Dlopen and unresolved symbols

Hi forum,
I have some .so files, some of them made by me(i.e., I have source files and Makefiles), some of them third party(i.e., I only have the .so file).
I'm trying to create an executable that is able to distinguish which ones are mine and which ones are not. In all my .so libraries I put a function called '_version'.
The problem comes here. When I try to load any of those third party .so, I get this error:
'ld.so.1: home/uf766857/projects/buscaversions/principal/output/versions:
fatal: relocation error: file <file_name.so>: symbol <symbol_name>: referenced symbol not found'
I'm using RTLD_LAZY mode. Is this not enough in order to avoid undefined symbol errors? I only want to check the presence of the '_version' function.
Could anyone help me? (I really need it)
TIA
David.

Hi,
I'm not able to use dlsym() because I'm not able to get a handle to the .so using dlopen().
I found the error using nm. This 3rd .so relies in another .so. I've added this new .so in my Makefile, but this new .so again relies in external symbols. Using nm, I found them inside the 3rd party main executable. How can I link using symbols inside this executable?
Thanks again.
David.

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System.LoadLibrary + dlopen -- callback causes unresolved symbol

Hi guys,
I am currently trying to use the API
System.loadLibrary(String name)in order to dynamically link shared libaries to SOLARIS JVM.
I am facing some unresolved symbol at run-time .
I load a shared library libhello1 (using system.LoadLibary)
and I call from this lib (via JNI interface) a method which
loads a second library libhello2(using dlopen) and invokes hello2().
hello2 will call back a method hello_bug which is implemented in libhello1.
There is the a mutual or cyclic dependence. This dependance is correctly handled if I link the libhello1 to a standard C implemented executable.
But if I load libHello1 via System.Load, the second lib is correctly loaded but the call back is not possible due to unresolved symbol.
It seems like the symbols are not kept in this case(or the dlopen creates a different thread?...)
The workaround to fix the issue is to link explicitely libHello1 to libHello2 when building libHello2.
I don't know if this is clear to everyone so
I have reproduced this on a very simple case.
Basicaly, I have implemented in standard C language 2 shared libraries:
libHelloModule1.so, libHelloModule2.so
one standard executable and one java interface to call the method
Below is the full code for reproduce:
hello1.h:
#include <dlfcn.h>
#include <stdlib.h>
#include <stdio.h>
#include <iostream>
#include <jni.h>
#include "hello_jni.h" [u]//automatically generated by javah -- ref Makefile[/u]
extern "C" void hello_bug();
hello1.cc :#include "hello1.h"
extern "C" {
JNIEXPORT void JNICALL Java_com_helloworld_Hello_ShowMessage
(JNIEnv *, jobject, jstring){
void *handle;
const char *error;
void (*init) (void);
printf(" load Hello2 \n");
handle = dlopen ("libHelloModule2.so", RTLD_LAZY);
printf (" lib Hello2 onload.. \n");
error = dlerror();
if (!handle) {
      printf ("lib HelloModule2 not loaded correctly %s \n", error);
      exit(1);
   dlerror();
   init =(void(*)()) dlsym(handle, "hello2");
error = dlerror();
        if(error)
                fprintf(stderr, "Could not find print_hello(): %s\n",
error);
                exit(1);
(*init)();
    dlclose(handle);
void hello_bug()
printf ("Hello bug correctly invoked : CQFD\n");
}// extern "C"
hello2.cc
#include "hello1.h"
