[mono] Implement Environment.GetFolderPath on iOS

src/libraries/Common/src/Interop/OSX/System.Native/Interop.SearchPath.cs

@@ -0,0 +1,15 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System;
+using System.Runtime.InteropServices;
+
+internal static partial class Interop
+{
+    internal static partial class Sys
+    {
+        [DllImport(Libraries.SystemNative, EntryPoint = "SystemNative_SearchPath")]
+        internal static extern string SearchPath(int folderId);
+    }
+}

src/libraries/Native/Unix/System.Native/CMakeLists.txt

@@ -23,7 +23,9 @@ set(NATIVE_SOURCES
 )
 
 if (CLR_CMAKE_TARGET_IOS)
-    set(NATIVE_SOURCES ${NATIVE_SOURCES} pal_log.m)
+    set(NATIVE_SOURCES ${NATIVE_SOURCES}
+        pal_log.m
+        pal_searchpath.m)
 else ()
     set(NATIVE_SOURCES ${NATIVE_SOURCES} pal_console.c)
 endif ()

src/libraries/Native/Unix/System.Native/pal_searchpath.h

@@ -0,0 +1,10 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+#pragma once
+
+#include "pal_compiler.h"
+#include "pal_types.h"
+
+PALEXPORT const char* SystemNative_SearchPath(int32_t folderId);

src/libraries/Native/Unix/System.Native/pal_searchpath.m

@@ -0,0 +1,13 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+#include "pal_searchpath.h"
+#import <Foundation/Foundation.h>
+
+const char* SystemNative_SearchPath(int32_t folderId)
+{
+    NSSearchPathDirectory spd = (NSSearchPathDirectory) folderId;
+    NSURL* url = [[[NSFileManager defaultManager] URLsForDirectory:spd inDomains:NSUserDomainMask] lastObject];
+    return strdup ([[url path] UTF8String]);
+}

src/libraries/System.Private.CoreLib/src/System/Environment.Unix.cs

@@ -15,7 +15,9 @@ namespace System
 {
     public static partial class Environment
     {
+#if !TARGET_IOS
         private static Func<string, object>? s_directoryCreateDirectory;
+#endif
 
         public static bool UserInteractive => true;
 
@@ -56,7 +58,10 @@ private static string GetFolderPathCore(SpecialFolder folder, SpecialFolderOptio
             // Get the path for the SpecialFolder
             string path = GetFolderPathCoreWithoutValidation(folder);
             Debug.Assert(path != null);
-
+#if TARGET_IOS
+            // ignore verification and SpecialFolderOption.Create on iOS
+            return path;
+#else
             // If we didn't get one, or if we got one but we're not supposed to verify it,
             // or if we're supposed to verify it and it passes verification, return the path.
             if (path.Length == 0 ||
@@ -86,17 +91,21 @@ private static string GetFolderPathCore(SpecialFolder folder, SpecialFolderOptio
 
                 return path;
             }
+#endif
         }
 
         private static string GetFolderPathCoreWithoutValidation(SpecialFolder folder)
         {
+#if TARGET_IOS
+            return GetFolderPathIos(folder);
+#else
             // First handle any paths that involve only static paths, avoiding the overheads of getting user-local paths.
             // https://www.freedesktop.org/software/systemd/man/file-hierarchy.html
             switch (folder)
             {
                 case SpecialFolder.CommonApplicationData: return "/usr/share";
                 case SpecialFolder.CommonTemplates: return "/usr/share/templates";
-#if TARGET_OSX || TARGET_IOS
+#if TARGET_OSX
                 case SpecialFolder.ProgramFiles: return "/Applications";
                 case SpecialFolder.System: return "/System";
 #endif
@@ -152,7 +161,7 @@ private static string GetFolderPathCoreWithoutValidation(SpecialFolder folder)
                 case SpecialFolder.MyVideos:
                     return ReadXdgDirectory(home, "XDG_VIDEOS_DIR", "Videos");
 
-#if TARGET_OSX || TARGET_IOS
+#if TARGET_OSX
                 case SpecialFolder.MyMusic:
                     return Path.Combine(home, "Music");
                 case SpecialFolder.MyPictures:
@@ -175,6 +184,7 @@ private static string GetFolderPathCoreWithoutValidation(SpecialFolder folder)
 
