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Mono AOT compiler does not prefix exported UnmanagedCallersOnly symbols with underscore when targeting iOS #79491
Description
Description
If a method is marked with UnmanagedCallersOnlyAttribute and a named export is specified via EntryPoint e.g.,
[UnmanagedCallersOnly(EntryPoint="exposed_managed_method")]
public static int ManagedMethod() => 42;Mono AOT compiler exports the symbols as-is without prefixing it with an _ which is required on iOS platforms.
This results in failures when trying to load the symbol dynamically from the native code via:
void *del = dlsym (RTLD_DEFAULT, "exposed_managed_method");Repro
To reproduce, apply the following patch:
diff --git a/src/mono/sample/iOS/Program.cs b/src/mono/sample/iOS/Program.cs
index 603ff2e4ebc..fbdc8032daa 100644
--- a/src/mono/sample/iOS/Program.cs
+++ b/src/mono/sample/iOS/Program.cs
@@ -24,6 +24,9 @@ private static void OnButtonClick()
ios_set_text("OnButtonClick! #" + counter++);
}
+ [UnmanagedCallersOnly(EntryPoint="exposed_managed_method")]
+ public static int ManagedMethod() => 42;
+
#if CI_TEST
public static async Task<int> Main(string[] args)
#else
diff --git a/src/mono/sample/iOS/Program.csproj b/src/mono/sample/iOS/Program.csproj
index 0e6aa8777fa..f0187ba8f81 100644
--- a/src/mono/sample/iOS/Program.csproj
+++ b/src/mono/sample/iOS/Program.csproj
@@ -16,6 +16,10 @@
<TrimMode>Link</TrimMode>
</PropertyGroup>
+ <ItemGroup>
+ <TrimmerRootDescriptor Include="$(MSBuildThisFileDirectory)ILLink.Descriptors.xml" />
+ </ItemGroup>
+
<PropertyGroup Condition="'$(TargetOS)' == 'MacCatalyst'">
<DevTeamProvisioning Condition="'$(TargetOS)' == 'MacCatalyst' and '$(DevTeamProvisioning)' == ''">adhoc</DevTeamProvisioning>
<EnableAppSandbox Condition="'$(EnableAppSandbox)' == ''">false</EnableAppSandbox>
@@ -79,6 +83,7 @@
TargetOS="$(TargetOS)"
Arch="$(TargetArchitecture)"
ProjectName="$(AppName)"
+ NativeMainSource="$(MSBuildThisFileDirectory)/main.m"
MonoRuntimeHeaders="$(MicrosoftNetCoreAppRuntimePackDir)runtimes\$(TargetOS.ToLower())-$(TargetArchitecture)\native\include\mono-2.0"
Assemblies="@(BundleAssemblies)"
MainLibraryFileName="Program.dll"
diff --git a/src/mono/sample/iOS/main.m b/src/mono/sample/iOS/main.m
index 0ab407e8398..e6d8a3f31f4 100644
--- a/src/mono/sample/iOS/main.m
+++ b/src/mono/sample/iOS/main.m
@@ -2,6 +2,7 @@
// The .NET Foundation licenses this file to you under the MIT license.
#import <UIKit/UIKit.h>
+#import <dlfcn.h>
#import "runtime.h"
@interface ViewController : UIViewController
@@ -45,6 +46,8 @@ void (*clickHandlerPtr)(void);
[self.view addSubview:button];
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
+ void *del = dlsym (RTLD_DEFAULT, "exposed_managed_method");
+ NSAssert(del != NULL, @"'exposed_managed_method' not found");
mono_ios_runtime_init ();
});
}
And add the ILLink.Descriptors.xml file to the project directory with the following contents:
<linker>
<!-- this is here to show how to configure the trimming -->
<assembly fullname="Program">
<type fullname="Program">
<method name="ManagedMethod" />
</type>
</assembly>
</linker>Finally, build it with:
cd src/mono/sample/iOS
make build-appbundle MONO_ARCH=arm64 AOT=true DEPLOY_AND_RUN=trueWorkaround
Possible workaround is to prefix the EntryPoint name with the underscore, but then such code is not platform independent.
/cc @mdh1418 @steveisok
Activity
steveisok commentedon Dec 21, 2022
@mdh1418 as this issue mentions, the symbol won't be written w/, for example, an underscore on osx, so
runtime/src/mono/mono/mini/aot-compiler.c
Line 5259 in 429cda7
[mono] Prefix exported symbols via UnmanagedCallersOnly attribute (#7…
[mono] Prefix exported symbols via UnmanagedCallersOnly attribute (do…