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tape: introduce trait BlockRead

This commit is contained in:
Dietmar Maurer 2021-03-29 10:09:49 +02:00
parent c47609fedb
commit 0db5712493
6 changed files with 146 additions and 82 deletions
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1
src/api2/tape/drive.rs
View File

@ -531,6 +531,7 @@ pub fn label_media(
Ok(Some(_file)) => bail!("media is not empty (erase first)"),
Ok(None) => { /* EOF mark at BOT, assume tape is empty */ },
Err(err) => {
println!("TEST {:?}", err);
if err.is_errno(nix::errno::Errno::ENOSPC) || err.is_errno(nix::errno::Errno::EIO) {
/* assume tape is empty */
} else {

53
src/tape/drive/linux_tape.rs
View File

@ -1,6 +1,7 @@
//! Driver for Linux SCSI tapes
use std::fs::{OpenOptions, File};
use std::io::Read;
use std::os::unix::fs::OpenOptionsExt;
use std::os::unix::io::{AsRawFd, FromRawFd, RawFd};
use std::convert::TryFrom;
@ -24,6 +25,8 @@ use crate::{
LinuxDriveAndMediaStatus,
},
tape::{
BlockRead,
BlockReadStatus,
TapeRead,
TapeWrite,
drive::{
@ -507,7 +510,8 @@ impl TapeDriver for LinuxTapeHandle {
}
fn read_next_file<'a>(&'a mut self) -> Result<Option<Box<dyn TapeRead + 'a>>, std::io::Error> {
match BlockedReader::open(&mut self.file)? {
let reader = LinuxTapeReader::new(&mut self.file);
match BlockedReader::open(reader)? {
Some(reader) => Ok(Some(Box::new(reader))),
None => Ok(None),
}
@ -766,3 +770,50 @@ impl TapeWrite for TapeWriterHandle<'_> {
self.writer.logical_end_of_media()
}
}
pub struct LinuxTapeReader<'a> {
/// Assumes that 'file' is a linux tape device.
file: &'a mut File,
got_eof: bool,
}
impl <'a> LinuxTapeReader<'a> {
pub fn new(file: &'a mut File) -> Self {
Self { file, got_eof: false }
}
}
impl <'a> BlockRead for LinuxTapeReader<'a> {
/// Read a single block from a linux tape device
///
/// Return true on success, false on EOD
fn read_block(&mut self, buffer: &mut [u8]) -> Result<BlockReadStatus, std::io::Error> {
loop {
match self.file.read(buffer) {
Ok(0) => {
let eod = self.got_eof;
self.got_eof = true;
if eod {
return Ok(BlockReadStatus::EndOfStream);
} else {
return Ok(BlockReadStatus::EndOfFile);
}
}
Ok(count) => {
if count == buffer.len() {
return Ok(BlockReadStatus::Ok(count));
}
proxmox::io_bail!("short block read ({} < {}). Tape drive uses wrong block size.",
count, buffer.len());
}
// handle interrupted system call
Err(err) if err.kind() == std::io::ErrorKind::Interrupted => {
continue;
}
Err(err) => return Err(err),
}
}
}
}

3
src/tape/drive/virtual_tape.rs
View File

@ -222,8 +222,7 @@ impl TapeDriver for VirtualTapeHandle {
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));
let reader = EmulateTapeReader::new(file);
match BlockedReader::open(reader)? {
Some(reader) => Ok(Some(Box::new(reader))),

