lyd_diff.c

#include <stdlib.h>
#include <stdio.h>
#include <stdint.h>
#include <string.h>
#include <err.h>

#include <libyang/libyang.h>

static struct ly_ctx *ly_ctx;
static struct lyd_node *running, *candidate;

static void print(struct lyd_node *config)
{
	lyd_print_fd(2, config, LYD_JSON,
		     LYP_FORMAT | LYP_WD_ALL | LYP_KEEPEMPTYCONT
			     | LYP_WITHSIBLINGS);
}

static void validate(struct lyd_node **config)
{
	if (lyd_validate(config, LYD_OPT_STRICT | LYD_OPT_CONFIG, ly_ctx) != 0)
		errx(1, "lyd_validate(): %s", ly_errmsg(ly_ctx));
}

static void diff(struct lyd_node *config1, struct lyd_node *config2)
{
	struct lyd_difflist *diff;
	int i = 0;

	// diff = lyd_diff(config1, config2, 0);
	diff = lyd_diff(config1, config2, LYD_DIFFOPT_WITHDEFAULTS);
	if (diff == NULL)
		errx(1, "lyd_diff(): %s", ly_errmsg(ly_ctx));

	while (diff->type[i] != LYD_DIFF_END) {
		LYD_DIFFTYPE type;
		struct lyd_node *first;
		struct lyd_node *second;
		char *xpath;

		type = diff->type[i];
		first = diff->first[i];
		second = diff->second[i];
		i++;

		switch (type) {
		case LYD_DIFF_CREATED:
			printf("LYD_DIFF_CREATED:\n");
			xpath = lyd_path(second);
			break;
		case LYD_DIFF_DELETED:
			printf("LYD_DIFF_DELETED:\n");
			xpath = lyd_path(first);
			break;
		case LYD_DIFF_CHANGED:
			printf("LYD_DIFF_CHANGED:\n");
			xpath = lyd_path(second);
			break;
		case LYD_DIFF_MOVEDAFTER1:
			printf("LYD_DIFF_MOVEDAFTER1:\n");
			break;
		case LYD_DIFF_MOVEDAFTER2:
			printf("LYD_DIFF_MOVEDAFTER2:\n");
			break;
		default:
			printf("unknown diff type:\n");
			break;
		}

		printf(" xpath: %s\n", xpath);
		free(xpath);
	}

	lyd_free_diff(diff);
}

int main(int argc, char **argv)
{
	const struct lys_module *module;
	struct lyd_node *node;
	const char *xpath = "/frr-ripd:ripd/instance/allow-ecmp";

	/* initialization */
	ly_ctx = ly_ctx_new(NULL, 0);
	if (!ly_ctx)
		errx(1, "ly_ctx_new(): %s", ly_errmsg(ly_ctx));

	ly_ctx_set_searchdir(ly_ctx, "/usr/local/share/yang/");
	module = lys_parse_path(ly_ctx, "/usr/local/share/yang/frr-ripd.yang",
				LYS_IN_YANG);
	if (module == NULL)
		errx(1, "lys_parse_path(): %s", ly_errmsg(ly_ctx));

	validate(&running);
	validate(&candidate);

	/* change candidate config - add presence container */
	ly_errno = 0;
	node = lyd_new_path(candidate, ly_ctx, xpath, (void *)"true", 0,
			    LYD_PATH_OPT_UPDATE);
	if (node == NULL && ly_errno)
		errx(1, "lyd_new_path(): %s", ly_errmsg(ly_ctx));

	validate(&candidate);

	/* print configs and the difference between them */
	printf("=================\n");
	printf("RUNNING CONFIG:\n");
	printf("=================\n");
	print(running);
	printf("=================\n");
	printf("CANDIDATE CONFIG:\n");
	printf("=================\n");
	print(candidate);
	printf("=================\n");
	printf("DIFF:\n");
	printf("=================\n");
	diff(running, candidate);

	/* cleanup */
	lyd_free_withsiblings(candidate);
	lyd_free_withsiblings(running);
	ly_ctx_remove_module(module, NULL);
	ly_ctx_destroy(ly_ctx, NULL);

	return 0;
}