t_nodes.c

#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <strings.h>
#include <string.h>

#define BASE		"/myroot/"

struct node {
	char data[128];
	struct node *parent;
};

struct node narray[128];

#define SETP(n, p)	(narray[n].parent = &narray[p])
#define SETN(n, s)	(strcpy(narray[n].data, s))

char *
fpath1(struct node *n)
{
	struct node *n1;
	char *buf, *tmp;

	buf = tmp = NULL;

	for (n1 = n; n1->parent != NULL; n1 = n1->parent) {
		if (buf == NULL)
			asprintf(&tmp, "%s", n1->data);
		else
			asprintf(&tmp, "%s/%s", n1->data, buf);

		if (tmp != NULL) {
			if (buf)
				free(buf);
			buf = tmp;
		} else {
			goto fail;
		}
	}
	return buf;

fail:
	if (buf)
		free(buf);
	if (tmp)
		free(tmp);

	return NULL;
}

char *
fpath(struct node *n)
{
	char **cnps = malloc(32 * sizeof(*cnps));
	char **tmp = cnps;

	struct node *n1;
	char *fullpath;
	size_t tlen, len;
	int ret;

	tlen = len = 0;

	for (n1 = n; n1->parent != NULL; cnps++) {
		*cnps = n1->data;
		tlen += strlen(*cnps) + 1;
		n1 = n1->parent;
	}
	fullpath = malloc(tlen + 1);

 	for (; cnps != tmp; cnps--) {
		if (*cnps) {
			ret = sprintf(fullpath + len, "%s/", *cnps);
			len += ret;
		}
	}
	fprintf(stdout, "%s\n", fullpath);

	return fullpath;
}

int
main(int argc, char *argv[])
{
	struct node *root;
	char *line[16] = { "this", "is", "the", "path", "to", "the",
			   "place", "where", "I", "belong", "to" };
	int i;

	root = &narray[0];

	root->parent = NULL;

	for (i = 0; i < 11; i++) {
		SETN(i+1, line[i]);
		SETP(i+1, i);
	}

	for (i = 16; i >= 0; i--)
		fprintf(stdout, "node%d=%s\n", i, fpath1(&narray[i]));

	return 0;
}