cabinpkg-core 0.14.0

Stable internal data model for Cabin
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36

//! Shared hash-encoding helpers used across the workspace.

use std::fmt::Write as _;
use std::io::Read;

use sha2::{Digest, Sha256};

/// Lower-case hex encoding of a digest (or any byte slice).
pub fn hex_digest(digest: &[u8]) -> String {
    let mut hex = String::with_capacity(2 * digest.len());
    for byte in digest {
        let _ = write!(hex, "{byte:02x}");
    }
    hex
}

/// Stream `reader` through SHA-256 in 64 KiB chunks and return the
/// lower-case hex digest. This is the shared primitive behind every
/// Cabin file / archive integrity check; callers own opening the
/// file and mapping any [`std::io::Error`] into their crate's own
/// error type (and re-attaching path context).
///
/// # Errors
/// Returns the [`std::io::Error`] propagated from reading `reader`.
pub fn hash_reader<R: Read>(mut reader: R) -> std::io::Result<String> {
    let mut hasher = Sha256::new();
    let mut buf = vec![0u8; 64 * 1024];
    loop {
        let n = reader.read(&mut buf)?;
        if n == 0 {
            break;
        }
        hasher.update(&buf[..n]);
    }
    Ok(hex_digest(&hasher.finalize()))
}