CODEWITHSUNDEEP
javaswigdynamic-linkingunsatisfiedlinkerror
samT
samT

Reputation: 31

UnsatisfiedLinkError using swig with Java

When trying to use swig to wrap a simple C program in Java I'm given the following error:

java.lang.UnsatisfiedLinkError: /Users/localadmin/example/libexample.dylib: dlopen(/Users/localadmin/example/libexample.dylib, 1): no suitable image found. Did find: /Users/localadmin/example/libexample.dylib: file too shortstart

Using Mac 10.9.5, Swig 3.0.7, Java 1.7

I started with the following files:

example.c

/* A global variable */
double Foo = 3.0;

/* Compute the greatest common divisor of positive integers */
int gcd(int x, int y) {
    int g;
    g = y;
    while (x > 0) {
        g = x;
        x = y % x;
        y = g;
    }
    return g;
}

example.i

%module example

%{
// code here is passed straight to example_wrap.c unmodified
extern int gcd(int x, int y);
extern double Foo;
%}

// code here is wrapped:
extern int gcd(int x, int y);
extern double Foo;

runme.java

public class runme {

  static {
    try {
    System.loadLibrary("example");
    } catch (UnsatisfiedLinkError e) {
      System.err.println("Native code library failed to load. See the chapter on Dynamic Linking Problems in the SWIG Java documentation for help.\n" + e);
      System.exit(1);
    }
  }

  public static void main(String argv[]) {
    // Call our gcd() function

    int x = 42;
    int y = 105;
    int g = example.gcd(x,y);
    System.out.println("The gcd of " + x + " and " + y + " is " + g);

    // Manipulate the Foo global variable

    // Output its current value
    System.out.println("Foo = " + example.getFoo());

    // Change its value
    example.setFoo(3.1415926);

    // See if the change took effect
    System.out.println("Foo = " + example.getFoo());
  }
}

My command line input is:

swig -java example.i
gcc -c example.c example_wrap.c -I/System/Library/Frameworks/JavaVM.framework/Versions/A/Headers
ld -r example.o example_wrap.o -o libexample.dylib
javac *.java
java -Djava.library.path=. runme

followed by the error:

Native code library failed to load. See the chapter on Dynamic Linking Problems in the SWIG Java documentation for help.
java.lang.UnsatisfiedLinkError: /Users/localadmin/example/libexample.dylib: dlopen(/Users/localadmin/example/libexample.dylib, 1): no suitable image found.  Did find:
    /Users/localadmin/example/libexample.dylib: file too short

I've tried searching a bunch with no success. Any help is appreciated.

Upvotes: 2

Views: 691

Answers (1)

samT
samT

Reputation: 31

Added an extra flag in this command:

ld -r -dylib example.o example_wrap.o -o libexample.dylib

The -dylib flag must be needed to specify the file type as MH_DYLIB.

Upvotes: 1

Related Questions