From 17ebfcd99d6d429dd4f0053794e8102fed1af251 Mon Sep 17 00:00:00 2001
From: Clinton Nkwocha <32041805+clintonpi@users.noreply.github.com>
Date: Fri, 11 Oct 2024 10:25:17 +0100
Subject: [PATCH] [NIOFileSystem] Provide an API to specify allowing unlimited
 sized reads (#2914)

Motivation:

As described in issue
[#2877](https://github.com/apple/swift-nio/issues/2877), there is no API
available to specify allowing a read of unlimited size.

Modifications:

- Add a new `public static` property, `unlimited`, to `ByteCount`
representing an unlimited amount of bytes.
- Adapt
`ReadableFileHandleProtocol.readToEnd(fromAbsoluteOffset:maximumSizeAllowed:)`
to work with `maximumSizeAllowed` being `ByteCount.unlimited`.

Result:

An API to specify allowing a read of an unlimited size will be
available.
---
 Sources/NIOFileSystem/ByteCount.swift                |  5 +++++
 Sources/NIOFileSystem/FileHandleProtocol.swift       |  1 +
 .../FileSystemTests.swift                            | 10 ++++++++++
 .../XCTestExtensions.swift                           | 12 ++++++++++++
 Tests/NIOFileSystemTests/ByteCountTests.swift        |  5 +++++
 5 files changed, 33 insertions(+)

diff --git a/Sources/NIOFileSystem/ByteCount.swift b/Sources/NIOFileSystem/ByteCount.swift
index f6b957700d..276b1f8eee 100644
--- a/Sources/NIOFileSystem/ByteCount.swift
+++ b/Sources/NIOFileSystem/ByteCount.swift
@@ -93,6 +93,11 @@ extension ByteCount {
 
         return ByteCount(bytes: Int64(byteBufferMaxIndex))
     }
+
+    /// A ``ByteCount`` for an unlimited amount of bytes.
+    public static var unlimited: ByteCount {
+        ByteCount(bytes: .max)
+    }
 }
 
 extension ByteCount: AdditiveArithmetic {
diff --git a/Sources/NIOFileSystem/FileHandleProtocol.swift b/Sources/NIOFileSystem/FileHandleProtocol.swift
index b8d2791c4c..b99136eb20 100644
--- a/Sources/NIOFileSystem/FileHandleProtocol.swift
+++ b/Sources/NIOFileSystem/FileHandleProtocol.swift
@@ -335,6 +335,7 @@ extension ReadableFileHandleProtocol {
         fromAbsoluteOffset offset: Int64 = 0,
         maximumSizeAllowed: ByteCount
     ) async throws -> ByteBuffer {
+        let maximumSizeAllowed = maximumSizeAllowed == .unlimited ? .byteBufferCapacity : maximumSizeAllowed
         let info = try await self.info()
         let fileSize = Int64(info.size)
         let readSize = max(Int(fileSize - offset), 0)
diff --git a/Tests/NIOFileSystemIntegrationTests/FileSystemTests.swift b/Tests/NIOFileSystemIntegrationTests/FileSystemTests.swift
index f0e6aee74a..409ef26cef 100644
--- a/Tests/NIOFileSystemIntegrationTests/FileSystemTests.swift
+++ b/Tests/NIOFileSystemIntegrationTests/FileSystemTests.swift
@@ -1818,6 +1818,16 @@ extension FileSystemTests {
             }
         }
     }
+
+    func testReadWithUnlimitedMaximumSizeAllowed() async throws {
+        let path = try await self.fs.temporaryFilePath()
+
+        try await self.fs.withFileHandle(forReadingAndWritingAt: path) { fileHandle in
+            await XCTAssertNoThrowAsync(
+                try await fileHandle.readToEnd(maximumSizeAllowed: .unlimited)
+            )
+        }
+    }
 }
 
 #if !canImport(Darwin) && swift(<5.9.2)
diff --git a/Tests/NIOFileSystemIntegrationTests/XCTestExtensions.swift b/Tests/NIOFileSystemIntegrationTests/XCTestExtensions.swift
index 008eedd306..2c46e5b844 100644
--- a/Tests/NIOFileSystemIntegrationTests/XCTestExtensions.swift
+++ b/Tests/NIOFileSystemIntegrationTests/XCTestExtensions.swift
@@ -69,4 +69,16 @@ func XCTAssertThrowsFileSystemErrorAsync<R>(
         }
     }
 }
+
+func XCTAssertNoThrowAsync<T>(
+    _ expression: @autoclosure () async throws -> T,
+    file: StaticString = #file,
+    line: UInt = #line
+) async {
+    do {
+        _ = try await expression()
+    } catch {
+        XCTFail("Expression did throw: \(error)", file: file, line: line)
+    }
+}
 #endif
diff --git a/Tests/NIOFileSystemTests/ByteCountTests.swift b/Tests/NIOFileSystemTests/ByteCountTests.swift
index 6a5c6297a1..f1a67387da 100644
--- a/Tests/NIOFileSystemTests/ByteCountTests.swift
+++ b/Tests/NIOFileSystemTests/ByteCountTests.swift
@@ -52,6 +52,11 @@ class ByteCountTests: XCTestCase {
         XCTAssertEqual(byteCount.bytes, 10_737_418_240)
     }
 
+    func testByteCountUnlimited() {
+        let byteCount = ByteCount.unlimited
+        XCTAssertEqual(byteCount.bytes, .max)
+    }
+
     func testByteCountEquality() {
         let byteCount1 = ByteCount.bytes(10)
         let byteCount2 = ByteCount.bytes(20)