Internalize SystemInternals

Scrap the separate module SystemInternals and instead have it be a
subdirectory. Adjust all access control accordingly. One day, when Swift gets
proper submodules or supermodules (i.e. resilience domains), we can reinstate
it. For now, a separate module makes binary distribution much more
complicated.

Author: milseman

Package.swift

@@ -15,18 +15,14 @@ import PackageDescription
 let targets: [PackageDescription.Target] = [
   .target(
     name: "SystemPackage",
-    dependencies: ["SystemInternals"],
-    path: "Sources/System"),
-  .target(
-    name: "SystemInternals",
     dependencies: ["CSystem"],
+    path: "Sources/System",
     swiftSettings: [
       .define("ENABLE_MOCKING", .when(configuration: .debug))
     ]),
   .target(
     name: "CSystem",
     dependencies: []),
-
   .testTarget(
     name: "SystemTests",
     dependencies: ["SystemPackage"],

Sources/System/Errno.swift

@@ -1472,7 +1472,6 @@ extension Errno {
 #endif
 }
 
-@_implementationOnly import SystemInternals
 // @available(macOS 10.16, iOS 14.0, watchOS 7.0, tvOS 14.0, *)
 extension Errno {
   // TODO: We want to provide safe access to `errno`, but we need a

Sources/System/FileOperations.swift

@@ -7,8 +7,6 @@
  See https://swift.org/LICENSE.txt for license information
 */
 
-@_implementationOnly import SystemInternals
-
 // @available(macOS 10.16, iOS 14.0, watchOS 7.0, tvOS 14.0, *)
 extension FileDescriptor {
   /// Opens or creates a file for reading or writing.
@@ -122,7 +120,7 @@ extension FileDescriptor {
   internal func _seek(
     offset: Int64, from whence: FileDescriptor.SeekOrigin
   ) -> Result<Int64, Errno> {
-    let newOffset = system_lseek(self.rawValue, COffT(offset), whence.rawValue)
+    let newOffset = system_lseek(self.rawValue, _COffT(offset), whence.rawValue)
     return valueOrErrno(Int64(newOffset))
   }
 
@@ -210,7 +208,7 @@ extension FileDescriptor {
     retryOnInterrupt: Bool
   ) -> Result<Int, Errno> {
     valueOrErrno(retryOnInterrupt: retryOnInterrupt) {
-      system_pread(self.rawValue, buffer.baseAddress, buffer.count, COffT(offset))
+      system_pread(self.rawValue, buffer.baseAddress, buffer.count, _COffT(offset))
     }
   }
 
@@ -292,7 +290,7 @@ extension FileDescriptor {
     retryOnInterrupt: Bool
   ) -> Result<Int, Errno> {
     valueOrErrno(retryOnInterrupt: retryOnInterrupt) {
-      system_pwrite(self.rawValue, buffer.baseAddress, buffer.count, COffT(offset))
+      system_pwrite(self.rawValue, buffer.baseAddress, buffer.count, _COffT(offset))
     }
   }
 

Sources/System/FilePath/FilePathParsing.swift

@@ -322,7 +322,6 @@ extension FilePath {
 }
 
 // Whether we are providing Windows paths
-@_implementationOnly import var SystemInternals.forceWindowsPaths
 @inline(__always)
 internal var _windowsPaths: Bool {
   #if os(Windows)

Sources/SystemInternals/Exports.swift renamed to Sources/System/Internals/Exports.swift

@@ -15,32 +15,26 @@ import CSystem
 // TODO: Should CSystem just include all the header files we need?
 
 #if os(macOS) || os(iOS) || os(watchOS) || os(tvOS)
-import Darwin
+@_implementationOnly import Darwin
 #elseif os(Linux) || os(FreeBSD) || os(Android)
-import Glibc
+@_implementationOnly import Glibc
 #elseif os(Windows)
-import ucrt
+@_implementationOnly import ucrt
 #else
 #error("Unsupported Platform")
 #endif
 
-public typealias COffT = off_t
-
-#if os(Windows)
-public typealias CModeT = CInt
-#else
-public typealias CModeT = mode_t
-#endif
+internal typealias _COffT = off_t
 
 // MARK: syscalls and variables
 
 #if os(macOS) || os(iOS) || os(watchOS) || os(tvOS)
-public var system_errno: CInt {
+internal var system_errno: CInt {
   get { Darwin.errno }
   set { Darwin.errno = newValue }
 }
 #elseif os(Windows)
-public var system_errno: CInt {
+internal var system_errno: CInt {
   get {
     var value: CInt = 0
     // TODO(compnerd) handle the error?
@@ -52,7 +46,7 @@ public var system_errno: CInt {
   }
 }
 #else
-public var system_errno: CInt {
+internal var system_errno: CInt {
   get { Glibc.errno }
   set { Glibc.errno = newValue }
 }
@@ -62,33 +56,21 @@ public var system_errno: CInt {
 
 // Convention: `system_foo` is system's wrapper for `foo`.
 
