Change IsolatedStorageFile path for mobile

src/libraries/System.IO.IsolatedStorage/src/System/IO/IsolatedStorage/Helper.AnyMobile.cs

@@ -5,6 +5,18 @@ namespace System.IO.IsolatedStorage
 {
     internal static partial class Helper
     {
+        // we're using a different directory name for compatibility with legacy Xamarin
         public const string IsolatedStorageDirectoryName = ".isolated-storage";
+
+        internal static string GetRandomDirectory(string rootDirectory, IsolatedStorageScope scope)
+        {
+            // In legacy Xamarin we didn't have a random directory inside of the isolated storage root for each app,
+            // we tried to preserve that in https://github.com/dotnet/runtime/pull/75541 but the fix wasn't complete enough
+            // and we still created random directories when not using the Roaming scope.
+            //
+            // Since we shipped that behavior as part of .NET 7 we can't change this now or upgraded apps wouldn't find their files anymore.
+            // We need to look for an existing random directory first before using the plain root directory.
+            return GetExistingRandomDirectory(rootDirectory) ?? rootDirectory;
+        }
     }
 }

src/libraries/System.IO.IsolatedStorage/src/System/IO/IsolatedStorage/Helper.NonMobile.cs

@@ -1,10 +1,43 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
+using System.Threading;
 
 namespace System.IO.IsolatedStorage
 {
     internal static partial class Helper
     {
         public const string IsolatedStorageDirectoryName = "IsolatedStorage";
+
+        internal static string GetRandomDirectory(string rootDirectory, IsolatedStorageScope scope)
+        {
+            string? randomDirectory = GetExistingRandomDirectory(rootDirectory);
+            if (string.IsNullOrEmpty(randomDirectory))
+            {
+                using (Mutex m = CreateMutexNotOwned(rootDirectory))
+                {
+                    if (!m.WaitOne())
+                    {
+                        throw new IsolatedStorageException(SR.IsolatedStorage_Init);
+                    }
+
+                    try
+                    {
+                        randomDirectory = GetExistingRandomDirectory(rootDirectory);
+                        if (string.IsNullOrEmpty(randomDirectory))
+                        {
+                            // Someone else hasn't created the directory before we took the lock
+                            randomDirectory = Path.Combine(rootDirectory, Path.GetRandomFileName(), Path.GetRandomFileName());
+                            CreateDirectory(randomDirectory, scope);
+                        }
+                    }
+                    finally
+                    {
+                        m.ReleaseMutex();
+                    }
+                }
+            }
+
+            return randomDirectory;
+        }
     }
 }

src/libraries/System.IO.IsolatedStorage/src/System/IO/IsolatedStorage/Helper.Win32Unix.cs

@@ -79,38 +79,6 @@ internal static void GetDefaultIdentityAndHash(out object identity, out string h
             identity = locationUri;
         }
 
-        internal static string GetRandomDirectory(string rootDirectory, IsolatedStorageScope scope)
-        {
-            string? randomDirectory = GetExistingRandomDirectory(rootDirectory);
-            if (string.IsNullOrEmpty(randomDirectory))
-            {
-                using (Mutex m = CreateMutexNotOwned(rootDirectory))
-                {
-                    if (!m.WaitOne())
-                    {
-                        throw new IsolatedStorageException(SR.IsolatedStorage_Init);
-                    }
-
-                    try
-                    {
-                        randomDirectory = GetExistingRandomDirectory(rootDirectory);
-                        if (string.IsNullOrEmpty(randomDirectory))
-                        {
-                            // Someone else hasn't created the directory before we took the lock
-                            randomDirectory = Path.Combine(rootDirectory, Path.GetRandomFileName(), Path.GetRandomFileName());
-                            CreateDirectory(randomDirectory, scope);
-                        }
-                    }
-                    finally
-                    {
-                        m.ReleaseMutex();
-                    }
-                }
-            }
-
-            return randomDirectory;
-        }
-
         internal static string? GetExistingRandomDirectory(string rootDirectory)
         {
             // Look for an existing random directory at the given root

src/libraries/System.IO.IsolatedStorage/src/System/IO/IsolatedStorage/Helper.cs

@@ -11,8 +11,8 @@ internal static partial class Helper
 
         /// <summary>
         /// The full root directory is the relevant special folder from Environment.GetFolderPath() plus IsolatedStorageDirectoryName
-        /// and a set of random directory names if not roaming. (The random directories aren't created for WinRT as
-        /// the FolderPath locations for WinRT are app isolated already.)
+        /// and a set of random directory names if not roaming. (The random directories aren't created for Android/iOS as
+        /// the FolderPath locations for Android/iOS are app isolated already.)
         ///
         /// Examples:
         ///

src/libraries/System.IO.IsolatedStorage/tests/System.IO.IsolatedStorage.Tests.csproj

