Make this work, and testable under Darwin and Linux.

Author: millenomi

Foundation/FileManager.swift

@@ -7,9 +7,11 @@
 // See http://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
 //
 
-#if os(macOS) || os(iOS)
+#if canImport(Darwin)
     import Darwin
-#elseif os(Linux) || CYGWIN
+#endif
+
+#if canImport(Glibc)
     import Glibc
 #endif
 
@@ -128,23 +130,22 @@ open class FileManager : NSObject {
 
         init?(_ domainMask: SearchPathDomainMask) {
             if domainMask == .systemDomainMask {
-                self = .system
+                self = .system; return
             }
             if domainMask == .localDomainMask {
-                self = .local
+                self = .local; return
             }
             if domainMask == .networkDomainMask {
-                self = .network
+                self = .network; return
             }
             if domainMask == .userDomainMask {
-                self = .user
+                self = .user; return
             }
 
             return nil
         }
     }
 
-    #if os(macOS) || os(iOS) || os(tvOS) || os(watchOS)
     private func darwinPathURLs(for domain: _SearchPathDomain, system: String?, local: String?, network: String?, userHomeSubpath: String?) -> [URL] {
         switch domain {
         case .system:
@@ -174,35 +175,140 @@ open class FileManager : NSObject {
             return [ URL(fileURLWithPath: all, isDirectory: true, relativeTo: URL(fileURLWithPath: NSHomeDirectory(), isDirectory: true)) ]
         }
     }
-    #endif
 
     #if os(Windows) // Non-Apple OSes that do not implement FHS/XDG are not currently supported.
     @available(*, unavailable, message: "Not implemented for this OS")
     open func urls(for directory: SearchPathDirectory, in domainMask: SearchPathDomainMask) -> [URL] {
         NSUnimplemented()
     }
     #else
-    
     /* -URLsForDirectory:inDomains: is analogous to NSSearchPathForDirectoriesInDomains(), but returns an array of NSURL instances for use with URL-taking APIs. This API is suitable when you need to search for a file or files which may live in one of a variety of locations in the domains specified.
      */
     open func urls(for directory: SearchPathDirectory, in domainMask: SearchPathDomainMask) -> [URL] {
-        
         guard let domain = _SearchPathDomain(domainMask) else {
             fatalError("Values other than .systemDomainMask, .localDomainMask, .userDomainMask, .networkDomainMask are unsupported")
         }
 
         // We are going to return appropriate paths on Darwin, but [] on platforms that do not have comparable locations.
         // For example, on FHS/XDG systems, applications are not installed in a single path.
-
-        #if os(macOS) || os(iOS) || os(tvOS) || os(watchOS)
-        // For Darwin:
+        
+        let useDarwinPaths: Bool
+        if let envVar = ProcessInfo.processInfo.environment["_NSFileManagerUseXDGPathsForDirectoryDomains"] {
+            useDarwinPaths = !NSString(string: envVar).boolValue
+        } else {
+            #if canImport(Darwin)
+                useDarwinPaths = true
+            #else
+                useDarwinPaths = false
+            #endif
+        }
+        
+        if useDarwinPaths {
+            return darwinURLs(for: directory, in: domain)
+        } else {
+            return xdgURLs(for: directory, in: domain)
+        }
+    }
+    #endif
+    
+    private func xdgURLs(for directory: SearchPathDirectory, in domain: _SearchPathDomain) -> [URL] {
+        // FHS/XDG-compliant OSes:
+        switch directory {
+        case .autosavedInformationDirectory:
+            let runtimePath = _SwiftValue.fetch(nonOptional: _CFXDGCreateDataHomePath()) as! String
+            return [ URL(fileURLWithPath: "Autosave Information", isDirectory: true, relativeTo: URL(fileURLWithPath: runtimePath, isDirectory: true)) ]
+            
+        case .desktopDirectory:
+            guard domain == .user else { return [] }
+            return [ _XDGUserDirectory.desktop.url ]
+            
+        case .documentDirectory:
+            guard domain == .user else { return [] }
+            return [ _XDGUserDirectory.documents.url ]
+            
+        case .cachesDirectory:
+            guard domain == .user else { return [] }
+            let path = _SwiftValue.fetch(nonOptional: _CFXDGCreateCacheDirectoryPath()) as! String
+            return [ URL(fileURLWithPath: path, isDirectory: true) ]
+            
+        case .applicationSupportDirectory:
+            guard domain == .user else { return [] }
+            let path = _SwiftValue.fetch(nonOptional: _CFXDGCreateDataHomePath()) as! String
+            return [ URL(fileURLWithPath: path, isDirectory: true) ]
+            
+        case .downloadsDirectory:
+            guard domain == .user else { return [] }
+            return [ _XDGUserDirectory.download.url ]
+            
+        case .userDirectory:
+            guard domain == .local else { return [] }
+            return [ URL(fileURLWithPath: "/home", isDirectory: true) ]
+            
+        case .moviesDirectory:
+            return [ _XDGUserDirectory.videos.url ]
+            
+        case .musicDirectory:
+            guard domain == .user else { return [] }
+            return [ _XDGUserDirectory.music.url ]
+            
+        case .picturesDirectory:
+            guard domain == .user else { return [] }
+            return [ _XDGUserDirectory.pictures.url ]
+            
+        case .sharedPublicDirectory:
+            guard domain == .user else { return [] }
+            return [ _XDGUserDirectory.publicShare.url ]
+            
+        case .trashDirectory:
+            let userTrashURL = URL(fileURLWithPath: ".Trash", isDirectory: true, relativeTo: URL(fileURLWithPath: NSHomeDirectory(), isDirectory: true))
+            if domain == .user || domain == .local {
+                return [ userTrashURL ]
+            } else {
+                return []
+            }
+            
+        // None of these are supported outside of Darwin:
+        case .applicationDirectory:
+            fallthrough
+        case .demoApplicationDirectory:
+            fallthrough
+        case .developerApplicationDirectory:
+            fallthrough
+        case .adminApplicationDirectory:
+            fallthrough
+        case .libraryDirectory:
+            fallthrough
+        case .developerDirectory:
+            fallthrough
+        case .documentationDirectory:
+            fallthrough
+        case .coreServiceDirectory:
+            fallthrough
+        case .inputMethodsDirectory:
+            fallthrough
+        case .preferencePanesDirectory:
+            fallthrough
+        case .applicationScriptsDirectory:
+            fallthrough
+        case .allApplicationsDirectory:
+            fallthrough
+        case .allLibrariesDirectory:
+            fallthrough
+        case .printerDescriptionDirectory:
+            fallthrough
+        case .itemReplacementDirectory:
+            return []
+        }
+    }
+    
+    private func darwinURLs(for directory: SearchPathDirectory, in domain: _SearchPathDomain) -> [URL] {
         switch directory {
         case .applicationDirectory:
             return darwinPathURLs(for: domain, all: "Applications", useLocalDirectoryForSystem: true)
-
+            
         case .demoApplicationDirectory:
             return darwinPathURLs(for: domain, all: "Demos", useLocalDirectoryForSystem: true)
-
+            
         case .developerApplicationDirectory:
             return darwinPathURLs(for: domain, all: "Developer/Applications", useLocalDirectoryForSystem: true)
 
