LOG(ERROR) << "Failed to launch subprocess";
     return 0;
   }

   pid_t pid = record->proc.pid();
   CHECK(process_reaper_.WatchForChild(FROM_HERE, pid, base::Bind(
       &Subprocess::ChildExitedCallback,
       base::Unretained(this))));

   record->stdout_fd = record->proc.GetPipe(STDOUT_FILENO);
   // Capture the subprocess output. Make our end of the pipe non-blocking.
   int fd_flags = fcntl(record->stdout_fd, F_GETFL, 0) | O_NONBLOCK;
   if (HANDLE_EINTR(fcntl(record->stdout_fd, F_SETFL, fd_flags)) < 0) {
     LOG(ERROR) << "Unable to set non-blocking I/O mode on fd "
                << record->stdout_fd << ".";
   }

   record->stdout_task_id = MessageLoop::current()->WatchFileDescriptor(
       FROM_HERE,
       record->stdout_fd,
       MessageLoop::WatchMode::kWatchRead,
       true,
       base::Bind(&Subprocess::OnStdoutReady, record.get()));

   subprocess_records_[pid].reset(record.release());
   return pid;
 }

 void Subprocess::KillExec(pid_t pid) {
   auto pid_record = subprocess_records_.find(pid);
   if (pid_record == subprocess_records_.end())
     return;
   pid_record->second->callback.Reset();
   kill(pid, SIGTERM);
 }

 bool Subprocess::SynchronousExec(const vector<string>& cmd,
                                  int* return_code,
                                  string* stdout) {
   // The default for SynchronousExec is to use kSearchPath since the code relies
   // on that.
   return SynchronousExecFlags(
       cmd,
       kRedirectStderrToStdout | kSearchPath,
       return_code,
       stdout);
 }

 bool Subprocess::SynchronousExecFlags(const vector<string>& cmd,
                                       uint32_t flags,
                                       int* return_code,
                                       string* stdout) {
   chromeos::ProcessImpl proc;
   if (!LaunchProcess(cmd, flags, &proc)) {
     LOG(ERROR) << "Failed to launch subprocess";
     return false;
   }

   if (stdout) {
     stdout->clear();
   }

   int fd = proc.GetPipe(STDOUT_FILENO);
   vector<char> buffer(32 * 1024);
   while (true) {
     int rc = HANDLE_EINTR(read(fd, buffer.data(), buffer.size()));
     if (rc < 0) {
       PLOG(ERROR) << "Reading from child's output";
       break;
     } else if (rc == 0) {
       break;
     } else {
       if (stdout)
         stdout->append(buffer.data(), rc);
     }
   }
   // At this point, the subprocess already closed the output, so we only need to
   // wait for it to finish.
   int proc_return_code = proc.Wait();
   if (return_code)
     *return_code = proc_return_code;
   return proc_return_code != chromeos::Process::kErrorExitStatus;
 }

 bool Subprocess::SubprocessInFlight() {
   for (const auto& pid_record : subprocess_records_) {
     if (!pid_record.second->callback.is_null())
       return true;
   }
   return false;
 }

 Subprocess* Subprocess::subprocess_singleton_ = nullptr;

 }  // namespace chromeos_update_engine
	//
	// Copyright (C) 2012 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 "update_engine/subprocess.h"

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

	#include <memory>
	#include <string>
	#include <vector>

	#include <base/bind.h>
	#include <base/logging.h>
	#include <base/posix/eintr_wrapper.h>
	#include <base/strings/string_util.h>
	#include <base/strings/stringprintf.h>
	#include <chromeos/process.h>
	#include <chromeos/secure_blob.h>

	using chromeos::MessageLoop;
	using std::string;
	using std::unique_ptr;
	using std::vector;

	namespace chromeos_update_engine {

	namespace {

	bool SetupChild(const std::map<string, string>& env, uint32_t flags) {
	// Setup the environment variables.
	clearenv();
	for (const auto& key_value : env) {
	setenv(key_value.first.c_str(), key_value.second.c_str(), 0);
	}