70
src/tape/file_formats/blocked_reader.rs
View File

@ -2,7 +2,8 @@ use std::io::Read;
use crate::tape::{
TapeRead,
tape_device_read_block,
BlockRead,
BlockReadStatus,
file_formats::{
PROXMOX_TAPE_BLOCK_HEADER_MAGIC_1_0,
BlockHeader,
@ -32,7 +33,7 @@ pub struct BlockedReader<R> {
read_pos: usize,
}
impl <R: Read> BlockedReader<R> {
impl <R: BlockRead> BlockedReader<R> {
/// Create a new BlockedReader instance.
///
@ -103,15 +104,41 @@ impl <R: Read> BlockedReader<R> {
)
};
tape_device_read_block(reader, data)
match reader.read_block(data) {
Ok(BlockReadStatus::Ok(bytes)) => {
if bytes != BlockHeader::SIZE {
proxmox::io_bail!("got wrong block size");
}
Ok(true)
}
Ok(BlockReadStatus::EndOfFile) => {
Ok(false)
}
Ok(BlockReadStatus::EndOfStream) => {
return Err(std::io::Error::from_raw_os_error(nix::errno::Errno::ENOSPC as i32));
}
Err(err) => {
Err(err)
}
}
}
fn consume_eof_marker(reader: &mut R) -> Result<(), std::io::Error> {
let mut tmp_buf = [0u8; 512]; // use a small buffer for testing EOF
if tape_device_read_block(reader, &mut tmp_buf)? {
proxmox::io_bail!("detected tape block after stream end marker");
match reader.read_block(&mut tmp_buf) {
Ok(BlockReadStatus::Ok(_)) => {
proxmox::io_bail!("detected tape block after block-stream end marker");
}
Ok(BlockReadStatus::EndOfFile) => {
return Ok(());
}
Ok(BlockReadStatus::EndOfStream) => {
proxmox::io_bail!("got unexpected end of tape");
}
Err(err) => {
return Err(err);
}
}
Ok(())
}
fn read_block(&mut self) -> Result<usize, std::io::Error> {
@ -141,7 +168,7 @@ impl <R: Read> BlockedReader<R> {
}
}
impl <R: Read> TapeRead for BlockedReader<R> {
impl <R: BlockRead> TapeRead for BlockedReader<R> {
fn is_incomplete(&self) -> Result<bool, std::io::Error> {
if !self.got_eod {
@ -163,7 +190,7 @@ impl <R: Read> TapeRead for BlockedReader<R> {
}
}
impl <R: Read> Read for BlockedReader<R> {
impl <R: BlockRead> Read for BlockedReader<R> {
fn read(&mut self, buffer: &mut [u8]) -> Result<usize, std::io::Error> {
@ -207,6 +234,7 @@ mod test {
use anyhow::Error;
use crate::tape::{
TapeWrite,
helpers::{EmulateTapeReader, EmulateTapeWriter},
file_formats::{
PROXMOX_TAPE_BLOCK_SIZE,
BlockedReader,
@ -218,11 +246,14 @@ mod test {
let mut tape_data = Vec::new();
let mut writer = BlockedWriter::new(&mut tape_data);
{
let writer = EmulateTapeWriter::new(&mut tape_data, 1024*1024*10);
let mut writer = BlockedWriter::new(writer);
writer.write_all(data)?;
writer.write_all(data)?;
writer.finish(false)?;
writer.finish(false)?;
}
assert_eq!(
tape_data.len(),
@ -231,6 +262,7 @@ mod test {
);
let reader = &mut &tape_data[..];
let reader = EmulateTapeReader::new(reader);
let mut reader = BlockedReader::open(reader)?.unwrap();
let mut read_data = Vec::with_capacity(PROXMOX_TAPE_BLOCK_SIZE);
@ -263,6 +295,7 @@ mod test {
fn no_data() -> Result<(), Error> {
let tape_data = Vec::new();
let reader = &mut &tape_data[..];
let reader = EmulateTapeReader::new(reader);
let reader = BlockedReader::open(reader)?;
assert!(reader.is_none());
@ -273,13 +306,16 @@ mod test {
fn no_end_marker() -> Result<(), Error> {
let mut tape_data = Vec::new();
{
let mut writer = BlockedWriter::new(&mut tape_data);
let writer = EmulateTapeWriter::new(&mut tape_data, 1024*1024);
let mut writer = BlockedWriter::new(writer);
// write at least one block
let data = proxmox::sys::linux::random_data(PROXMOX_TAPE_BLOCK_SIZE)?;
writer.write_all(&data)?;
// but do not call finish here
}
let reader = &mut &tape_data[..];
let reader = EmulateTapeReader::new(reader);
let mut reader = BlockedReader::open(reader)?.unwrap();
let mut data = Vec::with_capacity(PROXMOX_TAPE_BLOCK_SIZE);
@ -292,13 +328,17 @@ mod test {
fn small_read_buffer() -> Result<(), Error> {
let mut tape_data = Vec::new();
let mut writer = BlockedWriter::new(&mut tape_data);
{
let writer = EmulateTapeWriter::new(&mut tape_data, 1024*1024);
let mut writer = BlockedWriter::new(writer);
writer.write_all(b"ABC")?;
writer.write_all(b"ABC")?;
writer.finish(false)?;
writer.finish(false)?;
}
let reader = &mut &tape_data[..];
let reader = EmulateTapeReader::new(reader);
let mut reader = BlockedReader::open(reader)?.unwrap();
let mut buf = [0u8; 1];

