237 lines
8.2 KiB
Rust
237 lines
8.2 KiB
Rust
//! Interface for the `NOTIFY_SOCKET` readiness protocol
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//!
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//! The entry point of this module is the [`Notifier`] struct.
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//!
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//! # Example
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//!
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//! ```no_run
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//! # main() -> Result<(), Box<dyn std::error::Error>> {
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//! // Do whatever you need for your service to be ready.
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//! if let Some(notifier) = Notifier::new(true)? {
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//! notifier.notify(&[NotifyState::Ready])?
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//! }
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//! # Ok(())
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//! # }
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//! ```
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use core::fmt::Display;
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use std::env;
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use std::ffi::OsString;
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use std::io::IoSlice;
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use std::os::unix::net::UnixDatagram;
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use rustix::fd::{AsFd, BorrowedFd};
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use self::error::{FdNameError, NewNotifierError, NotifyError, SanityCheckError};
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pub mod error;
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/// A wrapper around the socket specified by `$NOTIFY_SOCKET`
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#[derive(Debug)]
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pub struct Notifier {
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sock_addr: rustix::net::SocketAddrUnix,
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socket: UnixDatagram,
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}
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impl Notifier {
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/// Create a new [`Notifier`].
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///
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/// If `unset_env` is set to `true` this will unset `NOTIFY_SOCKET` resulting in further call to this function to return `Ok(None)`.
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///
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/// Returns `Ok(None)` if notification isn't supported (`NOTIFY_SOCKET` isn't defined).
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///
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/// # Errors
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///
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/// This function error out if the socket couldn't be opened.
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pub fn new(unset_env: bool) -> Result<Option<Self>, NewNotifierError> {
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let env_sock = match env::var_os("NOTIFY_SOCKET") {
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None => return Ok(None),
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Some(v) => v,
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};
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if unset_env {
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env::remove_var("NOTIFY_SOCKET");
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}
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// If the first character of `$NOTIFY_SOCKET` is '@', the string
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// is understood as Linux abstract namespace socket.
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let socket_addr = match env_sock.as_encoded_bytes().strip_prefix(b"@").map(|v| {
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// SAFETY:
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// - Only strip ASCII '@' which is a non-empty UTF-8 substring
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unsafe { OsString::from_encoded_bytes_unchecked(v.to_vec()) }
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}) {
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Some(stripped_addr) => {
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rustix::net::SocketAddrUnix::new_abstract_name(stripped_addr.as_encoded_bytes())
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.map_err(NewNotifierError::InvalidAbstractSocket)?
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}
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None => rustix::net::SocketAddrUnix::new(env_sock)
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.map_err(NewNotifierError::InvalidSocketPath)?,
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};
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let socket = UnixDatagram::unbound().map_err(NewNotifierError::CouldntOpenSocket)?;
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let ret = Self {
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sock_addr: socket_addr,
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socket,
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};
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Ok(Some(ret))
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}
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/// Notify service manager about status change and send file descriptors.
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///
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/// Use this together with [`NotifyState::FdStore`]. Otherwise works like [`Notifier::notify()`].
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///
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/// # Errors
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///
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/// This function will error out if the passed [`NotifyState`] do not follow the rules set by systemd or if they couldn't be fully sent.
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pub fn notify_with_fds(
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&self,
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state: &[NotifyState<'_>],
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fds: &[BorrowedFd],
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) -> Result<(), NotifyError> {
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state.iter().try_for_each(NotifyState::sanity_check)?;
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let msg = state
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.iter()
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.fold(String::new(), |acc, state| format!("{acc}{state}\n"))
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.into_bytes();
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let msg_len = msg.len();
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let msg_iov = IoSlice::new(&msg);
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let mut ancillary = if !fds.is_empty() {
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let mut ancillary = rustix::net::SendAncillaryBuffer::default();
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let tmp = rustix::net::SendAncillaryMessage::ScmRights(fds);
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if !ancillary.push(tmp) {
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return Err(NotifyError::PushAncillaryMessage);
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}
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ancillary
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} else {
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rustix::net::SendAncillaryBuffer::default()
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};
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let sent_len = rustix::net::sendmsg_unix(
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self.socket.as_fd(),
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&self.sock_addr,
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&[msg_iov],
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&mut ancillary,
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rustix::net::SendFlags::empty(),
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)
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.map_err(NotifyError::SendMsg)?;
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if sent_len != msg_len {
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return Err(NotifyError::PartialSend);
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}
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Ok(())
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}
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/// Notify service manager about status changes.
