ripunzip3.rs

#[derive(Clone)]
struct CloneableFile {
    file: Arc<Mutex<File>>,
    pos: u64,
    // TODO determine and store this once instead of per cloneable file
    file_length: Option<u64>,
}

impl CloneableFile {
    fn new(file: File) -> Self {
        Self {
            file: Arc::new(Mutex::new(file)),
            pos: 0u64,
            file_length: None,
        }
    }
}

impl CloneableFile {
    fn ascertain_file_length(&mut self) -> u64 {
        match self.file_length {
            Some(file_length) => file_length,
            None => {
                let len = self.file.lock().unwrap().metadata().unwrap().len();
                self.file_length = Some(len);
                len
            }
        }
    }
}

impl Read for CloneableFile {
    fn read(&mut self, buf: &mut [u8]) -> std::io::Result<usize> {
        let mut underlying_file = self.file.lock().expect("Unable to get underlying file");
        // TODO share an object which knows current position to avoid unnecessary
        // seeks
        underlying_file.seek(SeekFrom::Start(self.pos))?;
        let read_result = underlying_file.read(buf);
        if let Ok(bytes_read) = read_result {
            // TODO, once stabilised, use checked_add_signed
            self.pos += bytes_read as u64;
        }
        read_result
    }
}

impl Seek for CloneableFile {
    fn seek(&mut self, pos: SeekFrom) -> std::io::Result<u64> {
        let new_pos = match pos {
            SeekFrom::Start(pos) => pos,
            SeekFrom::End(offset_from_end) => {
                let file_len = self.ascertain_file_length();
                // TODO, once stabilised, use checked_add_signed
                file_len - (-offset_from_end as u64)
            }
            // TODO, once stabilised, use checked_add_signed
            SeekFrom::Current(offset_from_pos) => {
                if offset_from_pos == 0 {
                    self.pos
                } else if offset_from_pos > 0 {
                    self.pos + (offset_from_pos as u64)
                } else {
                    self.pos - ((-offset_from_pos) as u64)
                }
            }
        };
        self.pos = new_pos;
        Ok(new_pos)
    }
}