[native] When preloading shared JNI libraries, update alias entries too

src/Xamarin.Android.Build.Tasks/Tests/Xamarin.ProjectTools/Resources/Forms/MainActivity.cs

@@ -23,5 +23,6 @@ protected override void OnCreate (Bundle savedInstanceState)
 			//${AFTER_FORMS_INIT}
 			LoadApplication (new App ());
 		}
+		//${AFTER_ONCREATE}
 	}
 }

src/Xamarin.Android.Build.Tasks/Utilities/ApplicationConfigNativeAssemblyGenerator.cs

@@ -161,7 +161,9 @@ sealed class DsoCacheState
 		{
 			public List<StructureInstance<DSOCacheEntry>> DsoCache = [];
 			public List<DSOCacheEntry> JniPreloadDSOs = [];
+			public List<string> JniPreloadNames = [];
 			public List<StructureInstance<DSOCacheEntry>> AotDsoCache = [];
+			public uint NameMutationsCount = 1;
 		}
 
 		// Keep in sync with FORMAT_TAG in src/monodroid/jni/xamarin-app.hh
@@ -274,10 +276,14 @@ protected override void Construct (LlvmIrModule module)
 			};
 			module.Add (dso_cache);
 
+			module.AddGlobalVariable ("dso_jni_preloads_idx_stride", dsoState.NameMutationsCount);
+
 			// This variable MUST be written after `dso_cache` since it relies on sorting performed by HashAndSortDSOCache
 			var dso_jni_preloads_idx = new LlvmIrGlobalVariable (new List<uint> (), "dso_jni_preloads_idx", LlvmIrVariableOptions.GlobalConstant) {
 				Comment = " Indices into dso_cache[] of DSO libraries to preload because of JNI use",
 				ArrayItemCount = (uint)dsoState.JniPreloadDSOs.Count,
+				GetArrayItemCommentCallback = GetPreloadIndicesLibraryName,
+				GetArrayItemCommentCallbackCallerState = dsoState,
 				BeforeWriteCallback = PopulatePreloadIndices,
 				BeforeWriteCallbackCallerState = dsoState,
 			};
@@ -346,6 +352,21 @@ void AddAssemblyStores (LlvmIrModule module)
 			module.Add (assembly_store);
 		}
 
+		string? GetPreloadIndicesLibraryName (LlvmIrVariable v, LlvmIrModuleTarget target, ulong index, object? value, object? callerState)
+		{
+			// Instead of throwing for such a triviality like a comment, we will return error messages as comments instead
+			var dsoState = callerState as DsoCacheState;
+			if (dsoState == null) {
+				return " Internal error: DSO state not present.";
+			}
+
+			if (index >= (ulong)dsoState.JniPreloadNames.Count) {
+				return $" Invalid index {index}";
+			}
+
+			return $" {dsoState.JniPreloadNames[(int)index]}";
+		}
+
 		void PopulatePreloadIndices (LlvmIrVariable variable, LlvmIrModuleTarget target, object? state)
 		{
 			var indices = variable.Value as List<uint>;
@@ -358,6 +379,9 @@ void PopulatePreloadIndices (LlvmIrVariable variable, LlvmIrModuleTarget target,
 				throw new InvalidOperationException ($"Internal error: DSO state not present.");
 			}
 
+			var dsoNames = new List<string> ();
+
+			// Indices array MUST NOT be sorted, since it groups alias entries together with the main entry
 			foreach (DSOCacheEntry preload in dsoState.JniPreloadDSOs) {
 				int dsoIdx = dsoState.DsoCache.FindIndex (entry => {
 					if (entry.Instance == null) {
@@ -372,8 +396,9 @@ void PopulatePreloadIndices (LlvmIrVariable variable, LlvmIrModuleTarget target,
 				}
 
 				indices.Add ((uint)dsoIdx);
+				dsoNames.Add (preload.HashedName ?? String.Empty);
 			}
-			indices.Sort ();
+			dsoState.JniPreloadNames = dsoNames;
 		}
 
 		void HashAndSortDSOCache (LlvmIrVariable variable, LlvmIrModuleTarget target, object? state)
@@ -427,15 +452,20 @@ DsoCacheState InitDSOCache ()
 			var jniPreloads = new List<DSOCacheEntry> ();
 			var aotDsoCache = new List<StructureInstance<DSOCacheEntry>> ();
 			var nameMutations = new List<string> ();
+			int nameMutationsCount = -1;
 
 			for (int i = 0; i < dsos.Count; i++) {
 				string name = dsos[i].name;
 
 				bool isJniLibrary = ELFHelper.IsJniLibrary (Log, dsos[i].item.ItemSpec);
 				bool ignore = dsos[i].ignore;
+				bool ignore_for_preload = !ApplicationConfigNativeAssemblyGeneratorCLR.DsoCacheJniPreloadIgnore.Contains (name);
 
 				nameMutations.Clear();
 				AddNameMutations (name);
+				if (nameMutationsCount == -1) {
+					nameMutationsCount = nameMutations.Count;
+				}
 