             // No known path for the SpecialFolder
             return string.Empty;
+#endif
         }
 
         private static string GetXdgConfig(string home)

src/mono/netcore/System.Private.CoreLib/System.Private.CoreLib.csproj

@@ -291,6 +291,12 @@
       <Compile Include="$(BclSourcesRoot)\Internal\Resources\WindowsRuntimeResourceManagerBase.cs" />
       <Compile Include="$(BclSourcesRoot)\Internal\Runtime\InteropServices\WindowsRuntime\ExceptionSupport.cs" />
   </ItemGroup>
+  <ItemGroup Condition="'$(TargetsiOS)' == 'true'">
+      <Compile Include="$(BclSourcesRoot)\System\Environment.iOS.cs" />
+      <Compile Include="$(CommonPath)Interop\OSX\System.Native\Interop.SearchPath.cs">
+        <Link>Common\Interop\OSX\Interop.SearchPath.cs</Link>
+      </Compile>
+  </ItemGroup>
   <ItemGroup>
       <Compile Include="$(BclSourcesRoot)\Mono\RuntimeStructs.cs" />
       <Compile Include="$(BclSourcesRoot)\Mono\RuntimeMarshal.cs" />

src/mono/netcore/System.Private.CoreLib/src/System/Environment.Unix.Mono.cs

@@ -19,17 +19,26 @@ static string GetEnvironmentVariableCore (string variable)
 		{
 			Debug.Assert(variable != null);
 
+			variable = TrimStringOnFirstZero (variable);
+
+			// call getenv directly if s_environment is not yet initialized
 			if (s_environment == null) {
 				using (var h = RuntimeMarshal.MarshalString (variable)) {
 					return internalGetEnvironmentVariable_native (h.Value);
 				}
 			}
 
-			variable = TrimStringOnFirstZero (variable);
+			string value = "";
 			lock (s_environment) {
-				s_environment.TryGetValue (variable, out string value);
-				return value;
+				if (!s_environment.TryGetValue (variable, out value)) {
+					// on some platform s_environment can be empty after EnsureEnvironmentCached (), e.g. iOS
+					using (var h = RuntimeMarshal.MarshalString (variable)) {
+						value = internalGetEnvironmentVariable_native (h.Value);
+						s_environment [variable] = value;
+					}
+				}
 			}
+			return value;
 		}
 
 		static unsafe void SetEnvironmentVariableCore (string variable, string? value)

src/mono/netcore/System.Private.CoreLib/src/System/Environment.iOS.cs

@@ -0,0 +1,84 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System.IO;
+using System.Runtime.InteropServices;
+
+namespace System
+{
+    public static partial class Environment
+    {
+        private const int NSDocumentDirectoryId = 9;
+        private const int NSLibraryDirectoryId = 5;
+
+        private static string s_document;
+        private static string s_library;
+
+        // TODO: fix for tvOS
+        // The "normal" NSDocumentDirectory is a read-only directory on tvOS
+        // and that breaks a lot of assumptions in the runtime and the BCL
+        private static string NSDocumentDirectory => s_document ??= Interop.Sys.SearchPath(NSDocumentDirectoryId);
+
+        // Various user-visible documentation, support, and configuration files
+        private static string NSLibraryDirectory => s_library ??= Interop.Sys.SearchPath(NSLibraryDirectoryId);
+
+        private static string GetFolderPathIos(SpecialFolder folder)
+        {
+            switch (folder)
+            {
+                case SpecialFolder.Personal:
+                case SpecialFolder.LocalApplicationData:
+                    return NSDocumentDirectory;
+
+                case SpecialFolder.ApplicationData:
+                    // note: at first glance that looked like a good place to return NSLibraryDirectory 
+                    // but it would break isolated storage for existing applications
+                    return Path.Combine(NSDocumentDirectory, ".config");
+
+                case SpecialFolder.Resources:
+                    return NSLibraryDirectory; // older (8.2 and previous) would return String.Empty
+
+                case SpecialFolder.Desktop:
+                case SpecialFolder.DesktopDirectory:
+                    return Path.Combine(NSDocumentDirectory, "Desktop");
+
+                case SpecialFolder.MyMusic:
+                    return Path.Combine(NSDocumentDirectory, "Music");
+
+                case SpecialFolder.MyPictures:
+                    return Path.Combine(NSDocumentDirectory, "Pictures");
+
+                case SpecialFolder.Templates:
+                    return Path.Combine(NSDocumentDirectory, "Templates");
+
+                case SpecialFolder.MyVideos:
+                    return Path.Combine(NSDocumentDirectory, "Videos");
+
+                case SpecialFolder.CommonTemplates:
+                    return "/usr/share/templates";
+
+                case SpecialFolder.Fonts:
+                    return Path.Combine(NSDocumentDirectory, ".fonts");
+
+                case SpecialFolder.Favorites:
+                    return Path.Combine(NSLibraryDirectory, "Favorites");
+
+                case SpecialFolder.ProgramFiles:
+                    return "/Applications";
+
+                case SpecialFolder.InternetCache:
+                    return Path.Combine(NSLibraryDirectory, "Caches");
+
+                case SpecialFolder.UserProfile:
+                    return Environment.GetEnvironmentVariable("HOME");
+
+                case SpecialFolder.CommonApplicationData:
+                    return "/usr/share";
+
+                default:
+                    return string.Empty;
+            }
+        }
+    }
+}