missing llvm-libc++/**/libc++_shared.so in unity NDK

[Thaina]

Plugin Version or Commit ID

403f484

Unity Version

6000.0.42f1

Your Host OS

Windows

Target Platform

Android

[Windows Only] Visual Studio C++ and Windows SDK Version

There is a bit of problem that NDK of unity 6000, specifically 6000.0.42f1, 6000.2.0a6 and maybe all unity 6 around these did not have folder NDK\sources\cxx-stl\llvm-libc++ and it then not grab libc++_shared.so into android build (and also report DLLNotFoundException for mediapipe_jni too)

I have copied this folder from 2022 version into 6000 to make it work. But I would like to be sure if it really not have other correct method?

[Linux Only] GCC/G++ and GLIBC Version

No response

[Android Only] Android Build Tools and NDK Version

ndkVersion "27.2.12479018"

compileSdk 35
buildToolsVersion = "34.0.0"

[iOS Only] XCode Version

No response

Command Sequences

Just build and run this project in unity 6000.0.42f

Log

DLLNotFoundException: libc++_shared.so

Additional Context

No response

[silingfei]

6000.0.28 include.
There is no 6000.0.42 installation folder

[homuler]

The Android NDK version has been updated, and it seems that the target path has been removed.

However, it still exists in a different path, making things a bit more complicated, but you can still copy libc++_shared.so in the same way.

./toolchains/llvm/prebuilt/linux-x86_64/sysroot/usr/lib/arm-linux-androideabi/libc++_shared.so
./toolchains/llvm/prebuilt/linux-x86_64/sysroot/usr/lib/x86_64-linux-android/libc++_shared.so
./toolchains/llvm/prebuilt/linux-x86_64/sysroot/usr/lib/riscv64-linux-android/libc++_shared.so
./toolchains/llvm/prebuilt/linux-x86_64/sysroot/usr/lib/aarch64-linux-android/libc++_shared.so
./toolchains/llvm/prebuilt/linux-x86_64/sysroot/usr/lib/i686-linux-android/libc++_shared.so

[Thaina]

@homuler I have also tried that but it seem it throw error that it cannot link some of libc++_shared.so that prebuilt for windows

I am not sure but I suspect maybe we can't grab all of them in the build but need to pinpoint only some of that. I have switch to the old version of NDK and it just work so I don't investigate further

[homuler]

need to pinpoint only some of that.

This is what I wanted to convey in the sentence "making things a bit more complicated".

[homuler]

The following link might be helpful.
https://forums.unrealengine.com/t/android-ndk-25-and-missing-libc-shared-so/758901

[Thaina]

I have try to use all of those libc++_shared.so but it was error in gradle build saying that all of those is not an ABI

[homuler]

How are you building it? Please describe how to reproduce it.
At the very least, I am able to build the sample app for armv8.

diff --git a/Assets/Plugins/Android/mainTemplate.gradle b/Assets/Plugins/Android/mainTemplate.gradle
index 579cdf7e..ba7f16aa 100644
--- a/Assets/Plugins/Android/mainTemplate.gradle
+++ b/Assets/Plugins/Android/mainTemplate.gradle
@@ -44,8 +44,9 @@ android {
     // Include libc++_shared.so
     task copyLibcppShared(type: Copy) {
         def ndkDir = android.ndkDirectory
-        from("$ndkDir/sources/cxx-stl/llvm-libc++/libs") { include '**/libc++_shared.so' }
-        into("$projectDir/src/main/jniLibs")
+        // from("$ndkDir/sources/cxx-stl/llvm-libc++/libs") { include '**/libc++_shared.so' }
+        from("$ndkDir/toolchains/llvm/prebuilt/linux-x86_64/sysroot/usr/lib/aarch64-linux-android") { include 'libc++_shared.so' }
+        into("$projectDir/src/main/jniLibs/arm64-v8a")
     }
     clean.dependsOn 'cleanCopyLibcppShared'
 

[Thaina]

I am doing something like this

    // Include libc++_shared.so
    task copyLibcppShared(type: Copy) {
        def ndkDir = android.ndkDirectory
        def libDir = VersionNumber.parse( android.ndkVersion ) < VersionNumber.parse( '25' )
            ? "$ndkDir/sources/cxx-stl/llvm-libc++/libs"
            : "$ndkDir/toolchains/llvm/prebuilt/windows-x86_64/sysroot/usr/lib";

        from(libDir) {
            include '**/libc++_shared.so'
            exclude '**/x86_64-linux-android/**' // add exclude line when it say "is not an ABI" one by one
            exclude '**/i686-linux-android/**' //
        }
        into("$projectDir/src/main/jniLibs")
    }
    clean.dependsOn 'cleanCopyLibcppShared'

Let me try your example again and I will report result

[homuler]

The selection of the directory directly under sysroot/usr/lib is important, so I don't think including **/libc++_shared.so is a good idea.
For example, if you are building for arm64, you need to select aarch64-linux-android.

[Thaina]

Thank you very much for your help

It seem it's not about using glob **/libc++_shared.so but because we need to specify destination for only ABI

But the old sdk provided in llvm-libc++ is matched the abi but the new structure are not, so copying directly didn't work

I have modified the function like this and it can build as of now

    // Include libc++_shared.so
    task copyLibcppShared() {
        def isOldNDK = VersionNumber.parse(android.ndkVersion) < VersionNumber.parse('22')
        def ndkDir = android.ndkDirectory
        def libDir = isOldNDK
                ? "$ndkDir/sources/cxx-stl/llvm-libc++/libs"
                : "$ndkDir/toolchains/llvm/prebuilt/windows-x86_64/sysroot/usr/lib/aarch64-linux-android"

        def targetDir = "$projectDir/src/main/jniLibs";
        def targetDirs = isOldNDK
                ? [targetDir]
                : [ **ABIFILTERS** ].findResults { arch -> targetDir + '/' + arch }

        targetDirs.forEach { jniLib ->
            copy {
                duplicatesStrategy 'include'
                from(libDir) {
                    include '**/libc++_shared.so'
                    exclude { file -> file.isDirectory() }
                }

                into(jniLib)
            }
        }
    }

[homuler]

fixed by #1409 and #1410