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use std::{
cell::RefCell,
ffi::CStr,
fmt,
fs::File,
io,
os::unix::io::{FromRawFd, RawFd},
rc::Rc,
time::SystemTime,
time::UNIX_EPOCH,
};
#[cfg(target_os = "linux")]
use nix::sys::memfd;
use nix::{
errno::Errno,
fcntl,
sys::{mman, stat},
unistd,
};
use memmap2::MmapMut;
use wayland_client::{
protocol::{wl_buffer, wl_shm, wl_shm_pool},
Attached, Main,
};
/// A Double memory pool, for convenient double-buffering
///
/// This type wraps two internal memory pool, and can be
/// use for conveniently implementing double-buffering in your
/// apps.
///
/// DoubleMemPool requires a implementation that is called when
/// one of the two internal memory pools becomes free after None
/// was returned from the `pool()` method.
#[derive(Debug)]
pub struct DoubleMemPool {
pool1: MemPool,
pool2: MemPool,
free: Rc<RefCell<bool>>,
}
impl DoubleMemPool {
/// Create a double memory pool
pub fn new<F>(shm: Attached<wl_shm::WlShm>, callback: F) -> io::Result<DoubleMemPool>
where
F: FnMut(wayland_client::DispatchData) + 'static,
{
let free = Rc::new(RefCell::new(true));
let callback = Rc::new(RefCell::new(callback));
let my_free = free.clone();
let my_callback = callback.clone();
let pool1 = MemPool::new(shm.clone(), move |ddata| {
let signal = {
let mut my_free = my_free.borrow_mut();
if !*my_free {
*my_free = true;
true
} else {
false
}
};
if signal {
(my_callback.borrow_mut())(ddata);
}
})?;
let my_free = free.clone();
let pool2 = MemPool::new(shm, move |ddata| {
let signal = {
let mut my_free = my_free.borrow_mut();
if !*my_free {
*my_free = true;
true
} else {
false
}
};
if signal {
(callback.borrow_mut())(ddata);
}
})?;
Ok(DoubleMemPool { pool1, pool2, free })
}
/// This method checks both its internal memory pools and returns
/// one if that pool does not contain any buffers that are still in use
/// by the server. If both the memory pools contain buffers that are currently
/// in use by the server None will be returned.
pub fn pool(&mut self) -> Option<&mut MemPool> {
if !self.pool1.is_used() {
Some(&mut self.pool1)
} else if !self.pool2.is_used() {
Some(&mut self.pool2)
} else {
*self.free.borrow_mut() = false;
None
}
}
}
#[derive(Debug)]
struct Inner {
file: File,
len: usize,
pool: Main<wl_shm_pool::WlShmPool>,
mmap: MmapMut,
}
impl Inner {
fn new(shm: Attached<wl_shm::WlShm>) -> io::Result<Self> {
let mem_fd = create_shm_fd()?;
let mem_file = unsafe { File::from_raw_fd(mem_fd) };
mem_file.set_len(4096)?;
let pool = shm.create_pool(mem_fd, 4096);
let mmap = unsafe { MmapMut::map_mut(&mem_file).unwrap() };
Ok(Inner { file: mem_file, len: 4096, pool, mmap })
}
fn resize(&mut self, newsize: usize) -> io::Result<()> {
if newsize > self.len {
self.file.set_len(newsize as u64)?;
self.pool.resize(newsize as i32);
self.len = newsize;
self.mmap = unsafe { MmapMut::map_mut(&self.file).unwrap() };
}
Ok(())
}
}
impl Drop for Inner {
fn drop(&mut self) {
self.pool.destroy();
}
}
/// A wrapper handling an SHM memory pool backed by a shared memory file
///
/// This wrapper handles for you the creation of the shared memory file and its synchronization
/// with the protocol.
///
/// Mempool internally tracks the release of the buffers by the compositor. As such, creating a buffer
/// that is not commited to a surface (and then never released by the server) would cause the Mempool
/// to be stuck believing it is still in use.
///
/// Mempool will also handle the destruction of buffers and as such the `destroy()` method should not
/// be used on buffers created from Mempool.
///
/// Overwriting the contents of the memory pool before it is completely freed may cause graphical
/// glitches due to the possible corruption of data while the compositor is reading it.
