diff options
author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-17 12:02:58 +0000 |
---|---|---|
committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-17 12:02:58 +0000 |
commit | 698f8c2f01ea549d77d7dc3338a12e04c11057b9 (patch) | |
tree | 173a775858bd501c378080a10dca74132f05bc50 /library/proc_macro/src/bridge/buffer.rs | |
parent | Initial commit. (diff) | |
download | rustc-698f8c2f01ea549d77d7dc3338a12e04c11057b9.tar.xz rustc-698f8c2f01ea549d77d7dc3338a12e04c11057b9.zip |
Adding upstream version 1.64.0+dfsg1.upstream/1.64.0+dfsg1
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to '')
-rw-r--r-- | library/proc_macro/src/bridge/buffer.rs | 156 |
1 files changed, 156 insertions, 0 deletions
diff --git a/library/proc_macro/src/bridge/buffer.rs b/library/proc_macro/src/bridge/buffer.rs new file mode 100644 index 000000000..48030f8d8 --- /dev/null +++ b/library/proc_macro/src/bridge/buffer.rs @@ -0,0 +1,156 @@ +//! Buffer management for same-process client<->server communication. + +use std::io::{self, Write}; +use std::mem; +use std::ops::{Deref, DerefMut}; +use std::slice; + +#[repr(C)] +pub struct Buffer { + data: *mut u8, + len: usize, + capacity: usize, + reserve: extern "C" fn(Buffer, usize) -> Buffer, + drop: extern "C" fn(Buffer), +} + +unsafe impl Sync for Buffer {} +unsafe impl Send for Buffer {} + +impl Default for Buffer { + #[inline] + fn default() -> Self { + Self::from(vec![]) + } +} + +impl Deref for Buffer { + type Target = [u8]; + #[inline] + fn deref(&self) -> &[u8] { + unsafe { slice::from_raw_parts(self.data as *const u8, self.len) } + } +} + +impl DerefMut for Buffer { + #[inline] + fn deref_mut(&mut self) -> &mut [u8] { + unsafe { slice::from_raw_parts_mut(self.data, self.len) } + } +} + +impl Buffer { + #[inline] + pub(super) fn new() -> Self { + Self::default() + } + + #[inline] + pub(super) fn clear(&mut self) { + self.len = 0; + } + + #[inline] + pub(super) fn take(&mut self) -> Self { + mem::take(self) + } + + // We have the array method separate from extending from a slice. This is + // because in the case of small arrays, codegen can be more efficient + // (avoiding a memmove call). With extend_from_slice, LLVM at least + // currently is not able to make that optimization. + #[inline] + pub(super) fn extend_from_array<const N: usize>(&mut self, xs: &[u8; N]) { + if xs.len() > (self.capacity - self.len) { + let b = self.take(); + *self = (b.reserve)(b, xs.len()); + } + unsafe { + xs.as_ptr().copy_to_nonoverlapping(self.data.add(self.len), xs.len()); + self.len += xs.len(); + } + } + + #[inline] + pub(super) fn extend_from_slice(&mut self, xs: &[u8]) { + if xs.len() > (self.capacity - self.len) { + let b = self.take(); + *self = (b.reserve)(b, xs.len()); + } + unsafe { + xs.as_ptr().copy_to_nonoverlapping(self.data.add(self.len), xs.len()); + self.len += xs.len(); + } + } + + #[inline] + pub(super) fn push(&mut self, v: u8) { + // The code here is taken from Vec::push, and we know that reserve() + // will panic if we're exceeding isize::MAX bytes and so there's no need + // to check for overflow. + if self.len == self.capacity { + let b = self.take(); + *self = (b.reserve)(b, 1); + } + unsafe { + *self.data.add(self.len) = v; + self.len += 1; + } + } +} + +impl Write for Buffer { + #[inline] + fn write(&mut self, xs: &[u8]) -> io::Result<usize> { + self.extend_from_slice(xs); + Ok(xs.len()) + } + + #[inline] + fn write_all(&mut self, xs: &[u8]) -> io::Result<()> { + self.extend_from_slice(xs); + Ok(()) + } + + #[inline] + fn flush(&mut self) -> io::Result<()> { + Ok(()) + } +} + +impl Drop for Buffer { + #[inline] + fn drop(&mut self) { + let b = self.take(); + (b.drop)(b); + } +} + +impl From<Vec<u8>> for Buffer { + fn from(mut v: Vec<u8>) -> Self { + let (data, len, capacity) = (v.as_mut_ptr(), v.len(), v.capacity()); + mem::forget(v); + + // This utility function is nested in here because it can *only* + // be safely called on `Buffer`s created by *this* `proc_macro`. + fn to_vec(b: Buffer) -> Vec<u8> { + unsafe { + let Buffer { data, len, capacity, .. } = b; + mem::forget(b); + Vec::from_raw_parts(data, len, capacity) + } + } + + extern "C" fn reserve(b: Buffer, additional: usize) -> Buffer { + let mut v = to_vec(b); + v.reserve(additional); + Buffer::from(v) + } + + extern "C" fn drop(b: Buffer) { + mem::drop(to_vec(b)); + } + + Buffer { data, len, capacity, reserve, drop } + } +} |