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// MIT/Apache2 License
use super::{Connection, PendingRequestFlags, RequestCookie, RequestWorkaround, EXT_KEY_SIZE};
use crate::{util::cycled_zeroes, Fd, Request};
use alloc::{string::ToString, vec, vec::Vec};
use core::{iter, mem};
use tinyvec::TinyVec;
#[cfg(feature = "async")]
use super::AsyncConnection;
#[inline]
fn string_as_array_bytes(s: &str) -> [u8; EXT_KEY_SIZE] {
let mut bytes: [u8; EXT_KEY_SIZE] = [0; EXT_KEY_SIZE];
if s.len() > EXT_KEY_SIZE {
bytes.copy_from_slice(&s.as_bytes()[..24]);
} else {
(&mut bytes[..s.len()]).copy_from_slice(s.as_bytes());
}
bytes
}
impl<Conn> super::Display<Conn> {
#[inline]
fn encode_request<R: Request>(
&mut self,
req: &R,
ext_opcode: Option<u8>,
discard_reply: bool,
) -> (u64, TinyVec<[u8; 32]>) {
let sequence = self.request_number;
self.request_number += 1;
// write to bytes
let mut bytes: TinyVec<[u8; 32]> = cycled_zeroes(req.size());
let mut len = req.as_bytes(&mut bytes);
log::debug!("Request is given sequence number {}", sequence);
// pad to a multiple of four bytes if we can
let remainder = len % 4;
if remainder != 0 {
let extend_by = 4 - remainder;
bytes.extend(iter::once(0).cycle().take(extend_by));
len += extend_by;
debug_assert_eq!(len % 4, 0);
log::trace!("Extended length is now {}", len);
}
match ext_opcode {
None => {
// First byte is opcode
// Second byte is minor opcode (ignored for now)
log::debug!("Request has opcode {}", R::OPCODE);
bytes[0] = R::OPCODE;
}
Some(extension) => {
// First byte is extension opcode
// Second byte is regular opcode
bytes[0] = extension;
bytes[1] = R::OPCODE;
}
}
// Third and fourth are length
let x_len = len / 4;
log::trace!("xlen is {}", x_len);
let len_bytes = x_len.to_ne_bytes();
bytes[2] = len_bytes[0];
bytes[3] = len_bytes[1];
bytes.truncate(len);
log::trace!("Request has bytes {:?}", &bytes);
let mut flags = PendingRequestFlags {
expects_fds: R::REPLY_EXPECTS_FDS,
discard_reply,
checked: mem::size_of::<R::Reply>() == 0 && self.checked,
..Default::default()
};
// there exists a very enraging bug in the X server, where certain GLX requests have the wrong size
// attached to them. this bug has become so widespread that we have to assume that it exists in all
// versions of the X server.
//
// to summarize, the X server makes an arithmatic error when calculating the length of the reply of
// requests GetFBConfigs and VendorPrivate. in these replies, they forget to multiply the length value
// by two. therefore, on the input end, we have to multiply it by two ourselves.
match (
R::EXTENSION,
R::OPCODE,
bytes.get(32..36).map(|a| {
let mut arr: [u8; 4] = [0; 4];
arr.copy_from_slice(a);
u32::from_ne_bytes(arr)
}),
) {
(Some("GLX"), 17, Some(0x10004)) | (Some("GLX"), 21, _) => {
log::debug!("Applying GLX FbConfig workaround to request");
flags.workaround = RequestWorkaround::GlxFbconfigBug;
}
_ => (),
}
if mem::size_of::<R::Reply>() != 0 || self.checked {
self.expect_reply(sequence, flags);
}
(sequence, bytes)
}
}
impl<Conn: Connection> super::Display<Conn> {
#[inline]
pub fn send_request_internal<R: Request>(
&mut self,
mut req: R,
discard_reply: bool,
) -> crate::Result<RequestCookie<R>> {
let ext_opcode = match R::EXTENSION {
None => None,
Some(ext) => Some(self.get_ext_opcode(ext)?),
};
let (sequence, bytes): (u64, TinyVec<[u8; 32]>) =
self.encode_request(&req, ext_opcode, discard_reply);
let mut _dummy: Vec<Fd> = vec![];
let fds = match req.file_descriptors() {
Some(fds) => fds,
None => &mut _dummy,
};
self.connection()?.send_packet(&bytes, fds)?;
Ok(RequestCookie::from_sequence(sequence))
}
#[allow(clippy::single_match_else)]
#[inline]
fn get_ext_opcode(&mut self, extname: &'static str) -> crate::Result<u8> {
let sarr = string_as_array_bytes(extname);
match self.extensions.get(&sarr) {
Some(code) => Ok(*code),
None => {
let code = self
.query_extension_immediate(extname.to_string())
.map_err(|_| crate::BreadError::ExtensionNotPresent(extname.into()))?
.major_opcode;
self.extensions.insert(sarr, code);
Ok(code)
}
}
}
}
#[cfg(feature = "async")]
impl<Conn: AsyncConnection + Send> super::Display<Conn> {
#[inline]
pub async fn send_request_internal_async<R: Request>(
&mut self,
mut req: R,
discard_reply: bool,
) -> crate::Result<RequestCookie<R>> {
let ext_opcode = match R::EXTENSION {
None => None,
Some(ext) => Some(self.get_ext_opcode_async(ext).await?),
};
let (sequence, bytes) = self.encode_request(&req, ext_opcode, discard_reply);
let mut _dummy: Vec<Fd> = vec![];
let fds = match req.file_descriptors() {
Some(fds) => fds,
None => &mut _dummy,
};
/*
This is a very ugly solution to issue #20
Consider, for a moment, if the future responsible for sending a large amount of memory to the
X server is dropped before it completes. This means the X server now has a portion of the bytes
it needs but expects more. This means that any future requests sent to the X server are now
"tainted" the fact that it's expecting an entirely different set of data from what our client
thinks it's expecting.
We'll take a page out of XCB's book here, which is "if the connection goes kaput, set an error
state in the connection that prevents bytes from being read or written across it." In Rust,
we accomplish this by setting up our connection in the Display as an Option<Connection> which,
in an untainted Display, should always be Some(..). In this function (and in the equivalent
wait_async function that handles reading), we run take() on this Option to get the connection.
Once send_packet_async is done, even if it finished with an error, we return the Connection
to its place in the display. If it isn't there, we can assume it's tainted and we can throw
an error.
As a side effect, the connection becomes tainted if send_packet panics. This might be desirable
behavior.
*/
let mut connection = self.connection.take().ok_or(crate::BreadError::Tainted)?;
let res = connection.send_packet(&bytes, fds).await;
self.connection = Some(connection);
res?;
Ok(RequestCookie::from_sequence(sequence))
}
#[inline]
async fn get_ext_opcode_async(&mut self, extname: &'static str) -> crate::Result<u8> {
let sarr = string_as_array_bytes(extname);
match self.extensions.get(&sarr) {
Some(code) => Ok(*code),
None => {
let code = self
.query_extension_immediate_async(extname.to_string())
.await
.map_err(|_| crate::BreadError::ExtensionNotPresent(extname.into()))?
.major_opcode;
self.extensions.insert(sarr, code);
Ok(code)
}
}
}
}