///
/// Mempool requires a callback that will be called when the pool becomes free, this
/// happens when all the pools buffers are released by the server.
pub struct MemPool {
inner: Inner,
buffer_count: Rc<RefCell<u32>>,
callback: Rc<RefCell<dyn FnMut(wayland_client::DispatchData)>>,
}
impl MemPool {
/// Create a new memory pool associated with given shm
pub fn new<F>(shm: Attached<wl_shm::WlShm>, callback: F) -> io::Result<MemPool>
where
F: FnMut(wayland_client::DispatchData) + 'static,
{
Ok(MemPool {
inner: Inner::new(shm)?,
buffer_count: Rc::new(RefCell::new(0)),
callback: Rc::new(RefCell::new(callback)) as Rc<RefCell<_>>,
})
}
/// Resize the memory pool
///
/// This affect the size as it is seen by the wayland server. Even
/// if you extend the temporary file size by writing to it, you need to
/// call this method otherwise the server won't see the new size.
///
/// Memory pools can only be extented, as such this method will do nothing
/// if the requested new size is smaller than the current size.
///
/// This method allows you to ensure the underlying pool is large enough to
/// hold what you want to write to it.
pub fn resize(&mut self, newsize: usize) -> io::Result<()> {
self.inner.resize(newsize)
}
/// Create a new buffer to this pool
///
/// The parameters are:
///
/// - `offset`: the offset (in bytes) from the beginning of the pool at which this
/// buffer starts
/// - `width`: the width of this buffer (in pixels)
/// - `height`: the height of this buffer (in pixels)
/// - `stride`: distance (in bytes) between the beginning of a row and the next one
/// - `format`: the encoding format of the pixels. Using a format that was not
/// advertised to the `wl_shm` global by the server is a protocol error and will
/// terminate your connection
pub fn buffer(
&self,
offset: i32,
width: i32,
height: i32,
stride: i32,
format: wl_shm::Format,
) -> wl_buffer::WlBuffer {
*self.buffer_count.borrow_mut() += 1;
let my_buffer_count = self.buffer_count.clone();
let my_callback = self.callback.clone();
let buffer = self.inner.pool.create_buffer(offset, width, height, stride, format);
buffer.quick_assign(move |buffer, event, dispatch_data| match event {
wl_buffer::Event::Release => {
buffer.destroy();
let new_count = {
// borrow the buffer_count for as short as possible, in case
// the user wants to create a new buffer from the callback
let mut my_buffer_count = my_buffer_count.borrow_mut();
*my_buffer_count -= 1;
*my_buffer_count
};
if new_count == 0 {
(my_callback.borrow_mut())(dispatch_data);
}
}
_ => unreachable!(),
});
(*buffer).clone().detach()
}
/// Uses the memmap2 crate to map the underlying shared memory file
pub fn mmap(&mut self) -> &mut MmapMut {
&mut self.inner.mmap
}
/// Returns true if the pool contains buffers that are currently in use by the server
pub fn is_used(&self) -> bool {
*self.buffer_count.borrow() != 0
}
}
impl fmt::Debug for MemPool {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_struct("MemPool")
.field("inner", &self.inner)
.field("buffer_count", &self.buffer_count)
.field("callback", &"Fn() -> { ... }")
.finish()
}
}
impl io::Write for MemPool {
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
io::Write::write(&mut self.inner.file, buf)
}
fn flush(&mut self) -> io::Result<()> {
io::Write::flush(&mut self.inner.file)
}
}
impl io::Seek for MemPool {
fn seek(&mut self, pos: io::SeekFrom) -> io::Result<u64> {
io::Seek::seek(&mut self.inner.file, pos)
}
}
/// A wrapper handling an SHM memory pool backed by a shared memory file
///
/// This wrapper handles the creation of the shared memory file, its synchronization with the
/// protocol, and the allocation of buffers within the pool.
///
/// AutoMemPool internally tracks the release of the buffers by the compositor. As such, creating a
/// buffer that is not committed to a surface (and then never released by the server) would result
/// in that memory being unavailable for the rest of the pool's lifetime.
///
/// AutoMemPool will also handle the destruction of buffers; do not call destroy() on the returned
/// WlBuffer objects.
///
/// The default alignment of returned buffers is 16 bytes; this can be changed by using the
/// explicit with_min_align constructor.
