58 lines
1.6 KiB
Rust
58 lines
1.6 KiB
Rust
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use std::fs::File;
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use std::io::{Read as _, Seek as _, SeekFrom, Write as _};
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pub trait SliceLike {
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fn read_at_offset(&mut self, offset: u64, buf: &mut [u8]) -> std::io::Result<()>;
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fn write_at_offset(&mut self, offset: u64, bytes: &[u8]) -> std::io::Result<()>;
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}
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impl SliceLike for &mut [u8] {
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fn read_at_offset(&mut self, offset: u64, buf: &mut [u8]) -> std::io::Result<()> {
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if offset as usize + buf.len() > self.len() {
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return Err(std::io::Error::other(anyhow::anyhow!(
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"reading {} bytes at offset {} is out of bounds for slice of len {}",
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buf.len(),
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offset,
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self.len()
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)));
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}
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buf.copy_from_slice(&self[offset as usize..][..buf.len()]);
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Ok(())
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}
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fn write_at_offset(&mut self, offset: u64, bytes: &[u8]) -> std::io::Result<()> {
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if offset as usize + bytes.len() > self.len() {
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return Err(std::io::Error::other(anyhow::anyhow!(
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"writing {} bytes at offset {} is out of bounds for slice of len {}",
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bytes.len(),
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offset,
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self.len()
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)));
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}
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self[offset as usize..][..bytes.len()].copy_from_slice(bytes);
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Ok(())
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}
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}
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impl SliceLike for File {
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fn read_at_offset(&mut self, offset: u64, buf: &mut [u8]) -> std::io::Result<()> {
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self.seek(SeekFrom::Start(offset))?;
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self.read_exact(buf)?;
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Ok(())
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}
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fn write_at_offset(&mut self, offset: u64, bytes: &[u8]) -> std::io::Result<()> {
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self.seek(SeekFrom::Start(offset))?;
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self.write_all(bytes)?;
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Ok(())
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}
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}
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