proxmox-backup/src/tape/drive/virtual_tape.rs

// Note: This is only for test an debug

use std::fs::File;
use std::io;

use anyhow::{bail, format_err, Error};
use serde::{Serialize, Deserialize};

use proxmox::tools::{
    fs::{replace_file, CreateOptions},
};

use crate::{
    tape::{
        TapeWrite,
        TapeRead,
        changer::MediaChange,
        drive::{
            VirtualTapeDrive,
            TapeDriver,
        },
        file_formats::{
            MediaSetLabel,
            MediaContentHeader,
            PROXMOX_BACKUP_MEDIA_SET_LABEL_MAGIC_1_0,
        },
        helpers::{
            EmulateTapeReader,
            EmulateTapeWriter,
            BlockedReader,
            BlockedWriter,
        },
    },
};

impl VirtualTapeDrive {

    /// This needs to lock the drive
    pub fn open(&self) -> Result<VirtualTapeHandle, Error> {
        let mut lock_path = std::path::PathBuf::from(&self.path);
        lock_path.push(".drive.lck");

        let timeout = std::time::Duration::new(10, 0);
        let lock = proxmox::tools::fs::open_file_locked(&lock_path, timeout, true)?;

        Ok(VirtualTapeHandle {
            _lock: lock,
            max_size: self.max_size.unwrap_or(64*1024*1024),
            path: std::path::PathBuf::from(&self.path),
        })
    }
}

#[derive(Serialize,Deserialize)]
struct VirtualTapeStatus {
    name: String,
    pos: usize,
}

#[derive(Serialize,Deserialize)]
struct VirtualDriveStatus {
    current_tape: Option<VirtualTapeStatus>,
}

#[derive(Serialize,Deserialize)]
struct TapeIndex {
    files: usize,
}

pub struct VirtualTapeHandle {
    path: std::path::PathBuf,
    max_size: usize,
    _lock: File,
}

impl  VirtualTapeHandle {

    pub fn insert_tape(&self, _tape_filename: &str) {
        unimplemented!();
    }

    pub fn eject_tape(&self) {
        unimplemented!();
    }

    fn status_file_path(&self) -> std::path::PathBuf {
        let mut path = self.path.clone();
        path.push("drive-status.json");
        path
    }

    fn tape_index_path(&self, tape_name: &str) -> std::path::PathBuf {
        let mut path = self.path.clone();
        path.push(format!("tape-{}.json", tape_name));
        path
    }

    fn tape_file_path(&self, tape_name: &str, pos: usize) -> std::path::PathBuf {
        let mut path = self.path.clone();
        path.push(format!("tapefile-{}-{}.json", pos, tape_name));
        path
    }

    fn load_tape_index(&self, tape_name: &str) -> Result<TapeIndex, Error> {
        let path = self.tape_index_path(tape_name);
        let raw = proxmox::tools::fs::file_get_contents(&path)?;
        if raw.is_empty() {
            return Ok(TapeIndex { files: 0 });
        }
        let data: TapeIndex = serde_json::from_slice(&raw)?;
        Ok(data)
    }

    fn store_tape_index(&self, tape_name: &str, index: &TapeIndex) -> Result<(), Error> {
        let path = self.tape_index_path(tape_name);
        let raw = serde_json::to_string_pretty(&serde_json::to_value(index)?)?;

        let options = CreateOptions::new();
        replace_file(&path, raw.as_bytes(), options)?;
        Ok(())
    }

    fn truncate_tape(&self, tape_name: &str, pos: usize) ->  Result<usize, Error> {
        let mut index = self.load_tape_index(tape_name)?;

        if index.files <= pos {
            return Ok(index.files)
        }

        for i in pos..index.files {
            let path = self.tape_file_path(tape_name, i);
            let _ = std::fs::remove_file(path);
        }

        index.files = pos;

        self.store_tape_index(tape_name, &index)?;