typedef void ( *PF1) (char *, char *);
extern "C" {
void hello2(){
printf ("Hello2 : ping Hello1\n");
/*simple call work in c not via JNI*/
hello_bug();
Hello.java :
package com.helloworld;
import java.util.*;
import java.io.*;
public class Hello {
private native void ShowMessage(String msg);
public void initialized() {
            System.out.println(" ShowMessage - called");
try {
          ShowMessage("Generated with JNI");
       } catch (Exception e ) {
            e.printStackTrace();         }
public Hello(){
System.loadLibrary("HelloModule1");
            System.out.println(" HelloModule1 loaded");
TestLocal.java :
import java.util.*;
import java.io.*;
import com.helloworld.Hello;
public class TestLocal{
public TestLocal(){
        System.out.println("test local");
public static void main(String[] args) {
        TestLocal test_local = new TestLocal();
        Hello test = new Hello();
        test.initialized();
}THE MOST IMPORTANT IS IN THE MAKEFILE:
Makefile :all: Hello.jar hello_jni.h libHelloModule1.so libHelloModule2.so TestLocal.class dummy
Hello.jar: com/helloworld/Hello.class
jar cvf $@ com/helloworld
com/helloworld/Hello.class: Hello.java
$(JAVAC) -d . Hello.java
hello_jni.h: Hello.jar
$(JAVAH) -jni -o $@ -classpath ./Hello.jar com.helloworld.Hello
libHelloModule1.so : hello_jni.h hello1.o
gcc -G -o $@ hello1.o -lstdc++
libHelloModule2.so : hello2.o
gcc   -G -o $@ hello2.o -Wl -lstdc++ -L. -lHelloModule1   [u] # -->CASE 1 :THIS WORKS [/u]
gcc   -G -o $@ hello2.o -Wl -lstdc++ [u] #-->CASE 2 :THIS DOES NOT WORK[/u]
dummy : dummy_main.o
gcc -o $@ dummy_main.o -L. -lHelloModule1 -L/usr/local/lib -lstdc++
hello2.o : hello2.cc
gcc -I. -O -c hello2.cc
hello1.o : hello1.cc
gcc -I. -O -c hello1.cc
TestLocal.class : TestLocal.java
$(JAVAC) -classpath . -d . TestLocal.java
dummy_main.o : dummy_main.cc
gcc -I. -O -c dummy_main.cc
clean:
rm -rf com *.o *.so *.class *.jar hello_jni.h dummyCASE 1 : libHelloModule1.so is explicitely linked to libHelloModule2
myhost % dummy
load Hello2
lib Hello2 onload..
Hello2 : ping Hello1
Hello bug correctly invoked : CQFD
myhost % java -cp . TestLocal
test local
HelloModule1 loaded
ShowMessage - called
load Hello2
lib Hello2 onload..
Hello2 : ping Hello1
Hello bug correctly invoked : CQFD
CASE 2 : libHelloModule1.so is not explicitely linked to libHelloModule2
myhost % dummy
load Hello2
lib Hello2 onload..
Hello2 : ping Hello1
Hello bug correctly invoked : CQFD
myhost % java -cp . TestLocal
test local
HelloModule1 loaded
ShowMessage - called
load Hello2
lib Hello2 onload..
lib HelloModule2 not loaded correctly ld.so.1: java: fatal: relocation error: file ./libHelloModule2.so: symbol hello_bug: referenced symbol not found
My concern is to have this working in CASE1 with the JNI interface the same way it does in standard C built runtime.
So does any have encountered this?
Is there something I missed somewhere?
Thanks lot for your help
Youss

Hi,
I have implemented JNative which seems to be close to your problem.
It works under Windows and Linux, and loads libraries via dlopen and dlsym.
You can have a look at it's implementation at http://jnative.cvs.sourceforge.net/jnative/JNativeCpp/
Don't forget to load your libraries before trying to call them with System.load("/path/to/your/lib.so"); if they are not referenced by LD_LIBRARY_PATH.
This post may be false since I know nothing about Solaris. Perhaps JNative may be ported under Solaris ?
--Marc (http://jnative.sf.net)

XmlSaveDom unresolved symbol, and special characters in output...