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///
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/// Send a notification to the manager about service status changes. Also see [`Notifier::notify_with_fds()`] to send file descriptors.
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///
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/// # Errors
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///
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/// This function will error out if the passed [`NotifyState`] do not follow the rules set by systemd or if they couldn't be fully sent.
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pub fn notify(&self, state: &[NotifyState<'_>]) -> Result<(), NotifyError> {
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self.notify_with_fds(state, &[])
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}
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}
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/// Status changes, see sd_notify(3).
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#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
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pub enum NotifyState<'a> {
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/// D-Bus error-style error code.
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BusError(&'a str),
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/// errno-style error code.
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Errno(u8),
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/// A name for the submitted file descriptors.
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FdName(&'a str),
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/// Stores additional file descriptors in the service manager. Use [`Notifier::notify_with_fds()`] with this.
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FdStore,
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/// Remove stored file descriptors. Must be used together with [`NotifyState::FdName`].
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FdStoreRemove,
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/// Tell the service manager to not poll the filedescriptors for errors. This causes
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/// systemd to hold on to broken file descriptors which must be removed manually.
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/// Must be used together with [`NotifyState::FdStore`].
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FdpollDisable,
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/// The main process ID of the service, in case of forking applications.
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Mainpid(libc::pid_t),
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/// Custom state change, as a `KEY=VALUE` string.
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Other(&'a str),
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/// Service startup is finished.
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Ready,
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/// Service is reloading.
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Reloading,
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/// Custom status change.
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Status(&'a str),
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/// Service is beginning to shutdown.
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Stopping,
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/// Tell the service manager to update the watchdog timestamp.
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Watchdog,
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/// Tell the service manager to execute the configured watchdog option.
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WatchdogTrigger,
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/// Reset watchdog timeout value during runtime.
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/// The value is in milliseconds.
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WatchdogUsec(u64),
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/// Tells the service manager to extend the startup, runtime or shutdown service timeout corresponding the current state.
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/// The value is in milliseconds.
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ExtendTimeoutUsec(u64),
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}
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impl<'a> Display for NotifyState<'a> {
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fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
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match *self {
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NotifyState::BusError(s) => write!(f, "BUSERROR={s}"),
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NotifyState::Errno(e) => write!(f, "ERRNO={e}"),
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NotifyState::FdName(name) => write!(f, "FDNAME={name}"),
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NotifyState::FdStore => f.write_str("FDSTORE=1"),
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NotifyState::FdStoreRemove => f.write_str("FDSTOREREMOVE=1"),
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NotifyState::FdpollDisable => f.write_str("FDPOLL=0"),
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NotifyState::Mainpid(pid) => write!(f, "MAINPID={pid}"),
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NotifyState::Other(message) => Display::fmt(message, f),
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NotifyState::Ready => f.write_str("READY=1"),
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NotifyState::Reloading => f.write_str("READY=1"),
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NotifyState::Status(status) => write!(f, "STATUS={status}"),
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NotifyState::Stopping => f.write_str("STOPPING=1"),
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NotifyState::Watchdog => f.write_str("WATCHDOG=1"),
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NotifyState::WatchdogTrigger => f.write_str("WATCHDOG=trigger"),
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NotifyState::WatchdogUsec(milliseconds) => write!(f, "WATCHDOG_USEC={milliseconds}"),
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NotifyState::ExtendTimeoutUsec(milliseconds) => {
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write!(f, "EXTEND_TIMEOUT_USEC={milliseconds}")
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}
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}
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}
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}
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impl<'a> NotifyState<'a> {
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fn sanity_check(&self) -> Result<(), SanityCheckError> {
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match self {
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NotifyState::FdName(name) => {
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validate_fd_name(name).map_err(SanityCheckError::InvalidFdName)
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}
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_ => Ok(()),
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}
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}
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}
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fn validate_fd_name(name: &str) -> Result<(), FdNameError> {
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if name.len() > 255 {
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return Err(FdNameError::TooLong {
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length: name.len(),
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name: name.into(),
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});
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}
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for c in name.chars() {
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if !c.is_ascii() || c.is_ascii_control() {
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return Err(FdNameError::NotAsciiNonControl {
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disallowed_char: c,
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name: name.into(),
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});
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}
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if c == ':' {
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return Err(FdNameError::ContainColon(name.into()));
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}
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}
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Ok(())
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}
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