-public func system_strerror(_ __errnum: Int32) -> UnsafeMutablePointer<Int8>! {
+internal func system_strerror(_ __errnum: Int32) -> UnsafeMutablePointer<Int8>! {
   strerror(__errnum)
 }
 
-public func system_strlen(_ s: UnsafePointer<Int8>) -> Int {
+internal func system_strlen(_ s: UnsafePointer<Int8>) -> Int {
   strlen(s)
 }
 
-#if os(Windows)
-public typealias _PlatformChar = UInt16
-#else
-public typealias _PlatformChar = CChar
-#endif
-#if os(Windows)
-public typealias _PlatformUnicodeEncoding = UTF16
-#else
-public typealias _PlatformUnicodeEncoding = UTF8
-#endif
-
-
 // Convention: `system_platform_foo` is a
 // platform-representation-abstracted wrapper around `foo`-like functionality.
 // Type and layout differences such as the `char` vs `wchar` are abstracted.
 //
 
 // strlen for the platform string
-public func system_platform_strlen(_ s: UnsafePointer<_PlatformChar>) -> Int {
+internal func system_platform_strlen(_ s: UnsafePointer<CInterop.PlatformChar>) -> Int {
   #if os(Windows)
   return wcslen(s)
   #else
@@ -98,8 +80,8 @@ public func system_platform_strlen(_ s: UnsafePointer<_PlatformChar>) -> Int {
 
 // Interop between String and platfrom string
 extension String {
-  public func _withPlatformString<Result>(
-    _ body: (UnsafePointer<_PlatformChar>) throws -> Result
+  internal func _withPlatformString<Result>(
+    _ body: (UnsafePointer<CInterop.PlatformChar>) throws -> Result
   ) rethrows -> Result {
     // Need to #if because CChar may be signed
     #if os(Windows)
@@ -109,7 +91,7 @@ extension String {
     #endif
   }
 
-  public init?(_platformString platformString: UnsafePointer<_PlatformChar>) {
+  internal init?(_platformString platformString: UnsafePointer<CInterop.PlatformChar>) {
     // Need to #if because CChar may be signed
     #if os(Windows)
     guard let strRes = String.decodeCString(
@@ -126,8 +108,8 @@ extension String {
     #endif
   }
 
-  public init(
-    _errorCorrectingPlatformString platformString: UnsafePointer<_PlatformChar>
+  internal init(
+    _errorCorrectingPlatformString platformString: UnsafePointer<CInterop.PlatformChar>
   ) {
     // Need to #if because CChar may be signed
     #if os(Windows)

Sources/SystemInternals/Mocking.swift renamed to Sources/System/Internals/Mocking.swift

@@ -53,7 +53,7 @@ internal enum ForceErrno: Equatable {
 }
 
 // Provide access to the driver, context, and trace stack of mocking
-public class MockingDriver {
+internal class MockingDriver {
   // Record syscalls and their arguments
   internal var trace = Trace()
 
@@ -109,7 +109,7 @@ private var contextualMockingEnabled: Bool {
 extension MockingDriver {
   internal static var enabled: Bool { mockingEnabled }
 
-  public static var forceWindowsPaths: Bool {
+  internal static var forceWindowsPaths: Bool {
     currentMockingDriver?.forceWindowsSyntaxForPaths ?? false
   }
 }
@@ -126,8 +126,8 @@ internal var mockingEnabled: Bool {
   #endif
 }
 
-@inline(__always) @inlinable
-public var forceWindowsPaths: Bool {
+@inline(__always)
+internal var forceWindowsPaths: Bool {
   #if !ENABLE_MOCKING
   return false
   #else
@@ -183,8 +183,8 @@ internal func _mockInt(
 
 internal func _mockOffT(
   name: String = #function, _ args: AnyHashable...
-) -> COffT {
-  COffT(mockImpl(name: name, args))
+) -> _COffT {
+  _COffT(mockImpl(name: name, args))
 }
 #endif // ENABLE_MOCKING
 

Sources/SystemInternals/Syscalls.swift renamed to Sources/System/Internals/Syscalls.swift

@@ -8,11 +8,11 @@
 */
 
 #if os(macOS) || os(iOS) || os(watchOS) || os(tvOS)
-import Darwin
+@_implementationOnly import Darwin
 #elseif os(Linux) || os(FreeBSD) || os(Android)
-import Glibc
+@_implementationOnly import Glibc
 #elseif os(Windows)
-import ucrt
+@_implementationOnly import ucrt
 #else
 #error("Unsupported Platform")
 #endif
@@ -21,8 +21,8 @@ import ucrt
 // amount of code size, so we hand outline that code for every syscall
 
 // open
-public func system_open(
-  _ path: UnsafePointer<_PlatformChar>, _ oflag: Int32
+internal func system_open(
+  _ path: UnsafePointer<CInterop.PlatformChar>, _ oflag: Int32
 ) -> CInt {
 #if ENABLE_MOCKING
   if mockingEnabled {
@@ -32,8 +32,9 @@ public func system_open(
   return open(path, oflag)
 }
 