 				// All mutations point to the actual library name, but have hash of the mutated one
 				foreach (string entryName in nameMutations) {
@@ -447,23 +477,27 @@ DsoCacheState InitDSOCache ()
 						name = name,
 					};
 
-					if (entry.is_jni_library && entry.HashedName == name && !ApplicationConfigNativeAssemblyGeneratorCLR.DsoCacheJniPreloadIgnore.Contains (name)) {
-						jniPreloads.Add (entry);
-					}
-
 					var item = new StructureInstance<DSOCacheEntry> (dsoCacheEntryStructureInfo, entry);
 					if (name.StartsWith ("libaot-", StringComparison.OrdinalIgnoreCase)) {
 						aotDsoCache.Add (item);
-					} else {
-						dsoCache.Add (item);
+						continue;
 					}
+
+					// We must add all aliases to the preloads indices array so that all of them have their handle
+					// set when the library is preloaded.
+					if (entry.is_jni_library && ignore_for_preload) {
+						jniPreloads.Add (entry);
+					}
+
+					dsoCache.Add (item);
 				}
 			}
 
 			return new DsoCacheState {
 				DsoCache = dsoCache,
 				AotDsoCache = aotDsoCache,
 				JniPreloadDSOs = jniPreloads,
+				NameMutationsCount = (uint)(nameMutationsCount <= 0 ? 1 : nameMutationsCount),
 			};
 
 			void AddNameMutations (string name)

src/Xamarin.Android.Build.Tasks/Utilities/ApplicationConfigNativeAssemblyGeneratorCLR.cs

@@ -243,8 +243,10 @@ sealed class DsoCacheState
 	{
 		public List<StructureInstance<DSOCacheEntry>> DsoCache = [];
 		public List<DSOCacheEntry> JniPreloadDSOs = [];
+		public List<string> JniPreloadNames = [];
 		public List<StructureInstance<DSOCacheEntry>> AotDsoCache = [];
 		public LlvmIrStringBlob NamesBlob = null!;
+		public uint NameMutationsCount = 1;
 	}
 
 	// Keep in sync with FORMAT_TAG in src/monodroid/jni/xamarin-app.hh
@@ -394,10 +396,14 @@ protected override void Construct (LlvmIrModule module)
 		};
 		module.Add (dso_cache);
 
+		module.AddGlobalVariable ("dso_jni_preloads_idx_stride", dsoState.NameMutationsCount);
+
 		// This variable MUST be written after `dso_cache` since it relies on sorting performed by HashAndSortDSOCache
 		var dso_jni_preloads_idx = new LlvmIrGlobalVariable (new List<uint> (), "dso_jni_preloads_idx", LlvmIrVariableOptions.GlobalConstant) {
 			Comment = " Indices into dso_cache[] of DSO libraries to preload because of JNI use",
 			ArrayItemCount = (uint)dsoState.JniPreloadDSOs.Count,
+			GetArrayItemCommentCallback = GetPreloadIndicesLibraryName,
+			GetArrayItemCommentCallbackCallerState = dsoState,
 			BeforeWriteCallback = PopulatePreloadIndices,
 			BeforeWriteCallbackCallerState = dsoState,
 		};
@@ -566,6 +572,21 @@ void AddAssemblyStores (LlvmIrModule module)
 		module.Add (assembly_store);
 	}
 
+	string? GetPreloadIndicesLibraryName (LlvmIrVariable v, LlvmIrModuleTarget target, ulong index, object? value, object? callerState)
+	{
+		// Instead of throwing for such a triviality like a comment, we will return error messages as comments instead
+		var dsoState = callerState as DsoCacheState;
+		if (dsoState == null) {
+			return " Internal error: DSO state not present.";
+		}
+
+		if (index >= (ulong)dsoState.JniPreloadNames.Count) {
+			return $" Invalid index {index}";
+		}
+
+		return $" {dsoState.JniPreloadNames[(int)index]}";
+	}
+
 	void PopulatePreloadIndices (LlvmIrVariable variable, LlvmIrModuleTarget target, object? state)
 	{
 		var indices = variable.Value as List<uint>;
@@ -578,6 +599,9 @@ void PopulatePreloadIndices (LlvmIrVariable variable, LlvmIrModuleTarget target,
 			throw new InvalidOperationException ($"Internal error: DSO state not present.");
 		}
 