@@ -229,7 +335,7 @@ open class FileManager : NSObject {
 
         case .preferencePanesDirectory:
             return darwinPathURLs(for: domain, system: "/System/Library/PreferencePanes", local: "/Library/PreferencePanes", network: nil, userHomeSubpath: "Library/PreferencePanes")
-
+            
         case .applicationScriptsDirectory:
             // Only the ObjC Foundation can know where this is.
             return []
@@ -251,27 +357,27 @@ open class FileManager : NSObject {
         case .printerDescriptionDirectory:
             guard domain == .system else { return [] }
             return [ URL(fileURLWithPath: "/System/Library/Printers/PPD", isDirectory: true) ]
-        
+            
         case .desktopDirectory:
             guard domain == .user else { return [] }
             return [ URL(fileURLWithPath: "Desktop", isDirectory: true, relativeTo: URL(fileURLWithPath: NSHomeDirectory(), isDirectory: true)) ]
 
         case .documentDirectory:
             guard domain == .user else { return [] }
             return [ URL(fileURLWithPath: "Documents", isDirectory: true, relativeTo: URL(fileURLWithPath: NSHomeDirectory(), isDirectory: true)) ]
-
+            
         case .cachesDirectory:
             guard domain == .user else { return [] }
             return [ URL(fileURLWithPath: "Library/Caches", isDirectory: true, relativeTo: URL(fileURLWithPath: NSHomeDirectory(), isDirectory: true)) ]
-
+            
         case .applicationSupportDirectory:
             guard domain == .user else { return [] }
             return [ URL(fileURLWithPath: "Library/Application Support", isDirectory: true, relativeTo: URL(fileURLWithPath: NSHomeDirectory(), isDirectory: true)) ]
-
+            
         case .downloadsDirectory:
             guard domain == .user else { return [] }
             return [ URL(fileURLWithPath: "Downloads", isDirectory: true, relativeTo: URL(fileURLWithPath: NSHomeDirectory(), isDirectory: true)) ]
-
+            
         case .userDirectory:
             return darwinPathURLs(for: domain, system: nil, local: "/Users", network: "/Network/Users", userHomeSubpath: nil)
 
