Could not load symbol with ccall

General Usage
,
1

I’m trying to call this function

#include <stdlib.h>
#include <stdio.h>
#include <time.h>
#include <math.h>
#include <string.h>

#define datatype double /* type of the elements in y */

static void simplexproj_Condat(datatype* y, datatype* x, 
const unsigned int length, const double a) {
	datatype*	aux = (x==y ? (datatype*)malloc(length*sizeof(datatype)) : x);
	datatype*  aux0=aux;
	int		auxlength=1; 
	int		auxlengthold=-1;	
	double	tau=(*aux=*y)-a;
	int 	i=1;
	for (; i<length; i++) 
		if (y[i]>tau) {
			if ((tau+=((aux[auxlength]=y[i])-tau)/(auxlength-auxlengthold))
			<=y[i]-a) {
				tau=y[i]-a;
				auxlengthold=auxlength-1;
			}
			auxlength++;
		} 
	if (auxlengthold>=0) {
		auxlength-=++auxlengthold;
		aux+=auxlengthold;
		while (--auxlengthold>=0) 
			if (aux0[auxlengthold]>tau) 
				tau+=((*(--aux)=aux0[auxlengthold])-tau)/(++auxlength);
	}
	do {
		auxlengthold=auxlength-1;
		for (i=auxlength=0; i<=auxlengthold; i++)
			if (aux[i]>tau) 
				aux[auxlength++]=aux[i];	
			else 
				tau+=(tau-aux[i])/(auxlengthold-i+auxlength);
	} while (auxlength<=auxlengthold);
	for (i=0; i<length; i++)
		x[i]=(y[i]>tau ? y[i]-tau : 0.0); 
	if (x==y) free(aux0);
}

with the following julia code

using Libdl

const ccode_lib = joinpath(@__DIR__,"libsimproj.so")
Libdl.dlopen(ccode_lib)
x = rand(10)
y = rand(10)

ccall((:simplexproj_Condat,ccode_lib),
       Cvoid,
       (Ptr{Cdouble},Ptr{Cdouble},Cuint,Cdouble),
       y,x,length(x),1.0)

but I have this error

ERROR: could not load symbol "simplexproj_Condat":
/path/to/libsimproj.so: undefined symbol: simplexproj_Condat

I don’t understand why… the ouput of nm libsimproj.so | grep simplex is
0000000000001139 t simplexproj_Condat

I compiled the library with the command gcc -shared -fPIC -o libsimproj.so condat_simplexproj.c

version info is

Julia Version 1.8.2
Commit 36034abf260 (2022-09-29 15:21 UTC)
Platform Info:
  OS: Linux (x86_64-linux-gnu)
  CPU: 12 × Intel(R) Core(TM) i7-9750H CPU @ 2.60GHz
  WORD_SIZE: 64
  LIBM: libopenlibm
  LLVM: libLLVM-13.0.1 (ORCJIT, skylake)
  Threads: 1 on 12 virtual cores
1 Like
2

Lower t means that is local, I suspect it has to do with the fact the function is static, if I remove that annotation the symbol is marked as T in the output of nm and I can call the function regularly.

2 Likes
3

Indeed, thanks !