Creating a dll in cygwin for use with jni without -mno-cygwin

On Wed, 8 Aug 2007 13:12:18 -0700 (PDT), robbincatz <...@gmail.com> wrote:

I am trying to create a dll in cygwin for use with jni. I have successfully
achieved this for a simple "hello world" type program using the following
command:

gcc -mno-cygwin -Wl,--add-stdcall-alias -shared -o myDll.dll myNativeCode.c

However I would like to create my dll without using the -mno-cygwin option
as my c code relies on additional C libraries which when included causes the
above command to produce a large number of errors involving the libraries I
am using:

/usr/local/lib/libpbc.a(libpbc_la-pairing.o): In function
`pairing_init_inp_gene
ric':
/home/me/pbc_build/pbc-0.4.11/ecc/pairing.c:80: undefined reference to
`___asse
rt'
/home/me/pbc_build/pbc-0.4.11/ecc/pairing.c:81: undefined reference to
`___asse
rt'
/home/me/pbc_build/pbc-0.4.11/ecc/pairing.c:147: undefined reference to
`___get
reent'
/usr/local/lib/libpbc.a(libpbc_la-pairing.o): In function
`pairing_init_inp_buf'
.
.
.
.
.
.
/usr/local/lib/libgmp.a(assert.o):assert.c:(.text+0x29): undefined reference
to
`___getreent'
/usr/local/lib/libgmp.a(assert.o):assert.c:(.text+0x4b): undefined reference
to
`___getreent'
/usr/local/lib/libgmp.a(assert.o):assert.c:(.text+0x98): undefined reference
to
`___getreent'
/usr/local/lib/libgmp.a(doprntf.o):doprntf.c:(.text+0x483): undefined
reference
to `__imp___ctype_'
collect2: ld returned 1 exit status

( I have just given the start and end of the errors produced )

I have looked at every bit of information on -mno-cygwin, building dlls in
cygwin and jni but nothing has helped although I now believe the problem
lies with the fact that i did not install my libraries for mingw but for
cygwin.

If I could create my dll without the -mno-cygwin option I think it would
solve my problem, I have tried with no success to do this. When I try this
everything appears to be fine ( i.e. I receive no error messages ) but when
I run my java code ( which calls the native c code ) it hangs, this happens
even for the most basic "hello world" ap.

My code is as follows:

main.java:

public class main
{
static
{
System.loadLibrary( "theNativeMethod" );
}

public static void main( String args[] )
{
AClassWithNativeMethods c = new AClassWithNativeMethods();
c.theNativeMethod();
}
}


AClassWithNativeMethods.java:

public class AClassWithNativeMethods
{
public native void theNativeMethod();

public void aJavaMethod()
{
theNativeMethod();
}
}

AClassWithNativeMethods.h:

/* DO NOT EDIT THIS FILE - it is machine generated */
#include <jni.h>
/* Header for class AClassWithNativeMethods */

#ifndef _Included_AClassWithNativeMethods
#define _Included_AClassWithNativeMethods
#ifdef __cplusplus
extern "C" {
#endif
/*
* Class: AClassWithNativeMethods
* Method: theNativeMethod
* Signature: ()V
*/
JNIEXPORT void JNICALL Java_AClassWithNativeMethods_theNativeMethod
(JNIEnv *, jobject);

#ifdef __cplusplus
}
#endif
#endif

theNativeMethod.c:

#include <stdio.h>
#include "AClassWithNativeMethods.h"

JNIEXPORT void JNICALL Java_AClassWithNativeMethods_theNativeMethod( JNIEnv*
env, jobject thisObj )
{
printf( "Hello JNI World\n" );
}

I used the following to compile and run my java code:
javac AClassWithNativeMethods.java main.java
javah -jni AClassWithNativeMethods
java main

I would really appreciate any help in producing a dll which works and doesnt
use the -mno-cygwin option. Or any other suggestions

Thanks

:)
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