Add support for capturing stdout/err in Application
This also makes it so that the Application object can poll instead of
just relying on SIGCHLD to watch for application stops, to make it a bit
cleaner for simple use-cases.
Change-Id: I8af71e1dd89e0cfa1b189ba1e5264df0df9b9560
Signed-off-by: James Kuszmaul <james.kuszmaul@bluerivertech.com>
diff --git a/aos/starter/subprocess.cc b/aos/starter/subprocess.cc
index e68f604..c1eb618 100644
--- a/aos/starter/subprocess.cc
+++ b/aos/starter/subprocess.cc
@@ -34,21 +34,12 @@
SignalListener::~SignalListener() { loop_->epoll()->DeleteFd(signalfd_.fd()); }
-Application::Application(const aos::Application *application,
+Application::Application(std::string_view name,
+ std::string_view executable_name,
aos::EventLoop *event_loop,
std::function<void()> on_change)
- : name_(application->name()->string_view()),
- path_(application->has_executable_name()
- ? application->executable_name()->string_view()
- : application->name()->string_view()),
- args_(1),
- user_name_(application->has_user() ? application->user()->str() : ""),
- user_(application->has_user() ? FindUid(user_name_.c_str())
- : std::nullopt),
- group_(application->has_user() ? FindPrimaryGidForUser(user_name_.c_str())
- : std::nullopt),
- autostart_(application->autostart()),
- autorestart_(application->autorestart()),
+ : name_(name),
+ path_(executable_name),
event_loop_(event_loop),
start_timer_(event_loop_->AddTimer([this] {
status_ = aos::starter::State::RUNNING;
@@ -61,7 +52,37 @@
<< "' pid: " << pid_;
}
})),
- on_change_(on_change) {}
+ pipe_timer_(event_loop_->AddTimer([this]() { FetchOutputs(); })),
+ child_status_handler_(
+ event_loop_->AddTimer([this]() { MaybeHandleSignal(); })),
+ on_change_(on_change) {
+ event_loop_->OnRun([this]() {
+ // Every second poll to check if the child is dead. This is used as a
+ // default for the case where the user is not directly catching SIGCHLD and
+ // calling MaybeHandleSignal for us.
+ child_status_handler_->Setup(event_loop_->monotonic_now(),
+ std::chrono::seconds(1));
+ });
+}
+
+Application::Application(const aos::Application *application,
+ aos::EventLoop *event_loop,
+ std::function<void()> on_change)
+ : Application(application->name()->string_view(),
+ application->has_executable_name()
+ ? application->executable_name()->string_view()
+ : application->name()->string_view(),
+ event_loop, on_change) {
+ user_name_ = application->has_user() ? application->user()->str() : "";
+ user_ = application->has_user() ? FindUid(user_name_.c_str()) : std::nullopt;
+ group_ = application->has_user() ? FindPrimaryGidForUser(user_name_.c_str())
+ : std::nullopt;
+ autostart_ = application->autostart();
+ autorestart_ = application->autorestart();
+ if (application->has_args()) {
+ set_args(*application->args());
+ }
+}
void Application::DoStart() {
if (status_ != aos::starter::State::WAITING) {
@@ -71,7 +92,19 @@
start_timer_->Disable();
restart_timer_->Disable();
- std::tie(read_pipe_, write_pipe_) = util::ScopedPipe::MakePipe();
+ status_pipes_ = util::ScopedPipe::MakePipe();
+
+ if (capture_stdout_) {
+ stdout_pipes_ = util::ScopedPipe::MakePipe();
+ stdout_.clear();
+ }
+ if (capture_stderr_) {
+ stderr_pipes_ = util::ScopedPipe::MakePipe();
+ stderr_.clear();
+ }
+
+ pipe_timer_->Setup(event_loop_->monotonic_now(),
+ std::chrono::milliseconds(100));
const pid_t pid = fork();
@@ -91,11 +124,23 @@
// alive in 1 second.
start_timer_->Setup(event_loop_->monotonic_now() +
std::chrono::seconds(1));
+ // Since we are the parent process, clear our write-side of all the pipes.
