Simple TAILQ based kv

kv.c

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

#include <sys/queue.h>

typedef struct _kv {
    char *k;
    char *v;
    TAILQ_ENTRY(_kv) _tailq;
} kv;

typedef TAILQ_HEAD(_kvlist, _kv) kvlist;

static bool kv_set(kvlist *keys, char *k, char *v) {
    kv *item;
    // Check for existing kv
    TAILQ_FOREACH(item, keys, _tailq) {
        if (strcmp(item->k,k) == 0) {
            char *old_v = item->v;
            if ((item->v = strdup(v)) == NULL) {
                return false;
            }
            free(old_v);
            return true;
        }
    }
    // Create new kv
    if ((item = calloc(1,sizeof(kv))) == NULL ||
        (item->k = strdup(k)) == NULL ||
        (item->v = strdup(v)) == NULL) {
        goto error;
    }
    TAILQ_INSERT_TAIL(keys, item, _tailq);
    return true;

error:
        free(item->v);
        free(item->k);
        free(item);
        return false;
}

static char *kv_get(kvlist *keys, char *k) {
    kv *item;
    TAILQ_FOREACH(item, keys, _tailq) {
        if (strcmp(item->k,k) == 0) {
            return item->v;
        }
    }
    return NULL;
}

static void kv_free(kvlist *keys) {
    kv *n1, *n2;
    n1 = TAILQ_FIRST(keys);
    while (n1 != NULL) {
        n2 = TAILQ_NEXT(n1, _tailq);
        free(n1->k);
        free(n1->v);
        free(n1);
        n1 = n2;
    }
}

int main(int argc, char **argv) {

    kvlist keys = TAILQ_HEAD_INITIALIZER(keys);

    kv_set(&keys, "aa", "123");
    kv_set(&keys, "bb", "456");
    kv_set(&keys, "cc", "789");
    kv_set(&keys, "aa", "999");

    printf(">>> %s = %s\n", "aa", kv_get(&keys,"aa"));
    printf(">>> %s = %s\n", "bb", kv_get(&keys,"bb"));
    printf(">>> %s = %s\n", "zz", kv_get(&keys,"zz"));

    kv_free(&keys);

    return 0;

}