Error with jni (java6) and X25 native code (C language) when code uses system call "connect()" on Solaris 5.9

Question

In past years, we created a program that uses X25 protocol. It was made in C language and works fine for a Sun-Fire machine with Solaris 5.9. Recently, we are working with java 6 in same machine, and we are trying to adapt that old program in C for working with java via jni. So I have done some modifications to the old C program and created a shared library named x25lib.so

But I have found a runtime problem using jni and X25: When the C function is invoked from java via jni, the C code does not work in a same way that when it is invoked from another C program.

Concrete, using jni, the C code in shared library works fine until is invoked the system call connect(), then returns -1,

But invoking the same C code of my shared library from another C program returns 0 (ok)

In both cases, the C code in shared library doesn´t receive external parameters so the conditions are the same, I don´t understand if loading my "x25lib.so" shared library from java have a little difference that induce connect() in C fails.

using "truss" command from java I have found the error:

/2: connect(5, 0xFD878B75, 112, 1)          Err#22 EINVAL

the same, but invoking the shared lib from another C program:

connect(4, 0xFFBFE794, 114, 1)          = 0

So it works ok only with pure C,

Is there another consideration for using jni and X25 for solaris 5.9?

IMPORTANT: C Code in shared library is identical in both cases.

COMPILATION TIME:

a. Creating x25lib.so

    cc  -w -fd -G -Kpic subs.o -L/opt/SUNWconn/lib -R/opt/SUNWconn/lib -lsockx25
        -lsocket -lnsl -I"/SDK/jdk/include/" -I"/SDK/jdk/include/solaris/"
        -o x25lib.so -h x25lib.so x25jni.c

b. Creating a test C program with that shared library:

    cc -w x25lib.so -o x25test x25test.c

where `x25test.c` contains:


    #include <stdio.h>
    main()
    {
        java_x25();
    }

c. Using java:

public class X25 {

        static {
           System.load("/home/x25lib.so");
        }
    public native void ejecutaComando();
}

---

public class TestX25 {

    public static void main(String ... args) {
    X25 x25 = new X25();

    x25.ejecutaComando();
    }

}

---

Then in C code shared library:

/*
 * Class:     X25
 * Method:    ejecutaComando
 * Signature: ()V
 */
JNIEXPORT void JNICALL Java_X25_ejecutaComando
  (JNIEnv *env, jobject obj)
{

        java_x25();

}

---

So finally both programs (java y C) call exactly the same C code in shared library:

java_x25()
Without parameters, so execute the same code.

Why works fine when is called from C, but fails when is called from java?

Thanks for any advice.

Answer 1

Thanks for your comments. I have found a solution while I was trying another approach: I decided not using jni, instead I adapted the old C program for listening for simple tcp connections from java and then could execute x25 code, but surprise, I got the same runtime error like using jni:

connect(5, 0xFD8789C5, 112, 1)          Err#22 EINVAL

including a size of 112 instead 114, it was the same problem.

So I noticed that the problem was that I had compiled the new C program with "-lsocket" option before "-lsockx25", so that was a clue. Then I searched in google and I found a similar problem:

link to java X25 Bug ID:4077576

At the end of that article, it is mentioned the option LD_PRELOAD to force sockx25 library be loaded first. Finally the solution was at runtime:

bash$ export LD_PRELOAD=/opt/SUNWconn/lib/libsockx25.so

bash$ java TestX25

and then all is working fine using jni.

Reference for LD_PRELOAD: link to java tuning