/*
* Copyright © 2013 Canonical Ltd.
*
* This program is free software: you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License version 3,
* as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program. If not, see .
*
* Authored by: Thomas Voß
*/
#include
#ifndef ANDROID
#include
#include
#endif
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#ifndef ANDROID
namespace io = boost::iostreams;
#endif
namespace
{
struct DeathObserverImpl : public core::posix::ChildProcess::DeathObserver
{
DeathObserverImpl(const std::shared_ptr& trap)
: on_sig_child_connection
{
trap->signal_raised().connect([this](core::posix::Signal signal)
{
switch (signal)
{
case core::posix::Signal::sig_chld:
on_sig_child();
break;
default:
break;
}
})
}
{
if (!trap->has(core::posix::Signal::sig_chld))
throw std::logic_error(
"DeathObserver::DeathObserverImpl: Given SignalTrap"
" instance does not trap Signal::sig_chld.");
}
bool add(const core::posix::ChildProcess& process) override
{
if (process.pid() == -1)
return false;
std::lock_guard lg(guard);
bool added = false;
auto new_process = std::make_pair(process.pid(), process);
std::tie(std::ignore, added) = children.insert(new_process);
if (added)
{
// The process may have died between it's instantiation and it
// being added to the children map. Check that it's still alive.
int status{-1};
if (::waitpid(process.pid(), &status, WNOHANG) != 0) // child no longer alive
{
// we missed the SIGCHLD signal so we must now manually
// inform our subscribers.
signals.child_died(new_process.second);
children.erase(new_process.first);
return false;
}
}
return added;
}
bool has(const core::posix::ChildProcess& process) const override
{
std::lock_guard lg(guard);
return children.count(process.pid()) > 0;
}
const core::Signal& child_died() const override
{
return signals.child_died;
}
void on_sig_child() override
{
pid_t pid{-1}; int status{-1};
while (true)
{
pid = ::waitpid(0, &status, WNOHANG);
if (pid == -1)
{
if (errno == ECHILD)
{
break; // No more children
}
continue; // Ignore stray SIGCHLD signals
}
else if (pid == 0)
{
break; // No more children
}
else
{
std::lock_guard lg(guard);
auto it = children.find(pid);
if (it != children.end())
{
if (WIFSIGNALED(status) || WIFEXITED(status))
{
signals.child_died(it->second);
children.erase(it);
}
}
}
}
}
mutable std::mutex guard;
std::unordered_map children;
core::ScopedConnection on_sig_child_connection;
struct
{
core::Signal child_died;
} signals;
};
}
std::unique_ptr
core::posix::ChildProcess::DeathObserver::create_once_with_signal_trap(
std::shared_ptr trap)
{
static std::atomic has_been_created_once{false};
if (has_been_created_once.exchange(true))
throw std::runtime_error
{
"DeathObserver::create_once_with_signal_trap: "
"Cannot create more than one instance."
};
try
{
std::unique_ptr result
{
new DeathObserverImpl{trap}
};
return result;
} catch(...)
{
// We make sure that a throwing c'tor does not impact our ability to
// retry creation of a DeathObserver instance.
has_been_created_once.store(false);
std::rethrow_exception(std::current_exception());
}
assert(false && "We should never reach here.");
// Silence the compiler.
return std::unique_ptr{};
}
namespace core
{
namespace posix
{
ChildProcess::Pipe ChildProcess::Pipe::invalid()
{
static Pipe p;
static std::once_flag flag;
std::call_once(flag, [&]() { p.close_read_fd(); p.close_write_fd(); });
return p;
}
ChildProcess::Pipe::Pipe()
{
int rc = ::pipe(fds);
if (rc == -1)
throw std::system_error(errno, std::system_category());
}
ChildProcess::Pipe::Pipe(const ChildProcess::Pipe& rhs) : fds{-1, -1}
{
if (rhs.fds[0] != -1)
fds[0] = ::dup(rhs.fds[0]);
if (rhs.fds[1] != -1)
fds[1] = ::dup(rhs.fds[1]);
}
ChildProcess::Pipe::~Pipe()
{
if (fds[0] != -1)
::close(fds[0]);
if (fds[1] != -1)
::close(fds[1]);
}
int ChildProcess::Pipe::read_fd() const
{
return fds[0];
}
void ChildProcess::Pipe::close_read_fd()
{
if (fds[0] != -1)
{
::close(fds[0]);
fds[0] = -1;
}
}
int ChildProcess::Pipe::write_fd() const
{
return fds[1];
}
void ChildProcess::Pipe::close_write_fd()
{
if (fds[1] != -1)
{
::close(fds[1]);
fds[1] = -1;
}
}
ChildProcess::Pipe& ChildProcess::Pipe::operator=(const ChildProcess::Pipe& rhs)
{
if (fds[0] != -1)
::close(fds[0]);
if (fds[1] != -1)
::close(fds[1]);
if (rhs.fds[0] != -1)
fds[0] = ::dup(rhs.fds[0]);
else
fds[0] = -1;
if (rhs.fds[1] != -1)
fds[1] = ::dup(rhs.fds[1]);
else
fds[1] = -1;
return *this;
}
struct ChildProcess::Private
{
// stdin and stdout are always "relative" to the childprocess, i.e., we
// write to stdin of the child process and read from its stdout.