	if ((flags & Subprocess::kRedirectStderrToStdout) != 0) {
	if (HANDLE_EINTR(dup2(STDOUT_FILENO, STDERR_FILENO)) != STDERR_FILENO)
	return false;
	}

	int fd = HANDLE_EINTR(open("/dev/null", O_RDONLY));
	if (fd < 0)
	return false;
	if (HANDLE_EINTR(dup2(fd, STDIN_FILENO)) != STDIN_FILENO)
	return false;
	IGNORE_EINTR(close(fd));

	return true;
	}

	// Helper function to launch a process with the given Subprocess::Flags.
	// This function only sets up and starts the process according to the \|flags\|.
	// The caller is responsible for watching the termination of the subprocess.
	// Return whether the process was successfully launched and fills in the \|proc\|
	// Process.
	bool LaunchProcess(const vector<string>& cmd,
	uint32_t flags,
	chromeos::Process* proc) {
	for (const string& arg : cmd)
	proc->AddArg(arg);
	proc->SetSearchPath((flags & Subprocess::kSearchPath) != 0);

	// Create an environment for the child process with just the required PATHs.
	std::map<string, string> env;
	for (const char* key : {"LD_LIBRARY_PATH", "PATH"}) {
	const char* value = getenv(key);
	if (value)
	env.emplace(key, value);
	}

	proc->RedirectUsingPipe(STDOUT_FILENO, false);
	proc->SetPreExecCallback(base::Bind(&SetupChild, env, flags));

	return proc->Start();
	}

	} // namespace

	void Subprocess::Init(
	chromeos::AsynchronousSignalHandlerInterface* async_signal_handler) {
	if (subprocess_singleton_ == this)
	return;
	CHECK(subprocess_singleton_ == nullptr);
	subprocess_singleton_ = this;

	process_reaper_.Register(async_signal_handler);
	}

	Subprocess::~Subprocess() {
	if (subprocess_singleton_ == this)
	subprocess_singleton_ = nullptr;
	}

	void Subprocess::OnStdoutReady(SubprocessRecord* record) {
	char buf[1024];
	ssize_t rc = 0;
	do {
	rc = HANDLE_EINTR(read(record->stdout_fd, buf, arraysize(buf)));
	if (rc < 0) {
	// EAGAIN and EWOULDBLOCK are normal return values when there's no more
	// input as we are in non-blocking mode.
	if (errno != EWOULDBLOCK && errno != EAGAIN) {
	PLOG(ERROR) << "Error reading fd " << record->stdout_fd;
	MessageLoop::current()->CancelTask(record->stdout_task_id);
	record->stdout_task_id = MessageLoop::kTaskIdNull;
	}
	} else if (rc == 0) {
	// A value of 0 means that the child closed its end of the pipe and there
	// is nothing else to read from stdout.
	MessageLoop::current()->CancelTask(record->stdout_task_id);
	record->stdout_task_id = MessageLoop::kTaskIdNull;
	} else {
	record->stdout.append(buf, rc);
	}
	} while (rc > 0);
	}

	void Subprocess::ChildExitedCallback(const siginfo_t& info) {
	auto pid_record = subprocess_records_.find(info.si_pid);
	if (pid_record == subprocess_records_.end())
	return;
	SubprocessRecord* record = pid_record->second.get();

	// Make sure we read any remaining process output and then close the pipe.
	OnStdoutReady(record);

	MessageLoop::current()->CancelTask(record->stdout_task_id);
	record->stdout_task_id = MessageLoop::kTaskIdNull;

	// Release and close all the pipes now.
	record->proc.Release();
	record->proc.Reset(0);

