Rewrite ChunkRange to use either a specified offset or the current of…

…fset

Sources/NIOFileSystem/FileChunks.swift

@@ -22,8 +22,10 @@ import NIOPosix
 @available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
 public struct FileChunks: AsyncSequence {
     enum ChunkRange {
-        case entireFile
-        case partial(Range<Int64>)
+        /// Read from the current file access offset. Useful for reading from unseekable files.
+        case current
+        /// Read from a specific offset.
+        case specified(Range<Int64>)
     }
 
     public typealias Element = ByteBuffer
@@ -39,13 +41,12 @@ public struct FileChunks: AsyncSequence {
     internal init(
         handle: SystemFileHandle,
         chunkLength: ByteCount,
-        range: Range<Int64>
+        range: Range<Int64>?
     ) {
-        let chunkRange: ChunkRange
-        if range.lowerBound == 0, range.upperBound == .max {
-            chunkRange = .entireFile
+        let chunkRange: ChunkRange = if let range {
+            .specified(range)
         } else {
-            chunkRange = .partial(range)
+            .current
         }
 
         // TODO: choose reasonable watermarks; this should likely be at least somewhat dependent
@@ -96,9 +97,9 @@ extension BufferedStream where Element == ByteBuffer {
     ) -> BufferedStream<ByteBuffer> {
         let state: ProducerState
         switch range {
-        case .entireFile:
+        case .current:
             state = ProducerState(handle: handle, range: nil)
-        case .partial(let partialRange):
+        case .specified(let partialRange):
             state = ProducerState(handle: handle, range: partialRange)
         }
         let protectedState = NIOLockedValueBox(state)

Sources/NIOFileSystem/FileHandle.swift

@@ -190,7 +190,7 @@ public struct ReadFileHandle: ReadableFileHandleProtocol, _HasFileHandle {
         )
     }
 
-    public func readChunks(in range: Range<Int64>, chunkLength: ByteCount) -> FileChunks {
+    public func readChunks(in range: Range<Int64>?, chunkLength: ByteCount) -> FileChunks {
         self.fileHandle.systemFileHandle.readChunks(in: range, chunkLength: chunkLength)
     }
 
@@ -265,7 +265,7 @@ public struct ReadWriteFileHandle: ReadableAndWritableFileHandleProtocol, _HasFi
         )
     }
 
-    public func readChunks(in offset: Range<Int64>, chunkLength: ByteCount) -> FileChunks {
+    public func readChunks(in offset: Range<Int64>?, chunkLength: ByteCount) -> FileChunks {
         self.fileHandle.systemFileHandle.readChunks(in: offset, chunkLength: chunkLength)
     }
 

Sources/NIOFileSystem/FileHandleProtocol.swift

@@ -201,7 +201,7 @@ public protocol ReadableFileHandleProtocol: FileHandleProtocol {
     ///   - range: The absolute offsets into the file to read.
     ///   - chunkLength: The maximum length of the chunk to read as a ``ByteCount``.
     /// - Returns: A sequence of chunks read from the file.
-    func readChunks(in range: Range<Int64>, chunkLength: ByteCount) -> FileChunks
+    func readChunks(in range: Range<Int64>?, chunkLength: ByteCount) -> FileChunks
 }
 
 // MARK: - Read chunks with default chunk length
@@ -227,15 +227,13 @@ extension ReadableFileHandleProtocol {
     ///
     /// - Parameters:
     ///   - range: A range of offsets in the file to read.
-    ///   - chunkLength: The length of chunks to read, defaults to 128 KiB.
     ///   - as: Type of chunk to read.
     /// - SeeAlso: ``ReadableFileHandleProtocol/readChunks(in:chunkLength:)-2dz6``
     /// - Returns: An `AsyncSequence` of chunks read from the file.
     public func readChunks(
-        in range: Range<Int64>,
-        chunkLength: ByteCount = .kibibytes(128)
+        in range: Range<Int64>?
     ) -> FileChunks {
-        return self.readChunks(in: range, chunkLength: chunkLength)
+        return self.readChunks(in: range, chunkLength: .kibibytes(128))
     }
 
     /// Returns an asynchronous sequence of chunks read from the file.
@@ -413,7 +411,7 @@ extension ReadableFileHandleProtocol {
             var accumulator = ByteBuffer()
             accumulator.reserveCapacity(readSize)
 
-            for try await chunk in self.readChunks(in: ..., chunkLength: .mebibytes(8)) {
+            for try await chunk in self.readChunks(in: nil, chunkLength: .mebibytes(8)) {
                 accumulator.writeImmutableBuffer(chunk)
                 if accumulator.readableBytes > maximumSizeAllowed.bytes {
                     throw FileSystemError(

Sources/NIOFileSystem/Internal/SystemFileHandle.swift

@@ -1069,7 +1069,7 @@ extension SystemFileHandle: ReadableFileHandleProtocol {
     }
 
     public func readChunks(
-        in range: Range<Int64>,
+        in range: Range<Int64>?,
         chunkLength size: ByteCount
     ) -> FileChunks {
         return FileChunks(handle: self, chunkLength: size, range: range)

Tests/NIOFileSystemIntegrationTests/FileHandleTests.swift

@@ -61,8 +61,11 @@ final class FileHandleTests: XCTestCase {
             self.bytes.getSlice(at: Int(offset), length: Int(min(length.bytes, self.chunkSize.bytes))) ?? .init()
         }
 
-        func readChunks(in range: Range<Int64>, chunkLength: ByteCount) -> FileChunks {
-            .init(wrapping: ChunkedByteBufferSequence(buffer: self.bytes, range: range, chunkLength: chunkLength))
+        func readChunks(in range: Range<Int64>?, chunkLength: ByteCount) -> FileChunks {
+            guard let range else {
+                preconditionFailure("Reading from the current offset is not implemented for MockFileHandle")
+            }
+            return .init(wrapping: ChunkedByteBufferSequence(buffer: self.bytes, range: range, chunkLength: chunkLength))
         }
 
         func info() async throws -> FileInfo {
@@ -436,10 +439,11 @@ final class FileHandleTests: XCTestCase {
         try await self.withHandle(forFileAtPath: privateTempDirPath.appending("fifo"), accessMode: .readWrite) {
             handle in
             let someBytes = ByteBuffer(repeating: 42, count: 1546)
+
             try await handle.write(contentsOf: someBytes.readableBytesView, toAbsoluteOffset: 0)
 
-            let readSomeBytes = try await handle.readToEnd(maximumSizeAllowed: .bytes(1546))
-            XCTAssertEqual(readSomeBytes, someBytes)
+            let contents = try await handle.readToEnd(maximumSizeAllowed: .bytes(1546))
+            XCTAssertEqual(contents, someBytes, "Data read back from the fifo should match what was written")
         }
     }