pbs-tape/src/tape_write.rs

   1 use endian_trait::Endian;
   2
   3 use crate::MediaContentHeader;
   4
   5 /// Write trait for tape devices
   6 ///
   7 /// The 'write_all' function returns if the drive reached the Logical
   8 /// End Of Media (early warning).
   9 ///
  10 /// It is mandatory to call 'finish' before closing the stream to mark it
  11 /// as correctly written.
  12 ///
  13 /// Please note that there is no flush method. Tapes flush there internal
  14 /// buffer when they write an EOF marker.
  15 pub trait TapeWrite {
  16     /// writes all data, returns true on LEOM
  17     fn write_all(&mut self, data: &[u8]) -> Result<bool, std::io::Error>;
  18
  19     /// Returns how many bytes (raw data on tape) have been written
  20     fn bytes_written(&self) -> usize;
  21
  22     /// flush last block, write file end mark
  23     ///
  24     /// The incomplete flag is used to mark multivolume stream.
  25     fn finish(&mut self, incomplete: bool) -> Result<bool, std::io::Error>;
  26
  27     /// Returns true if the writer already detected the logical end of media
  28     fn logical_end_of_media(&self) -> bool;
  29
  30     /// writes header and data, returns true on LEOM
  31     fn write_header(
  32         &mut self,
  33         header: &MediaContentHeader,
  34         data: &[u8],
  35     ) -> Result<bool, std::io::Error> {
  36         if header.size as usize != data.len() {
  37             proxmox_sys::io_bail!("write_header with wrong size - internal error");
  38         }
  39         let header = header.to_le();
  40
  41         let res = self.write_all(unsafe { std::slice::from_raw_parts(
  42             &header as *const MediaContentHeader as *const u8,
  43             std::mem::size_of::<MediaContentHeader>(),
  44         )})?;
  45
  46         if data.is_empty() { return Ok(res); }
  47
  48         self.write_all(data)
  49     }
  50 }
  51
  52 /// Write streams of blocks
  53 pub trait BlockWrite {
  54     /// Write a data block
  55     ///
  56     /// Returns true if the drive reached the Logical End Of Media
  57     /// (early warning)
  58     fn write_block(&mut self, buffer: &[u8]) -> Result<bool, std::io::Error>;
  59
  60     /// Write a filemark
  61     fn write_filemark(&mut self) -> Result<(), std::io::Error>;
  62 }