I have a couple of issues with XmlSaveDom() that I'm hoping someone can help with...
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The DOM is not required to escape the characters, so it is correct that you get the literal ampersand characters when you ask the DOM for a getNodeValue().
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Hello all,
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SNIP
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Hi Guys,
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The fix for this is pretty much straight forward and solution lies in the Project settings only.
To my knowledge, with /MDd switch, it causes the compiler to place the library name MSVCRTD.lib into the .obj file.
But with /MTd switch, This option just causes the compiler to place the library name LIBCMTD.lib into the .obj file so that the linker will use LIBCMTD.lib to resolve external symbols. For details, please refer to this MSDN article:
https://msdn.microsoft.com/en-us/library/2kzt1wy3(VS.71).aspx
Its very useful.
Also
MDd stands for Multi-threaded Debug DLL
MTd stands for Multi-threaded Debug
Thanks,
Kiran

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Hi All
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null

Hi Tofubug,
Since I'm not familiar about C#, however, if want to run powershell script in C#, the script below may be helpful for you:
RunspaceConfiguration runspaceConfiguration = RunspaceConfiguration.Create();
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Unresolved symbol after migrating Pro*C from Oracle 8i to Oracle 10gR2

Hello,
We are currently migrating a 32bits application written in Pro*C and Pro*Cobol from Oracle 8i client to Oracle 10gR2 client (Oracle 10gR2 server).
Precompiling, compiling and linking the source files are ok. But at runtime, the following error appears :
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proc maxopencursors=100 hold_cursor=yes release_cursor=yes ireclen=500 oreclen=132 mode=ORACLE code=ANSI_C dbms=v8 unsafe_null=yes ltype=none include=(inc,/logiciel/oracle/client_10203/network/public,/logiciel/oracle/client_10203/plsql/public,/logiciel/oracle/client_10203/precomp/public,/vtcvd10/vcour/common/alimentation_com/afonction_partagee/inc,/logiciel/oracle/client_10203/rdbms/public,/logiciel/oracle/client_10203/rdbms/demo,) iname=src/its_execute_lmd.pc
Pro*C/C++: Release 10.2.0.3.0 - Production on Mer. Déc. 5 10:16:56 2007
Copyright (c) 1982, 2005, Oracle. All rights reserved.
Valeurs des options système par défaut extraites de : /logiciel/oracle/client_10203/precomp/admin/pcscfg.cfg
+----> .................... src/its_execute_lmd.c OK
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cc -Ae -Iinc -I/logiciel/oracle/client_10203/network/public -I/logiciel/oracle/client_10203/plsql/public -I/logiciel/oracle/client_10203/precomp/public -I/logiciel/oracle/client_10203/rdbms/public -I/logiciel/oracle/client_10203/rdbms/demo -I/vtcvd10/vcour/common/alimentation_com/afonction_partagee/inc -c src/its_execute_lmd.c -o src/its_execute_lmd.o
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SHLIB_PATH=/logiciel/oracle/client_10203/lib32
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Thank you in advance.

What does the program do? It might make more sense, given the tremendous number of changes and enhancements to just rewrite it.

Clueless about this "unresolved symbols"

Hi there!
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code:
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First, you should be linking your shared object (ugs.so) with the flag "-z defs", and probably with "-z defs -z text". By doing this, you will force the errors that you are now getting at runtime to be exposed at build time.
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FORTE 30M+HP11 - Unresolved symbol __shlinit ?

