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// Copyright 2018 Yuya Nishihara <yuya@tcha.org>
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//
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// This software may be used and distributed according to the terms of the
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// GNU General Public License version 2 or any later version.
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//! Low-level utility for signal and process handling.
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use libc::{self, c_int, pid_t, size_t, ssize_t};
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use std::io;
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use std::os::unix::io::RawFd;
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use std::sync;
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#[link(name = "procutil", kind = "static")]
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extern "C" {
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// sendfds.c
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fn sendfds(sockfd: c_int, fds: *const c_int, fdlen: size_t) -> ssize_t;
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// sighandlers.c
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fn setupsignalhandler(pid: pid_t, pgid: pid_t) -> c_int;
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fn restoresignalhandler() -> c_int;
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}
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/// Returns the effective uid of the current process.
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pub fn get_effective_uid() -> u32 {
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unsafe { libc::geteuid() }
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}
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/// Returns the umask of the current process.
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///
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/// # Safety
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///
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/// This is unsafe because the umask value is temporarily changed, and
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/// the change can be observed from the other threads. Don't call this in
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/// multi-threaded context.
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pub unsafe fn get_umask() -> u32 {
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let mask = libc::umask(0);
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libc::umask(mask);
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mask
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}
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/// Changes the given fd to blocking mode.
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pub fn set_blocking_fd(fd: RawFd) -> io::Result<()> {
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let flags = unsafe { libc::fcntl(fd, libc::F_GETFL) };
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if flags < 0 {
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return Err(io::Error::last_os_error());
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}
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let r = unsafe { libc::fcntl(fd, libc::F_SETFL, flags & !libc::O_NONBLOCK) };
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if r < 0 {
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return Err(io::Error::last_os_error());
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}
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Ok(())
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}
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/// Sends file descriptors via the given socket.
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pub fn send_raw_fds(sock_fd: RawFd, fds: &[RawFd]) -> io::Result<()> {
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let r = unsafe { sendfds(sock_fd, fds.as_ptr(), fds.len() as size_t) };
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if r < 0 {
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return Err(io::Error::last_os_error());
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}
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Ok(())
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}
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static SETUP_SIGNAL_HANDLER: sync::Once = sync::Once::new();
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static RESTORE_SIGNAL_HANDLER: sync::Once = sync::Once::new();
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/// Installs signal handlers to forward signals to the server.
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///
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/// # Safety
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///
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/// This touches global states, and thus synchronized as a one-time
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/// initialization function.
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pub fn setup_signal_handler_once(pid: u32, pgid: Option<u32>) -> io::Result<()> {
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let pid_signed = pid as i32;
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let pgid_signed = pgid.map(|n| n as i32).unwrap_or(0);
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let mut r = 0;
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SETUP_SIGNAL_HANDLER.call_once(|| {
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r = unsafe { setupsignalhandler(pid_signed, pgid_signed) };
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});
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if r < 0 {
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return Err(io::Error::last_os_error());
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}
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Ok(())
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}
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/// Restores the original signal handlers.
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///
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/// # Safety
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///
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/// This touches global states, and thus synchronized as a one-time
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/// initialization function.
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pub fn restore_signal_handler_once() -> io::Result<()> {
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let mut r = 0;
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RESTORE_SIGNAL_HANDLER.call_once(|| {
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r = unsafe { restoresignalhandler() };
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});
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if r < 0 {
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return Err(io::Error::last_os_error());
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}
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Ok(())
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}
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