        Ok(index.files)
    }

    fn load_status(&self) -> Result<VirtualDriveStatus, Error> {
        let path = self.status_file_path();

        let default = serde_json::to_value(VirtualDriveStatus {
            current_tape: None,
        })?;

        let data = proxmox::tools::fs::file_get_json(&path, Some(default))?;
        let status: VirtualDriveStatus = serde_json::from_value(data)?;
        Ok(status)
    }

    fn store_status(&self, status: &VirtualDriveStatus) -> Result<(), Error> {
        let path = self.status_file_path();
        let raw = serde_json::to_string_pretty(&serde_json::to_value(status)?)?;

        let options = CreateOptions::new();
        replace_file(&path, raw.as_bytes(), options)?;
        Ok(())
    }
}

impl TapeDriver for VirtualTapeHandle {

    fn sync(&mut self) -> Result<(), Error> {
        Ok(()) // do nothing for now
    }

    fn current_file_number(&mut self) -> Result<usize, Error> {
       let status = self.load_status()
            .map_err(|err| format_err!("current_file_number failed: {}", err.to_string()))?;

        match status.current_tape {
            Some(VirtualTapeStatus { pos, .. }) => { Ok(pos)},
            None => bail!("current_file_number failed: drive is empty (no tape loaded)."),
        }
    }

    fn read_next_file(&mut self) -> Result<Option<Box<dyn TapeRead>>, io::Error> {
        let mut status = self.load_status()
            .map_err(|err| io::Error::new(io::ErrorKind::Other, err.to_string()))?;

        match status.current_tape {
            Some(VirtualTapeStatus { ref name, ref mut pos }) => {

                let index = self.load_tape_index(name)
                    .map_err(|err| io::Error::new(io::ErrorKind::Other, err.to_string()))?;

                if *pos >= index.files {
                    return Ok(None); // EOM
                }

                let path = self.tape_file_path(name, *pos);
                let file = std::fs::OpenOptions::new()
                    .read(true)
                    .open(path)?;

                *pos += 1;
                self.store_status(&status)
                    .map_err(|err| io::Error::new(io::ErrorKind::Other, err.to_string()))?;

                let reader = Box::new(file);
                let reader = Box::new(EmulateTapeReader::new(reader));

                match BlockedReader::open(reader)? {
                    Some(reader) => Ok(Some(Box::new(reader))),
                    None => Ok(None),
                }
            }
            None => proxmox::io_bail!("drive is empty (no tape loaded)."),
        }
    }

    fn write_file(&mut self) -> Result<Box<dyn TapeWrite>, io::Error> {
        let mut status = self.load_status()
            .map_err(|err| io::Error::new(io::ErrorKind::Other, err.to_string()))?;

        match status.current_tape {
            Some(VirtualTapeStatus { ref name, ref mut pos }) => {

                let mut index = self.load_tape_index(name)
                    .map_err(|err| io::Error::new(io::ErrorKind::Other, err.to_string()))?;

                for i in *pos..index.files {
                    let path = self.tape_file_path(name, i);
                    let _ = std::fs::remove_file(path);
                }

                let mut used_space = 0;
                for i in 0..*pos {
                    let path = self.tape_file_path(name, i);
                    used_space += path.metadata()?.len() as usize;

                }
                index.files = *pos + 1;

                self.store_tape_index(name, &index)
                    .map_err(|err| io::Error::new(io::ErrorKind::Other, err.to_string()))?;

                let path = self.tape_file_path(name, *pos);
                let file = std::fs::OpenOptions::new()
                    .write(true)
                    .create(true)
                    .truncate(true)
                    .open(path)?;

                *pos = index.files;

                self.store_status(&status)
                    .map_err(|err| io::Error::new(io::ErrorKind::Other, err.to_string()))?;

                let mut free_space = 0;
                if used_space < self.max_size {
                    free_space = self.max_size - used_space;
                }

                let writer = Box::new(file);
                let writer = Box::new(EmulateTapeWriter::new(writer, free_space));
                let writer = Box::new(BlockedWriter::new(writer));

                Ok(writer)
            }
            None => proxmox::io_bail!("drive is empty (no tape loaded)."),
        }
    }

    fn move_to_eom(&mut self) -> Result<(), Error> {
        let mut status = self.load_status()?;
        match status.current_tape {
            Some(VirtualTapeStatus { ref name, ref mut pos }) => {

                let index = self.load_tape_index(name)
                    .map_err(|err| io::Error::new(io::ErrorKind::Other, err.to_string()))?;

