Segmentation fault on startup while trying to initialize monitors

[Sigmanificient]

Describe the bug

Using Xephyr -br -ac -noreset -screen 800x600 :1, and DISPLAY=:1 bin/ragnar I get a segmentation fault
The config file is the example from the repository.

While debugging, I found out that after this line:

uint32_t registered_monitors = updatemons(s);

registered_monitors is equal to 0.

Valgrind dump

[nix-shell:~/ragnar]$ DISPLAY=:1 valgrind bin/ragnar
==862634== Memcheck, a memory error detector
==862634== Copyright (C) 2002-2024, and GNU GPL'd, by Julian Seward et al.
==862634== Using Valgrind-3.23.0 and LibVEX; rerun with -h for copyright info
==862634== Command: bin/ragnar
==862634== 
sh: line 1: ragnarstart: command not found
==862634== Conditional jump or move depends on uninitialised value(s)
==862634==    at 0x40834A: cursormon (ragnar.c:3149)
==862634==    by 0x40BBFD: setupatoms (ragnar.c:1803)
==862634==    by 0x40D6AE: setup (ragnar.c:198)
==862634==    by 0x404B10: main (ragnar.c:3602)
==862634== 
==862634== Conditional jump or move depends on uninitialised value(s)
==862634==    at 0x40BC11: setupatoms (ragnar.c:1805)
==862634==    by 0x40D6AE: setup (ragnar.c:198)
==862634==    by 0x404B10: main (ragnar.c:3602)
==862634== 
==862634== Use of uninitialised value of size 8
==862634==    at 0x406E21: uploaddesktopnames (ragnar.c:1695)
==862634==    by 0x40BC9E: setupatoms (ragnar.c:1816)
==862634==    by 0x40D6AE: setup (ragnar.c:198)
==862634==    by 0x404B10: main (ragnar.c:3602)
==862634== 
==862634== Invalid read of size 4
==862634==    at 0x406E21: uploaddesktopnames (ragnar.c:1695)
==862634==    by 0x40BC9E: setupatoms (ragnar.c:1816)
==862634==    by 0x40D6AE: setup (ragnar.c:198)
==862634==    by 0x404B10: main (ragnar.c:3602)
==862634==  Address 0x28 is not stack'd, malloc'd or (recently) free'd
==862634== 
==862634== 
==862634== Process terminating with default action of signal 11 (SIGSEGV): dumping core
==862634==  Access not within mapped region at address 0x28
==862634==    at 0x406E21: uploaddesktopnames (ragnar.c:1695)
==862634==    by 0x40BC9E: setupatoms (ragnar.c:1816)
==862634==    by 0x40D6AE: setup (ragnar.c:198)
==862634==    by 0x404B10: main (ragnar.c:3602)
==862634== 
==862634== HEAP SUMMARY:
==862634==     in use at exit: 103,623 bytes in 1,076 blocks
==862634==   total heap usage: 1,934 allocs, 858 frees, 1,336,850 bytes allocated
==862634== 
==862634== LEAK SUMMARY:
==862634==    definitely lost: 640 bytes in 116 blocks
==862634==    indirectly lost: 0 bytes in 0 blocks
==862634==      possibly lost: 448 bytes in 3 blocks
==862634==    still reachable: 102,535 bytes in 957 blocks
==862634==         suppressed: 0 bytes in 0 blocks
==862634== Rerun with --leak-check=full to see details of leaked memory
==862634== 
==862634== Use --track-origins=yes to see where uninitialised values come from
==862634== For lists of detected and suppressed errors, rerun with: -s
==862634== ERROR SUMMARY: 4 errors from 4 contexts (suppressed: 0 from 0)
Segmentation fault (core dumped)

The following code seems to detect 1 monitor:

  xcb_generic_error_t *err;
  xcb_randr_get_monitors_reply_t *monitors =
      xcb_randr_get_monitors_reply(
          s->con, xcb_randr_get_monitors(s->con, s->screen->root, true), &err);
    if (err != NULL) {
        free(err);
        return false;
    }

  int32_t num_outputs = xcb_randr_get_monitors_monitors_length(monitors);

However, I couldn't fully solve the issue and get ragnar to work

[cococry]

you cannot use Xephyr with ragnar as ragnar uses monitor detection as a primary feature to run. As far as i know, xeyphyr does not have a way to work with virtual monitors well.