file.rs

use core::ops::{Deref, DerefMut};
#[cfg(feature = "fs_locks")]
use fs4::FileExt;
use std::{
    fs::{File as StdFile, OpenOptions},
    io::{Result as IoResult, Seek, Write},
    path::Path,
    thread::panicking,
};

pub fn open_rwlocked<P: AsRef<Path>>(path: P) -> IoResult<File> {
    let path = path.as_ref();
    let mut file = OpenOptions::new()
        .read(true)
        .write(true)
        .create(true)
        // truncate as needed during store_to_disk
        //.truncate(truncate)
        .open(path)?;

    //println!("File::open_rwlocked(... {:?}) at {}",path.file_name(),file.stream_position()?);

    file.rewind()?;
    #[cfg(feature = "fs_locks")]
    {
        file.lock_exclusive()?;
    }
    Ok(File(file))
}

pub struct File(StdFile);
impl Drop for File {
    fn drop(&mut self) {
        if let Err(e) = self.0.flush().and_then(|_| self.0.unlock()) {
            let error = format!(
                "unable to flush and unlock multi_key_manager::File: {:?}",
                e
            );
            if panicking() {
                eprintln!("{error}");
            } else {
                panic!("{error}");
            }
        };
    }
}
impl File {
    pub fn empty(&self) -> IoResult<bool> {
        Ok(self.0.metadata()?.len() == 0)
    }
}
impl Deref for File {
    type Target = StdFile;

    fn deref(&self) -> &Self::Target {
        &self.0
    }
}
impl DerefMut for File {
    fn deref_mut(&mut self) -> &mut Self::Target {
        &mut self.0
    }
}
impl std::fmt::Debug for File {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.debug_struct("File").finish()
    }
}

/*
#[cfg(unix)]
use std::os::unix::prelude::OpenOptionsExt;


pub fn open_rwlocked<P: AsRef<Path>>(path: P) -> IoResult<File> {
    let path = path.as_ref();
    let mut file = OpenOptions::new();

    file.write(true).create(true).truncate(true);

    #[cfg(unix)]
    {
        file.custom_flags(libc::F_LOCK | libc::O_DSYNC);
    }
    #[cfg(windows)]
    {
        file.share_mode(winapi);
    }

    file.open(path)
    //?;
}
*/