Ultrabug created AVRO-3240:
------------------------------
Summary: Schema deserialization is not backwards compatible
Key: AVRO-3240
URL: https://issues.apache.org/jira/browse/AVRO-3240
Project: Apache Avro
Issue Type: Bug
Components: rust
Reporter: Ultrabug
Hello,
When providing your own schema to `from_avro_datum`, the deserialization is not
backward compatible with messages containing a previous schema even if the
schemas are created to be backward compatible.
This is due to the `decode_variable` function in `utils` returning
`Error::ReadVariableIntegerBytes` when the reader object is smaller than
expected when reading a message with previous schema version (which is indeed
smaller) and trying to decode it with a backward compatible schema.
I have fixed the issue locally with the following patch which I will submit as
a PR
```
diff --git a/lang/rust/src/util.rs b/lang/rust/src/util.rs
index f9daf285..3538399e 100644
--- a/lang/rust/src/util.rs
+++ b/lang/rust/src/util.rs
@@ -96,7 +96,7 @@ fn decode_variable<R: Read>(reader: &mut R) ->
AvroResult<u64> {
}
reader
.read_exact(&mut buf[..])
- .map_err(Error::ReadVariableIntegerBytes)?;
+ .or(Ok(()))?; // return nullable to support avro schemas backward
compatibility
i |= (u64::from(buf[0] & 0x7F)) << (j * 7);
if (buf[0] >> 7) == 0 {
break;
```
--
This message was sent by Atlassian Jira
(v8.3.4#803005)
