Re: cygwin crashes when loading DLL

[Alan Thompson <athompson at alphatech dot com>]

Shaddy -

I have uploaded some sample code to http://www.whitecaps.net/jni/expr.jar .  The expr/jni/hello directory contains a "standard" JNI example (where java calls into a C++ program) that works on Cygwin and has an ant buildfile (I assume you are using ant.....if not, get it and you'll be happy).  The expr/jni/invoke directory has an example using the JNI invocation interface, where a C++ program creates a JVM to print "hello".  Output is pasted below.

Also, if you haven't seen it, look at the excellent writeup on JNI for Cygwin at http://www.inonit.com/cygwin/

Alan Thompson

****************************************************************************************************

cd expr/jni/hello
ant

Buildfile: build.xml

clean:

init:
    [mkdir] Created dir: C:\export\expr\jni\hello\bin
    [mkdir] Created dir: C:\export\expr\jni\hello\gen

javaSrcComp:
    [javac] Compiling 2 source files to C:\export\expr\jni\hello\bin

ctags:

javaComp:

javah:
     [echo] building *_jni.h...

ccComp:
    [mkdir] Created dir: C:\export\expr\jni\hello\ctmp
     [copy] Copying 2 files to C:\export\expr\jni\hello\ctmp

     [echo] Compiler Name:     g++
     [echo] Compiler Version:  
     [exec] g++ (GCC) 3.2 20020927 (prerelease)
     [exec] Copyright (C) 2002 Free Software Foundation, Inc.
     [exec] This is free software; see the source for copying conditions.  There is NO
     [exec] warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.


     [echo] Compiling for Cygwin...
     [echo] Linking for Cygwin...
   [delete] Deleting directory C:\export\expr\jni\hello\ctmp

build:

go:
     [java] loading library
     [java] calling sayHello
     [java] Hello World from C!
     [java] trying to get array
     [java] answerArrayObj=0x8b74cc
     [java] trying to get elem[0]
     [java] elem0=0x8b74d0
     [java] elemClass=0x8b74d4
     [java] valueFieldID=0x22
     [java] trying to get valueObj
     [java] valueObj=0x8b74d8
     [java] trying to get string chars
     [java] initial string = 'initial value from java'
     [java] trying to set string chars
     [java] newJString=0x8b74dc
     [java] getting constructor MID
     [java] msgCID=0x8bbf18
     [java] calling constructor
     [java] trying to set string chars
     [java] newJString2=0x8b74e4
     [java] setting newElem value
     [java] trying to set elem[1]
     [java] sayHello() returning
     [java] sayHello done
     [java] answer[ 0 ] = 'Hello World from C!'
     [java] answer[ 1 ] = 'the new C string value'
     [java] answer[ 2 ] = 'initial value from java'

clean:
   [delete] Deleting directory C:\export\expr\jni\hello\bin
   [delete] Deleting directory C:\export\expr\jni\hello\gen

BUILD SUCCESSFUL
Total time: 9 seconds






cd expr/jni/invoke
ant

Buildfile: build.xml

clean:

init:
    [mkdir] Created dir: C:\export\expr\jni\invoke\bin

javaComp:
    [javac] Compiling 1 source file to C:\export\expr\jni\invoke\bin

ccCygwin:
     [echo] Compiling C++ for Cygwin

dlltoolCygwin:


ccCompCygwin:

     [echo] Compiler Name:     g++
     [echo] Compiler Version:  
     [exec] g++ (GCC) 3.2 20020927 (prerelease)
     [exec] Copyright (C) 2002 Free Software Foundation, Inc.
     [exec] This is free software; see the source for copying conditions.  There is NO
     [exec] warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.



ccSun:

ccComp:

build:

go:

goCygwin:
     [exec] <C++> program starting
     [exec]   <java> Hello World from C!
     [exec] <C++> program terminating

goSun:

clean:
   [delete] Deleting directory C:\export\expr\jni\invoke\bin

BUILD SUCCESSFUL
Total time: 12 seconds


At 02:12 PM 5/20/2003 +0800, Shaddy Baddah wrote:

>I am having exactly the same problem trying to build Java JNI's under Cygwin
>(actually, they are the examples from the 'GNU Win32 related projects'
>page ). Robert Bercik, did discover a fix for the problem you encountered?
>
>I have more weirdness to describe. I can run the Java app that loads in the
>JNI under a regular Windows 2000 'cmd' window and it works fine, regardless
>of whether there is a cygwin1.dll active or not. But if I try and run the
>same Java app from within a cygwin shell, it crashes in the same way. There
>must be a simple explanation/fix to this one. Help would be greatly
>appreciated.
>
>Thanks in advance,
>Shaddy



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