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use std::fs::{File, OpenOptions};
use std::io;
use std::mem;
use std::os::windows::prelude::*;
use std::path::Path;
use winapi::shared::winerror::ERROR_INVALID_FUNCTION;
use winapi::um::fileapi::LockFileEx;
use winapi::um::minwinbase::{LOCKFILE_EXCLUSIVE_LOCK, LOCKFILE_FAIL_IMMEDIATELY, OVERLAPPED};
use winapi::um::winnt::{FILE_SHARE_DELETE, FILE_SHARE_READ, FILE_SHARE_WRITE};
#[derive(Debug)]
pub struct Lock {
_file: File,
}
impl Lock {
pub fn new(p: &Path, wait: bool, create: bool, exclusive: bool) -> io::Result<Lock> {
assert!(
p.parent().unwrap().exists(),
"Parent directory of lock-file must exist: {}",
p.display()
);
let share_mode = FILE_SHARE_DELETE | FILE_SHARE_READ | FILE_SHARE_WRITE;
let mut open_options = OpenOptions::new();
open_options.read(true).share_mode(share_mode);
if create {
open_options.create(true).write(true);
}
debug!("attempting to open lock file `{}`", p.display());
let file = match open_options.open(p) {
Ok(file) => {
debug!("lock file opened successfully");
file
}
Err(err) => {
debug!("error opening lock file: {}", err);
return Err(err);
}
};
let ret = unsafe {
let mut overlapped: OVERLAPPED = mem::zeroed();
let mut dwFlags = 0;
if !wait {
dwFlags |= LOCKFILE_FAIL_IMMEDIATELY;
}
if exclusive {
dwFlags |= LOCKFILE_EXCLUSIVE_LOCK;
}
debug!("attempting to acquire lock on lock file `{}`", p.display());
LockFileEx(file.as_raw_handle(), dwFlags, 0, 0xFFFF_FFFF, 0xFFFF_FFFF, &mut overlapped)
};
if ret == 0 {
let err = io::Error::last_os_error();
debug!("failed acquiring file lock: {}", err);
Err(err)
} else {
debug!("successfully acquired lock");
Ok(Lock { _file: file })
}
}
pub fn error_unsupported(err: &io::Error) -> bool {
err.raw_os_error() == Some(ERROR_INVALID_FUNCTION as i32)
}
}
// Note that we don't need a Drop impl on Windows: The file is unlocked
// automatically when it's closed.
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