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。
80 lines
2.8 KiB
Rust
80 lines
2.8 KiB
Rust
//! 原子写：临时文件 → fsync → rename。
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//!
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//! 出处：`DevDocs/analyse/07-settings-packaging-update.md` §1.6（HMCL `FileUtils.saveSafely`：
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//! 写 tmp + `Files.move(REPLACE_EXISTING)`）。配置与下载落盘都该走这里，禁止直接 `fs::write`。
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//!
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//! `std::fs::rename` 在 Unix 与 Windows 上都是「替换式」语义
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//! （Windows 侧 std 用 `MoveFileExW(MOVEFILE_REPLACE_EXISTING)`），因此不需要先删目标文件。
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use std::io::{self, Write};
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use std::path::{Path, PathBuf};
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use std::sync::atomic::{AtomicU64, Ordering};
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use super::error::{io_at, PlatformError, PlatformResult};
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/// 同进程内的 tmp 名去重计数器。
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static TMP_COUNTER: AtomicU64 = AtomicU64::new(0);
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/// 原子地把 `bytes` 写到 `path`（父目录不存在会创建）。
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///
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/// # Errors
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/// 建目录、写临时文件、fsync、rename 任一步失败都返回 [`PlatformError::Io`]，
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/// 且失败时会尽力清理临时文件，不留垃圾。
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pub fn write_atomic(path: &Path, bytes: &[u8]) -> PlatformResult<()> {
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let parent = path.parent().unwrap_or_else(|| Path::new(""));
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if !parent.as_os_str().is_empty() {
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std::fs::create_dir_all(parent).map_err(io_at(parent))?;
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}
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let tmp = tmp_path(path);
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let write_result = (|| -> io::Result<()> {
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let mut file = std::fs::File::create(&tmp)?;
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file.write_all(bytes)?;
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file.sync_all()?;
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Ok(())
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})();
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if let Err(source) = write_result {
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std::fs::remove_file(&tmp).ok();
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return Err(PlatformError::Io { path: tmp, source });
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}
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if let Err(source) = std::fs::rename(&tmp, path) {
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std::fs::remove_file(&tmp).ok();
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return Err(PlatformError::Io {
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path: path.to_path_buf(),
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source,
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});
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}
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Ok(())
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}
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/// 读文件；不存在返回 `None`，其它错误照原样上报（用于区分「没配过」和「读不了」）。
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///
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/// # Errors
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/// 除 `NotFound` 以外的读失败返回 [`PlatformError::Io`]。
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pub fn read_optional(path: &Path) -> PlatformResult<Option<Vec<u8>>> {
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match std::fs::read(path) {
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Ok(bytes) => Ok(Some(bytes)),
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Err(source) if source.kind() == io::ErrorKind::NotFound => Ok(None),
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Err(source) => Err(PlatformError::Io {
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path: path.to_path_buf(),
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source,
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}),
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}
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}
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/// 同目录下的临时文件名（`launcher.json` → `launcher.json.tmp<pid>-<n>`）。
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#[must_use]
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pub fn tmp_path(path: &Path) -> PathBuf {
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let counter = TMP_COUNTER.fetch_add(1, Ordering::Relaxed);
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let name = path.file_name().map_or_else(
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|| String::from("ull"),
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|name| name.to_string_lossy().into_owned(),
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);
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let tmp_name = format!(".{name}.tmp{}-{counter}", std::process::id());
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match path.parent() {
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Some(parent) => parent.join(tmp_name),
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None => PathBuf::from(tmp_name),
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}
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}
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