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extern crate libc;
use std::{io, env, ffi, path, process};
#[derive(Debug)]
pub enum Error {
FirstFork(Option<i32>),
SecondFork(Option<i32>),
Setsid(Option<i32>),
Chdir(io::Error),
FilenameToStr(path::PathBuf),
FilenameFFI(path::PathBuf, ffi::NulError),
OpenStd(path::PathBuf, Option<i32>),
Dup2(Option<i32>),
}
#[derive(Debug)]
pub enum ChdirMode {
NoChdir,
ChdirRoot,
}
struct Redirected(libc::c_int);
impl Drop for Redirected {
fn drop(&mut self) {
if self.0 >= 0 {
unsafe { libc::close(self.0) };
self.0 = -1;
}
}
}
fn to_path_buf<P>(path: &Option<P>) -> path::PathBuf where P: AsRef<path::Path> {
if let &Some(ref p) = path {
p.as_ref().to_owned()
} else {
let null: &path::Path = "/dev/null".as_ref();
null.to_path_buf()
}
}
fn redirect<P>(std: Option<P>) -> Result<Redirected, Error> where P: AsRef<path::Path> {
let filename = std.as_ref()
.map(|s| s.as_ref().to_str())
.unwrap_or(Some("/dev/null"))
.ok_or(Error::FilenameToStr(to_path_buf(&std)));
let path = try!(ffi::CString::new(try!(filename)).map_err(|e| Error::FilenameFFI(to_path_buf(&std), e)));
let fd = unsafe { libc::open(path.as_ptr(),
libc::O_CREAT | libc::O_WRONLY | libc::O_APPEND,
(libc::S_IRUSR | libc::S_IRGRP | libc::S_IWGRP | libc::S_IWUSR) as libc::c_uint) };
if fd < 0 {
Err(Error::OpenStd(to_path_buf(&std), io::Error::last_os_error().raw_os_error()))
} else {
Ok(Redirected(fd))
}
}
pub fn daemonize_redirect<PO, PE>(stdout: Option<PO>, stderr: Option<PE>, chdir: ChdirMode) -> Result<libc::pid_t, Error>
where PO: AsRef<path::Path>, PE: AsRef<path::Path>
{
daemonize(try!(redirect(stdout)), try!(redirect(stderr)), chdir)
}
fn daemonize(mut stdout_fd: Redirected, mut stderr_fd: Redirected, chdir: ChdirMode) -> Result<libc::pid_t, Error> {
macro_rules! errno {
($err:ident) => ({ return Err(Error::$err(io::Error::last_os_error().raw_os_error())) })
}
let pid = unsafe { libc::fork() };
if pid < 0 {
errno!(FirstFork)
} else if pid != 0 {
process::exit(0)
}
if unsafe { libc::setsid() } < 0 {
errno!(Setsid)
}
unsafe { libc::signal(libc::SIGHUP, libc::SIG_IGN); }
let pid = unsafe { libc::fork() };
if pid < 0 {
errno!(SecondFork)
} else if pid != 0 {
process::exit(0)
}
if let ChdirMode::ChdirRoot = chdir {
match env::set_current_dir("/") {
Ok(()) => (),
Err(e) => {
return Err(Error::Chdir(e))
},
}
}
if unsafe { libc::dup2(stdout_fd.0, libc::STDOUT_FILENO) } < 0 {
errno!(Dup2)
} else {
stdout_fd.0 = -1
}
if unsafe { libc::dup2(stderr_fd.0, libc::STDERR_FILENO) } < 0 {
errno!(Dup2)
} else {
stderr_fd.0 = -1
}
Ok(unsafe { libc::getpid() })
}