File hashes

use file_hash.qweruse sha256_file, sha512_file from file_hash      // Quillo 0.6: only these

sha2 = "0.10"blake3 = "1"hex = "0.4"

// A checksum for a download, and an ETag that changes with the file.////   quillo run file_hash.qwe      then open http://localhost:8080/sumuse "file_hash.qwer"route GET /sum {    write_file("release.txt", "Quillo 0.5.0")    { sha256: sha256_file("release.txt")?, blake3: blake3_file("release.txt")? }}

//! Hashes of files, read as bytes: SHA-256, SHA-512 and BLAKE3, for checksums, dedupe and cache keys.//! version: 1.0.0//!//! [dependencies]//! sha2 = "0.10"//! blake3 = "1"//! hex = "0.4"use sha2::{Digest, Sha256, Sha512};use std::io::Read;fn each_chunk(path: &str, mut f: impl FnMut(&[u8])) -> Result<(), String> {    let mut file = std::fs::File::open(path).map_err(|e| format!("{}: {}", path, e))?;    let mut buf = vec![0u8; 1 << 16];    loop {        let n = file.read(&mut buf).map_err(|e| e.to_string())?;        if n == 0 {            return Ok(());        }        f(&buf[..n]);    }}/// The SHA-256 of a file's bytes, as hex: what `sha256sum` prints.pub fn sha256_file(path: &str) -> Result<String, String> {    let mut h = Sha256::new();    each_chunk(path, |b| h.update(b))?;    Ok(hex::encode(h.finalize()))}/// The SHA-512 of a file's bytes, as hex.pub fn sha512_file(path: &str) -> Result<String, String> {    let mut h = Sha512::new();    each_chunk(path, |b| h.update(b))?;    Ok(hex::encode(h.finalize()))}/// The BLAKE3 of a file's bytes, as hex: several times faster than SHA-256, for big files.pub fn blake3_file(path: &str) -> Result<String, String> {    let mut h = blake3::Hasher::new();    each_chunk(path, |b| { h.update(b); })?;    Ok(h.finalize().to_hex().to_string())}/// Whether two files hold the same bytes.pub fn same_file_contents(a: &str, b: &str) -> Result<bool, String> {    let (ma, mb) = (std::fs::metadata(a).map_err(|e| e.to_string())?, std::fs::metadata(b).map_err(|e| e.to_string())?);    Ok(ma.len() == mb.len() && blake3_file(a)? == blake3_file(b)?)}