pbs-tape/src/emulate_tape_reader.rs

   1 use std::io::Read;
   2
   3 use proxmox_io::ReadExt;
   4
   5 use crate::{BlockRead, BlockReadError, PROXMOX_TAPE_BLOCK_SIZE};
   6
   7 /// Emulate tape read behavior on a normal Reader
   8 ///
   9 /// Tapes reads are always return one whole block PROXMOX_TAPE_BLOCK_SIZE.
  10 pub struct EmulateTapeReader<R: Read> {
  11     reader: R,
  12     got_eof: bool,
  13 }
  14
  15 impl <R: Read> EmulateTapeReader<R> {
  16
  17     pub fn new(reader: R) -> Self {
  18         Self { reader, got_eof: false }
  19     }
  20 }
  21
  22 impl <R: Read> BlockRead for EmulateTapeReader<R> {
  23     fn read_block(&mut self, buffer: &mut [u8]) -> Result<usize, BlockReadError> {
  24         if self.got_eof {
  25              return Err(BlockReadError::Error(proxmox_sys::io_format_err!("detected read after EOF!")));
  26         }
  27         match self.reader.read_exact_or_eof(buffer)? {
  28             false => {
  29                 self.got_eof = true;
  30                 Err(BlockReadError::EndOfFile)
  31             }
  32             true => {
  33                 // test buffer len after EOF test (to allow EOF test with small buffers in BufferedReader)
  34                 if buffer.len() != PROXMOX_TAPE_BLOCK_SIZE {
  35                     return Err(BlockReadError::Error(
  36                         proxmox_sys::io_format_err!(
  37                             "EmulateTapeReader: read_block with wrong block size ({} != {})",
  38                             buffer.len(),
  39                             PROXMOX_TAPE_BLOCK_SIZE,
  40                         )
  41                     ));
  42                 }
  43                 Ok(buffer.len())
  44             }
  45         }
  46     }
  47 }