[System.Configuration] Fix settings upgrade on iOS and tvOS by steveisok · Pull Request #132283 · dotnet/runtime

steveisok · 2026-08-13T16:12:42Z

Packaged applications can move between installation paths when updated. ClientConfigPaths previously hashed that installation-specific executable path, so ApplicationSettingsBase.Upgrade() could not locate settings from an earlier installation.

This change:

uses the stable main bundle identifier for iOS and tvOS through direct CoreFoundation APIs;
uses the stable package family name for packaged Windows applications;
hashes stable identities using the existing bounded identity format;
preserves the version as the final directory component;
falls back to legacy path-based directories when no stable previous version exists;
restricts legacy lookup to the same settings root, company, and application prefix;
ignores malformed, current, future, unrelated, and ambiguously tied candidates;
leaves unpackaged Windows, Linux, macOS, Mac Catalyst, and Android behavior unchanged.

No public APIs are added. The standalone package does not depend on runtime-private native shims.

Validation:

System.Configuration.ConfigurationManager desktop tests: 663 passed
CoreCLR iOS simulator tests: 664 run, 655 passed, 9 platform-ignored, 0 failed
Windows and tvOS targeted builds passed

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azure-pipelines · 2026-08-13T16:13:30Z

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Pull request overview

Fixes settings upgrade discovery on iOS/tvOS by switching the identity component used for user.config paths from an installation-specific executable path hash to a stable main bundle identifier hash, with a constrained fallback scan of legacy directories to locate prior-version settings.

Changes:

Add a System.Native PAL entrypoint to retrieve the main app bundle identifier on Apple platforms.
Update ClientConfigPaths to use a bounded hash of the bundle identifier for iOS/tvOS settings identity, and expose a legacy prefix for constrained migration lookup.
Extend LocalFileSettingsProvider previous-config resolution to prefer stable-identity history, then (when applicable) fall back to legacy identity directories with filtering/ambiguity safeguards; add targeted tests.

Show a summary per file

File	Description
src/native/libs/System.Native/pal_environment.m	Implements `SystemNative_GetMainBundleIdentifier` via `NSBundle.mainBundle.bundleIdentifier`.
src/native/libs/System.Native/pal_environment.h	Exposes the new PAL export for managed interop.
src/native/libs/System.Native/pal_environment.c	Provides a non-Apple stub returning `NULL`.
src/native/libs/System.Native/entrypoints.c	Registers the new entrypoint for `libSystem.Native` DllImport dispatch.
src/libraries/System.Configuration.ConfigurationManager/src/System/Configuration/AppleApplication.cs	Adds managed interop helper to retrieve and free the bundle identifier string.
src/libraries/System.Configuration.ConfigurationManager/src/System/Configuration/ClientConfigPaths.cs	Uses bundle identifier hashing for iOS/tvOS identity suffix; adds `LegacyConfigDirectoryPrefix`.
src/libraries/System.Configuration.ConfigurationManager/src/System/Configuration/LocalFileSettingsProvider.cs	Refactors previous-config discovery into `FindPreviousConfigFile` with stable-first + constrained legacy fallback.
src/libraries/System.Configuration.ConfigurationManager/tests/System/Configuration/LocalFileSettingsProviderTests.cs	Adds unit tests covering stable identity hashing and prior-config selection/fallback rules.
src/libraries/System.Configuration.ConfigurationManager/src/System.Configuration.ConfigurationManager.csproj	Includes the new `AppleApplication.cs` in compilation.

Review details

Files reviewed: 9/9 changed files
Comments generated: 0
Review effort level: Lite

dotnet-policy-service · 2026-08-13T16:26:50Z

Tagging subscribers to 'os-ios': @vitek-karas, @kotlarmilos, @steveisok, @akoeplinger
See info in area-owners.md if you want to be subscribed.

jkotas · 2026-08-13T16:37:53Z

+            [LibraryImport("libSystem.Native", EntryPoint = "SystemNative_Free")]
+            internal static partial void Free(IntPtr ptr);
+
+            [LibraryImport("libSystem.Native", EntryPoint = "SystemNative_GetMainBundleIdentifier")]


System.Configuration.ConfigurationManager is standalone nuget package. It cannot depend on native shims.

From https://github.com/dotnet/runtime/blob/main/docs/coding-guidelines/interop-guidelines.md#unix-shims : The System.Native shims are a private implementation detail of the Microsoft.NETCore.App shared framework and are intended only for use by code inside of the shared framework.

Thanks - I couldn't remember and was operating on like it was ok. I'll adjust to something else.

Agreed. I removed the System.Native dependency and now import the required CFBundle/CFString APIs directly from CoreFoundation, keeping the OOB package self-contained. The direct CoreFoundation path also passed the full iOS simulator suite.