                *pos = index.files;
                self.store_status(&status)
                    .map_err(|err| io::Error::new(io::ErrorKind::Other, err.to_string()))?;

                Ok(())
            }
            None => bail!("drive is empty (no tape loaded)."),
        }
    }

    fn rewind(&mut self) -> Result<(), Error> {
        let mut status = self.load_status()?;
        match status.current_tape {
            Some(ref mut tape_status) => {
                tape_status.pos = 0;
                self.store_status(&status)?;
                Ok(())
            }
            None => bail!("drive is empty (no tape loaded)."),
        }
    }

    fn erase_media(&mut self, _fast: bool) -> Result<(), Error> {
        let mut status = self.load_status()?;
        match status.current_tape {
            Some(VirtualTapeStatus { ref name, ref mut pos }) => {
                *pos = self.truncate_tape(name, 0)?;
                self.store_status(&status)?;
                Ok(())
            }
            None => bail!("drive is empty (no tape loaded)."),
        }
    }

    fn write_media_set_label(&mut self, media_set_label: &MediaSetLabel) -> Result<(), Error> {

        let mut status = self.load_status()?;
        match status.current_tape {
            Some(VirtualTapeStatus { ref name, ref mut pos }) => {
                *pos = self.truncate_tape(name, 1)?;
                let pos = *pos;
                self.store_status(&status)?;

                if pos == 0 {
                    bail!("media is empty (no label).");
                }
                if pos != 1 {
                    bail!("write_media_set_label: truncate failed - got wrong pos '{}'", pos);
                }

                let raw = serde_json::to_string_pretty(&serde_json::to_value(media_set_label)?)?;
                let header = MediaContentHeader::new(PROXMOX_BACKUP_MEDIA_SET_LABEL_MAGIC_1_0, raw.len() as u32);

                {
                    let mut writer = self.write_file()?;
                    writer.write_header(&header, raw.as_bytes())?;
                    writer.finish(false)?;
                }

                Ok(())
            }
            None => bail!("drive is empty (no tape loaded)."),
        }
    }

    fn eject_media(&mut self) -> Result<(), Error> {
        let status = VirtualDriveStatus {
            current_tape: None,
        };
        self.store_status(&status)
    }
}

impl MediaChange for VirtualTapeHandle {

    /// Try to load media
    ///
    /// We automatically create an empty virtual tape here (if it does
    /// not exist already)
    fn load_media(&mut self, label: &str) -> Result<(), Error> {
        let name = format!("tape-{}.json", label);
        let mut path = self.path.clone();
        path.push(&name);
        if !path.exists() {
            eprintln!("unable to find tape {} - creating file {:?}", label, path);
            let index = TapeIndex { files: 0 };
            self.store_tape_index(label, &index)?;
        }

        let status = VirtualDriveStatus {
            current_tape: Some(VirtualTapeStatus {
                name: label.to_string(),
                pos: 0,
            }),
        };
        self.store_status(&status)
    }

    fn unload_media(&mut self) -> Result<(), Error> {
        self.eject_media()?;
        Ok(())
    }

    fn eject_on_unload(&self) -> bool {
        true
    }

    fn list_media_changer_ids(&self) -> Result<Vec<String>, Error> {
        let mut list = Vec::new();
        for entry in std::fs::read_dir(&self.path)? {
            let entry = entry?;
            let path = entry.path();
            if path.is_file() && path.extension() == Some(std::ffi::OsStr::new("json")) {
                if let Some(name) = path.file_stem() {
                    if let Some(name) = name.to_str() {
                        if name.starts_with("tape-") {
                            list.push(name[5..].to_string());
                        }
                    }
                }
            }
        }
        Ok(list)
    }
}

impl MediaChange for VirtualTapeDrive {

    fn load_media(&mut self, changer_id: &str) -> Result<(), Error> {
        let mut handle = self.open()?;
        handle.load_media(changer_id)
    }

    fn unload_media(&mut self) -> Result<(), Error> {
        let mut handle = self.open()?;
        handle.eject_media()?;
        Ok(())
    }

    fn eject_on_unload(&self) -> bool {
        true
    }

    fn list_media_changer_ids(&self) -> Result<Vec<String>, Error> {
        let handle = self.open()?;
        handle.list_media_changer_ids()
    }
}