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Doing a C library using 3.0.G.2 & HP 10.20 enables me
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Doing the same on 3.0.M & HP 11 enables me to link as
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<pre>
Hi Donald,
You should have logged this as new problem under new thread.
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P.S: Use bottom search engine.
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Hi all!
I'm a newbie in Java and wondering if anyone can help me out
I've been using the following code:
int j = new Integer.parseInt(i);
where i contains a string that is always a number like 18 or 67
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sigh
what type of Object does 'session.getAttribute("Type")' return?
if its a String, and is properly formatted, Integer.parseInt((String)session.getAttribute("Type")) will work. (don't 4get about the NumberFormatException)
if its an Integer object, ((Integer)session.getAttribute("Type")).intValue(); will work.
rob,
Thanks I haven't tried that yet but it's similar to
what I did. This one works:
int j =
Integer.parseInt((String)session.getAttribute("Type"));
I was wondering if I can skip the conversion to string
and got straight and convert to an integer. Is that
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Depending on the documentation I read, this board has a native ANSI C interface with a C++ wrapper.
In their forums, they say to rename the ".cpp" file to "c", and then go forward with calling the default constructor & keep track of the pointer. Their functions are all in an externally loadable DLL.
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I have written a REALLY simple app to ease my way in - it does nothing more than allow the user to throw a switch, and when this happens, it goes off to connect to the board:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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I then started working with the XEM_Connect function.
The first step is to run their LoadDLL function as such:
int XEM_Connect ( okFrontPanel_HANDLE   XEM_Device )
   int   NoDevices = 0;   //   Number of devices attached to the PC
   //   Load the DLL (?)
   // Load the FrontPanel DLL
   if (FALSE == okFrontPanelDLL_LoadLib(NULL))
       printf("Could not load FrontPanel DLL\n");
       exit(-1);
    return XEM_SUCCESS;
And this would compile and run just fine.
Now, when I added the functions to start trying to get info about the device, I started getting "missing prototype" errors.
int XEM_Connect ( okFrontPanel_HANDLE   XEM_Device )
   int   NoDevices = 0;   //   Number of devices attached to the PC
   //   Load the DLL (?)
   // Load the FrontPanel DLL
   if (FALSE == okFrontPanelDLL_LoadLib(NULL))
       printf("Could not load FrontPanel DLL\n");
       exit(-1);
   //   Find out how many devices are attached
   XEM_Device = okFrontPanel_Construct( );
//   XEM_Device = okCFrontPanel( void );
//   NoDevices = GetDeviceCount( );
   printf("%d OK devices attached\n", NoDevices);
   //   Call the contructor?
//   okCFrontPanel ();
    return XEM_SUCCESS;
Now, I searched the forums and found the bits about adding #define _WIN32_WINNT 0x0501 prior to inclusion of windows.h. Did that. No joy.
Then I searched some more and found the bit about changing the build options to uncheck the "prototype required" flag.
Done.
This seemed to work at first (the above code could be built with no errors, and appeared to run).
So I thought maybe I had it, and added the next line, so:
int XEM_Connect ( okFrontPanel_HANDLE   XEM_Device )
   int   NoDevices = 0;   //   Number of devices attached to the PC
   //   Load the DLL (?)
   // Load the FrontPanel DLL
   if (FALSE == okFrontPanelDLL_LoadLib(NULL))
       printf("Could not load FrontPanel DLL\n");
       exit(-1);
   //   Find out how many devices are attached
   XEM_Device = okFrontPanel_Construct( );
   OpenBySerial( XEM_Device, "UaLgzvVpBJ" );
//   XEM_Device = okCFrontPanel( void );
//   NoDevices = GetDeviceCount( );
   printf("%d OK devices attached\n", NoDevices);
   //   Call the contructor?
//   okCFrontPanel ();
    return XEM_SUCCESS;
Now it doesn't complain about no prototypes (duh), but instead I get linker errors:
Undefined symbol '_OpenBySerial@0' referenced in "XEM.c".
So, dredging through the .h and .c files, I found a couple of things:
in the okFrontPanel.c file I found the following:
okDLLEXPORT ok_ErrorCode DLL_ENTRY
okFrontPanel_OpenBySerial(okFrontPanel_HANDLE hnd, const char *serial)
   if (_okFrontPanel_OpenBySerial)
; return((*_okFrontPanel_OpenBySerial)(hnd, serial));
   return(ok_UnsupportedFeature);
In the okFrontPanel.h file I found:
and also:
okDLLEXPORT ok_ErrorCode DLL_ENTRY okFrontPanel_OpenBySerial(okFrontPanel_HANDLE hnd, const char *serial);
So, I see them in the .h & .c files, but the linker is bombing out.
I smell a problem with actual code to link being in the DLL... How do I resolve this, any ideas? Or am I doing something so stupidly (and obviously) wrong that I'm being blinded to it?

