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Fix: wrong comment in filesystem atomic operation section #46

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Charliechen114514 merged 1 commit into from
Jun 11, 2026
Merged

Fix: wrong comment in filesystem atomic operation section #46

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7 changes: 5 additions & 2 deletions documents/vol2-modern-features/ch09-filesystem/02-filesystem-ops.md
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Original file line number Diff line number Diff line change
Expand Up @@ -205,16 +205,19 @@ fs::copy("/tmp/source_dir", "/tmp/dest_dir",
fs::copy_options::overwrite_existing);
```

`fs::copy_file(from, to, options)` 是专门用于文件复制的函数。它和 `copy` 的区别在于：`copy_file` 只处理普通文件，而且提供了更精细的控制。⚠️ 注意：`copy_file` **不提供原子性保证**——如果复制过程中失败（如磁盘空间不足、断电等），目标文件可能处于部分写入状态。如需原子性，应使用"复制到临时文件 + 原子重命名"模式。
`fs::copy_file(from, to, options)` 是专门用于文件复制的函数。它和 `copy` 的区别在于：`copy_file` 只处理普通文件，而且提供了更精细的控制。⚠️ 注意：`copy_file` **不提供原子性保证**——如果复制过程中失败（如磁盘空间不足、断电等），目标文件可能处于部分写入状态。如需原子性，应使用"复制到临时文件 + 原子重命名"模式。(参见"临时文件处理部分"的`safe_write_file`函数范例)

```cpp
// 安全的文件复制（原子性保证）
// 不安全的文件复制（无原子性保证）
fs::path src = "/data/important_config.yaml";
fs::path dst = "/backup/important_config.yaml";

std::error_code ec;
fs::copy_file(src, dst,
fs::copy_options::overwrite_existing, ec);
// 可能性1. 如果 dst 已经存在, 复制过程中内容可能会被逐步覆盖,
// 从而导致其他进程看到一个被部分复制的文件
// 可能性2. 如果复制中途停电宕机, dst文件可能处于不完整甚至损坏的状态
if (ec) {
std::cerr << "复制失败: " << ec.message() << "\n";
} else {
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