src/backup/checksum_writer.rs

   1 use std::sync::Arc;
   2 use std::io::Write;
   3
   4 use anyhow::{Error};
   5
   6 use super::CryptConfig;
   7 use crate::tools::borrow::Tied;
   8
   9 pub struct ChecksumWriter<W> {
  10     writer: W,
  11     hasher: crc32fast::Hasher,
  12     signer: Option<Tied<Arc<CryptConfig>, openssl::sign::Signer<'static>>>,
  13 }
  14
  15 impl <W: Write> ChecksumWriter<W> {
  16
  17     pub fn new(writer: W, config: Option<Arc<CryptConfig>>) -> Self {
  18         let hasher = crc32fast::Hasher::new();
  19         let signer = match config {
  20             Some(config) => {
  21                 let tied_signer = Tied::new(config, |config| {
  22                     Box::new(unsafe { (*config).data_signer() })
  23                 });
  24                 Some(tied_signer)
  25             }
  26             None => None,
  27         };
  28         Self { writer, hasher, signer }
  29     }
  30
  31     pub fn finish(mut self) -> Result<(W, u32, Option<[u8; 32]>), Error> {
  32         let crc = self.hasher.finalize();
  33
  34         if let Some(ref mut signer) = self.signer {
  35             let mut tag = [0u8; 32];
  36             signer.sign(&mut tag)?;
  37             Ok((self.writer, crc, Some(tag)))
  38         } else {
  39             Ok((self.writer, crc, None))
  40         }
  41     }
  42 }
  43
  44 impl <W: Write> Write for ChecksumWriter<W> {
  45
  46     fn write(&mut self, buf: &[u8]) -> Result<usize, std::io::Error> {
  47         self.hasher.update(buf);
  48         if let Some(ref mut signer) = self.signer {
  49             signer.update(buf)
  50                 .map_err(|err| {
  51                     std::io::Error::new(
  52                         std::io::ErrorKind::Other,
  53                         format!("hmac update failed - {}", err))
  54                 })?;
  55         }
  56         self.writer.write(buf)
  57     }
  58
  59     fn flush(&mut self) -> Result<(), std::io::Error> {
  60         self.writer.flush()
  61     }
  62 }