list.c

#include <stdio.h>
#include <stdlib.h>

#include "list.h"
#include "errs.h"

void free_list(node_t *head)
{
    node_t *tmp = head;
    for (; head; head = tmp)
    {
        tmp = head->next;
        free(head);
        head = NULL;
    }
}

int print_list(node_t * head)
{
    int rc = (head == NULL) * ERR_NULL_HEAD;
    if (!rc)
    {
        for (node_t *tmp = head; tmp; tmp = tmp->next)
            printf("%d ", tmp->data);
        printf("\n");
    }
    return rc;
}

node_t *create_node(int data)
{
    node_t *temp = malloc(sizeof(node_t));
    if (temp)
    {
        temp->data = data;
        temp->next = NULL;
    }

    return temp;
}

int pop_front(node_t **head)
{
    int pop_data = 0;
    if (head != NULL && *head != NULL)
    {
        node_t *prev = *head;
        pop_data = (*head)->data;
        *head = (*head)->next;
        free(prev);
    }

    return pop_data;
}

int pop_back(node_t **head)
{
    int pop_data = 0;
    if (head != NULL && *head != NULL)
    {
        node_t *tmp = *head;
        node_t *prev_tmp = tmp;
        for (; tmp->next; prev_tmp = tmp, tmp = tmp->next);
        pop_data = tmp->data;
        prev_tmp->next = NULL;
        free(tmp);
        if (*head == tmp)
            *head = NULL;
    }

    return pop_data;
}

int push_back_value(node_t **head, int data)
{
    int rc = (head == NULL) * ERR_NULL_HEAD;
    if (!rc)
    {
        node_t *new_node = create_node(data);
        if (*head == NULL)
            *head = new_node;
        else
        {
            node_t *tmp = *head;
            for (; tmp->next; tmp = tmp->next);
            tmp->next = new_node;
        }
    }

    return rc;
}