prebuild prefab package can't be used with ndk > 21.0.6113669

[brunotl]

due to ndk issues android/ndk#1166

tested with "hello-oboe" sample project : https://github.com/android/ndk-samples/tree/master/hello-oboe

2020-08-04 10:47:28.120 6570-6570/com.google.example.hellooboe E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.google.example.hellooboe, PID: 6570
    java.lang.UnsatisfiedLinkError: dlopen failed: cannot locate symbol "_Unwind_Resume" referenced by "/data/app/com.google.example.hellooboe-V_WR6gfOI4FnWmQn9ax7oA==/lib/arm64/liboboe.so"...
        at java.lang.Runtime.loadLibrary0(Runtime.java:1071)
        at java.lang.Runtime.loadLibrary0(Runtime.java:1007)
        at java.lang.System.loadLibrary(System.java:1668)
        at com.google.example.hellooboe.MainActivity.<clinit>(MainActivity.kt:74)

[dturner]

Thanks for filing this. I just tried reproducing with the latest version of the NDK (version 21.3.6528147) and did not experience this issue, so it looks like it's already been fixed.

[brunotl]

• i can reproduce with ndkVersion : '21.3.6528147' and '21.2.6472646' and '21.1.6352462'
• same error on x86 AVD and arm64 device
• prefab package come from Google maven repository : https://maven.google.com/web/index.html#com.google.oboe:oboe:1.4.2
• same result using https://maven.google.com/web/index.html#com.google.oboe:oboe:1.3.0
• my build host is windows 10.

[dturner]

Thanks for the extra info. I will follow up with the NDK team.

[dturner]

It seems that Oboe was built using a version of the NDK which contained a bug (thanks to Dan Albert for help with diagnosis):

Here's the readelf output from liboboe.so version 1.4.2:

$ readelf -sW liboboe.so| grep _Unwind
    55: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND _Unwind_Resume
  2007: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND _Unwind_Resume

The UND in the Ndx column means Undefined symbol.

Rebuilding with NDK r21d I get the following output:

$ /Users/donturner/Library/Android/sdk/ndk-bundle/toolchains/aarch64-linux-android-4.9/prebuilt/darwin-x86_64/bin/aarch64-linux-android-readelf -sW arm64-v8a/liboboe.so | grep _Unwind
  1480: 000000000002babc    60 FUNC    LOCAL  DEFAULT   11 _Unwind_SetSpColumn
  1481: 000000000002baf8    88 FUNC    LOCAL  DEFAULT   11 _Unwind_GetGR.localalias.0
  1490: 000000000002cfa4   192 FUNC    LOCAL  DEFAULT   11 _Unwind_RaiseException_Phase2
  1491: 000000000002d064   236 FUNC    LOCAL  DEFAULT   11 _Unwind_ForcedUnwind_Phase2
  1492: 000000000002d244     4 FUNC    LOCAL  DEFAULT   11 _Unwind_DebugHook
  1513: 000000000002dea0  1052 FUNC    LOCAL  DEFAULT   11 _Unwind_IteratePhdrCallback
  1531: 000000000002d6cc   208 FUNC    LOCAL  DEFAULT   11 _Unwind_Backtrace
  1532: 000000000002bce8     8 FUNC    LOCAL  DEFAULT   11 _Unwind_GetRegionStart
  1533: 000000000002baf8    88 FUNC    LOCAL  DEFAULT   11 _Unwind_GetGR
  1535: 000000000002d248   376 FUNC    LOCAL  DEFAULT   11 _Unwind_RaiseException
  1537: 000000000002bcd8     8 FUNC    LOCAL  DEFAULT   11 _Unwind_SetIP
  1538: 000000000002bce0     8 FUNC    LOCAL  DEFAULT   11 _Unwind_GetLanguageSpecificData
  1544: 000000000002bd20     8 FUNC    LOCAL  DEFAULT   11 _Unwind_GetTextRelBase
  1546: 000000000002d5b0   248 FUNC    LOCAL  DEFAULT   11 _Unwind_Resume_or_Rethrow
  1548: 000000000002bc5c     8 FUNC    LOCAL  DEFAULT   11 _Unwind_GetCFA
  1549: 000000000002d3c0   244 FUNC    LOCAL  DEFAULT   11 _Unwind_ForcedUnwind
  1551: 000000000002bcc4    20 FUNC    LOCAL  DEFAULT   11 _Unwind_GetIPInfo
  1557: 000000000002ee38   452 FUNC    LOCAL  DEFAULT   11 _Unwind_Find_FDE
  1564: 000000000002d4b4   252 FUNC    LOCAL  DEFAULT   11 _Unwind_Resume
  1566: 000000000002bcf0    40 FUNC    LOCAL  DEFAULT   11 _Unwind_FindEnclosingFunction
  1567: 000000000002bcbc     8 FUNC    LOCAL  DEFAULT   11 _Unwind_GetIP
  1569: 000000000002bc64    88 FUNC    LOCAL  DEFAULT   11 _Unwind_SetGR
  1575: 000000000002d6a8    36 FUNC    LOCAL  DEFAULT   11 _Unwind_DeleteException
  1576: 000000000002bd18     8 FUNC    LOCAL  DEFAULT   11 _Unwind_GetDataRelBase

Note the UND has been replaced with 11 indicating that the symbols are in section 11.

Why did this happen? (paraphrased from Dan)
The UND doesn't necessarily mean that a library is built incorrectly - it is normal for symbols that come from a shared lib. But the unwind stuff is static on Android, so should always be defined in every executable/shared lib.

The symbols were wrongly reexported from libc++ this bug, so if libc++ appears on the link command before libgcc the linker resolves the symbol from libc++ instead.

Oboe 1.4.2 was built against a version of the NDK which contained this bug. So when users attempt to link against Oboe using versions of the NDK which don't contain this bug (i.e. have a fixed libc++ that no longer reexports the symbol) it causes this error.

What now?
I will rebuild Oboe 1.4.2 and upload a new prefab package.

[dturner]

I have created a new release: 1.4.3 which should fix this issue. I am just waiting on approval from @philburk or @android-usb to publish to GMaven.

I have published an updated AAR in case you would like to test it out without waiting for the GMaven artifact.

[philburk]

Don release the new version.