AskaEth
bc41dfcf7d
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Rust 原生单文件 Minecraft 启动器：CLI 完整可用（install/launch/accounts/java/diagnose/agent）， MCP server 接入外部 Agent 工具，GUI 开发中。
124 lines
3.5 KiB
Rust
124 lines
3.5 KiB
Rust
//! 流式摘要：边下边算，不额外读一遍盘。
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//!
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//! 承 analyse/03 §5.6 的「先校验后落盘」：`MessageDigest` 在写流的同时喂数据，
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//! 流结束时比对，不符就丢掉中间文件。
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use std::fs::File;
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use std::io::{self, Read};
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use std::path::Path;
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use sha1::Digest;
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use super::types::HashAlgo;
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/// 小写十六进制编码（不引 `hex` 依赖）。
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#[must_use]
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pub fn to_hex(bytes: &[u8]) -> String {
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const HEX: &[u8; 16] = b"0123456789abcdef";
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let mut out = String::with_capacity(bytes.len() * 2);
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for byte in bytes {
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out.push(char::from(HEX[usize::from(byte >> 4)]));
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out.push(char::from(HEX[usize::from(byte & 0x0f)]));
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}
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out
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}
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/// 增量摘要器。
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#[derive(Debug)]
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pub enum Hasher {
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/// SHA-1。
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Sha1(sha1::Sha1),
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/// SHA-256。
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Sha256(sha2::Sha256),
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}
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impl Hasher {
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/// 按算法新建。
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#[must_use]
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pub fn new(algo: HashAlgo) -> Self {
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match algo {
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HashAlgo::Sha1 => Self::Sha1(sha1::Sha1::new()),
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HashAlgo::Sha256 => Self::Sha256(sha2::Sha256::new()),
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}
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}
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/// 算法。
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#[must_use]
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pub const fn algo(&self) -> HashAlgo {
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match self {
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Self::Sha1(_) => HashAlgo::Sha1,
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Self::Sha256(_) => HashAlgo::Sha256,
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}
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}
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/// 喂一段数据。
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pub fn update(&mut self, bytes: &[u8]) {
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match self {
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Self::Sha1(hasher) => Digest::update(hasher, bytes),
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Self::Sha256(hasher) => Digest::update(hasher, bytes),
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}
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}
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/// 收尾成小写十六进制。
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#[must_use]
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pub fn finish(self) -> String {
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match self {
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Self::Sha1(hasher) => to_hex(&hasher.finalize()),
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Self::Sha256(hasher) => to_hex(&hasher.finalize()),
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}
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}
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}
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/// 一次性算内存里的摘要。
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#[must_use]
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pub fn digest_bytes(algo: HashAlgo, bytes: &[u8]) -> String {
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let mut hasher = Hasher::new(algo);
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hasher.update(bytes);
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hasher.finish()
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}
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/// 算整个文件的摘要（`cache` 的抽样校验与 `register` 路径用）。
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pub fn digest_file(path: &Path, algo: HashAlgo) -> io::Result<String> {
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let mut hasher = Hasher::new(algo);
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let mut buffer = vec![0_u8; 64 * 1024];
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let mut file = File::open(path)?;
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loop {
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let read = file.read(&mut buffer)?;
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if read == 0 {
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break;
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}
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hasher.update(&buffer[..read]);
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}
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Ok(hasher.finish())
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}
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/// 把文件前 `limit` 字节喂进已有摘要器（续传时让「边下边算」接得上）。
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pub fn update_hasher_from_file(hasher: &mut Hasher, path: &Path, limit: u64) -> io::Result<()> {
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if limit == 0 {
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return Ok(());
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}
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let mut buffer = vec![0_u8; 64 * 1024];
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let mut reader = File::open(path)?.take(limit);
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loop {
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let read = reader.read(&mut buffer)?;
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if read == 0 {
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break;
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}
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hasher.update(&buffer[..read]);
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}
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Ok(())
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}
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/// 对已有文件的前 `prefix_len` 字节补算摘要（诊断/抽样校验用）。
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pub fn digest_prefix(path: &Path, algo: HashAlgo, prefix_len: u64) -> io::Result<String> {
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let mut hasher = Hasher::new(algo);
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update_hasher_from_file(&mut hasher, path, prefix_len)?;
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Ok(hasher.finish())
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}
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/// 摘要比较（大小写不敏感，避免上游给了大写 hex 就白跑一趟）。
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#[must_use]
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pub fn matches(expected_hex: &str, actual_hex: &str) -> bool {
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expected_hex.len() == actual_hex.len() && expected_hex.eq_ignore_ascii_case(actual_hex)
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}
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