IssueTracker

DataStore Component used: datastore-core

DataStore Version used: 1.0.0-alpha02

Devices/Android versions reproduced on: Emulator/Pixel 3, API 30

I've created a sample project that demonstrates the issue here: https://github.com/chris-horner/DataStore-Bug

I've written a custom Serializer that attempts to encrypt and decrypt the data written to disk. The problem I've run into is that I need to close the OutputStream provided in writeTo(), as I'm making use of Okio's CipherSink. Closing the stream is how CipherSink writes final data to the stream.

However closing OutputStream causes SingleProcessDataStore to throw a java.io.SyncFailedException when it attempts to invoke

stream.fd.sync()

with the stracktrace being

java.io.SyncFailedException: sync failed
    at java.io.FileDescriptor.sync(Native Method)
    at androidx.datastore.SingleProcessDataStore.writeData$datastore_core_release(SingleProcessDataStore.kt:299)
    at androidx.datastore.SingleProcessDataStore.transformAndWrite(SingleProcessDataStore.kt:282)
    at androidx.datastore.SingleProcessDataStore$actor$1.invokeSuspend(SingleProcessDataStore.kt:165)