begin to integrate SwiftSystem (#262)

motivation: SwiftSystem provides infra that can replace some bespoke implementations in TSC, improving the cross-platform support

changes: add SwiftPM and CMake setup for including SwiftSystem as a dependency

Author: tomerd

.gitignore

@@ -6,3 +6,4 @@ xcuserdata/
 .swiftpm
 build
 .vscode
+Package.resolved

CMakeLists.txt

@@ -29,6 +29,7 @@ find_package(dispatch QUIET)
 find_package(Foundation QUIET)
 find_package(Threads QUIET)
 find_package(SQLite3 REQUIRED)
+find_package(SwiftSystem CONFIG REQUIRED)
 
 add_subdirectory(Sources)
 add_subdirectory(cmake/modules)

Package.swift

@@ -2,10 +2,10 @@
 
 /*
  This source file is part of the Swift.org open source project
- 
+
  Copyright (c) 2019 - 2021 Apple Inc. and the Swift project authors
  Licensed under Apache License v2.0 with Runtime Library Exception
- 
+
  See http://swift.org/LICENSE.txt for license information
  See http://swift.org/CONTRIBUTORS.txt for Swift project authors
  */
@@ -46,9 +46,9 @@ let package = Package(
     ],
     dependencies: [],
     targets: [
-        
+
         // MARK: Tools support core targets
-        
+
         .target(
             /** Shim target to import missing C headers in Darwin and Glibc modulemap. */
             name: "TSCclibc",
@@ -62,24 +62,28 @@ let package = Package(
         .target(
             /** TSCBasic support library */
             name: "TSCBasic",
-            dependencies: ["TSCLibc", "TSCclibc"],
+            dependencies: [
+              "TSCLibc",
+              "TSCclibc",
+              .product(name: "SystemPackage", package: "swift-system"),
+            ],
             exclude: CMakeFiles + ["README.md"]),
         .target(
             /** Abstractions for common operations, should migrate to TSCBasic */
             name: "TSCUtility",
             dependencies: ["TSCBasic", "TSCclibc"],
             exclude: CMakeFiles),
-        
+
         // MARK: Additional Test Dependencies
-        
+
         .target(
             /** Generic test support library */
             name: "TSCTestSupport",
             dependencies: ["TSCBasic", "TSCUtility"]),
-        
-        
+
+
         // MARK: Tools support core tests
-        
+
         .testTarget(
             name: "TSCBasicTests",
             dependencies: ["TSCTestSupport", "TSCclibc"],
@@ -97,6 +101,19 @@ let package = Package(
     ]
 )
 
+/// When not using local dependencies, the branch to use for llbuild and TSC repositories.
+ let relatedDependenciesBranch = "main"
+
+ if ProcessInfo.processInfo.environment["SWIFTCI_USE_LOCAL_DEPS"] == nil {
+     package.dependencies += [
+         .package(url: "https://github.com/apple/swift-system.git", from: "1.0.0"),
+     ]
+ } else {
+     package.dependencies += [
+         .package(path: "../swift-system"),
+     ]
+ }
+
 // FIXME: conditionalise these flags since SwiftPM 5.3 and earlier will crash
 // for platforms they don't know about.
 #if os(Windows)

Sources/TSCBasic/CMakeLists.txt

@@ -50,13 +50,14 @@ add_library(TSCBasic
   Thread.swift
   Tuple.swift
   misc.swift)
-  
+
 target_compile_options(TSCBasic PUBLIC
   # Don't use GNU strerror_r on Android.
   "$<$<PLATFORM_ID:Android>:SHELL:-Xcc -U_GNU_SOURCE>"
   # Ignore secure function warnings on Windows.
   "$<$<PLATFORM_ID:Windows>:SHELL:-Xcc -D_CRT_SECURE_NO_WARNINGS>")
 target_link_libraries(TSCBasic PUBLIC
+  SwiftSystem::SystemPackage
   TSCLibc)
 target_link_libraries(TSCBasic PRIVATE
    TSCclibc)

