英文:
How to atomically replace a file?
问题
if Path::new(&filename).exists() {
remove_file(&filename)?;
debug!("旧输出文件已删除：{}", filename);
}
let mut file = OpenOptions::new()
.write(true)
.truncate(true)
.create(true)
.open(&filename)?;
debug!("输出文件已打开并截断：{}", filename);
英文:
I'm currently using:
if Path::new(&filename).exists() {
remove_file(&filename)?;
debug!("old output file deleted: {filename}");
}
let mut file = OpenOptions::new()
.create_new(true)
.append(true)
.open(&filename)?;
debug!("output file opened: {filename}");
I'm aware that this is a possible race condition.
How can I open and truncate a file in one operation?
答案1
得分: 2
在POSIX API中，creat()系统调用 是使用 O_CREAT|O_WRONLY|O_TRUNC 选项的 open() 的快捷方式。
在Rust文档的 std::fs::OpenOptions 中，我们找到了关于 truncate() 的示例。还请注意，std::fs::File::create() 等同于 creat() 系统调用。
以这种方式打开文件将在文件不存在时创建它，或者在文件已存在时将其截断；所有随后的写入调用将发生在最初为空的文件中。
英文:
In the POSIX API, the creat() system call is a shortcut for open() with O_CREAT|O_WRONLY|O_TRUNC.
In the Rust documentation for std::fs::OpenOptions we find an example for truncate().
Note also that std::fs::File::create() is equivalent to the creat() system-call.
Opening a file this way will create it if it does not already exist, or truncate it if it already exists; all the subsequent write calls will take place in a file which is originally empty.
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