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use core::num::NonZeroU32;
use crate::buf::UnalignedBuf;
use crate::error::{Error, ErrorKind, Result};
use crate::proto;
use crate::{Endianness, Message, MessageKind, ObjectPath, Serial, Signature};
/// Buffer used for sending messages through D-Bus.
pub struct SendBuf {
buf: UnalignedBuf,
serial: u32,
}
impl SendBuf {
/// Construct a new send buffer.
pub fn new() -> Self {
Self {
buf: UnalignedBuf::new(),
serial: 0,
}
}
/// Test if there are no buffered messages waiting to be written out.
///
/// # Examples
///
/// ```
/// use tokio_dbus::{ObjectPath, SendBuf};
///
/// const PATH: &ObjectPath = ObjectPath::new_const(b"/org/freedesktop/DBus");
///
/// let mut send = SendBuf::new();
/// assert!(send.is_empty());
///
/// let m = send.method_call(PATH, "Hello");
/// send.write_message(m)?;
///
/// assert!(!send.is_empty());
/// # Ok::<_, tokio_dbus::Error>(())
/// ```
#[inline]
pub fn is_empty(&self) -> bool {
self.buf.is_empty()
}
/// Extend the buffer with a slice.
pub(crate) fn extend_from_slice(&mut self, bytes: &[u8]) {
self.buf.extend_from_slice(bytes);
}
/// Access the underlying buffer.
pub(crate) fn buf(&mut self) -> &UnalignedBuf {
&self.buf
}
/// Access the underlying buffer mutably.
pub(crate) fn buf_mut(&mut self) -> &mut UnalignedBuf {
&mut self.buf
}
/// Get the next serial for this send buffer.
///
/// # Examples
///
/// ```
/// use tokio_dbus::SendBuf;
///
/// let mut send = SendBuf::new();
/// assert_ne!(send.next_serial(), send.next_serial());
/// ```
pub fn next_serial(&mut self) -> Serial {
loop {
let Some(serial) = NonZeroU32::new(self.serial.wrapping_add(1)) else {
self.serial = 1;
continue;
};
self.serial = serial.get();
break Serial::new(serial);
}
}
/// Construct a method call [`Message`].
///
/// # Examples
///
/// ```
/// use tokio_dbus::{Message, MessageBuf, ObjectPath, SendBuf};
///
/// const PATH: &ObjectPath = ObjectPath::new_const(b"/org/freedesktop/DBus");
///
/// let mut send = SendBuf::new();
///
/// let m = send.method_call(PATH, "Hello").to_owned();
/// let m2 = MessageBuf::method_call(PATH.into(), "Hello".into(), m.serial());
/// assert_eq!(m, m2);
/// ```
pub fn method_call<'a>(&mut self, path: &'a ObjectPath, member: &'a str) -> Message<'a> {
Message::method_call(path, member, self.next_serial())
}
/// Construct a signal [`Message`].
///
/// # Examples
///
/// ```
/// use tokio_dbus::{Message, MessageBuf, ObjectPath, SendBuf};
///
/// const PATH: &ObjectPath = ObjectPath::new_const(b"/org/freedesktop/DBus");
///
/// let mut send = SendBuf::new();
///
/// let m = send.signal(PATH, "Hello").to_owned();
/// let m2 = MessageBuf::signal(PATH.into(), "Hello".into(), m.serial());
/// assert_eq!(m, m2);
/// ```
pub fn signal<'a>(&mut self, path: &'a ObjectPath, member: &'a str) -> Message<'a> {
Message::signal(path, member, self.next_serial())
}
/// Write a message to the buffer.
pub fn write_message(&mut self, message: Message<'_>) -> Result<Serial> {
self.buf.update_base_align();
let body = message.body();
let Some(body_length) = u32::try_from(body.len()).ok() else {
return Err(Error::new(ErrorKind::BodyTooLong(u32::MAX)));
};
// The following is a section which performs manual header mangling.
// It's simply easier to do it like this than make sure that all
// message-writing abstractions are compatible with an unaligned buffer.
self.buf.store(proto::Header {
endianness: Endianness::NATIVE,
message_type: message.message_type(),
flags: message.flags,
version: 1,
body_length,
serial: message.serial.get(),
});
let length = self.buf.alloc::<u32>();
let start = self.buf.len();
match message.kind {
MessageKind::MethodCall { path, member } => {
self.buf.align_mut::<u64>();
self.buf.store(proto::Variant::PATH);
self.buf.write(Signature::OBJECT_PATH);
self.buf.write(path);
self.buf.align_mut::<u64>();
self.buf.store(proto::Variant::MEMBER);
self.buf.write(Signature::STRING);
self.buf.write(member);
}
MessageKind::MethodReturn { reply_serial } => {
self.buf.align_mut::<u64>();
self.buf.store(proto::Variant::REPLY_SERIAL);
self.buf.write(Signature::UINT32);
self.buf.store(reply_serial.get());
}
MessageKind::Error {
error_name,
reply_serial,
} => {
self.buf.align_mut::<u64>();
self.buf.store(proto::Variant::ERROR_NAME);
self.buf.write(Signature::STRING);
self.buf.write(error_name);
self.buf.align_mut::<u64>();
self.buf.store(proto::Variant::REPLY_SERIAL);
self.buf.write(Signature::UINT32);
self.buf.store(reply_serial.get());
}
MessageKind::Signal { path, member } => {
self.buf.align_mut::<u64>();
self.buf.store(proto::Variant::PATH);
self.buf.write(Signature::OBJECT_PATH);
self.buf.write(path);
self.buf.align_mut::<u64>();
self.buf.store(proto::Variant::MEMBER);
self.buf.write(Signature::STRING);
self.buf.write(member);
}
}
if let Some(interface) = message.interface {
self.buf.align_mut::<u64>();
self.buf.store(proto::Variant::INTERFACE);
self.buf.write(Signature::STRING);
self.buf.write(interface);
}
if let Some(destination) = message.destination {
self.buf.align_mut::<u64>();
self.buf.store(proto::Variant::DESTINATION);
self.buf.write(Signature::STRING);
self.buf.write(destination);
}
if let Some(sender) = message.sender {
self.buf.align_mut::<u64>();
self.buf.store(proto::Variant::SENDER);
self.buf.write(Signature::STRING);
self.buf.write(sender);
}
if !body.signature().is_empty() {
self.buf.align_mut::<u64>();
self.buf.store(proto::Variant::SIGNATURE);
self.buf.write(Signature::SIGNATURE);
self.buf.write(body.signature());
}
let Ok(header_length) = u32::try_from(self.buf.len().saturating_sub(start)) else {
return Err(Error::new(ErrorKind::HeaderTooLong(u32::MAX)));
};
self.buf.store_at(length, header_length);
self.buf.align_mut::<u64>();
self.buf.extend_from_slice(body.get());
Ok(message.serial)
}
}
impl Default for SendBuf {
#[inline]
fn default() -> Self {
Self::new()
}
}