	// Don't print any log if the subprocess exited with exit code 0.
	if (info.si_code != CLD_EXITED) {
	LOG(INFO) << "Subprocess terminated with si_code " << info.si_code;
	} else if (info.si_status != 0) {
	LOG(INFO) << "Subprocess exited with si_status: " << info.si_status;
	}

	if (!record->stdout.empty()) {
	LOG(INFO) << "Subprocess output:\n" << record->stdout;
	}
	if (!record->callback.is_null()) {
	record->callback.Run(info.si_status, record->stdout);
	}
	subprocess_records_.erase(pid_record);
	}

	pid_t Subprocess::Exec(const vector<string>& cmd,
	const ExecCallback& callback) {
	return ExecFlags(cmd, kRedirectStderrToStdout, callback);
	}

	pid_t Subprocess::ExecFlags(const vector<string>& cmd,
	uint32_t flags,
	const ExecCallback& callback) {
	unique_ptr<SubprocessRecord> record(new SubprocessRecord(callback));

	if (!LaunchProcess(cmd, flags, &record->proc)) {
	LOG(ERROR) << "Failed to launch subprocess";
	return 0;
	}

	pid_t pid = record->proc.pid();
	CHECK(process_reaper_.WatchForChild(FROM_HERE, pid, base::Bind(
	&Subprocess::ChildExitedCallback,
	base::Unretained(this))));

	record->stdout_fd = record->proc.GetPipe(STDOUT_FILENO);
	// Capture the subprocess output. Make our end of the pipe non-blocking.
	int fd_flags = fcntl(record->stdout_fd, F_GETFL, 0) \| O_NONBLOCK;
	if (HANDLE_EINTR(fcntl(record->stdout_fd, F_SETFL, fd_flags)) < 0) {
	LOG(ERROR) << "Unable to set non-blocking I/O mode on fd "
	<< record->stdout_fd << ".";
	}

	record->stdout_task_id = MessageLoop::current()->WatchFileDescriptor(
	FROM_HERE,
	record->stdout_fd,
	MessageLoop::WatchMode::kWatchRead,
	true,
	base::Bind(&Subprocess::OnStdoutReady, record.get()));

	subprocess_records_[pid].reset(record.release());
	return pid;
	}

	void Subprocess::KillExec(pid_t pid) {
	auto pid_record = subprocess_records_.find(pid);
	if (pid_record == subprocess_records_.end())
	return;
	pid_record->second->callback.Reset();
	kill(pid, SIGTERM);
	}

	bool Subprocess::SynchronousExec(const vector<string>& cmd,
	int* return_code,
	string* stdout) {
	// The default for SynchronousExec is to use kSearchPath since the code relies
	// on that.
	return SynchronousExecFlags(
	cmd,
	kRedirectStderrToStdout \| kSearchPath,
	return_code,
	stdout);
	}

	bool Subprocess::SynchronousExecFlags(const vector<string>& cmd,
	uint32_t flags,
	int* return_code,
	string* stdout) {
	chromeos::ProcessImpl proc;
	if (!LaunchProcess(cmd, flags, &proc)) {
	LOG(ERROR) << "Failed to launch subprocess";
	return false;
	}

	if (stdout) {
	stdout->clear();
	}

	int fd = proc.GetPipe(STDOUT_FILENO);
	vector<char> buffer(32 * 1024);
	while (true) {
	int rc = HANDLE_EINTR(read(fd, buffer.data(), buffer.size()));
	if (rc < 0) {
	PLOG(ERROR) << "Reading from child's output";
	break;
	} else if (rc == 0) {
	break;
	} else {
	if (stdout)
	stdout->append(buffer.data(), rc);
	}
	}
	// At this point, the subprocess already closed the output, so we only need to
	// wait for it to finish.
	int proc_return_code = proc.Wait();
	if (return_code)
	*return_code = proc_return_code;
	return proc_return_code != chromeos::Process::kErrorExitStatus;
	}

	bool Subprocess::SubprocessInFlight() {
	for (const auto& pid_record : subprocess_records_) {
	if (!pid_record.second->callback.is_null())
	return true;
	}
	return false;
	}

	Subprocess* Subprocess::subprocess_singleton_ = nullptr;

	} // namespace chromeos_update_engine