Sources/TSCBasic/FileSystem.swift

@@ -11,6 +11,7 @@
 import TSCLibc
 import Foundation
 import Dispatch
+import SystemPackage
 
 public struct FileSystemError: Error, Equatable {
     public enum Kind: Equatable {
@@ -175,7 +176,7 @@ public protocol FileSystem: AnyObject {
 
     /// Get the home directory of current user
     var homeDirectory: AbsolutePath { get }
-    
+
     /// Get the caches directory of current user
     var cachesDirectory: AbsolutePath? { get }
 
@@ -346,7 +347,7 @@ private class LocalFileSystem: FileSystem {
     var homeDirectory: AbsolutePath {
         return AbsolutePath(NSHomeDirectory())
     }
-    
+
     var cachesDirectory: AbsolutePath? {
         return FileManager.default.urls(for: .cachesDirectory, in: .userDomainMask).first.flatMap { AbsolutePath($0.path) }
     }
@@ -515,7 +516,7 @@ private class LocalFileSystem: FileSystem {
 //
 /// Concrete FileSystem implementation which simulates an empty disk.
 public class InMemoryFileSystem: FileSystem {
-    
+
     /// Private internal representation of a file system node.
     /// Not threadsafe.
     private class Node {
@@ -551,7 +552,7 @@ public class InMemoryFileSystem: FileSystem {
             }
         }
     }
-    
+
     /// Private internal representation the contents of a directory.
     /// Not threadsafe.
     private class DirectoryContents {
@@ -573,7 +574,7 @@ public class InMemoryFileSystem: FileSystem {
 
     /// The root node of the filesytem.
     private var root: Node
-    
+
     /// Protects `root` and everything underneath it.
     /// FIXME: Using a single lock for this is a performance problem, but in
     /// reality, the only practical use for InMemoryFileSystem is for unit
@@ -583,7 +584,7 @@ public class InMemoryFileSystem: FileSystem {
     private var lockFiles = Dictionary<AbsolutePath, WeakReference<DispatchQueue>>()
     /// Used to access lockFiles in a thread safe manner.
     private let lockFilesLock = Lock()
-    
+
     /// Exclusive file system lock vended to clients through `withLock()`.
     // Used to ensure that DispatchQueues are releassed when they are no longer in use.
     private struct WeakReference<Value: AnyObject> {
@@ -717,7 +718,7 @@ public class InMemoryFileSystem: FileSystem {
         // FIXME: Maybe we should allow setting this when creating the fs.
         return AbsolutePath("/home/user")
     }
-    
+
     public var cachesDirectory: AbsolutePath? {
         return self.homeDirectory.appending(component: "caches")
     }
@@ -735,7 +736,7 @@ public class InMemoryFileSystem: FileSystem {
             return [String](contents.entries.keys)
         }
     }
-    
+
     /// Not threadsafe.
     private func _createDirectory(_ path: AbsolutePath, recursive: Bool) throws {
         // Ignore if client passes root.
@@ -882,7 +883,7 @@ public class InMemoryFileSystem: FileSystem {
     public func chmod(_ mode: FileMode, path: AbsolutePath, options: Set<FileMode.Option>) throws {
         // FIXME: We don't have these semantics in InMemoryFileSystem.
     }
-    
+
     /// Private implementation of core copying function.
     /// Not threadsafe.
     private func _copy(from sourcePath: AbsolutePath, to destinationPath: AbsolutePath) throws {
@@ -1023,7 +1024,7 @@ public class RerootedFileSystemView: FileSystem {
     public var homeDirectory: AbsolutePath {
         fatalError("homeDirectory on RerootedFileSystemView is not supported.")
     }
-    
+
     public var cachesDirectory: AbsolutePath? {
         fatalError("cachesDirectory on RerootedFileSystemView is not supported.")
     }