Thread: shared library, but not dynamic !?

Hi,

To be more specific, I can give some more explanations:

- I am compiling the program.
- I am then running it.
- The program check if a shared lib which was not loaded exists, and if a function exists in it (with dlopen and dlsym).
- It first does not exit, so it compile a new library.
- The program open the library with dlopen, then launch a function of that library using dlsym.
And that's when I get a "Segmentation fault".
What is strange is that dlerror shows no problem...

Then:

- I relaunch the program.
- The lib and function exit, so the program does not compile it.
- The program runs well with these functions... No segmentation fault until the next missing function is compiled and loaded...

That's very strange, I don't see what the problem could be.

I paid very much attention at closing correctly the newly compiled lib, so there should not be any problem in here.

I test dlopen with RTLD_NEW and RTLD_LAZY, but it doesn't change anything.
I compile with gcc, with the option -rdynamic...

I really have no idea what to do or test.

Hi,

I am posting the interesting part of my code, but I am not sure it will be so easy to read. The code mix fortran and C.

First, the main code is in C, but needs to call fortran procedure. Everything is standard and works fine until it reaches this part of the fortran code:

Code:

        double precision function dWeffdcostree(sqrtS,costh)
        implicit none

#include "decl.h"
#include "Weff_tree.h"

        double precision sqrtS,costh
        double precision result
        double precision result_tmp(NCOMP)

        result=0.D0

        if((sqrtS .ge. (aMNeu(1)+aMNeu(1))) .AND.
     &  ((aMNeu(1)+aMNeu(1)) .le. maxenergy)) then
           
        call dlwefftree("n1n1",result_tmp,sqrtS,costh);
(...)

dlwefftree needs the following routine in C, which dlopen/create librelictreedyn.so:

Code:

void dlwefftree_(char* name[], double result[], double* sqrtS, double* costh)
{
	char Weffname[100];
	void* handle=dlopen("src/relic/sharedlibtree/librelictreedyn.so", RTLD_LAZY);		
	
	sprintf(Weffname,"weff_tree_%s_",name);
	
	void (*Weff)(double result[], double* sqrtS, double* costh) = dlsym(handle,Weffname);

	char *error;
	if( (error=dlerror()) != NULL ) 
	{
		if(handle) dlclose(handle);
          	/* printf("%s\n",error); */
  		char complete_name[300];
	
		chdir("src/relic/sharedlibtree");
		
		sprintf(complete_name,"rm -f *.o");
		system(complete_name); 	
			
		sprintf(complete_name,"%s %s -c ../Weff_tree/Weff_tree_%s.F -I../Weff_tree -I..",FC,FFLAGS,name);
		
		printf("%s\n",complete_name);
		
		system(complete_name);
		
		sprintf(complete_name,"ar x librelictreedyn.a");
		system(complete_name);    	
		
		sprintf(complete_name,"ld -shared -o librelictreedyn.so *.o");
		system(complete_name);    	

		sprintf(complete_name,"ar r librelictreedyn.a *.o");
		system(complete_name);    	
		
		sprintf(complete_name,"rm -f *.o");
		system(complete_name);   	
		
		chdir("../../..");
		
		handle=dlopen("./src/relic/sharedlibtree/librelictreedyn.so", RTLD_LAZY);
		
		/* if( !handle ) printf("%s\n",dlerror()); */
		
		void (*Weff)(double result[], double* sqrtS, double* costh) = dlsym(handle,Weffname);
		
          	/* if( (error=dlerror()) != NULL ) printf("%s\n",error); */
	}

	(*Weff)(result,sqrtS,costh);

	dlclose(handle);	
		
	return;
}

The routine which should be in (*Weff) should be the following (in fortran):

Code:

        subroutine weff_tree_n1n1(result,sqrtS,costh)
        implicit none

#include "decl.h"
#include "Weff_tree.h"

        double precision sqrtS,costh
        double precision result(NCOMP)
        double precision result_tmp(NCOMP)
	
       call Weff_tree_n1n1ZZ(result_tmp,sqrtS,costh)

	end

Weff_tree_n1n1ZZ is written as:

Code:

        subroutine Weff_tree_n1n1ZZ(result,sqrtS,costh)
        implicit none
        
#include "decl.h"

        double precision result(NCOMP),result_tmp(NCOMP)
        double precision sqrtS
        double precision costh
         
	call squaredtree("n1n1ZZ",result_tmp, helicities, flags)
	                   
        result(1)=result_tmp(1)
       
        end

squaredtree is a C function dlopening or creating the library libsquaredtreedyn.so:

Code:

void squaredtree_(char* name[], double result[], double* sqrtS, double* costh)
{
	char Weffname[100];
	int i=0;
	void* handle=dlopen("src/relic/sharedlibtree/libsquaredtreedyn.so", RTLD_LAZY);		
	
	sprintf(Weffname,"tree_%ssquaredme_",name);
	
	while (Weffname[i])
  	{
    		Weffname[i]=tolower(Weffname[i]);
		i++;
	}
			
	void (*Weff)(double result[], double* sqrtS, double* costh) = dlsym(handle,Weffname);

	char *error;
	if( (error=dlerror()) != NULL ) 
	{
 		if(handle) dlclose(handle);
 		char complete_name[300];
	
		chdir("src/relic/sharedlibtree");
		
		sprintf(complete_name,"rm -f *.o");
		system(complete_name);    	
			
		sprintf(complete_name,"%s %s -c ../squared_tree/squaredmetree_%s/squaredtree_%s.F -I../squared_tree/squaredmetree_%s -I..",FC,FFLAGS,name,name,name);
		printf("%s\n",complete_name);	
		system(complete_name);
		
		sprintf(complete_name,"ar x libsquaredtreedyn.a");
		system(complete_name);    	
		
		sprintf(complete_name,"ld -shared -o libsquaredtreedyn.so *.o");
		system(complete_name);    	

		sprintf(complete_name,"ar r libsquaredtreedyn.a *.o");
		system(complete_name);    	
		
		sprintf(complete_name,"rm -f *.o");
		system(complete_name);   	
	
		handle=dlopen("./libsquaredtreedyn.so", RTLD_LAZY);
		
		if( !handle ) printf("%s\n",dlerror());
				
		void (*Weff)(double result[], double* sqrtS, double* costh) = dlsym(handle,Weffname);
		
		chdir("../../..");
		
          	if( (error=dlerror()) != NULL ) printf("%s\n",error);
	}

	(*Weff)(result,sqrtS,costh);
			
	dlclose(handle);
	return;
}

At the end, the routine in (*Weff) is a big fortran code which was working pretty well when static...

Hope this can help...

Note that I simplified a bit the code. I hope I have not broken anything.

Thanks,
CCox

Thanks for all these good comments.

For the compilation, I am using either gfortran or ifort with -fPIC, so it should work.

Concerning the error checkings, I will test that. In fact the code needs to compile hundreds of different fortran procedures similar to the one I showed. All of them either go in librelictreedyn.so or in libsquaredtreedyn.so . I agree that the first step is dangerous... But once both librairies are created, I was thinking it should work.

I have unfortunately no time to test you advices now, but I will do that for tomorrow, and I will keep you informed.

Thanks again,
Best,
CCox