64
src/tape/helpers/emulate_tape_reader.rs
View File

@ -1,56 +1,46 @@
use std::io::{self, Read};
use std::io::Read;
use crate::tape::file_formats::PROXMOX_TAPE_BLOCK_SIZE;
use proxmox::tools::io::ReadExt;
use crate::tape::{
BlockRead,
BlockReadStatus,
file_formats::PROXMOX_TAPE_BLOCK_SIZE,
};
/// Emulate tape read behavior on a normal Reader
///
/// Tapes reads are always return one whole block PROXMOX_TAPE_BLOCK_SIZE.
pub struct EmulateTapeReader<R> {
pub struct EmulateTapeReader<R: Read> {
reader: R,
got_eof: bool,
}
impl <R: Read> EmulateTapeReader<R> {
pub fn new(reader: R) -> Self {
Self { reader }
Self { reader, got_eof: false }
}
}
impl <R: Read> Read for EmulateTapeReader<R> {
fn read(&mut self, mut buffer: &mut [u8]) -> Result<usize, io::Error> {
let initial_buffer_len = buffer.len(); // store, check later
let mut bytes = 0;
while !buffer.is_empty() {
match self.reader.read(buffer) {
Ok(0) => break,
Ok(n) => {
bytes += n;
let tmp = buffer;
buffer = &mut tmp[n..];
impl <R: Read> BlockRead for EmulateTapeReader<R> {
fn read_block(&mut self, buffer: &mut [u8]) -> Result<BlockReadStatus, std::io::Error> {
if self.got_eof {
proxmox::io_bail!("detected read after EOF!");
}
match self.reader.read_exact_or_eof(buffer)? {
false => {
self.got_eof = true;
Ok(BlockReadStatus::EndOfFile)
}
true => {
// test buffer len after EOF test (to allow EOF test with small buffers in BufferedReader)
if buffer.len() != PROXMOX_TAPE_BLOCK_SIZE {
proxmox::io_bail!("EmulateTapeReader: read_block with wrong block size ({} != {})",
buffer.len(), PROXMOX_TAPE_BLOCK_SIZE);
}
Err(ref e) if e.kind() == io::ErrorKind::Interrupted => {}
Err(e) => return Err(e),
Ok(BlockReadStatus::Ok(buffer.len()))
}
}
if bytes == 0 {
return Ok(0);
}
// test buffer len after EOF test (to allow EOF test with small buffers in BufferedReader)
if initial_buffer_len != PROXMOX_TAPE_BLOCK_SIZE {
proxmox::io_bail!("EmulateTapeReader: got read with wrong block size ({} != {})",
buffer.len(), PROXMOX_TAPE_BLOCK_SIZE);
}
if !buffer.is_empty() {
Err(io::Error::new(io::ErrorKind::UnexpectedEof, "failed to fill whole buffer"))
} else {
Ok(bytes)
}
}
}

37
src/tape/tape_read.rs
View File

@ -15,31 +15,14 @@ pub trait TapeRead: Read {
fn has_end_marker(&self) -> Result<bool, std::io::Error>;
}
/// Read a single block from a tape device
///
/// Assumes that 'reader' is a linux tape device.
///
/// Return true on success, false on EOD
pub fn tape_device_read_block<R: Read>(
reader: &mut R,
buffer: &mut [u8],
) -> Result<bool, std::io::Error> {
loop {
match reader.read(buffer) {
Ok(0) => { return Ok(false); /* EOD */ }
Ok(count) => {
if count == buffer.len() {
return Ok(true);
}
proxmox::io_bail!("short block read ({} < {}). Tape drive uses wrong block size.",
count, buffer.len());
}
// handle interrupted system call
Err(err) if err.kind() == std::io::ErrorKind::Interrupted => {
continue;
}
Err(err) => return Err(err),
}
}
pub enum BlockReadStatus {
Ok(usize),
EndOfFile,
EndOfStream,
}
/// Read streams of blocks
pub trait BlockRead {
/// Read the next block (whole buffer)
fn read_block(&mut self, buffer: &mut [u8]) -> Result<BlockReadStatus, std::io::Error>;
}