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