Implement the dup3 and pipe2 wrappers for Darwin

Sources/System/FileDescriptor.swift

@@ -328,11 +328,7 @@ extension FileDescriptor {
 
   /// Options that specify behavior for a newly-created pipe.
   @frozen
-  @available(macOS, unavailable)
-  @available(iOS, unavailable)
-  @available(tvOS, unavailable)
-  @available(watchOS, unavailable)
-  @available(visionOS, unavailable)
+  @available(macOS 27.0, iOS 27.0, watchOS 27.0, tvOS 27.0, visionOS 27.0, *)
   public struct PipeOptions: OptionSet, Sendable, Hashable, Codable {
     /// The raw C options.
     @_alwaysEmitIntoClient
@@ -403,11 +399,7 @@ extension FileDescriptor {
   /// Options that specify behavior for a duplicated file descriptor.
   @frozen
   @available(Windows, unavailable)
-  @available(macOS, unavailable)
-  @available(iOS, unavailable)
-  @available(tvOS, unavailable)
-  @available(watchOS, unavailable)
-  @available(visionOS, unavailable)
+  @available(macOS 27.0, iOS 27.0, watchOS 27.0, tvOS 27.0, visionOS 27.0, *)
   public struct DuplicateOptions: OptionSet, Sendable, Hashable, Codable {
     /// The raw C options.
     @_alwaysEmitIntoClient
@@ -532,7 +524,6 @@ extension FileDescriptor {
     @available(*, unavailable, renamed: "nextData")
     public static var SEEK_DATA: SeekOrigin { nextData }
 #endif
-
   }
 }
 

Sources/System/FileOperations.swift

@@ -370,13 +370,13 @@ extension FileDescriptor {
 #if !os(WASI)
 @available(System 0.0.2, *)
 extension FileDescriptor {
-  /// Duplicates this file descriptor and return the newly created copy.
+  /// Duplicates this file descriptor and returns the newly created copy.
   ///
   /// - Parameters:
   ///   - `target`: The desired target file descriptor, or `nil`, in which case
   ///      the copy is assigned to the file descriptor with the lowest raw value
   ///      that is not currently in use by the process.
-  ///   - retryOnInterrupt: Whether to retry the write operation
+  ///   - retryOnInterrupt: Whether to retry the duplicate operation
   ///      if it throws ``Errno/interrupted``. The default is `true`.
   ///      Pass `false` to try only once and throw an error upon interruption.
   /// - Returns: The new file descriptor.
@@ -436,20 +436,19 @@ extension FileDescriptor {
   /// close-on-fork flags.
   ///
   /// The corresponding C function is `dup3`.
-  @discardableResult
-  @_alwaysEmitIntoClient
   @available(Windows, unavailable)
-  @available(macOS, unavailable)
-  @available(iOS, unavailable)
-  @available(tvOS, unavailable)
-  @available(watchOS, unavailable)
-  @available(visionOS, unavailable)
+  @available(macOS 27.0, iOS 27.0, watchOS 27.0, tvOS 27.0, visionOS 27.0, *)
+  @_alwaysEmitIntoClient
+  @discardableResult
   public func duplicate(
     as target: FileDescriptor,
     options: DuplicateOptions,
     retryOnInterrupt: Bool = true
   ) throws(Errno) -> FileDescriptor {
-    try _duplicate(as: target, options: options.rawValue, retryOnInterrupt: retryOnInterrupt).get()
+    let result = _duplicate(
+      as: target, options: options.rawValue, retryOnInterrupt: retryOnInterrupt
+    )
+    return try result.get()
   }
 
   @available(System 0.0.2, *)
@@ -468,11 +467,7 @@ extension FileDescriptor {
   }
 
   @available(Windows, unavailable)
-  @available(macOS, unavailable)
-  @available(iOS, unavailable)
-  @available(tvOS, unavailable)
-  @available(watchOS, unavailable)
-  @available(visionOS, unavailable)
+  @available(macOS 27.0, iOS 27.0, watchOS 27.0, tvOS 27.0, visionOS 27.0, *)
   @usableFromInline
   internal func _duplicate(
     as target: FileDescriptor,
@@ -502,7 +497,7 @@ extension FileDescriptor {
     fatalError("Not implemented")
   }
 }
-#endif
+#endif // !os(WASI)
 