@@ -56,10 +56,12 @@
    <ItemGroup Condition="'$(TargetPlatformIdentifier)' == 'android' or '$(TargetPlatformIdentifier)' == 'ios' or '$(TargetPlatformIdentifier)' == 'maccatalyst' or '$(TargetPlatformIdentifier)' == 'tvos'">
     <Compile Include="..\src\System\IO\IsolatedStorage\Helper.AnyMobile.cs" />
     <Compile Include="System\IO\IsolatedStorage\TestHelper.AnyMobile.cs" />
+    <Compile Include="System\IO\IsolatedStorage\HelperTests.AnyMobile.cs" />
   </ItemGroup>
   <ItemGroup Condition="'$(TargetPlatformIdentifier)' != 'android' and '$(TargetPlatformIdentifier)' != 'ios' and '$(TargetPlatformIdentifier)' != 'maccatalyst' and '$(TargetPlatformIdentifier)' != 'tvos' and '$(TargetPlatformIdentifier)' != ''">
     <Compile Include="..\src\System\IO\IsolatedStorage\Helper.NonMobile.cs" />
     <Compile Include="System\IO\IsolatedStorage\TestHelper.NonMobile.cs" />
+    <Compile Include="System\IO\IsolatedStorage\HelperTests.NonMobile.cs" />
   </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="$(LibrariesProjectRoot)System.DirectoryServices\src\System.DirectoryServices.csproj" />

src/libraries/System.IO.IsolatedStorage/tests/System/IO/IsolatedStorage/HelperTests.AnyMobile.cs

@@ -0,0 +1,52 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using Xunit;
+
+namespace System.IO.IsolatedStorage
+{
+    public partial class HelperTests
+    {                
+        [Theory, InlineData(IsolatedStorageScope.User)]
+        public void GetRandomDirectory(IsolatedStorageScope scope)
+        {
+            using (var temp = new TempDirectory())
+            {
+                string randomDir = Helper.GetRandomDirectory(temp.Path, scope);
+                Assert.True(Directory.Exists(randomDir.Replace(Helper.IsolatedStorageDirectoryName, "")));
+            }
+        }        
+
+        [Theory,
+            InlineData(IsolatedStorageScope.Assembly),
+            InlineData(IsolatedStorageScope.Assembly | IsolatedStorageScope.Roaming),
+            InlineData(IsolatedStorageScope.User)
+            ]
+        public void GetRandomDirectoryWithExistingDir(IsolatedStorageScope scope)
+        {
+            using (var temp = new TempDirectory())
+            {
+                Assert.Null(Helper.GetExistingRandomDirectory(temp.Path));
+
+                string randomPath = Path.Combine(temp.Path, Path.GetRandomFileName(), Path.GetRandomFileName());
+                Directory.CreateDirectory(randomPath);
+                Assert.Equal(randomPath, Helper.GetExistingRandomDirectory(temp.Path));
+                Assert.Equal(Helper.GetRandomDirectory(temp.Path, scope), Helper.GetExistingRandomDirectory(temp.Path));
+            }
+        }
+
+        [Theory,
+            InlineData(IsolatedStorageScope.Assembly),
+            InlineData(IsolatedStorageScope.Assembly | IsolatedStorageScope.Roaming),
+            InlineData(IsolatedStorageScope.User)
+            ]
+        public void GetRandomDirectoryWithNotExistingDir(IsolatedStorageScope scope)
+        {
+            using (var temp = new TempDirectory())
+            {
+                Assert.Null(Helper.GetExistingRandomDirectory(temp.Path));  
+                Assert.Equal(Helper.GetRandomDirectory(temp.Path, scope), Helper.GetDataDirectory(scope));
+            }
+        }
+    }
+}

src/libraries/System.IO.IsolatedStorage/tests/System/IO/IsolatedStorage/HelperTests.NonMobile.cs

@@ -0,0 +1,23 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using Xunit;
+
+namespace System.IO.IsolatedStorage
+{
+    public partial class HelperTests
+    {        
+        [Theory,
+            InlineData(IsolatedStorageScope.User),
+            InlineData(IsolatedStorageScope.Machine),
+            ]
+        public void GetRandomDirectory(IsolatedStorageScope scope)
+        {
+            using (var temp = new TempDirectory())
+            {
+                string randomDir = Helper.GetRandomDirectory(temp.Path, scope);
+                Assert.True(Directory.Exists(randomDir));
+            }
+        }       
+    }
+}

src/libraries/System.IO.IsolatedStorage/tests/System/IO/IsolatedStorage/HelperTests.Win32Unix.cs

@@ -19,18 +19,5 @@ public void GetExistingRandomDirectory()
                 Assert.Equal(randomPath, Helper.GetExistingRandomDirectory(temp.Path));
             }
         }
-
-        [Theory,
-            InlineData(IsolatedStorageScope.User),
-            InlineData(IsolatedStorageScope.Machine),
-            ]
-        public void GetRandomDirectory(IsolatedStorageScope scope)
-        {
-            using (var temp = new TempDirectory())
-            {
-                string randomDir = Helper.GetRandomDirectory(temp.Path, scope);
-                Assert.True(Directory.Exists(randomDir));
-            }
-        }
     }
 }