1 files changed, 86 insertions, 0 deletions
diff --git a/tvix/castore/src/digests.rs b/tvix/castore/src/digests.rs
new file mode 100644
index 0000000000..2311c95c4d
--- /dev/null
+++ b/tvix/castore/src/digests.rs
@@ -0,0 +1,86 @@
+use bytes::Bytes;
+use data_encoding::BASE64;
+use thiserror::Error;
+
+#[derive(PartialEq, Eq, Hash)]
+pub struct B3Digest(Bytes);
+
+// TODO: allow converting these errors to crate::Error
+#[derive(Error, Debug)]
+pub enum Error {
+    #[error("invalid digest length: {0}")]
+    InvalidDigestLen(usize),
+}
+
+pub const B3_LEN: usize = 32;
+
+impl B3Digest {
+    pub fn as_slice(&self) -> &[u8] {
+        &self.0[..]
+    }
+}
+
+impl From<B3Digest> for bytes::Bytes {
+    fn from(val: B3Digest) -> Self {
+        val.0
+    }
+}
+
+impl From<digest::Output<blake3::Hasher>> for B3Digest {
+    fn from(value: digest::Output<blake3::Hasher>) -> Self {
+        let v = Into::<[u8; B3_LEN]>::into(value);
+        Self(Bytes::copy_from_slice(&v))
+    }
+}
+
+impl TryFrom<Vec<u8>> for B3Digest {
+    type Error = Error;
+
+    // constructs a [B3Digest] from a [Vec<u8>].
+    // Returns an error if the digest has the wrong length.
+    fn try_from(value: Vec<u8>) -> Result<Self, Self::Error> {
+        if value.len() != B3_LEN {
+            Err(Error::InvalidDigestLen(value.len()))
+        } else {
+            Ok(Self(value.into()))
+        }
+    }
+}
+
+impl TryFrom<bytes::Bytes> for B3Digest {
+    type Error = Error;
+
+    // constructs a [B3Digest] from a [bytes::Bytes].
+    // Returns an error if the digest has the wrong length.
+    fn try_from(value: bytes::Bytes) -> Result<Self, Self::Error> {
+        if value.len() != B3_LEN {
+            Err(Error::InvalidDigestLen(value.len()))
+        } else {
+            Ok(Self(value))
+        }
+    }
+}
+
+impl From<&[u8; B3_LEN]> for B3Digest {
+    fn from(value: &[u8; B3_LEN]) -> Self {
+        Self(value.to_vec().into())
+    }
+}
+
+impl Clone for B3Digest {
+    fn clone(&self) -> Self {
+        Self(self.0.to_owned())
+    }
+}
+
+impl std::fmt::Display for B3Digest {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "b3:{}", BASE64.encode(&self.0))
+    }
+}
+
+impl std::fmt::Debug for B3Digest {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "b3:{}", BASE64.encode(&self.0))
+    }
+}