Arch Linux

cmtptr

Member

Registered: 2008-09-01

Posts: 135

[solved] Java AWT JNI, undefined symbol in libawt, but ldd shows no...

I'm experimenting with the Java AWT native interface.  My project (which so far is a near clone of the code in the Sun tutorial) compiles and links without a problem:

[corey@sariss jstuff]$ ls
MANIFEST.MF  Makefile  MyCanvas.c  MyCanvas.h  MyCanvas.java
[corey@sariss jstuff]$ make
cc -ansi -fPIC -shared -Wall -Wpointer-arith -MM -MP -MT "MyCanvas.o MyCanvas.d" -o MyCanvas.d MyCanvas.c
javac -Xlint:deprecation MyCanvas.java
cc -ansi -fPIC -shared -Wall -Wpointer-arith -c -o MyCanvas.o MyCanvas.c
cc -ansi -fPIC -shared -Wall -Wpointer-arith -Wl,-soname,libMyCanvas.so -o libMyCanvas.so MyCanvas.o -lawt -ljava -ljvm -lverify -lX11
jar cfm test.jar MANIFEST.MF *.class libMyCanvas.so
[corey@sariss jstuff]$ ls
MANIFEST.MF  MyCanvas$1.class  MyCanvas.class  MyCanvas.h     MyCanvas.o      test.jar
Makefile     MyCanvas.c        MyCanvas.d      MyCanvas.java  libMyCanvas.so

Yet when I try to run it, it seems as though it doesn't load libawt:

corey@sariss jstuff]$ java -jar test.jar
java: symbol lookup error: /home/corey/src/jstuff/libMyCanvas.so: undefined symbol: JAWT_GetAWT

So I try `ldd` to ensure that my shared object linked correctly and that my LD_LIBRARY_PATH environment variable is good:

corey@sariss jstuff]$ ldd libMyCanvas.so 
    linux-vdso.so.1 =>  (0x00007fff7a5ff000)
    libawt.so => /opt/java/jre/lib/amd64/libawt.so (0x00007fef154bd000)
    libjava.so => /opt/java/jre/lib/amd64/libjava.so (0x00007fef1538e000)
    libjvm.so => /opt/java/jre/lib/amd64/server/libjvm.so (0x00007fef148ab000)
    libverify.so => /opt/java/jre/lib/amd64/libverify.so (0x00007fef1479c000)
    libX11.so.6 => /usr/lib/libX11.so.6 (0x00007fef14440000)
    libc.so.6 => /lib/libc.so.6 (0x00007fef140e3000)
    libm.so.6 => /lib/libm.so.6 (0x00007fef13e61000)
    libdl.so.2 => /lib/libdl.so.2 (0x00007fef13c5d000)
    libnsl.so.1 => /lib/libnsl.so.1 (0x00007fef13a44000)
    libpthread.so.0 => /lib/libpthread.so.0 (0x00007fef13827000)
    libxcb.so.1 => /usr/lib/libxcb.so.1 (0x00007fef1360c000)
    /lib/ld-linux-x86-64.so.2 (0x00007fef1588e000)
    libXau.so.6 => /usr/lib/libXau.so.6 (0x00007fef13409000)
    libXdmcp.so.6 => /usr/lib/libXdmcp.so.6 (0x00007fef13204000)

Looks fine to me.  Any JNI experts here who can shed some light on this?

Thanks.

Last edited by cmtptr (2011-01-20 03:31:02)

cmtptr

Member

Registered: 2008-09-01

Posts: 135

Re: [solved] Java AWT JNI, undefined symbol in libawt, but ldd shows no...

So after three days of messing around with LD_PRELOAD and library paths, Googling like a madman, and banging my head against the wall over this, I just discovered that I was linking against libawt.so instead of libjawt.so.  Unfortunately there is a libawt.so, so I didn't get a "library not found" error as a hint.