C-API YANG: don't work extension

[khromenokroman]

@olofhagsand Good afternoon I need your help :)

module my_module {
  namespace "http://example.com/ns/my-module";
  prefix "mm";
  
  extension my_ext {
    description "This is my custom extension for enumeration type";
  }
}

I have a main module that I want to add the module that I described above to

module main_module {
  namespace "http://example.com/ns/main-module";
  prefix "main";
  
  import my_module {
    prefix "mm";
  }

  mm:my_ext; 
}

At the same time, I want to add enum to it in runtime

typedef my-enum-type {
    type enumeration {
        enum "value0";
        enum "value1";
        enum "value2";
    }
}

below is the code how I do it in runtime https://clixon-docs.readthedocs.io/en/latest/yang.html#extensions

int extension([[maybe_unused]] clicon_handle handle, yang_stmt *yext, [[maybe_unused]] yang_stmt *ys) {
    char *extname;
    char *modname;
    yang_stmt *ymod;

    ymod = ys_module(yext);
    modname = yang_argument_get(ymod);
    extname = yang_argument_get(yext);
    if (strcmp(modname, "my_module") != 0 || strcmp(extname, "my_ext") != 0) {
        return 0;
    }
    clixon_log(handle, LOG_WARNING, "[%s]: Find my_module and my_ext", NAME_PLUGIN);
    // Создаем новый YANG узел 'typedef'.
    yang_stmt *yt = nullptr;
    if (yt = ys_new(rfc_6020::Y_TYPEDEF); yt == nullptr) {
        return -1;
    }
    clixon_log(handle, LOG_WARNING, "[%s]: Create new node", NAME_PLUGIN);
    // Устанавливаем название для нового типа 'typedef'.
    if (yang_argument_set(yt, (char *)"my-enum-type")) {
        return -1;
    }
    clixon_log(handle, LOG_WARNING, "[%s]: set my-enum-type", NAME_PLUGIN);
    // Создаем новый YANG узел 'type' для 'typedef'.
    yang_stmt *ye;
    if (ye = ys_new(rfc_6020::Y_TYPE); ye == nullptr) {
        return -1;
    }
    clixon_log(handle, LOG_WARNING, "[%s]: new type", NAME_PLUGIN);
    // Устанавливаем значение для 'type' как "enumeration"
    if (yang_argument_set(ye, (char *)"enumeration")) {
        return -1;
    }
    clixon_log(handle, LOG_WARNING, "[%s]: create enumeration", NAME_PLUGIN);
    // Добавляем 'type' в 'typedef' узел.
    if (yn_insert(yt, ye) < 0) {
        return -1;
    }
    clixon_log(handle, LOG_WARNING, "[%s]: add type in typedef", NAME_PLUGIN);
    //  Создаем значения enum и добавляем их в 'type'.
    for (auto i = 0; i < 3; i++) {
        yang_stmt *yn = nullptr;
        if (yn = ys_new(rfc_6020::Y_ENUM); yn == nullptr) {
            return -1;
        }

        // Устанавливаем название для нового 'enum'. Будет - value1, value2, value3.
        char enum_val[20];
        sprintf(enum_val, "value%d", i);
        if (yang_argument_set(yn, enum_val)) {
            return -1;
        }

        // Вставляем 'enum' в 'type'.
        if (yn_insert(ye, yn) < 0) {
            return -1;
        }
    }
    clixon_log(handle, LOG_WARNING, "[%s]: add value in enum end", NAME_PLUGIN);

    // Добавляем 'typedef' в модуль.
    if (yn_insert(ymod, yt) < 0) {
        return -1;
    }

    clixon_log(handle, LOG_WARNING, "[%s]: add typedef in module end", NAME_PLUGIN);

    return 0;
}

everything works out fine, but as soon as I add a place where I want to use it, I get a coredamp

$ systemctl restart clixon-backend

Stack trace of thread 29464:
#0  0x00007c3d07ee1e2c __pthread_kill_implementation (libc.so.6 + 0x8ae2c)
#1  0x00007c3d07e92fb2 __GI_raise (libc.so.6 + 0x3bfb2)
#2  0x00007c3d07e7d472 __GI_abort (libc.so.6 + 0x26472)
#3  0x00007c3d07ed6430 __libc_message (libc.so.6 + 0x7f430)
#4  0x00007c3d07eeb7aa malloc_printerr (libc.so.6 + 0x947aa)
#5  0x00007c3d07eed534 _int_free (libc.so.6 + 0x96534)
#6  0x00007c3d07eefe8f __GI___libc_free (libc.so.6 + 0x98e8f)
#7  0x00007c3d080c381b ys_free1 (libclixon.so.7 + 0x4d81b)
#8  0x00007c3d080c3a93 ys_free (libclixon.so.7 + 0x4da93)
#9  0x00007c3d080c3ae6 n/a (libclixon.so.7 + 0x4dae6)
#10 0x00007c3d080c3a86 ys_free (libclixon.so.7 + 0x4da86)
#11 0x00007c3d080c3ae6 n/a (libclixon.so.7 + 0x4dae6)
#12 0x00007c3d080c3a86 ys_free (libclixon.so.7 + 0x4da86)
#13 0x00007c3d080c3ae6 n/a (libclixon.so.7 + 0x4dae6)
#14 0x00007c3d080c3a86 ys_free (libclixon.so.7 + 0x4da86)
#15 0x00007c3d080c3ae6 n/a (libclixon.so.7 + 0x4dae6)
#16 0x00007c3d080c3a86 ys_free (libclixon.so.7 + 0x4da86)
#17 0x00005802cfb8c0bc n/a (clixon_backend + 0x90bc)
#18 0x00005802cfb8a6ed n/a (clixon_backend + 0x76ed)
#19 0x00007c3d07e7e24a __libc_start_call_main (libc.so.6 + 0x2724a)
#20 0x00007c3d07e7e305 __libc_start_main_impl (libc.so.6 + 0x27305)
#21 0x00005802cfb8bc71 n/a (clixon_backend + 0x8c71)
ELF object binary architecture: AMD x86-64

grouping hw-interfaces-top{
	description "Настройка физических интерфейсов";
	
	list hw-interface {
		key "pci-address";
		description "Настройка физических интерфейсов";
		leaf pci-address {
			type my-enum-type;
			description "PCI адрес интерфейса";
		}
		leaf description{
			type string;
			description "Описание интерфейса";
		}
		leaf qcount {
			default 1;
			type uint32 {
				range 1..16;
			}
			description "Количество входящих очередей";
		}
		leaf port-index{
			description "Номер порта в DPDK";
			type pci-ifname;
			mandatory true;
		}
	}
}

here in this place type my-enum-type;

What am I doing wrong? I took the information here https://clixon-docs.readthedocs.io/en/latest/yang.html#extensions And here it is

clixon/lib/src/clixon_yang.c

Line 1037 in be5a7c4

ys_new(enum rfc_6020 keyw)

[olofhagsand]

It seems to be a memory error using the YANG C-API, judging by the that the SEGV is in ys_free.
I dont think it is the YANG extension mechanism per se.
One way could be to use valgrind or some other mechanism to pin-point where the yang structure was created/freed/invalidly accessed.
Your stack trace is incomplete and only shows the last (invalid access) point.
Adding YANG using the C-API is pretty advanced and it is not properly documented.
I can guide to source code, or load YANG from file, although that API assumes a complete module.

[khromenokroman]

https://datatracker.ietf.org/doc/html/rfc6020#section-7.17
It seems to me that the problem may be that you cannot create an enum in extensions