+		var dsoNames = new List<string> ();
+
+		// Indices array MUST NOT be sorted, since it groups alias entries together with the main entry
 		foreach (DSOCacheEntry preload in dsoState.JniPreloadDSOs) {
 			int dsoIdx = dsoState.DsoCache.FindIndex (entry => {
 				if (entry.Instance == null) {
@@ -592,8 +616,9 @@ void PopulatePreloadIndices (LlvmIrVariable variable, LlvmIrModuleTarget target,
 			}
 
 			indices.Add ((uint)dsoIdx);
+			dsoNames.Add (preload.HashedName ?? String.Empty);
 		}
-		indices.Sort ();
+		dsoState.JniPreloadNames = dsoNames;
 	}
 
 	void HashAndSortDSOCache (LlvmIrVariable variable, LlvmIrModuleTarget target, object? state)
@@ -648,16 +673,22 @@ DsoCacheState InitDSOCache ()
 		var aotDsoCache = new List<StructureInstance<DSOCacheEntry>> ();
 		var nameMutations = new List<string> ();
 		var dsoNamesBlob = new LlvmIrStringBlob ();
+		int nameMutationsCount = -1;
 
 		for (int i = 0; i < dsos.Count; i++) {
 			string name = dsos[i].name;
 			(int nameOffset, _) = dsoNamesBlob.Add (name);
 
 			bool isJniLibrary = ELFHelper.IsJniLibrary (Log, dsos[i].item.ItemSpec);
 			bool ignore = dsos[i].ignore;
+			bool ignore_for_preload = !DsoCacheJniPreloadIgnore.Contains (name);
 
 			nameMutations.Clear();
 			AddNameMutations (name);
+			if (nameMutationsCount == -1) {
+				nameMutationsCount = nameMutations.Count;
+			}
+
 			// All mutations point to the actual library name, but have hash of the mutated one
 			foreach (string entryName in nameMutations) {
 				var entry = new DSOCacheEntry {
@@ -670,16 +701,19 @@ DsoCacheState InitDSOCache ()
 					name_index = (uint)nameOffset,
 				};
 
-				if (entry.is_jni_library && entry.HashedName == name && !DsoCacheJniPreloadIgnore.Contains (name)) {
-					jniPreloads.Add (entry);
-				}
-
 				var item = new StructureInstance<DSOCacheEntry> (dsoCacheEntryStructureInfo, entry);
 				if (name.StartsWith ("libaot-", StringComparison.OrdinalIgnoreCase)) {
 					aotDsoCache.Add (item);
-				} else {
-					dsoCache.Add (item);
+					continue;
 				}
+
+				// We must add all aliases to the preloads indices array so that all of them have their handle
+				// set when the library is preloaded.
+				if (entry.is_jni_library && ignore_for_preload) {
+					jniPreloads.Add (entry);
+				}
+
+				dsoCache.Add (item);
 			}
 		}
 
@@ -688,6 +722,7 @@ DsoCacheState InitDSOCache ()
 			JniPreloadDSOs = jniPreloads,
 			AotDsoCache = aotDsoCache,
 			NamesBlob = dsoNamesBlob,
+			NameMutationsCount = (uint)(nameMutationsCount <= 0 ? 1 : nameMutationsCount),
 		};
 
 		void AddNameMutations (string name)