+ status_pipes_.write.reset();
+ stdout_pipes_.write.reset();
+ stderr_pipes_.write.reset();
}
on_change_();
return;
}
+ // Since we are the child process, clear our read-side of all the pipes.
+ status_pipes_.read.reset();
+ stdout_pipes_.read.reset();
+ stderr_pipes_.read.reset();
+
+ // The status pipe will not be needed if the execve succeeds.
+ status_pipes_.write->SetCloexec();
+
// Clear out signal mask of parent so forked process receives all signals
// normally.
sigset_t empty_mask;
@@ -104,7 +149,7 @@
// Cleanup children if starter dies in a way that is not handled gracefully.
if (prctl(PR_SET_PDEATHSIG, SIGKILL) == -1) {
- write_pipe_.Write(
+ status_pipes_.write->Write(
static_cast<uint32_t>(aos::starter::LastStopReason::SET_PRCTL_ERR));
PLOG(FATAL) << "Could not set PR_SET_PDEATHSIG to SIGKILL";
}
@@ -116,19 +161,19 @@
// be set so we change this effective UID back later.
CHECK(user_);
if (seteuid(0) == -1) {
- write_pipe_.Write(
+ status_pipes_.write->Write(
static_cast<uint32_t>(aos::starter::LastStopReason::SET_GRP_ERR));
PLOG(FATAL) << "Could not seteuid(0) for " << name_
<< " in preparation for setting groups";
}
if (initgroups(user_name_.c_str(), *group_) == -1) {
- write_pipe_.Write(
+ status_pipes_.write->Write(
static_cast<uint32_t>(aos::starter::LastStopReason::SET_GRP_ERR));
PLOG(FATAL) << "Could not initialize normal groups for " << name_
<< " as " << user_name_ << " with " << *group_;
}
if (setgid(*group_) == -1) {
- write_pipe_.Write(
+ status_pipes_.write->Write(
static_cast<uint32_t>(aos::starter::LastStopReason::SET_GRP_ERR));
PLOG(FATAL) << "Could not set group for " << name_ << " to " << *group_;
}
@@ -136,31 +181,65 @@
if (user_) {
if (setuid(*user_) == -1) {
- write_pipe_.Write(
+ status_pipes_.write->Write(
static_cast<uint32_t>(aos::starter::LastStopReason::SET_USR_ERR));
PLOG(FATAL) << "Could not set user for " << name_ << " to " << *user_;
}
}
- // argv[0] should be the program name
- args_.insert(args_.begin(), path_.data());
+ if (capture_stdout_) {
+ PCHECK(STDOUT_FILENO == dup2(stdout_pipes_.write->fd(), STDOUT_FILENO));
+ stdout_pipes_.write.reset();
+ }
- execvp(path_.c_str(), args_.data());
+ if (capture_stderr_) {
+ PCHECK(STDERR_FILENO == dup2(stderr_pipes_.write->fd(), STDERR_FILENO));
+ stderr_pipes_.write.reset();
+ }
+
+ // argv[0] should be the program name
+ args_.insert(args_.begin(), path_);
+
+ std::vector<char *> cargs = CArgs();
+ execvp(path_.c_str(), cargs.data());
// If we got here, something went wrong
- write_pipe_.Write(
+ status_pipes_.write->Write(
static_cast<uint32_t>(aos::starter::LastStopReason::EXECV_ERR));
PLOG(WARNING) << "Could not execute " << name_ << " (" << path_ << ')';
_exit(EXIT_FAILURE);
}
+void Application::FetchOutputs() {
+ if (capture_stdout_) {
+ stdout_pipes_.read->Read(&stdout_);
+ }
+ if (capture_stderr_) {
+ stderr_pipes_.read->Read(&stderr_);
+ }
+}
+
+const std::string &Application::GetStdout() {
+ CHECK(capture_stdout_);
+ FetchOutputs();
+ return stdout_;
+}
+
+const std::string &Application::GetStderr() {
+ CHECK(capture_stderr_);
+ FetchOutputs();
+ return stderr_;
+}
+
void Application::DoStop(bool restart) {
// If stop or restart received, the old state of these is no longer applicable
// so cancel both.