Private(pid_t pid,
const ChildProcess::Pipe& stderr,
const ChildProcess::Pipe& stdin,
const ChildProcess::Pipe& stdout)
: pipes{stderr, stdin, stdout},
#ifndef ANDROID
serr(pipes.stderr.read_fd(), io::never_close_handle),
sin(pipes.stdin.write_fd(), io::never_close_handle),
sout(pipes.stdout.read_fd(), io::never_close_handle),
cerr(&serr),
cin(&sin),
cout(&sout),
#endif
original_parent_pid(::getpid()),
original_child_pid(pid)
{
}
~Private()
{
// Check if we are in the original parent process.
if (original_parent_pid == getpid() && !dont_kill_on_cleanup)
{
// If so, check if we are considering a valid pid here.
// If so, we kill the original child.
if (original_child_pid != -1)
::kill(original_child_pid, SIGKILL);
}
}
struct
{
ChildProcess::Pipe stdin;
ChildProcess::Pipe stdout;
ChildProcess::Pipe stderr;
} pipes;
#ifndef ANDROID
io::stream_buffer serr;
io::stream_buffer sin;
io::stream_buffer sout;
std::istream cerr;
std::ostream cin;
std::istream cout;
#endif
// We need to store the original parent pid as we might have been forked
// and with our automatic cleanup in place, it might happen that the d'tor
// is called from the child process.
pid_t original_parent_pid;
pid_t original_child_pid;
bool dont_kill_on_cleanup = false;
};
ChildProcess ChildProcess::invalid()
{
// We take the init process as child.
static const pid_t invalid_pid = 1;
return ChildProcess(invalid_pid, Pipe::invalid(), Pipe::invalid(), Pipe::invalid());
}
ChildProcess::ChildProcess(pid_t pid,
const ChildProcess::Pipe& stdin_pipe,
const ChildProcess::Pipe& stdout_pipe,
const ChildProcess::Pipe& stderr_pipe)
: Process(pid),
d(new Private{pid, stdin_pipe, stdout_pipe, stderr_pipe})
{
}
ChildProcess::~ChildProcess()
{
}
wait::Result ChildProcess::wait_for(const wait::Flags& flags)
{
int status = -1;
pid_t result_pid = ::waitpid(pid(), std::addressof(status), static_cast(flags));
if (result_pid == -1)
throw std::system_error(errno, std::system_category());
wait::Result result;
if (result_pid == 0)
{
result.status = wait::Result::Status::no_state_change;
return result;
}
if (WIFEXITED(status))
{
result.status = wait::Result::Status::exited;
result.detail.if_exited.status = static_cast(WEXITSTATUS(status));
} else if (WIFSIGNALED(status))
{
result.status = wait::Result::Status::signaled;
result.detail.if_signaled.signal = static_cast(WTERMSIG(status));
result.detail.if_signaled.core_dumped = WCOREDUMP(status);
} else if (WIFSTOPPED(status))
{
result.status = wait::Result::Status::stopped;
result.detail.if_stopped.signal = static_cast(WSTOPSIG(status));
}
#ifndef ANDROID
else if (WIFCONTINUED(status))
{
result.status = wait::Result::Status::continued;
}
#endif
return result;
}
void ChildProcess::dont_kill_on_cleanup()
{
d->dont_kill_on_cleanup = true;
}
#ifndef ANDROID
std::istream& ChildProcess::cerr()
{
return d->cerr;
}
std::ostream& ChildProcess::cin()
{
return d->cin;
}
std::istream& ChildProcess::cout()
{
return d->cout;
}
#endif
}
}