Potential memory leak from XInitThreads

Question

I am using a library called minilibx which is a wrapper to X11.

I changed the library by adding XInitThreads() to be initialisation function to use threading with the library (it will not work without this).

The program I compile is called fdf. When I check my program for leaks (valgrind --log-file=v.log --leak-check=full ./fdf test2.fdf), Valgrind complains there is some allocation from XInitThreads, that has not been freed. Is there anything I can do to free this actively? Is there any function that I have to call at the end of the program to release allocation from XInitThreads?

Kind regards Bastian

My system (Ubuntu):

Linux 6.11.0-1-t2-jammy #1 SMP PREEMPT_DYNAMIC Tue Sep 17 06:47:39 UTC 2024 x86_64 x86_64 x86_64 GNU/Linux

v.log:

==1546656== Memcheck, a memory error detector
==1546656== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et al.
==1546656== Using Valgrind-3.18.1 and LibVEX; rerun with -h for copyright info
==1546656== Command: ./fdf test2.fdf
==1546656== Parent PID: 1464122
==1546656== 
==1546656== 
==1546656== HEAP SUMMARY:
==1546656==     in use at exit: 120 bytes in 3 blocks
==1546656==   total heap usage: 53,837 allocs, 53,834 frees, 1,199,360 bytes allocated
==1546656== 
==1546656== 40 bytes in 1 blocks are still reachable in loss record 1 of 3
==1546656==    at 0x4848899: malloc (in /usr/libexec/valgrind/vgpreload_memcheck-amd64-linux.so)
==1546656==    by 0x48B09E9: XInitThreads (in /usr/lib/x86_64-linux-gnu/libX11.so.6.4.0)
==1546656==    by 0x11422A: mlx_init (in /home/baschnit/repos/42fdf_new/fdf)
==1546656==    by 0x10AAB1: main (main.c:59)
==1546656== 
==1546656== 40 bytes in 1 blocks are still reachable in loss record 2 of 3
==1546656==    at 0x4848899: malloc (in /usr/libexec/valgrind/vgpreload_memcheck-amd64-linux.so)
==1546656==    by 0x48B0A06: XInitThreads (in /usr/lib/x86_64-linux-gnu/libX11.so.6.4.0)
==1546656==    by 0x11422A: mlx_init (in /home/baschnit/repos/42fdf_new/fdf)
==1546656==    by 0x10AAB1: main (main.c:59)
==1546656== 
==1546656== 40 bytes in 1 blocks are still reachable in loss record 3 of 3
==1546656==    at 0x4848899: malloc (in /usr/libexec/valgrind/vgpreload_memcheck-amd64-linux.so)
==1546656==    by 0x48B0A23: XInitThreads (in /usr/lib/x86_64-linux-gnu/libX11.so.6.4.0)
==1546656==    by 0x11422A: mlx_init (in /home/baschnit/repos/42fdf_new/fdf)
==1546656==    by 0x10AAB1: main (main.c:59)
==1546656== 
==1546656== LEAK SUMMARY:
==1546656==    definitely lost: 0 bytes in 0 blocks
==1546656==    indirectly lost: 0 bytes in 0 blocks
==1546656==      possibly lost: 0 bytes in 0 blocks
==1546656==    still reachable: 120 bytes in 3 blocks
==1546656==         suppressed: 0 bytes in 0 blocks
==1546656== 
==1546656== For lists of detected and suppressed errors, rerun with: -s
==1546656== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 1 from 1)

---

minimal reproducible example:

1. download minilibx from git to a folder libx
2. create main file in parent folder and compile with cc main.c libx/libmlx.a -Ilibx -lX11 -lXext
3. valgrind --leak-check=full --show-leak-kinds=all ./a.out

main.c:

#include <stdlib.h>
#include <X11/Xlib.h>
#include "mlx.h"

int main(void)
{
    void *mlx;

    XInitThreads();
    mlx = mlx_init();
    mlx_destroy_display(mlx);
    free(mlx);
}