92 lines
2.9 KiB
Swift
92 lines
2.9 KiB
Swift
//
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// Copyright 2023 Signal Messenger, LLC
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// SPDX-License-Identifier: AGPL-3.0-only
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//
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import Wire
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extension MessageBackup {
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public enum ProtoOutputStreamWriteResult {
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case success
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/// Unable to serialize the provided proto object.
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/// Should never happen, and catastrophic if it does.
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case protoSerializationError(Swift.Error)
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/// Failure writing at file I/O level.
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case fileIOError(Swift.Error)
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}
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}
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/**
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* Output stream for reading and writing a backup file on disk.
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*
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* The backup file is just a sequence of serialized proto bytes, back to back, delimited by varint
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* byte sizes so we know how much to read into memory to deserialize the next proto.
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* The output stream abstracts over this, and allows callers to just think in terms of "frames",
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* the individual proto objects that we write one at a time.
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*/
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public protocol MessageBackupProtoOutputStream {
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/// Write a header (BakckupInfo) to the backup file.
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/// It is the caller's responsibility to ensure this is always written, and is the first thing written,
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/// in order to produce a valid backup file.
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func writeHeader(_ header: BackupProto.BackupInfo) -> MessageBackup.ProtoOutputStreamWriteResult
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/// Write a frame to the backup file.
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func writeFrame(_ frame: BackupProto.Frame) -> MessageBackup.ProtoOutputStreamWriteResult
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/// Closes the output stream.
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func closeFileStream() throws
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}
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internal class MessageBackupProtoOutputStreamImpl: MessageBackupProtoOutputStream {
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private var outputStream: OutputStreamable
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private var outputStreamDelegate: StreamDelegate
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private var fileUrl: URL
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private var uploadMetadata: Upload.BackupUploadMetadata?
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internal init(
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outputStream: OutputStreamable,
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outputStreamDelegate: StreamDelegate,
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fileURL: URL
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) {
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self.outputStream = outputStream
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self.outputStreamDelegate = outputStreamDelegate
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self.fileUrl = fileURL
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}
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internal func writeHeader(_ header: BackupProto.BackupInfo) -> MessageBackup.ProtoOutputStreamWriteResult {
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let bytes: Data
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do {
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bytes = try ProtoEncoder().encode(header)
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} catch {
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return .protoSerializationError(error)
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}
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do {
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try outputStream.write(data: bytes)
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} catch {
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return .fileIOError(error)
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}
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return .success
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}
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internal func writeFrame(_ frame: BackupProto.Frame) -> MessageBackup.ProtoOutputStreamWriteResult {
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let bytes: Data
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do {
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bytes = try ProtoEncoder().encode(frame)
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} catch {
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return .protoSerializationError(error)
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}
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do {
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try outputStream.write(data: bytes)
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} catch {
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return .fileIOError(error)
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}
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return .success
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}
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public func closeFileStream() throws {
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try? outputStream.close()
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}
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}
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