src/native/clr/host/host.cc

@@ -334,6 +334,60 @@ auto Host::create_delegate (
 	return delegate;
 }
 
+[[gnu::flatten, gnu::always_inline]]
+void Host::preload_jni_libraries () noexcept
+{
+	// NOTE: when fixing a bug here, fix also the MonoVM code in src/native/mono/monodroid-glue.cc@preload_jni_libraries
+	if (application_config.number_of_shared_libraries == 0) [[unlikely]] {
+		return;
+	}
+
+	log_debug (LOG_ASSEMBLY, "DSO jni preloads index stride == {}", dso_jni_preloads_idx_stride);
+
+	if ((dso_jni_preloads_idx_count % dso_jni_preloads_idx_stride) != 0) [[unlikely]] {
+		Helpers::abort_application (
+			LOG_ASSEMBLY,
+			std::format (
+				"DSO preload index is invalid, size ({}) is not a multiple of {}"sv,
+				dso_jni_preloads_idx_count,
+				dso_jni_preloads_idx_stride
+			)
+		);
+	}
+
+	for (size_t i = 0; i < dso_jni_preloads_idx_count; i += dso_jni_preloads_idx_stride) {
+		const size_t entry_index = dso_jni_preloads_idx[i];
+		DSOCacheEntry &entry = dso_cache[entry_index];
+		const std::string_view dso_name = MonodroidDl::get_dso_name (&entry);
+
+		log_debug (
+			LOG_ASSEMBLY,
+			"Preloading JNI shared library: {} (entry's index: {}; real name hash: {:x}; name hash: {:x})",
+			dso_name,
+			entry_index,
+			entry.real_name_hash,
+			entry.hash
+		);
+
+		void *handle = MonodroidDl::monodroid_dlopen (&entry, dso_name, RTLD_NOW);
+
+		// Set handle in all the alias entries
+		for (size_t j = 1; j < dso_jni_preloads_idx_stride; j++) {
+			const size_t entry_alias_index = dso_jni_preloads_idx[i + j];
+			DSOCacheEntry &entry_alias = dso_cache[entry_alias_index];
+			const std::string_view entry_alias_name = MonodroidDl::get_dso_name (&entry);
+
+			log_debug (
+				LOG_ASSEMBLY,
+				"Putting JNI library handle in alias entry at index {}: {}",
+				entry_alias_index,
+				entry_alias_name
+			);
+			entry_alias.handle = handle;
+		}
+	}
+}
+
 void Host::Java_mono_android_Runtime_initInternal (
 	JNIEnv *env, jclass runtimeClass, jstring lang, jobjectArray runtimeApksJava,
 
@@ -433,12 +487,7 @@ void Host::Java_mono_android_Runtime_initInternal (
 		gettid ()
 	);
 
-	for (size_t i = 0; i < dso_jni_preloads_idx_count; i++) {
-		DSOCacheEntry &entry = dso_cache[dso_jni_preloads_idx[i]];
-		const std::string_view dso_name = MonodroidDl::get_dso_name (&entry);
-		log_debug (LOG_ASSEMBLY, "Preloading JNI shared library: {}", dso_name);
-		MonodroidDl::monodroid_dlopen (&entry, dso_name, RTLD_NOW);
-	}
+	preload_jni_libraries ();
 
 	struct JnienvInitializeArgs init = {};
 	init.javaVm                                         = jvm;

src/native/clr/include/host/host.hh

@@ -49,6 +49,8 @@ namespace xamarin::android {
 			std::string_view const& assembly_name, std::string_view const& type_name,
 			std::string_view const& method_name) noexcept -> void*;
 
+		static void preload_jni_libraries () noexcept;
+
 	private:
 		static inline void *clr_host = nullptr;
 		static inline unsigned int domain_id = 0;

src/native/clr/include/xamarin-app.hh

@@ -348,6 +348,7 @@ extern "C" {
 	[[gnu::visibility("default")]] extern AssemblyStoreRuntimeData assembly_store;
 
 	[[gnu::visibility("default")]] extern DSOCacheEntry dso_cache[];
+	[[gnu::visibility("default")]] extern const uint dso_jni_preloads_idx_stride;
 	[[gnu::visibility("default")]] extern const uint dso_jni_preloads_idx_count;
 	[[gnu::visibility("default")]] extern const uint dso_jni_preloads_idx[];
 	[[gnu::visibility("default")]] extern DSOCacheEntry aot_dso_cache[];

src/native/clr/xamarin-app-stub/application_dso_stub.cc

@@ -127,6 +127,7 @@ DSOCacheEntry dso_cache[] = {
 	},
 };
 
+const uint dso_jni_preloads_idx_stride = 1;
 const uint dso_jni_preloads_idx_count = 1;
 const uint dso_jni_preloads_idx[1] = {
 	0

src/native/mono/monodroid/monodroid-glue-internal.hh

@@ -162,6 +162,7 @@ namespace xamarin::android::internal
 		static void monodroid_unhandled_exception (MonoObject *java_exception);
 		static MonoClass* get_android_runtime_class () noexcept;
 
+		static void preload_jni_libraries () noexcept;
 		static MonoDomain* create_domain (JNIEnv *env, jstring_array_wrapper &runtimeApks, bool is_root_domain, bool have_split_apks) noexcept;
 		static MonoDomain* create_and_initialize_domain (JNIEnv* env, jclass runtimeClass, jstring_array_wrapper &runtimeApks,
 		                                          jstring_array_wrapper &assemblies, jobjectArray assembliesBytes, jstring_array_wrapper &assembliesPaths,