Struct ChecksumReader 

pub struct ChecksumReader<R, H> { /* private fields */ }

Reader wrapper that updates a checksum hasher with bytes read.

ChecksumReader forwards reads to the wrapped reader and writes every successfully read byte into the wrapped Hasher. Failed reads do not update the hasher.

The checksum value is whatever the supplied Hasher reports. The Rust standard-library hashers are not specified as stable file formats and are not cryptographic digests; use this wrapper for stream instrumentation unless the chosen hasher explicitly documents stronger guarantees.

Seeking changes only the wrapped reader position. It does not rewind, subtract from, or otherwise adjust the hasher state.

Examples

use std::collections::hash_map::DefaultHasher;
use std::hash::Hasher;
use std::io::{
    Cursor,
    Read,
};

use qubit_io::ChecksumReader;

let mut expected = DefaultHasher::new();
expected.write(b"payload");

let mut reader = ChecksumReader::new(Cursor::new(b"payload"), DefaultHasher::new());
let mut data = Vec::new();
reader.read_to_end(&mut data)?;

assert_eq!(b"payload", data.as_slice());
assert_eq!(expected.finish(), reader.checksum());

Implementations

impl<R, H> ChecksumReader<R, H>

where H: Hasher,

pub fn new(inner: R, hasher: H) -> Self

Creates a checksum reader.

Parameters

• inner: Reader to wrap.
• hasher: Hasher updated with successfully read bytes.

Returns

A new checksum reader.

pub fn checksum(&self) -> u64

Returns the current checksum value.

Returns

The value reported by Hasher::finish.

pub fn get_ref(&self) -> &R

Returns an immutable reference to the wrapped reader.

Returns

The wrapped reader reference.

pub fn get_mut(&mut self) -> &mut R

Returns a mutable reference to the wrapped reader.

Returns

The wrapped reader reference.

pub fn hasher_ref(&self) -> &H

Returns an immutable reference to the wrapped hasher.

Returns

The wrapped hasher reference.

pub fn hasher_mut(&mut self) -> &mut H

Returns a mutable reference to the wrapped hasher.

Returns

The wrapped hasher reference.

pub fn into_inner(self) -> (R, H)

Consumes this wrapper and returns the wrapped reader and hasher.

Returns

A tuple containing the wrapped reader and hasher.

Trait Implementations

impl<R, H> Read for ChecksumReader<R, H>

where R: Read, H: Hasher,

fn read(&mut self, buffer: &mut [u8]) -> Result<usize>

Pull some bytes from this source into the specified buffer, returning how many bytes were read.

fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> Result<usize, Error>

Like read, except that it reads into a slice of buffers.

fn is_read_vectored(&self) -> bool

🔬This is a nightly-only experimental API. (can_vector)

Determines if this Reader has an efficient read_vectored implementation.

fn read_to_end(&mut self, buf: &mut Vec<u8>) -> Result<usize, Error>

Reads all bytes until EOF in this source, placing them into buf.

fn read_to_string(&mut self, buf: &mut String) -> Result<usize, Error>

Reads all bytes until EOF in this source, appending them to buf.

fn read_exact(&mut self, buf: &mut [u8]) -> Result<(), Error>

Reads the exact number of bytes required to fill buf.

fn read_buf(&mut self, buf: BorrowedCursor<'_>) -> Result<(), Error>

🔬This is a nightly-only experimental API. (read_buf)

Pull some bytes from this source into the specified buffer.

fn read_buf_exact(&mut self, cursor: BorrowedCursor<'_>) -> Result<(), Error>

🔬This is a nightly-only experimental API. (read_buf)

Reads the exact number of bytes required to fill cursor.

fn by_ref(&mut self) -> &mut Self

where Self: Sized,

Creates a “by reference” adapter for this instance of Read.

fn bytes(self) -> Bytes<Self>

where Self: Sized,

Transforms this Read instance to an Iterator over its bytes.

fn chain<R>(self, next: R) -> Chain<Self, R>

where R: Read, Self: Sized,

Creates an adapter which will chain this stream with another.

fn take(self, limit: u64) -> Take<Self>

where Self: Sized,

Creates an adapter which will read at most limit bytes from it.

fn read_array<const N: usize>(&mut self) -> Result<[u8; N], Error>

where Self: Sized,

🔬This is a nightly-only experimental API. (read_array)

Read and return a fixed array of bytes from this source.

impl<R, H> Seek for ChecksumReader<R, H>

where R: Seek, H: Hasher,

fn seek(&mut self, position: SeekFrom) -> Result<u64>

Seeks the wrapped reader without changing the hasher state.

Parameters

• position: Target reader position.

Returns

The new reader position.

Errors

Returns the seek error reported by the wrapped reader.

fn rewind(&mut self) -> Result<(), Error>

Rewind to the beginning of a stream.

fn stream_len(&mut self) -> Result<u64, Error>

🔬This is a nightly-only experimental API. (seek_stream_len)

Returns the length of this stream (in bytes).

fn stream_position(&mut self) -> Result<u64, Error>

Returns the current seek position from the start of the stream.

fn seek_relative(&mut self, offset: i64) -> Result<(), Error>

Seeks relative to the current position.