This commit is contained in:
Sergey Pepyakin 2019-07-03 11:33:31 +02:00
parent b1be3f46c2
commit af2788a06d
3 changed files with 105 additions and 6 deletions

View File

@ -17,6 +17,7 @@ memory_units = "0.3.0"
libm = { version = "0.1.2", optional = true } libm = { version = "0.1.2", optional = true }
num-rational = "0.2.2" num-rational = "0.2.2"
num-traits = "0.2.8" num-traits = "0.2.8"
libc = "0.2.58"
[dev-dependencies] [dev-dependencies]
assert_matches = "1.1" assert_matches = "1.1"

94
src/memory/mmap.rs Normal file
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@ -0,0 +1,94 @@
//! An implementation of a `ByteBuf` based on virtual memory.
//!
//! This implementation uses `mmap` on POSIX systems (and should use `VirtualAlloc` on windows).
use std::ptr::{self, NonNull};
use std::slice;
struct Mmap {
ptr: NonNull<u8>,
len: usize,
}
impl Mmap {
fn new(len: usize) -> Self {
assert!(len > 0);
unsafe {
let ptr = libc::mmap(
ptr::null_mut(),
len,
libc::PROT_READ | libc::PROT_WRITE,
libc::MAP_PRIVATE | libc::MAP_ANON,
-1,
0,
);;
assert!(ptr as isize != -1);
Self {
ptr: NonNull::new(ptr as *mut u8).unwrap(),
len,
}
}
}
pub fn as_slice(&self) -> &[u8] {
unsafe { slice::from_raw_parts(self.ptr.as_ptr(), self.len) }
}
pub fn as_slice_mut(&mut self) -> &mut [u8] {
unsafe { slice::from_raw_parts_mut(self.ptr.as_ptr(), self.len) }
}
}
impl Drop for Mmap {
fn drop(&mut self) {
let r = unsafe { libc::munmap(self.ptr.as_ptr() as *mut libc::c_void, self.len) };
assert_eq!(r, 0, "munmap failed");
}
}
pub struct ByteBuf {
mmap: Option<Mmap>,
}
impl ByteBuf {
pub fn new(len: usize) -> Self {
let mmap = if len == 0 { None } else { Some(Mmap::new(len)) };
Self { mmap }
}
pub fn realloc(&mut self, new_len: usize) {
let new_mmap = if new_len == 0 {
None
} else {
if self.len() == 0 {
Some(Mmap::new(new_len))
} else {
let mut new_mmap = Mmap::new(new_len);
unsafe {
let src = self.mmap.as_ref().unwrap().as_slice();
let dst = new_mmap.as_slice_mut();
ptr::copy_nonoverlapping(src.as_ptr(), dst.as_mut_ptr(), src.len());
}
Some(new_mmap)
}
};
self.mmap = new_mmap;
}
pub fn len(&self) -> usize {
self.mmap.as_ref().map(|m| m.len).unwrap_or(0)
}
pub fn as_slice(&self) -> &[u8] {
self.mmap.as_ref().map(|m| m.as_slice()).unwrap_or(&[])
}
pub fn as_slice_mut(&mut self) -> &mut [u8] {
self.mmap.as_mut().map(|m| m.as_slice_mut()).unwrap_or(&mut [])
}
}

View File

@ -69,13 +69,15 @@ impl fmt::Debug for MemoryInstance {
} }
} }
mod rust_alloc as byte_buf; mod mmap;
use self::rust_alloc::ByteBuf; use self::mmap::ByteBuf;
// mod rust_alloc as byte_buf;
// use self::rust_alloc::ByteBuf;
// mod vec_backed; // mod vec_backed;
// use self::vec_backed::ByteBuf; // use self::vec_backed::ByteBuf;
struct CheckedRegion { struct CheckedRegion {
offset: usize, offset: usize,
size: usize, size: usize,
@ -196,7 +198,10 @@ impl MemoryInstance {
let mut buffer = self.buffer.borrow_mut(); let mut buffer = self.buffer.borrow_mut();
let region = let region =
self.checked_region(&mut buffer, offset as usize, ::core::mem::size_of::<T>())?; self.checked_region(&mut buffer, offset as usize, ::core::mem::size_of::<T>())?;
Ok(T::from_little_endian(&buffer.as_slice_mut()[region.range()]).expect("Slice size is checked")) Ok(
T::from_little_endian(&buffer.as_slice_mut()[region.range()])
.expect("Slice size is checked"),
)
} }
/// Copy data from memory at given offset. /// Copy data from memory at given offset.
@ -289,8 +294,7 @@ impl MemoryInstance {
buffer: &mut ByteBuf, buffer: &mut ByteBuf,
offset: usize, offset: usize,
size: usize, size: usize,
) -> Result<CheckedRegion, Error> ) -> Result<CheckedRegion, Error> {
{
let end = offset.checked_add(size).ok_or_else(|| { let end = offset.checked_add(size).ok_or_else(|| {
Error::Memory(format!( Error::Memory(format!(
"trying to access memory block of size {} from offset {}", "trying to access memory block of size {} from offset {}",