Segmentation Fault ... Shared Libraries in Linux

spooshah · #1 12-Nov-2008, 06:49

Halo 'World'.

I am trying to make a simple program of shared libraries on a LInux platform.
I am getting an error of segmentation fault when I try to execute the program.
It is compiling without any warnings and errors.

I know that segmentation faults are normally caused by pointer malfunctions and that is probably the case over here.

However I am not able to figure it out.
Will be very greatful if you can help me.

Am posting the programs here.

MainExample.C

CPP / C++ / C Code:

#include "header.h"
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <dlfcn.h>
#include <string.h>

void *handle;
void (*F_PRODRATES) ( double *, double *)=NULL;
char *error;

int DLL::rif_ch_attachdll_(char* LibMech , int thisLength)
{
	char buffer[1024];
	int two;
	
	strcpy(buffer,LibMech/*, (size_t)lejo*/);
	buffer[thisLength]='\0';          /* need a null terminated string */
	
	two = 2;
	
	handle = dlopen (buffer, RTLD_LAZY);		      
   	 if (!handle) {					      
		fprintf (stderr, "%s\n", dlerror());		      
	printf(" NOT attached to DLL \n .... %s .....\n",buffer);
 
                _exit(-1);
		return -1; 					      
    }
		
	printf(" successfully attached to DLL \t %s .\n",buffer);
 
	return 0;
}

void DLL::dlltest_(double* X , double* Y)
{
	if (handle == NULL) {
		fprintf (stderr, "%s\n", "no DLL attached, error");
		_Exit(-1);
		 return ;
	}
		
	if ( (*F_PRODRATES) == NULL) {
		dlerror();
	     *(void **) (&F_PRODRATES) = dlsym(handle, "test_");
	     if ((error = dlerror()) != NULL)  {                       
                  fprintf (stderr, "%s\n", error);  
             }
        }
        (*F_PRODRATES)(X , Y);	

}

int main()
{
	
	double  X,Y=0;
	char LibMech[1024];
	int thisLength;
	DLL call;
	
	strcpy(LibMech, "home/spoo0/FinalLinking/lib1Fortran.so");
/*	printf("%s",LibMech);*/
	
	thisLength = strlen(LibMech);
/*	printf("hgfhjg %s",LibMech);
	      if(thisLength < 1) 
	      {
	      thisLength= sizeof(LibMech);
	      }*/
	      
                call.rif_ch_attachdll_(LibMech , thisLength);
	
		printf("I am in Dll 12345");
		call.dlltest_(&X,&Y);
		
}

header.h

CPP / C++ / C Code:

#ifndef HEADER_H
#define HEADER_H
#include <cstdio> 
#include <cstdlib>
#include <cmath>
#include <cstring>
#include <ctime>
#include <csignal>
#include <dlfcn.h>

#ifdef  __cplusplus
extern "C" {
#endif

class DLL {
public:
DLL();
~DLL();
int rif_ch_attachdll_(char* LibMech , int thisLength);
void dlltest_(double* X , double* Y);

private:
char* LibMech;
int thisLength;
double* X;
double* Y;
};
#ifdef  __cplusplus
}
#endif

#endif

Just in case you are wondering why I am using such a format of header.h and everything. It is only because I am making this model to incorporate in a much larger program and this is the format I have to use.

This is my small Makefile.

g++ -c -fPIC -shared MainExample.C
g++ -fPIC -shared -o exec MainExample.o
./exec

Will gladly provide any more information that maybe require to solve this.

Thank You

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