63 lines
1.9 KiB
Rust
63 lines
1.9 KiB
Rust
use endian_trait::Endian;
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use crate::MediaContentHeader;
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/// Write trait for tape devices
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///
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/// The 'write_all' function returns if the drive reached the Logical
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/// End Of Media (early warning).
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///
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/// It is mandatory to call 'finish' before closing the stream to mark it
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/// as correctly written.
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///
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/// Please note that there is no flush method. Tapes flush there internal
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/// buffer when they write an EOF marker.
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pub trait TapeWrite {
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/// writes all data, returns true on LEOM
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fn write_all(&mut self, data: &[u8]) -> Result<bool, std::io::Error>;
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/// Returns how many bytes (raw data on tape) have been written
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fn bytes_written(&self) -> usize;
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/// flush last block, write file end mark
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///
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/// The incomplete flag is used to mark multivolume stream.
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fn finish(&mut self, incomplete: bool) -> Result<bool, std::io::Error>;
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/// Returns true if the writer already detected the logical end of media
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fn logical_end_of_media(&self) -> bool;
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/// writes header and data, returns true on LEOM
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fn write_header(
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&mut self,
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header: &MediaContentHeader,
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data: &[u8],
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) -> Result<bool, std::io::Error> {
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if header.size as usize != data.len() {
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proxmox::io_bail!("write_header with wrong size - internal error");
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}
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let header = header.to_le();
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let res = self.write_all(unsafe { std::slice::from_raw_parts(
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&header as *const MediaContentHeader as *const u8,
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std::mem::size_of::<MediaContentHeader>(),
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)})?;
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if data.is_empty() { return Ok(res); }
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self.write_all(data)
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}
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}
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/// Write streams of blocks
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pub trait BlockWrite {
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/// Write a data block
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///
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/// Returns true if the drive reached the Logical End Of Media
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/// (early warning)
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fn write_block(&mut self, buffer: &[u8]) -> Result<bool, std::io::Error>;
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/// Write a filemark
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fn write_filemark(&mut self) -> Result<(), std::io::Error>;
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}
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