-public func system_open(
-  _ path: UnsafePointer<_PlatformChar>, _ oflag: Int32, _ mode: CModeT
+internal func system_open(
+  _ path: UnsafePointer<CInterop.PlatformChar>,
+  _ oflag: Int32, _ mode: CInterop.Mode
 ) -> CInt {
 #if ENABLE_MOCKING
   if mockingEnabled {
@@ -44,15 +45,15 @@ public func system_open(
 }
 
 // close
-public func system_close(_ fd: Int32) -> Int32 {
+internal func system_close(_ fd: Int32) -> Int32 {
 #if ENABLE_MOCKING
   if mockingEnabled { return _mock(fd) }
 #endif
   return close(fd)
 }
 
 // read
-public func system_read(
+internal func system_read(
   _ fd: Int32, _ buf: UnsafeMutableRawPointer!, _ nbyte: Int
 ) -> Int {
 #if ENABLE_MOCKING
@@ -62,7 +63,7 @@ public func system_read(
 }
 
 // pread
-public func system_pread(
+internal func system_pread(
   _ fd: Int32, _ buf: UnsafeMutableRawPointer!, _ nbyte: Int, _ offset: off_t
 ) -> Int {
 #if ENABLE_MOCKING
@@ -72,7 +73,7 @@ public func system_pread(
 }
 
 // lseek
-public func system_lseek(
+internal func system_lseek(
   _ fd: Int32, _ off: off_t, _ whence: Int32
 ) -> off_t {
 #if ENABLE_MOCKING
@@ -82,7 +83,7 @@ public func system_lseek(
 }
 
 // write
-public func system_write(
+internal func system_write(
   _ fd: Int32, _ buf: UnsafeRawPointer!, _ nbyte: Int
 ) -> Int {
 #if ENABLE_MOCKING
@@ -92,7 +93,7 @@ public func system_write(
 }
 
 // pwrite
-public func system_pwrite(
+internal func system_pwrite(
   _ fd: Int32, _ buf: UnsafeRawPointer!, _ nbyte: Int, _ offset: off_t
 ) -> Int {
 #if ENABLE_MOCKING

Sources/SystemInternals/WindowsSyscallAdapters.swift renamed to Sources/System/Internals/WindowsSyscallAdapters.swift

@@ -9,12 +9,12 @@
 
 #if os(Windows)
 
-import ucrt
-import WinSDK
+@_implementationOnly import ucrt
+@_implementationOnly import WinSDK
 
 @inline(__always)
 internal func open(
-  _ path: UnsafePointer<_PlatformChar>, _ oflag: Int32
+  _ path: UnsafePointer<CInterop.PlatformChar>, _ oflag: Int32
 ) -> CInt {
   var fh: CInt = -1
   _ = _wsopen_s(&fh, path, oflag, _SH_DENYNO, _S_IREAD | _S_IWRITE)
@@ -23,7 +23,7 @@ internal func open(
 
 @inline(__always)
 internal func open(
-  _ path: UnsafePointer<_PlatformChar>, _ oflag: Int32, _ mode: CModeT
+  _ path: UnsafePointer<CInterop.PlatformChar>, _ oflag: Int32, _ mode: CModeT
 ) -> CInt {
   // TODO(compnerd): Apply read/write permissions
   var fh: CInt = -1

Sources/System/Platform/Platform.swift

@@ -7,9 +7,7 @@
  See https://swift.org/LICENSE.txt for license information
 */
 
-@_implementationOnly import SystemInternals
-
-// Public typealiases that can't be reexported from SystemInternals
+// MARK: - Public typealiases
 
 /// The C `mode_t` type.
 // @available(macOS 10.16, iOS 14.0, watchOS 7.0, tvOS 14.0, *)
@@ -32,4 +30,30 @@ public enum CInterop {
 
   /// The C `char` type
   public typealias Char = CChar
+
+  #if os(Windows)
+  /// The platform's preferred character type. On Unix, this is an 8-bit C
+  /// `char` (which may be signed or unsigned, depending on platform). On
+  /// Windows, this is `UInt16` (a "wide" character).
+  public typealias PlatformChar = UInt16
+  #else
+  /// The platform's preferred character type. On Unix, this is an 8-bit C
+  /// `char` (which may be signed or unsigned, depending on platform). On
+  /// Windows, this is `UInt16` (a "wide" character).
+  public typealias PlatformChar = CInterop.Char
+  #endif
+
+  #if os(Windows)
+  /// The platform's preferred Unicode encoding. On Unix this is UTF-8 and on
+  /// Windows it is UTF-16. Native strings may contain invalid Unicode,
+  /// which will be handled by either error-correction or failing, depending
+  /// on API.
+  public typealias PlatformUnicodeEncoding = UTF16
+  #else
+  /// The platform's preferred Unicode encoding. On Unix this is UTF-8 and on
+  /// Windows it is UTF-16. Native strings may contain invalid Unicode,
+  /// which will be handled by either error-correction or failing, depending
+  /// on API.
+  public typealias PlatformUnicodeEncoding = UTF8
+  #endif
 }