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jkotas · 2026-08-13T16:45:26Z

        }
+
+        [Fact]
+        public void AppleMobileIdentity_UsesStableBoundedBundleIdentifierHash()


This problem is not limited to Apple.

Windows store apps have it too. The paths to Windows store apps look like C:\Program Files\WindowsApps\Microsoft.Windows.Photos_2026.11080.5006.0_x64__8wekyb3d8bbwe and they are changing with each update.

I'll see if I can address this too.

Addressed as well. Packaged Windows apps now use GetCurrentPackageFamilyName as the stable identity, while unpackaged Windows retains the existing behavior. The constrained legacy lookup is shared by both stable identity paths.

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jkotas · 2026-08-13T17:00:01Z

System.Configuration.Manager is not trimming and AOT compatible (by design). Is it really worth trying to "fix it" to work better on mobile? It is never going to be in a happy place on mobile and other form factors that require trimming or AOT to work well.

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steveisok · 2026-08-13T17:42:43Z

System.Configuration.Manager is not trimming and AOT compatible (by design). Is it really worth trying to "fix it" to work better on mobile? It is never going to be in a happy place on mobile and other form factors that require trimming or AOT to work well.

Fair point. There's still some use in the face of that as I've seen issues around this pop up over time. I think a narrow fix is still worthwhile.

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Review details

Suppressed comments (3)

src/libraries/System.Configuration.ConfigurationManager/src/System/Configuration/WindowsApplication.cs:38

GetCurrentPackageFamilyName currently throws Win32Exception for unexpected return codes. Since the package family name is used only as a best-effort stable identity (with an existing legacy fallback), letting this throw will make ClientConfigPaths construction fail and can break settings access in packaged apps if the API ever returns an error. Consider treating non-success as "no stable identity" and returning null instead.

            if (error != ERROR_INSUFFICIENT_BUFFER)
            {
                throw new Win32Exception(error);
            }

src/libraries/System.Configuration.ConfigurationManager/tests/System/Configuration/LocalFileSettingsProviderTests.cs:134

This test uses reflection to locate AppleApplication/GetMainBundleIdentifier; if the type or method name changes, it will currently fail with a NullReferenceException rather than a clear assertion failure. Adding explicit null asserts makes failures easier to diagnose.

            Type appleApplication = typeof(LocalFileSettingsProvider).Assembly.GetType("System.Configuration.AppleApplication");
            MethodInfo getMainBundleIdentifier = appleApplication.GetMethod(
                "GetMainBundleIdentifier",
                BindingFlags.NonPublic | BindingFlags.Static);

src/libraries/System.Configuration.ConfigurationManager/src/System/Configuration/ClientConfigPaths.cs:162

LegacyConfigDirectoryPrefix/StableConfigDirectoryName are currently enabled based only on stableIdentity being non-empty. If hashing the stable identity falls back to the legacy exe-path/strong-name suffix (e.g., due to PlatformNotSupportedException in GetApplicationIdentitySuffix), this will still treat the current legacy directory as "stable" and change the upgrade lookup behavior (searching across legacy identity directories). Consider enabling these properties only when the computed hashSuffix actually used the stable identity type.

            LegacyConfigDirectoryPrefix = !string.IsNullOrEmpty(stableIdentity) &&
                !string.IsNullOrEmpty(namePrefix)
                ? namePrefix + "_"
                : null;

Files reviewed: 9/9 changed files
Comments generated: 0 new
Review effort level: Lite

…stem/Configuration/WindowsApplication.cs Co-authored-by: Jan Kotas <jkotas@microsoft.com>

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jeremy-visionaid · 2026-08-15T02:57:39Z

+                return null;
+            }
+
+            foreach (DirectoryInfo versionDirectory in identityDirectory.GetDirectories())


Just curious if there's a reason to prefer GetDirectories over EnumerateDirectories here?

Fix settings upgrade on iOS and tvOS

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Copilot AI lite review requested due to automatic review settings August 13, 2026 16:12

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steveisok added the os-ios Apple iOS label Aug 13, 2026

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Use OS package identities for settings paths

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Comment thread ...ies/System.Configuration.ConfigurationManager/src/System/Configuration/WindowsApplication.cs Outdated

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jkotas requested review from a team and jkotas August 13, 2026 19:48

Update src/libraries/System.Configuration.ConfigurationManager/src/Sy…

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…stem/Configuration/WindowsApplication.cs Co-authored-by: Jan Kotas <jkotas@microsoft.com>

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Update src/libraries/System.Configuration.ConfigurationManager/src/Sy…

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…stem/Configuration/WindowsApplication.cs Co-authored-by: Jan Kotas <jkotas@microsoft.com>

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