74 lines
2.5 KiB
Swift
74 lines
2.5 KiB
Swift
//
|
|
// Copyright 2023 Signal Messenger, LLC
|
|
// SPDX-License-Identifier: AGPL-3.0-only
|
|
//
|
|
|
|
import Foundation
|
|
|
|
extension MessageBackup {
|
|
public enum ProtoInputStreamReadResult<T> {
|
|
case success(T, moreBytesAvailable: Bool)
|
|
case invalidByteLengthDelimiter
|
|
case protoDeserializationError(Swift.Error)
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Input stream for reading and writing a backup file on disk.
|
|
*
|
|
* The backup file is just a sequence of serialized proto bytes, back to back, delimited by varint
|
|
* byte sizes so we know how much to read into memory to deserialize the next proto.
|
|
* The input stream abstracts over this, and allows callers to just think in terms of "frames",
|
|
* the individual proto objects that we read one at a time.
|
|
*/
|
|
public protocol MessageBackupProtoInputStream {
|
|
|
|
/// Read the single header object at the start of every backup file.
|
|
/// If this header is missing or invalid, the backup should be discarded.
|
|
func readHeader() -> MessageBackup.ProtoInputStreamReadResult<BackupProtoBackupInfo>
|
|
|
|
/// Read a the next frame from the backup file.
|
|
func readFrame() -> MessageBackup.ProtoInputStreamReadResult<BackupProtoFrame>
|
|
|
|
/// Close the stream. Attempting to read after closing will result in failures.
|
|
func closeFileStream()
|
|
}
|
|
|
|
internal class MessageBackupProtoInputStreamImpl: MessageBackupProtoInputStream {
|
|
|
|
private var inputStream: InputStreamable
|
|
private var inputStreamDelegate: StreamDelegate
|
|
|
|
internal init(
|
|
inputStream: InputStreamable,
|
|
inputStreamDelegate: StreamDelegate
|
|
) {
|
|
self.inputStream = inputStream
|
|
self.inputStreamDelegate = inputStreamDelegate
|
|
}
|
|
|
|
internal func readHeader() -> MessageBackup.ProtoInputStreamReadResult<BackupProtoBackupInfo> {
|
|
return readProto(BackupProtoBackupInfo.init(serializedData:))
|
|
}
|
|
|
|
internal func readFrame() -> MessageBackup.ProtoInputStreamReadResult<BackupProtoFrame> {
|
|
return readProto(BackupProtoFrame.init(serializedData:))
|
|
}
|
|
|
|
public func closeFileStream() {
|
|
try? inputStream.close()
|
|
}
|
|
|
|
private func readProto<T>(
|
|
_ initializer: (Data) throws -> T
|
|
) -> MessageBackup.ProtoInputStreamReadResult<T> {
|
|
do {
|
|
let data = try inputStream.read(maxLength: 8192)
|
|
let protoObject = try initializer(data)
|
|
return .success(protoObject, moreBytesAvailable: inputStream.hasBytesAvailable)
|
|
} catch {
|
|
return .protoDeserializationError(error)
|
|
}
|
|
}
|
|
}
|