restart_timer_->Disable();
start_timer_->Disable();
+ FetchOutputs();
+
switch (status_) {
case aos::starter::State::STARTING:
case aos::starter::State::RUNNING: {
@@ -217,14 +296,31 @@
on_change_();
}
+std::vector<char *> Application::CArgs() {
+ std::vector<char *> cargs;
+ std::transform(args_.begin(), args_.end(), std::back_inserter(cargs),
+ [](std::string &str) { return str.data(); });
+ cargs.push_back(nullptr);
+ return cargs;
+}
+
void Application::set_args(
const flatbuffers::Vector<flatbuffers::Offset<flatbuffers::String>> &v) {
args_.clear();
std::transform(v.begin(), v.end(), std::back_inserter(args_),
- [](const flatbuffers::String *str) {
- return const_cast<char *>(str->c_str());
- });
- args_.push_back(nullptr);
+ [](const flatbuffers::String *str) { return str->str(); });
+}
+
+void Application::set_args(std::vector<std::string> args) {
+ args_ = std::move(args);
+}
+
+void Application::set_capture_stdout(bool capture) {
+ capture_stdout_ = capture;
+}
+
+void Application::set_capture_stderr(bool capture) {
+ capture_stderr_ = capture;
}
std::optional<uid_t> Application::FindUid(const char *name) {
@@ -257,7 +353,9 @@
aos::starter::ApplicationStatus::Builder status_builder(*builder);
status_builder.add_name(name_fbs);
status_builder.add_state(status_);
- status_builder.add_last_exit_code(exit_code_);
+ if (exit_code_.has_value()) {
+ status_builder.add_last_exit_code(exit_code_.value());
+ }
status_builder.add_last_stop_reason(stop_reason_);
if (pid_ != -1) {
status_builder.add_pid(pid_);
@@ -326,38 +424,51 @@
return false;
}
+ start_timer_->Disable();
exit_time_ = event_loop_->monotonic_now();
exit_code_ = WIFEXITED(status) ? WEXITSTATUS(status) : WTERMSIG(status);
- if (auto read_result = read_pipe_.Read()) {
+ if (auto read_result = status_pipes_.read->Read()) {
stop_reason_ = static_cast<aos::starter::LastStopReason>(*read_result);
}
switch (status_) {
case aos::starter::State::STARTING: {
- LOG(WARNING) << "Failed to start '" << name_ << "' on pid " << pid_
- << " : Exited with status " << exit_code_;
+ if (exit_code_.value() == 0) {
+ LOG(INFO) << "Application '" << name_ << "' pid " << pid_
+ << " exited with status " << exit_code_.value();
+ } else {
+ LOG(WARNING) << "Failed to start '" << name_ << "' on pid " << pid_
+ << " : Exited with status " << exit_code_.value();
+ }
if (autorestart()) {
QueueStart();
+ } else {
+ status_ = aos::starter::State::STOPPED;
+ on_change_();
}
break;
}
case aos::starter::State::RUNNING: {
- if (exit_code_ == 0) {
+ if (exit_code_.value() == 0) {
LOG(INFO) << "Application '" << name_ << "' pid " << pid_
- << " exited with status " << exit_code_;
+ << " exited with status " << exit_code_.value();
} else {
LOG(WARNING) << "Application '" << name_ << "' pid " << pid_
- << " exited unexpectedly with status " << exit_code_;
+ << " exited unexpectedly with status "
+ << exit_code_.value();
}
if (autorestart()) {
QueueStart();
+ } else {
+ status_ = aos::starter::State::STOPPED;
+ on_change_();
}
break;
}
case aos::starter::State::STOPPING: {
LOG(INFO) << "Successfully stopped '" << name_ << "' pid: " << pid_
- << " with status " << exit_code_;
+ << " with status " << exit_code_.value();
status_ = aos::starter::State::STOPPED;
// Disable force stop timer since the process already died