cerbero jni compilation __register_atfork problem

[Carl Blake]

I'm pretty sure I'm linking to libc, or at least I am when I use
gstreamer 1.16.0 downloaded binaries.  The problem occurs when I use
gstreamer 1.16.0 compiled using cerbero.

I'm having some difficulty figuring out what libraries are being linked
because of how android studio hides things.  I'm looking through make
files to try and figure it out.

I think part of the problem is that android studio is using ndk r19 and
gstreamer compiled with cerbero wants to use ndk r18.  I attempted to
change android studio to use the ndk r18 cerbero is using, but then I
couldn't get anything to link.  For example, android studio could no
longer even find crtbegin_so.o.  So now I'm trying to get cerbero to
compile using android studio's ndk r19.

I didn't think this would be this difficult.  I suspect I have
something wrong with my setup.

----------------------------------------------------

Andrew Esh andrew.esh at qterics.com wrote:

Do you have the API specific library path as a -L argument to your
linker?
Here's what I found:

andrewes at
ubuntu:~/Android/Sdk/ndk/20.0.5594570/toolchains/llvm/prebuilt/linux-
x86_64/sysroot/usr/lib/aarch64-linux-android/23$
for file in * ; do echo $file; objdump -x $file | grep register_atfork;
done
crtbegin_dynamic.o
0000000000000000         *UND* 0000000000000000 __register_atfork
0000000000000080 UNKNOWN           __register_atfork
crtbegin_so.o
0000000000000000         *UND* 0000000000000000 __register_atfork
0000000000000044 UNKNOWN           __register_atfork
crtbegin_static.o
0000000000000000         *UND* 0000000000000000 __register_atfork
0000000000000080 UNKNOWN           __register_atfork
...
libc.a
  4 .text.__register_atfork
0000009c  0000000000000000  0000000000000000
 00000128  2**2
  5 .text.__unregister_atfork
000000a0  0000000000000000  0000000000000000
 000001c4  2**2
0000000000000000 l       .text.__register_atfork 0000000000000000 $x.3
0000000000000000 l       .text.__unregister_atfork 0000000000000000
$x.4
...
libc.so
000000000000d144 g     F .text 0000000000000004
 __register_atfork

(Note the path in my CLI prompt.) So, linking with either one of those
files will provide the symbol. Perhaps you are getting your libc.so
from
another place?

On Fri, Jun 28, 2019 at 6:49 AM Carl Blake <carlb at williamsav.com>
wrote:

> I have an android app being compiled with gstreamer.  When I use
> gstreamer 1.16.0 from the download I'm able to compile the app
without
> any problems.  When I attempt to use gstreamer compiled using cerbero
> (1.16.0) I get the following compilation error:
>
> Build command failed.
> Error while executing process /home/cdb/Android/Sdk/ndk-bundle/ndk-
> build with arguments {NDK_PROJECT_PATH=null
> APP_BUILD_SCRIPT=/home/cdb/WaveCAST_Receiver/app/jni/Android.mk
> NDK_APPLICATION_MK=/home/cdb/WaveCAST_Receiver/app/jni/Application.mk
> APP_ABI=x86_64 NDK_ALL_ABIS=x86_64 NDK_DEBUG=1 APP_PLATFORM=android-
23
>
NDK_OUT=/home/cdb/WaveCAST_Receiver/app/build/intermediates/ndkBuild/de
> bug/obj
>
NDK_LIBS_OUT=/home/cdb/WaveCAST_Receiver/app/build/intermediates/ndkBui
> ld/debug/lib NDK_APPLICATION_MK=jni/Application.mk
> GSTREAMER_JAVA_SRC_DIR=src GSTREAMER_ROOT_ANDROID=/opt/gstreamer-1.0-
> android-universal-1.16.0-wav GSTREAMER_ASSETS_DIR=src/assets
>
/home/cdb/WaveCAST_Receiver/app/build/intermediates/ndkBuild/debug/obj/
> local/x86_64/libgststart.so}
> [x86_64] Compile        : gststart <= gststart.c
> [x86_64] Compile++      : gststart <= dummy.cpp
> GStreamer      : [GEN] => gst-build-x86_64/gstreamer_android.c
> GStreamer      : [COMPILE] => gst-build-x86_64/gstreamer_android.c
> GStreamer      : [LINK] => gst-build-x86_64/libgstreamer_android.so
>
> /home/cdb/Android/Sdk/ndk-bundle/toolchains/llvm/prebuilt/linux-
> x86_64/sysroot/usr/lib/x86_64-linux-
> android/23/crtbegin_so.o:crtbegin_so.c:function pthread_atfork:
error:
> undefined reference to '__register_atfork'
> clang++: error: linker command failed with exit code 1 (use -v to see
> invocation)
> make: *** [buildsharedlibrary_x86_64] Error 1
>
> I'm using android studio 3.3.1.
>
> Does anybody have any ideas why this might be happening?
>
> Carl
>
>
> _______________________________________________
> gstreamer-android mailing list
> gstreamer-android at lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/gstreamer-android



-- 
Andrew Esh
Senior Software Engineer
Qterics
612-564-2580
www.qterics.com
<http://www.nielsen.com/>