103 lines
3.1 KiB
Rust
103 lines
3.1 KiB
Rust
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use std::io::{Read};
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use anyhow::{bail, Error};
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use proxmox::tools::io::ReadExt;
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use crate::tape::{
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TapeRead,
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file_formats::MediaContentHeader,
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};
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/// Read multi volume data streams written by `MultiVolumeWriter`
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///
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/// Note: We do not use this feature currently.
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pub struct MultiVolumeReader<'a> {
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reader: Option<Box<dyn TapeRead + 'a>>,
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next_reader_fn: Box<dyn 'a + FnMut() -> Result<Box<dyn TapeRead +'a>, Error>>,
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complete: bool,
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header: MediaContentHeader,
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}
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impl <'a> MultiVolumeReader<'a> {
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/// Creates a new instance
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pub fn new(
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reader: Box<dyn TapeRead +'a>,
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header: MediaContentHeader,
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next_reader_fn: Box<dyn 'a + FnMut() -> Result<Box<dyn TapeRead +'a>, Error>>,
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) -> Result<Self, Error> {
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if header.part_number != 0 {
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bail!("MultiVolumeReader::new - got wrong header part_number ({} != 0)",
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header.part_number);
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}
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Ok(Self {
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reader: Some(reader),
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next_reader_fn,
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complete: false,
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header,
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})
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}
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}
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impl <'a> Read for MultiVolumeReader<'a> {
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fn read(&mut self, buf: &mut [u8]) -> Result<usize, std::io::Error> {
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if self.complete {
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return Ok(0);
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}
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if self.reader.is_none() {
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let mut reader = (self.next_reader_fn)()
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.map_err(|err| proxmox::io_format_err!("multi-volume next failed: {}", err))?;
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proxmox::try_block!({
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let part_header: MediaContentHeader = unsafe { reader.read_le_value()? };
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self.reader = Some(reader);
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if part_header.uuid != self.header.uuid {
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proxmox::io_bail!("got wrong part uuid");
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}
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if part_header.content_magic!= self.header.content_magic {
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proxmox::io_bail!("got wrong part content magic");
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}
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let expect_part_number = self.header.part_number + 1;
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if part_header.part_number != expect_part_number {
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proxmox::io_bail!("got wrong part number ({} != {})",
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part_header.part_number, expect_part_number);
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}
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self.header.part_number = expect_part_number;
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Ok(())
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}).map_err(|err| {
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proxmox::io_format_err!("multi-volume read content header failed: {}", err)
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})?;
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}
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match self.reader {
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None => unreachable!(),
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Some(ref mut reader) => {
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match reader.read(buf) {
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Ok(0) => {
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if reader.is_incomplete()? {
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self.reader = None;
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self.read(buf)
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} else {
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self.reader = None;
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self.complete = true;
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Ok(0)
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}
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}
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Ok(n) => Ok(n),
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Err(err) => Err(err)
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}
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}
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}
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}
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}
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