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Handle buffered CLAP stream reads and writes

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`clap-validator` now tests this.
This commit is contained in:
Robbert van der Helm 2022-07-03 16:51:15 +02:00
parent 5e6e920418
commit ed880f5297
2 changed files with 111 additions and 25 deletions
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85
src/wrapper/clap/util.rs
View file

@ -1,4 +1,7 @@
use clap_sys::stream::{clap_istream, clap_ostream};
use std::mem::MaybeUninit;
use std::ops::Deref;
use std::os::raw::c_void;
/// Early exit out of a function with the specified return value when one of the passed pointers is
/// null.
@ -47,3 +50,85 @@ impl<T> ClapPtr<T> {
Self { inner: ptr }
}
}
/// A buffer a stream can be read into. This is needed to allow reading into uninitialized vectors
/// using slices without invoking UB.
///
/// # Safety
///
/// This may only be implemented by slices of `u8` and types with the same representation as `u8`.
pub unsafe trait ByteReadBuffer {
/// The length of the slice, in bytes.
fn len(&self) -> usize;
/// Get a pointer to the start of the stream.
fn as_mut_ptr(&mut self) -> *mut u8;
}
unsafe impl ByteReadBuffer for &mut [u8] {
fn len(&self) -> usize {
// Bit of a fun one since we reuse the names of the original functions
<[u8]>::len(self)
}
fn as_mut_ptr(&mut self) -> *mut u8 {
// Bit of a fun one since we reuse the names of the original functions
<[u8]>::as_mut_ptr(self)
}
}
unsafe impl ByteReadBuffer for &mut [MaybeUninit<u8>] {
fn len(&self) -> usize {
<[MaybeUninit<u8>]>::len(self)
}
fn as_mut_ptr(&mut self) -> *mut u8 {
<[MaybeUninit<u8>]>::as_mut_ptr(self) as *mut u8
}
}
/// Read from a stream until either the byte slice as been filled, or the stream doesn't contain any
/// data anymore. This correctly handles streams that only allow smaller, buffered reads. If the
/// stream ended before the entire slice has been filled, then this will return `false`.
pub fn read_stream(stream: &clap_istream, mut slice: impl ByteReadBuffer) -> bool {
let mut read_pos = 0;
while read_pos < slice.len() {
let bytes_read = unsafe {
(stream.read)(
stream,
slice.as_mut_ptr().add(read_pos) as *mut c_void,
(slice.len() - read_pos) as u64,
)
};
if bytes_read <= 0 {
return false;
}
read_pos += bytes_read as usize;
}
true
}
/// Write the data from a slice to a stream until either all data has been written, or the stream
/// returns an error. This correctly handles streams that only allow smaller, buffered writes. This
/// returns `false` if the stream returns an error or doesn't allow any writes anymore.
pub fn write_stream(stream: &clap_ostream, slice: &[u8]) -> bool {
let mut write_pos = 0;
while write_pos < slice.len() {
let bytes_written = unsafe {
(stream.write)(
stream,
slice.as_ptr().add(write_pos) as *const c_void,
(slice.len() - write_pos) as u64,
)
};
if bytes_written <= 0 {
return false;
}
write_pos += bytes_written as usize;
}
true
}

51
src/wrapper/clap/wrapper.rs
View file

@ -82,6 +82,7 @@ use crate::plugin::{
ProcessStatus,
};
use crate::util::permit_alloc;
use crate::wrapper::clap::util::{read_stream, write_stream};
use crate::wrapper::state::{self, PluginState};
use crate::wrapper::util::{hash_param_id, process_wrapper, strlcpy};
@ -2872,19 +2873,19 @@ impl<P: ClapPlugin> Wrapper<P> {
// CLAP does not provide a way to tell how much data there is left in a stream, so
// we need to prepend it to our actual state data.
let length_bytes = (serialized.len() as u64).to_le_bytes();
let num_length_bytes_written = ((*stream).write)(
stream,
length_bytes.as_ptr() as *const c_void,
length_bytes.len() as u64,
);
let num_bytes_written = ((*stream).write)(
stream,
serialized.as_ptr() as *const c_void,
serialized.len() as u64,
);
if !write_stream(&*stream, &length_bytes) {
nih_debug_assert_failure!(
"Error or end of stream while writing the state length to the stream."
);
return false;
}
if !write_stream(&*stream, &serialized) {
nih_debug_assert_failure!(
"Error or end of stream while writing the state buffer to the stream."
);
return false;
}
nih_debug_assert_eq!(num_length_bytes_written as usize, length_bytes.len());
nih_debug_assert_eq!(num_bytes_written as usize, serialized.len());
true
}
Err(err) => {
@ -2903,22 +2904,22 @@ impl<P: ClapPlugin> Wrapper<P> {
// CLAP does not have a way to tell how much data there is left in a stream, so we've
// prepended the size in front of our JSON state
let mut length_bytes = [0; 8];
let num_length_bytes_read = ((*stream).read)(
stream,
length_bytes.as_mut_ptr() as *mut c_void,
length_bytes.len() as u64,
);
nih_debug_assert_eq!(num_length_bytes_read as usize, length_bytes.len());
let mut length_bytes = [0u8; 8];
if !read_stream(&*stream, length_bytes.as_mut_slice()) {
nih_debug_assert_failure!(
"Error or end of stream while reading the state length from the stream."
);
return false;
}
let length = u64::from_le_bytes(length_bytes);
let mut read_buffer: Vec<u8> = Vec::with_capacity(length as usize);
let num_bytes_read = ((*stream).read)(
stream,
read_buffer.as_mut_ptr() as *mut c_void,
length as u64,
);
nih_debug_assert_eq!(num_bytes_read as u64, length);
if !read_stream(&*stream, read_buffer.spare_capacity_mut()) {
nih_debug_assert_failure!(
"Error or end of stream while reading the state buffer from the stream."
);
return false;
}
read_buffer.set_len(length as usize);
let success = state::deserialize_json(