 #if !os(WASI)
 @available(System 1.1.0, *)
@@ -535,11 +530,7 @@ extension FileDescriptor {
   ///
   /// The corresponding C function is `pipe2`.
   @_alwaysEmitIntoClient
-  @available(macOS, unavailable)
-  @available(iOS, unavailable)
-  @available(tvOS, unavailable)
-  @available(watchOS, unavailable)
-  @available(visionOS, unavailable)
+  @available(macOS 27.0, iOS 27.0, watchOS 27.0, tvOS 27.0, visionOS 27.0, *)
   public static func pipe(
     options: PipeOptions
   ) throws(Errno) -> (readEnd: FileDescriptor, writeEnd: FileDescriptor) {
@@ -560,11 +551,7 @@ extension FileDescriptor {
     }
   }
 
-  @available(macOS, unavailable)
-  @available(iOS, unavailable)
-  @available(tvOS, unavailable)
-  @available(watchOS, unavailable)
-  @available(visionOS, unavailable)
+  @available(macOS 27.0, iOS 27.0, watchOS 27.0, tvOS 27.0, visionOS 27.0, *)
   @usableFromInline
   internal static func _pipe(
     options: Int32,
@@ -585,7 +572,7 @@ extension FileDescriptor {
     fatalError("Not implemented")
   }
 }
-#endif
+#endif // !os(WASI)
 
 @available(System 1.2.0, *)
 extension FileDescriptor {
@@ -674,4 +661,4 @@ extension FilePermissions {
     return system_umask(mode)
   }
 }
-#endif
+#endif // !os(WASI)

Sources/System/Internals/Constants.swift

@@ -631,7 +631,7 @@ internal var _O_CLOEXEC: CInt {
 #if !os(Windows)
 @_alwaysEmitIntoClient
 internal var _O_CLOFORK: CInt {
-  #if !os(WASI) && !os(Linux) && !os(Android) && !canImport(Darwin) && !os(FreeBSD)
+  #if !os(WASI) && !os(Linux) && !os(Android) && !os(FreeBSD)
   O_CLOFORK
   #elseif os(FreeBSD)
   FREEBSD_O_CLOFORK

Sources/System/Internals/Syscalls.swift

@@ -23,7 +23,9 @@ import Android
 #error("Unsupported Platform")
 #endif
 
+#if !SYSTEM_PACKAGE_DARWIN
 import CSystem
+#endif
 
 // Interacting with the mocking system, tracing, etc., is a potentially significant
 // amount of code size, so we hand outline that code for every syscall
@@ -141,13 +143,18 @@ internal func system_dup2(_ fd: Int32, _ fd2: Int32) -> Int32 {
   return dup2(fd, fd2)
 }
 
+@available(macOS 27.0, iOS 27.0, watchOS 27.0, tvOS 27.0, visionOS 27.0, *)
 internal func system_dup3(_ fd: Int32, _ fd2: Int32, _ oflag: Int32) -> Int32 {
-  #if ENABLE_MOCKING
+#if ENABLE_MOCKING
   if mockingEnabled { return _mock(fd, fd2, oflag) }
-  #endif
+#endif
+#if SYSTEM_PACKAGE_DARWIN
+  return dup3(fd, fd2, oflag)
+#else
   return csystem_posix_dup3(fd, fd2, oflag)
-}
 #endif
+}
+#endif // !os(WASI)
 
 #if !os(WASI)
 internal func system_pipe(_ fds: UnsafeMutablePointer<Int32>) -> CInt {
@@ -157,13 +164,18 @@ internal func system_pipe(_ fds: UnsafeMutablePointer<Int32>) -> CInt {
   return pipe(fds)
 }
 
+@available(macOS 27.0, iOS 27.0, watchOS 27.0, tvOS 27.0, visionOS 27.0, *)
 internal func system_pipe2(_ fds: UnsafeMutablePointer<Int32>, _ oflag: Int32) -> CInt {
 #if ENABLE_MOCKING
   if mockingEnabled { return _mock(fds, oflag) }
 #endif
+#if SYSTEM_PACKAGE_DARWIN
+  return pipe2(fds, oflag)
+#else
   return csystem_posix_pipe2(fds, oflag)
-}
 #endif
+}
+#endif // !os(WASI)
 
 internal func system_ftruncate(_ fd: Int32, _ length: off_t) -> Int32 {
 #if ENABLE_MOCKING
@@ -201,7 +213,7 @@ internal func system_confstr(
 ) -> Int {
   return confstr(name, buf, len)
 }
-#endif
+#endif // SYSTEM_PACKAGE_DARWIN
 