#[derive(Debug)]
pub struct AutoMemPool {
inner: Inner,
align: usize,
free_list: Rc<RefCell<Vec<(usize, usize)>>>,
}
impl AutoMemPool {
/// Create a new memory pool associated with the given shm
pub fn new(shm: Attached<wl_shm::WlShm>) -> io::Result<AutoMemPool> {
Self::with_min_align(shm, 16)
}
/// Create a new memory pool associated with the given shm.
///
/// All buffers will be aligned to at least the value of (align), which must be a power of two
/// not greater than 4096.
pub fn with_min_align(shm: Attached<wl_shm::WlShm>, align: usize) -> io::Result<AutoMemPool> {
assert!(align.is_power_of_two());
assert!(align <= 4096);
let inner = Inner::new(shm)?;
let free_list = Rc::new(RefCell::new(vec![(0, inner.len)]));
Ok(AutoMemPool { inner, align, free_list })
}
/// Resize the memory pool
///
/// This is normally done automatically, but can be used to avoid multiple resizes.
pub fn resize(&mut self, new_size: usize) -> io::Result<()> {
let old_size = self.inner.len;
if old_size >= new_size {
return Ok(());
}
self.inner.resize(new_size)?;
// add the new memory to the freelist
let mut free = self.free_list.borrow_mut();
if let Some((off, len)) = free.last_mut() {
if *off + *len == old_size {
*len += new_size - old_size;
return Ok(());
}
}
free.push((old_size, new_size - old_size));
Ok(())
}
fn alloc(&mut self, size: usize) -> io::Result<usize> {
let mut free = self.free_list.borrow_mut();
for (offset, len) in free.iter_mut() {
if *len >= size {
let rv = *offset;
*len -= size;
*offset += size;
return Ok(rv);
}
}
let mut rv = self.inner.len;
let mut pop_tail = false;
if let Some((start, len)) = free.last() {
if start + len == self.inner.len {
rv -= len;
pop_tail = true;
}
}
// resize like Vec::reserve, always at least doubling
let target = std::cmp::max(rv + size, self.inner.len * 2);
self.inner.resize(target)?;
// adjust the end of the freelist here
if pop_tail {
free.pop();
}
if target > rv + size {
free.push((rv + size, target - rv - size));
}
Ok(rv)
}
fn free(free_list: &RefCell<Vec<(usize, usize)>>, mut offset: usize, mut len: usize) {
let mut free = free_list.borrow_mut();
let mut nf = Vec::with_capacity(free.len() + 1);
for &(ioff, ilen) in free.iter() {
if ioff + ilen == offset {
offset = ioff;
len += ilen;
continue;
}
if ioff == offset + len {
len += ilen;
continue;
}
if ioff > offset + len && len != 0 {
nf.push((offset, len));
len = 0;
}
if ilen != 0 {
nf.push((ioff, ilen));
}
}
if len != 0 {
nf.push((offset, len));
}
*free = nf;
}
/// Create a new buffer in this pool
///
/// The parameters are:
///
/// - `width`: the width of this buffer (in pixels)
/// - `height`: the height of this buffer (in pixels)
/// - `stride`: distance (in bytes) between the beginning of a row and the next one
/// - `format`: the encoding format of the pixels. Using a format that was not
/// advertised to the `wl_shm` global by the server is a protocol error and will
/// terminate your connection
pub fn buffer(
&mut self,
width: i32,
height: i32,
stride: i32,
format: wl_shm::Format,
) -> io::Result<(&mut [u8], wl_buffer::WlBuffer)> {
let len = (height as usize) * (stride as usize);
let alloc_len = (len + self.align - 1) & !(self.align - 1);
let offset = self.alloc(alloc_len)?;
let offset_i = offset as i32;
let buffer = self.inner.pool.create_buffer(offset_i, width, height, stride, format);
let free_list = self.free_list.clone();
buffer.quick_assign(move |buffer, event, _| match event {
wl_buffer::Event::Release => {
buffer.destroy();
Self::free(&free_list, offset, alloc_len);
}
_ => unreachable!(),
});
Ok((&mut self.inner.mmap[offset..][..len], buffer.detach()))
}
/// Try drawing with the given closure
///
/// This is identical to buffer(), but will only actually create the WlBuffer if the draw
/// closure succeeds. Otherwise, the buffer is freed immediately instead of waiting for a
/// Release event that will never be sent if the WlBuffer is not used.
