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