add pbs-datastore module

Signed-off-by: Wolfgang Bumiller <w.bumiller@proxmox.com>

pbs-datastore/src/checksum_reader.rs

@@ -0,0 +1,62 @@
+use anyhow::{Error};
+use std::sync::Arc;
+use std::io::Read;
+
+use pbs_tools::borrow::Tied;
+
+use super::CryptConfig;
+
+pub struct ChecksumReader<R> {
+    reader: R,
+    hasher: crc32fast::Hasher,
+    signer: Option<Tied<Arc<CryptConfig>, openssl::sign::Signer<'static>>>,
+}
+
+impl <R: Read> ChecksumReader<R> {
+
+    pub fn new(reader: R, config: Option<Arc<CryptConfig>>) -> Self {
+        let hasher = crc32fast::Hasher::new();
+        let signer = match config {
+            Some(config) => {
+                let tied_signer = Tied::new(config, |config| {
+                    Box::new(unsafe { (*config).data_signer() })
+                });
+                Some(tied_signer)
+            }
+            None => None,
+        };
+
+        Self { reader, hasher, signer }
+    }
+
+    pub fn finish(mut self) -> Result<(R, u32, Option<[u8; 32]>), Error> {
+        let crc = self.hasher.finalize();
+
+        if let Some(ref mut signer) = self.signer {
+            let mut tag = [0u8; 32];
+            signer.sign(&mut tag)?;
+            Ok((self.reader, crc, Some(tag)))
+        } else {
+            Ok((self.reader, crc, None))
+        }
+    }
+}
+
+impl <R: Read> Read for ChecksumReader<R> {
+
+    fn read(&mut self, buf: &mut [u8]) -> Result<usize, std::io::Error> {
+        let count = self.reader.read(buf)?;
+        if count > 0 {
+            self.hasher.update(&buf[..count]);
+            if let Some(ref mut signer) = self.signer {
+                signer.update(&buf[..count])
+                    .map_err(|err| {
+                        std::io::Error::new(
+                            std::io::ErrorKind::Other,
+                            format!("hmac update failed - {}", err))
+                    })?;
+            }
+        }
+        Ok(count)
+    }
+}