@@ -282,15 +388,15 @@ open class FileManager : NSObject {
         case .musicDirectory:
             guard domain == .user else { return [] }
             return [ URL(fileURLWithPath: "Music", isDirectory: true, relativeTo: URL(fileURLWithPath: NSHomeDirectory(), isDirectory: true)) ]
-
+            
         case .picturesDirectory:
             guard domain == .user else { return [] }
             return [ URL(fileURLWithPath: "Pictures", isDirectory: true, relativeTo: URL(fileURLWithPath: NSHomeDirectory(), isDirectory: true)) ]
-
+            
         case .sharedPublicDirectory:
             guard domain == .user else { return [] }
             return [ URL(fileURLWithPath: "Public", isDirectory: true, relativeTo: URL(fileURLWithPath: NSHomeDirectory(), isDirectory: true)) ]
-
+            
         case .trashDirectory:
             let userTrashURL = URL(fileURLWithPath: ".Trash", isDirectory: true, relativeTo: URL(fileURLWithPath: NSHomeDirectory(), isDirectory: true))
             if domain == .user || domain == .local {
@@ -303,99 +409,8 @@ open class FileManager : NSObject {
             // This directory is only returned by url(for:in:appropriateFor:create:)
             return []
         }
-        #elseif !os(Windows)
-        // FHS/XDG-compliant OSes:
-        switch directory {
-        case .autosavedInformationDirectory:
-            let runtimePath = _SwiftValue.fetch(nonOptional: _CFXDGCreateDataHomePath()) as! String
-            return [ URL(fileURLWithPath: "Autosave Information", isDirectory: true, relativeTo: URL(fileURLWithPath: runtimePath, isDirectory: true)) ]
-            
-        case .desktopDirectory:
-            guard domain == .user else { return [] }
-            return [ _XDGUserDirectory.desktop.url ]
-            
-        case .documentDirectory:
-            guard domain == .user else { return [] }
-            return [ _XDGUserDirectory.documents.url ]
-            
-        case .cachesDirectory:
-            guard domain == .user else { return [] }
-            let path = _SwiftValue.fetch(nonOptional: _CFXDGCreateCacheDirectoryPath()) as! String
-            return [ URL(fileURLWithPath: path, isDirectory: true) ]
-            
-        case .applicationSupportDirectory:
-            guard domain == .user else { return [] }
-            let path = _SwiftValue.fetch(nonOptional: _CFXDGCreateDataHomePath()) as! String
-            return [ URL(fileURLWithPath: path, isDirectory: true) ]
-
-        case .downloadsDirectory:
-            guard domain == .user else { return [] }
-            return [ _XDGUserDirectory.download.url ]
-            
-        case .userDirectory:
-            guard domain == .local else { return [] }
-            return [ URL(fileURLWithPath: "/home", isDirectory: true) ]
-            
-        case .moviesDirectory:
-            return [ _XDGUserDirectory.videos.url ]
-            
-        case .musicDirectory:
-            guard domain == .user else { return [] }
-            return [ _XDGUserDirectory.music.url ]
-            
-        case .picturesDirectory:
-            guard domain == .user else { return [] }
-            return [ _XDGUserDirectory.pictures.url ]
-            
-        case .sharedPublicDirectory:
-            guard domain == .user else { return [] }
-            return [ _XDGUserDirectory.publicShare.url ]
-            
-        case .trashDirectory:
-            let userTrashURL = URL(fileURLWithPath: ".Trash", isDirectory: true, relativeTo: URL(fileURLWithPath: NSHomeDirectory(), isDirectory: true))
-            if domain == .user || domain == .local {
-                return [ userTrashURL ]
-            } else {
-                return []
-            }
-        
-        // None of these are supported outside of Darwin:
-        case .applicationDirectory:
-            fallthrough
-        case .demoApplicationDirectory:
-            fallthrough
-        case .developerApplicationDirectory:
-            fallthrough
-        case .adminApplicationDirectory:
-            fallthrough
-        case .libraryDirectory:
-            fallthrough
-        case .developerDirectory:
-            fallthrough
-        case .documentationDirectory:
-            fallthrough
-        case .coreServiceDirectory:
-            fallthrough
-        case .inputMethodsDirectory:
-            fallthrough
-        case .preferencePanesDirectory:
-            fallthrough
-        case .applicationScriptsDirectory:
-            fallthrough
-        case .allApplicationsDirectory:
-            fallthrough
-        case .allLibrariesDirectory:
-            fallthrough
-        case .printerDescriptionDirectory:
-            fallthrough
-        case .itemReplacementDirectory:
-            return []
-        }
-        #endif
-        
     }
-    #endif
-    
+        
     private enum URLForDirectoryError: Error {
         case directoryUnknown
     }

Foundation/NSPathUtilities.swift

@@ -578,7 +578,7 @@ public func NSSearchPathForDirectoriesInDomains(_ directory: FileManager.SearchP
     }
 
     return result.map { (url) in
-        var path = url.path
+        var path = url.absoluteURL.path
         if expandTilde {
             path = NSString(string: path).expandingTildeInPath
         }