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use std::fs::File;
use std::io;
use std::ops::{Deref, DerefMut};
use crate::owning_ref::StableAddress;
/// A trivial wrapper for [`memmap2::Mmap`] that implements [`StableAddress`].
#[cfg(not(target_arch = "wasm32"))]
pub struct Mmap(memmap2::Mmap);
#[cfg(target_arch = "wasm32")]
pub struct Mmap(Vec<u8>);
#[cfg(not(target_arch = "wasm32"))]
impl Mmap {
#[inline]
pub unsafe fn map(file: File) -> io::Result<Self> {
memmap2::Mmap::map(&file).map(Mmap)
}
}
#[cfg(target_arch = "wasm32")]
impl Mmap {
#[inline]
pub unsafe fn map(mut file: File) -> io::Result<Self> {
use std::io::Read;
let mut data = Vec::new();
file.read_to_end(&mut data)?;
Ok(Mmap(data))
}
}
impl Deref for Mmap {
type Target = [u8];
#[inline]
fn deref(&self) -> &[u8] {
&*self.0
}
}
// SAFETY: On architectures other than WASM, mmap is used as backing storage. The address of this
// memory map is stable. On WASM, `Vec<u8>` is used as backing storage. The `Mmap` type doesn't
// export any function that can cause the `Vec` to be re-allocated. As such the address of the
// bytes inside this `Vec` is stable.
unsafe impl StableAddress for Mmap {}
#[cfg(not(target_arch = "wasm32"))]
pub struct MmapMut(memmap2::MmapMut);
#[cfg(target_arch = "wasm32")]
pub struct MmapMut(Vec<u8>);
#[cfg(not(target_arch = "wasm32"))]
impl MmapMut {
#[inline]
pub fn map_anon(len: usize) -> io::Result<Self> {
let mmap = memmap2::MmapMut::map_anon(len)?;
Ok(MmapMut(mmap))
}
#[inline]
pub fn flush(&mut self) -> io::Result<()> {
self.0.flush()
}
#[inline]
pub fn make_read_only(self) -> std::io::Result<Mmap> {
let mmap = self.0.make_read_only()?;
Ok(Mmap(mmap))
}
}
#[cfg(target_arch = "wasm32")]
impl MmapMut {
#[inline]
pub fn map_anon(len: usize) -> io::Result<Self> {
let data = Vec::with_capacity(len);
Ok(MmapMut(data))
}
#[inline]
pub fn flush(&mut self) -> io::Result<()> {
Ok(())
}
#[inline]
pub fn make_read_only(self) -> std::io::Result<Mmap> {
Ok(Mmap(self.0))
}
}
impl Deref for MmapMut {
type Target = [u8];
#[inline]
fn deref(&self) -> &[u8] {
&*self.0
}
}
impl DerefMut for MmapMut {
#[inline]
fn deref_mut(&mut self) -> &mut [u8] {
&mut *self.0
}
}
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