Hi tomii,
My suspicion is that these issues are due to using a C++ dll in a C environment. There are inherent challenges with performing such an operation as you have to make sure all your parameters and settings are correct.
I also could not find the documentation that the Opal Kelly dll is ANSI C but it sounds like you can use this in C with some reconfiguration. I would recommend using their forums to get more information on what steps need to take place to get things working in ANSI C.
From the information you provided, I did find some resources on the missing prototype error and undefined symbol issue with the linker.
For the missing prototype I found a thread of someone actually using LabWindows and seeing this compiler error you may want to look at
http://bytes.com/topic/c/answers/695019-missing-prototype
I found a few cases where using a function definition of int func(void) removes such issue when int func() does not.
Another link I found that may be worth a look can be found at http://www.parashift.com/c++-faq-lite/mixing-c-and-cpp.html
It gives some good pointers to mixing C and C++ code. Some of it may be applicible in your case.
And, a resource for your undefined symbol linking issue.
http://www.cprogramming.com/tutorial/compiler_linker_errors.html
Hopefully these resources will give some context for getting things compiling and working with your dll.
Good luck!
James W.
Applications Engineer
National Instruments

My kid just got an iPod 5th gen (today from Santa) and it won't power up or charge. The only response is when I connect the USB and press the power button or front button the Battery appears with red line and lightning symbol. No other response at all.

Sorry about the long title.....its my first post.
My kid just got a brand new iPod 5th generation (today from Santa) and it won't power up or charge. The only response is when I connect the USB and press the power button or front button the Battery appears with red line on left and lightning symbol below. There is no other response at all no matter what I do, including holding both buttons down for extended period. My other kid got one and it works perfectly.....I have interchanged usb cables ports etc. but still no response....I would really appreciate any help.

Try:
- Reset the iOS device. Nothing will be lost
Reset iOS device: Hold down the On/Off button and the Home button at the same time for at
least ten seconds, until the Apple logo appears.
- Make an appointment at the Genius Bar of an Apple store since you have a hardware problem with the iPod. This is because as you said the same cable works with another iPod.
Apple Retail Store - Genius Bar

After updating my Iphone 4s to os 7.1.1 ota, my phone went into recovery mode. Yet when I try to restore it with Itunes on my windows 7 laptop it says the network connection has been reset! My phone has the itunes logo and charger symbol on it .

After updating my Iphone 4s to os 7.1.1 from 7.1 over the air, my phone went into recovery mode. Yet when I try to restore it with Itunes on my windows 7 laptop it says the network connection has been reset. Make sure your network settings are correct and your network is active, or try again later. My phone has the itunes logo and charger symbol on it, as well as an arrow pointing at the Itunes logo. After holding the sleep button down or even doing the hard reset the same screen comes up on my phone regardless of whether it is plugged in or not to my computer. I have turned my computer off and on again. It is plugged in and charging as it's battery life is very short. I also reset my modem and the same error message pops up. The only option on my computer when my phone is plugged in is to restore it. My firewall also allows Itunes through it. I have literally tried everything I know being someone who knows very little about technology. I also do not want to hear about how the update worked for other people. My phone has been in recovery mode for 5 hours at least now so it will just make me more frustrated if a bunch of people post about how the update worked for them.

Once the Device is asking to be Restored with iTunes... it is too late to save anything... and you must continue with the Recovery...
kevinpowell1 wrote:
how can i get it out of recovery mode?
Make sure you have the Current Version of iTunes Installed on your computer
iTunes free download from www.itunes.com/download
Then See Here > http://support.apple.com/kb/HT1808
You may need to try this More than Once... Be sure to Follow ALL the Steps...
Take your time... Pay particular attention to Steps 3 and 4.
Some users have reported as many as 8 or 9 attempts were necessary before success.
After you have Recovered your Device...
Re-Sync your Content or Restore from the most recent Backup...
Restore from Backup > http://support.apple.com/kb/ht1766
If the issue persists...
Then a Visit to an Apple Store or AASP (Authorized Apple Service Provider) is the Next Step...
Be sure to make an appointment first...

I have just purchased an iphone today and it is coming up with a picture on the screen of the usb connector and itunes symbol. It also says that I now have no service and can only make emergency calls

I have just purchased an iphone today and it is coming up with a picture on the screen of the usb connector and itunes symbol. It also says that I now have no service and can only make emergency calls

Just a thought, but maybe consider returning the device. Seems it might be a bit too complicated for you.

Dlopen and unresolved symbols

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