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#include <EventsSourceSpawner.h>
#include <memory>
#include <cstring>
#include <utils.h>
extern "C"
{
#include <unistd.h>
#include <signal.h>
#include <spawn.h>
#include <fcntl.h>
#include <sys/wait.h>
#include <errno.h>
}
const char* EventsSourceSpawner::EVENTS_PROGRAM = "drbdsetup";
const char* EventsSourceSpawner::EVENTS_PROGRAM_ARGS[] =
{
"drbdsetup",
"events2",
"all",
nullptr
};
EventsSourceSpawner::EventsSourceSpawner(MessageLog& logRef):
log(logRef)
{
}
EventsSourceSpawner::~EventsSourceSpawner()
{
try
{
cleanup_child_processes_impl();
}
catch (EventsSourceException&)
{
// Triggered by cleanup_child_processes_impl() if the events source
// process tracked by this instance exited
}
terminate_child_process();
int io_flags = fcntl(STDIN_FILENO, F_GETFL, 0);
fcntl(STDIN_FILENO, F_SETFL, io_flags & ~O_NONBLOCK);
}
pid_t EventsSourceSpawner::get_process_id()
{
return spawned_pid;
}
int EventsSourceSpawner::get_events_out_fd()
{
return out_pipe_fd[posix::PIPE_READ_SIDE];
}
int EventsSourceSpawner::get_events_err_fd()
{
return err_pipe_fd[posix::PIPE_READ_SIDE];
}
// @throws std::bad_alloc, EventSourceException
void EventsSourceSpawner::spawn_source()
{
// Initialize the pipes
posix::Pipe out_pipe_mgr(&out_pipe_fd);
posix::Pipe err_pipe_mgr(&err_pipe_fd);
// Make the pipes' read end nonblocking
set_nonblocking(out_pipe_fd[posix::PIPE_READ_SIDE]);
set_nonblocking(err_pipe_fd[posix::PIPE_READ_SIDE]);
// Make stdin nonblocking
set_nonblocking(STDIN_FILENO);
// Initialize the datastructures for posix_spawn())
posix::SpawnFileActions pipe_init;
posix::SpawnAttr spawn_attr;
posix::SpawnArgs spawn_args(EVENTS_PROGRAM_ARGS);
// Redirect stdout to the pipes write side
checked_int_rc(
posix_spawn_file_actions_adddup2(
pipe_init.actions,
out_pipe_fd[posix::PIPE_WRITE_SIDE],
STDOUT_FILENO
)
);
checked_int_rc(
posix_spawn_file_actions_adddup2(
pipe_init.actions,
err_pipe_fd[posix::PIPE_WRITE_SIDE],
STDERR_FILENO
)
);
// Close the read end of the pipes
checked_int_rc(
posix_spawn_file_actions_addclose(
pipe_init.actions,
out_pipe_fd[posix::PIPE_READ_SIDE]
)
);
checked_int_rc(
posix_spawn_file_actions_addclose(
pipe_init.actions,
err_pipe_fd[posix::PIPE_READ_SIDE]
)
);
// Reset ignored signals to the default action
sigset_t mask;
checked_int_rc(sigemptyset(&mask));
checked_int_rc(sigaddset(&mask, SIGTERM));
checked_int_rc(sigaddset(&mask, SIGHUP));
checked_int_rc(sigaddset(&mask, SIGINT));
checked_int_rc(sigaddset(&mask, SIGWINCH));
checked_int_rc(sigaddset(&mask, SIGCHLD));
checked_int_rc(posix_spawnattr_setsigdefault(spawn_attr.attr, &mask));
checked_int_rc(posix_spawnattr_setflags(spawn_attr.attr, POSIX_SPAWN_SETSIGDEF));
// Attempt to spawn the events source program
int spawn_rc = posix_spawnp(&spawned_pid, EVENTS_PROGRAM, pipe_init.actions, spawn_attr.attr,
spawn_args.args, environ);
if (spawn_rc != 0)
{
spawned_pid = -1;
log.add_entry(
MessageLog::log_level::ALERT,
"Spawning the events source process failed"
);
throw EventsSourceException();
}
// Close the local write side of the pipes
out_pipe_mgr.close_write_side();
err_pipe_mgr.close_write_side();
// Keep the pipes open when leaving scope
out_pipe_mgr.release();
err_pipe_mgr.release();
}
// @throws EventsSourceException
void EventsSourceSpawner::cleanup_child_processes()
{
cleanup_child_processes_impl();
}
// @throws EventsSourceException
void EventsSourceSpawner::cleanup_child_processes_impl()
{
// Cleanup any child processes that have exited (zombie processes))
pid_t child_pid {0};
do
{
int exit_status;
child_pid = waitpid(-1, &exit_status, WNOHANG);
if (spawned_pid != -1 && child_pid == spawned_pid &&
(WIFEXITED(exit_status) || WIFSIGNALED(exit_status)))
{
// Events source process exited, throw an EventsSourceException
// to trigger reinitialization of the application and
// thereby a respawn of the events source process
spawned_pid = -1;
throw EventsSourceException();
}
}
while (child_pid > 0);
}
void EventsSourceSpawner::terminate_child_process() noexcept
{
// Unless the child process exited already or was not ever spawned,
// tell the child process to terminate
if (spawned_pid != -1)
{
static_cast<void> (kill(spawned_pid, SIGTERM));
}
}
// Sets O_NONBLOCK on the specified filedescriptor
void EventsSourceSpawner::set_nonblocking(int fd)
{
int io_flags = fcntl(fd, F_GETFL, 0);
fcntl(fd, F_SETFL, io_flags | O_NONBLOCK);
}
// Throws EventsSourceException if rc is not equal to 0
// @throws EventsSourceException
void EventsSourceSpawner::checked_int_rc(int rc) const
{
if (rc != 0)
{
throw EventsSourceException();
}
}
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