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use std::ffi::OsStr;
use std::fmt::Debug;
use std::io;
#[cfg(not(windows))]
use std::os::unix::process::CommandExt;
#[cfg(windows)]
use std::os::windows::process::CommandExt;
use std::process::{Command, Stdio};
use log::{debug, warn};
#[cfg(windows)]
use winapi::um::winbase::{CREATE_NEW_PROCESS_GROUP, CREATE_NO_WINDOW};
/// Start the daemon and log error on failure.
pub fn start_daemon<I, S>(program: &str, args: I)
where
I: IntoIterator<Item = S> + Debug + Copy,
S: AsRef<OsStr>,
{
match spawn_daemon(program, args) {
Ok(_) => debug!("Launched {} with args {:?}", program, args),
Err(_) => warn!("Unable to launch {} with args {:?}", program, args),
}
}
#[cfg(windows)]
fn spawn_daemon<I, S>(program: &str, args: I) -> io::Result<()>
where
I: IntoIterator<Item = S> + Copy,
S: AsRef<OsStr>,
{
// Setting all the I/O handles to null and setting the
// CREATE_NEW_PROCESS_GROUP and CREATE_NO_WINDOW has the effect
// that console applications will run without opening a new
// console window.
Command::new(program)
.args(args)
.stdin(Stdio::null())
.stdout(Stdio::null())
.stderr(Stdio::null())
.creation_flags(CREATE_NEW_PROCESS_GROUP | CREATE_NO_WINDOW)
.spawn()
.map(|_| ())
}
#[cfg(not(windows))]
fn spawn_daemon<I, S>(program: &str, args: I) -> io::Result<()>
where
I: IntoIterator<Item = S> + Copy,
S: AsRef<OsStr>,
{
unsafe {
Command::new(program)
.args(args)
.stdin(Stdio::null())
.stdout(Stdio::null())
.stderr(Stdio::null())
.pre_exec(|| {
match libc::fork() {
-1 => return Err(io::Error::last_os_error()),
0 => (),
_ => libc::_exit(0),
}
if libc::setsid() == -1 {
return Err(io::Error::last_os_error());
}
Ok(())
})
.spawn()?
.wait()
.map(|_| ())
}
}
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