"Aaron M. Stromas" wrote:
>
> greetings,
>
> I need a little assistance with building a shared library for JNI under
> Linux 2.2.
> This is how I went about creating the library:
>
> compiling: g++ -I /usr/local/java/include
> -I/usr/local/java/include/linux -shared -fPIC -o keys.o keys.c
>
> linking: gcc -shared -Wl,-soname,libkeys.so -o libkeys.so.0 keys.o -lc
>
> $ java -Djava.library.path=/home/ams/work/keys T
> Exception in thread "main" java.lang.UnsatisfiedLinkError:
>/home/ams/work/keys/libkeys.so: keys.o: cannot open shared object file: No such file
>or directory
> at java.lang.ClassLoader$NativeLibrary.load(Native Method)
> at java.lang.ClassLoader.loadLibrary0(ClassLoader.java:1357)
> at java.lang.ClassLoader.loadLibrary(ClassLoader.java:1281)
> at java.lang.Runtime.loadLibrary0(Runtime.java:469)
> at java.lang.System.loadLibrary(System.java:774)
> at T.<clinit>(T.java:5)
>
> I have also tried another way of building the library (ld -G -f
> /lib/libuuid.so.1 keys.o -o libkeys.so) but got the same error. I have
> to mention that the native code accesses the libdb.so library which i
> copied to /home/ams/work/keys. Why doesn't java find my library? TIA,
I found that JNI code can compile and link without error and still be
incorrect, and the only error you do get is the one above. I diagnose
this with 'ldd -r /path/to/library/file' and see if there are any
unresolved references that don't point to an existing library.
Your library is looking for a routine "keys" which does not exist in
that library, or any of the other .o files you sent through the linker.
Here's bits of a Makefile with the gcc/library commands I use:
JAVA_HOME=/usr/local/java/jdk1.2.2
JAVA_INC= -I$(JAVA_HOME)/include -I$(JAVA_HOME)/include/linux
#
# gcc configurable compile options of interest
# -H list include header names
# -g debugging code enabled
GCCOPT= -g
LDOPT=-Xlinker -t -Xlinker -Map -Xlinker /tmp/linkmap
GCCDEF=-DIP_SUPPORT -DUNIX
LIBOUT=$(HOME)/lib
SRC=$(PROJ)/src
$(LIBOUT)/libjsystem.so: \
$(SRC)/JNsApiSubsystemInterfaces.h \
$(SRC)/JNsApiSubsystemInterfaces.c \
$(CLASSES)/com/aravox/nsapi/subsystem/JNsApiSubsystemInterfaces.class
- rm -f $@
@echo Creating $@...
gcc $(GCCOPT) $(GCCDEF) $(JAVA_INC) -I$(SRC) \
$(LDOPT) \
-shared -o $@ $(SRC)/JNsApiSubsystemInterfaces.c \
$(LIBOUT)/lib*.so
/home/joi/bin/anyUndefined $(LIBOUT)/lib*.so
anyUndefined is a bash script which inspects the resulting .so for
unresolved references and exits with an error code make will detect.
#!/bin/bash
tmp=/tmp/anyUndefined.$$
ldd -r $1 >$tmp 2>&1
echo "----------"
cat $tmp
echo "----------"
if
grep undefined $tmp;
then
exit 1
else
exit 0
fi
--
Joi Ellis Software Engineer
Aravox Technologies [EMAIL PROTECTED], [EMAIL PROTECTED]
No matter what we think of Linux versus FreeBSD, etc., the one thing I
really like about Linux is that it has Microsoft worried. Anything
that kicks a monopoly in the pants has got to be good for something.
- Chris Johnson
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