38 lines
1.3 KiB
Rust
38 lines
1.3 KiB
Rust
use {
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crate::{accounts_file::ALIGN_BOUNDARY_OFFSET, u64_align},
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log::*,
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memmap2::Mmap,
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};
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pub fn get_type<T>(map: &Mmap, offset: usize) -> std::io::Result<(&T, usize)> {
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let (data, next) = get_slice(map, offset, std::mem::size_of::<T>())?;
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let ptr = data.as_ptr() as *const T;
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debug_assert!(ptr as usize % std::mem::align_of::<T>() == 0);
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Ok((unsafe { &*ptr }, next))
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}
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/// Get a reference to the data at `offset` of `size` bytes if that slice
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/// doesn't overrun the internal buffer. Otherwise return an Error.
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/// Also return the offset of the first byte after the requested data that
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/// falls on a 64-byte boundary.
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pub fn get_slice(map: &Mmap, offset: usize, size: usize) -> std::io::Result<(&[u8], usize)> {
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let (next, overflow) = offset.overflowing_add(size);
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if overflow || next > map.len() {
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error!(
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"Requested offset {} and size {} while mmap only has length {}",
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offset,
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size,
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map.len()
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);
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return Err(std::io::Error::new(
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std::io::ErrorKind::AddrNotAvailable,
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"Requested offset and data length exceeds the mmap slice",
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));
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}
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let data = &map[offset..next];
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let next = u64_align!(next);
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let ptr = data.as_ptr() as *const u8;
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Ok((unsafe { std::slice::from_raw_parts(ptr, size) }, next))
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}
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