 #if !os(Windows)
 internal let SYSTEM_AT_REMOVE_DIR = AT_REMOVEDIR
@@ -269,15 +281,15 @@ internal func system_openat(
 #endif
   return openat(fd, path, oflag)
 }
-#endif
+#endif // !os(Windows)
 
 #if !os(WASI) // WASI has no umask
 internal func system_umask(
   _ mode: CInterop.Mode
 ) -> CInterop.Mode {
   return umask(mode)
 }
-#endif
+#endif // !os(WASI)
 
 internal func system_getenv(
   _ name: UnsafePointer<CChar>

Tests/SystemTests/FileOperationsTest.swift

@@ -1,7 +1,7 @@
 /*
  This source file is part of the Swift System open source project
 
- Copyright (c) 2020 - 2025 Apple Inc. and the Swift System project authors
+ Copyright (c) 2020 - 2026 Apple Inc. and the Swift System project authors
  Licensed under Apache License v2.0 with Runtime Library Exception
 
  See https://swift.org/LICENSE.txt for license information
@@ -157,7 +157,8 @@ final class FileOperationsTest: XCTestCase {
     // TODO: Test writeAll, writeAll(toAbsoluteOffset), closeAfter
   }
 
-  #if !os(WASI) // WASI has no pipe
+#if !os(WASI) // WASI has no pipe
+  @available(System 1.1.0, *)
   func testAdHocPipe() throws {
     // Ad-hoc test testing `Pipe` functionality.
     // We cannot test `Pipe` using `MockTestCase` because it calls `pipe` with a pointer to an array local to the `Pipe`, the address of which we do not know prior to invoking `Pipe`.
@@ -177,7 +178,7 @@ final class FileOperationsTest: XCTestCase {
     }
   }
 
-  #if !SYSTEM_PACKAGE_DARWIN
+  @available(macOS 27.0, iOS 27.0, watchOS 27.0, tvOS 27.0, visionOS 27.0, *)
   func testAdHocPipeWithOptions() throws {
     // Ad-hoc test testing `Pipe` functionality.
     // We cannot test `Pipe` using `MockTestCase` because it calls `pipe` with a pointer to an array local to the `Pipe`, the address of which we do not know prior to invoking `Pipe`.
@@ -198,10 +199,9 @@ final class FileOperationsTest: XCTestCase {
       }
     }
   }
-  #endif // !SYSTEM_PACKAGE_DARWIN
-  #endif // !os(WASI)
+#endif // !os(WASI)
 
-  #if !os(Windows)
+#if !os(Windows)
   func testAdHocDuplicate2() throws {
     try withTemporaryFilePath(basename: "test") {
       let path = $0.appending("foo2.txt")
@@ -238,9 +238,8 @@ final class FileOperationsTest: XCTestCase {
       }
     }
   }
-  #endif // !os(Windows)
 
-  #if !SYSTEM_PACKAGE_DARWIN && !os(Windows)
+  @available(macOS 27.0, iOS 27.0, watchOS 27.0, tvOS 27.0, visionOS 27.0, *)
   func testAdHocDuplicate3() throws {
 
     try withTemporaryFilePath(basename: "test") {
@@ -274,7 +273,7 @@ final class FileOperationsTest: XCTestCase {
       }
     }
   }
-  #endif // !SYSTEM_PACKAGE_DARWIN && !os(Windows)
+#endif // !os(Windows)
 
   func testAdHocOpen() {
     // Ad-hoc test touching a file system.
@@ -334,6 +333,7 @@ final class FileOperationsTest: XCTestCase {
   }
   #endif // ENABLE_MOCKING
 
+  @available(System 1.2.0, *)
   func testResizeFile() throws {
     try withTemporaryFilePath(basename: "testResizeFile") { path in 
       let fd = try FileDescriptor.open(path.appending("\(UUID().uuidString).txt"), .readWrite, options: [.create, .truncate], permissions: .ownerReadWrite)