Storage ReadChannel can read blob after 416-range exception #3016
Description
When ReadChannel tries to read slice first time and it's out of range it returns -1, because internally hit 416 range exception. But if blob is changed after this first unsuccessful call, then following read operation on the same ReadChannel succeeds with new blob that satisfies the range.
It does violate API contract for the java.nio.channels.ReadableByteChannel#read. If read() returns -1 once, all following read operations should return -1 consistently.
Returns:
The number of bytes read, possibly zero, or -1 if the channel has reached end-of-stream
Minimal reproduction set:
Storage storage = StorageOptions.http().setCredentials(creds).build().getService();
String bucket = "bucket";
String blob = "blob";
BlobId blobid = BlobId.of(bucket, blob);
BlobInfo blobInfo = ...
ReadChannel reader = storage.reader(BlobId.of(bucket, blob));
ByteBuffer buf = ByteBuffer.allocate(10);
// create 2-byte blob
byte[] content1 = new byte[]{1, 2};
storage.create(blobInfo, content1);
// move reader out of range
reader.seek(2);
int read1 = reader.read(buf);
assert read1 == -1; // expect 416 code and read -1
// create 4-byte blob
byte[] content2 = new byte[]{1, 2, 3, 4};
storage.create(blobInfo, content2);
// now can read data
int read2 = reader.read(buf);
assert read2 == 2;I assume https://github.com/googleapis/java-storage/blob/v2.50.0/google-cloud-storage/src/main/java/com/google/cloud/storage/BaseStorageReadChannel.java#L135-L141 needs to remember result of 416 error?
if (eof) return -1;
...
} catch (StorageException e) {
if (e.getCode() == 416) {
// HttpStorageRpc turns 416 into a null etag with an empty byte array, leading
// BlobReadChannel to believe it read 0 bytes, returning -1 and leaving the channel open.
// Emulate that same behavior here to preserve behavior compatibility, though this should
// be removed in the next major version.
eof = true;
return -1;