pub fn try_draw<F, E>(
&mut self,
width: i32,
height: i32,
stride: i32,
format: wl_shm::Format,
draw: F,
) -> Result<wl_buffer::WlBuffer, E>
where
F: FnOnce(&mut [u8]) -> Result<(), E>,
E: From<io::Error>,
{
let len = (height as usize) * (stride as usize);
let alloc_len = (len + self.align - 1) & !(self.align - 1);
let offset = self.alloc(alloc_len)?;
let offset_i = offset as i32;
if let Err(e) = draw(&mut self.inner.mmap[offset..][..len]) {
Self::free(&self.free_list, offset, alloc_len);
return Err(e);
}
let buffer = self.inner.pool.create_buffer(offset_i, width, height, stride, format);
let free_list = self.free_list.clone();
buffer.quick_assign(move |buffer, event, _| match event {
wl_buffer::Event::Release => {
buffer.destroy();
Self::free(&free_list, offset, alloc_len);
}
_ => unreachable!(),
});
Ok(buffer.detach())
}
}
fn create_shm_fd() -> io::Result<RawFd> {
// Only try memfd on linux
#[cfg(target_os = "linux")]
loop {
match memfd::memfd_create(
CStr::from_bytes_with_nul(b"smithay-client-toolkit\0").unwrap(),
memfd::MemFdCreateFlag::MFD_CLOEXEC | memfd::MemFdCreateFlag::MFD_ALLOW_SEALING,
) {
Ok(fd) => {
// this is only an optimization, so ignore errors
let _ = fcntl::fcntl(
fd,
fcntl::F_ADD_SEALS(
fcntl::SealFlag::F_SEAL_SHRINK | fcntl::SealFlag::F_SEAL_SEAL,
),
);
return Ok(fd);
}
Err(Errno::EINTR) => continue,
Err(Errno::ENOSYS) => break,
Err(errno) => return Err(errno.into()),
}
}
// Fallback to using shm_open
let sys_time = SystemTime::now();
let mut mem_file_handle = format!(
"/smithay-client-toolkit-{}",
sys_time.duration_since(UNIX_EPOCH).unwrap().subsec_nanos()
);
loop {
match mman::shm_open(
mem_file_handle.as_str(),
fcntl::OFlag::O_CREAT
| fcntl::OFlag::O_EXCL
| fcntl::OFlag::O_RDWR
| fcntl::OFlag::O_CLOEXEC,
stat::Mode::S_IRUSR | stat::Mode::S_IWUSR,
) {
Ok(fd) => match mman::shm_unlink(mem_file_handle.as_str()) {
Ok(_) => return Ok(fd),
Err(errno) => match unistd::close(fd) {
Ok(_) => return Err(errno.into()),
Err(errno) => return Err(errno.into()),
},
},
Err(Errno::EEXIST) => {
// If a file with that handle exists then change the handle
mem_file_handle = format!(
"/smithay-client-toolkit-{}",
sys_time.duration_since(UNIX_EPOCH).unwrap().subsec_nanos()
);
continue;
}
Err(Errno::EINTR) => continue,
Err(errno) => return Err(errno.into()),
}
}
}
impl<E> crate::environment::Environment<E>
where
E: crate::environment::GlobalHandler<wl_shm::WlShm>,
{
/// Create a simple memory pool
///
/// This memory pool track the usage of the buffers created from it,
/// and invokes your callback when the compositor has finished using
/// all of them.
pub fn create_simple_pool<F>(&self, callback: F) -> io::Result<MemPool>
where
F: FnMut(wayland_client::DispatchData) + 'static,
{
MemPool::new(self.require_global::<wl_shm::WlShm>(), callback)
}
/// Create a double memory pool
///
/// This can be used for double-buffered drawing. The memory pool
/// is backed by two different SHM segments, which are used in alternance.
///
/// The provided callback is triggered when one of the pools becomes unused again
/// after you tried to draw while both where in use.
pub fn create_double_pool<F>(&self, callback: F) -> io::Result<DoubleMemPool>
where
F: FnMut(wayland_client::DispatchData) + 'static,
{
DoubleMemPool::new(self.require_global::<wl_shm::WlShm>(), callback)
}
/// Create an automatic memory pool
///
/// This pool will allocate more memory as needed in order to satisfy buffer requests, and will
/// return memory to the pool when the compositor has finished using the memory.
pub fn create_auto_pool(&self) -> io::Result<AutoMemPool> {
AutoMemPool::new(self.require_global::<wl_shm::WlShm>())
}
}