Doubly linked list

bidirection_linked_list.c

#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sqlite3.h>
#include <stdarg.h>

#define ESCAPE 27

#define CREATE_TABLE(table_name, ...) \
    "CREATE TABLE " #table_name  " (" \
        #__VA_ARGS__                  \
    ");"

#define INSERT_INTO(tmp, table_name, columns, fmt, ...) \
  char *buffer = tmp; \
  asprintf(&(tmp), "INSERT INTO %s (%s) VALUES (" fmt ")", table_name, columns, ## __VA_ARGS__); \
  free(buffer);

struct Node
{
    int index;
    struct Node *next;
    struct Node *previous;
} *current = NULL;

typedef struct Node node;

node *
create_node()
{
  // create a new node
    node *nd = (node *)malloc(sizeof(node));

    // if we dont have current node
    if ( current == NULL )
    {
        // we don't have previous
        nd->previous = NULL;
        // Set index to 0
        nd->index = 0;
        // it's the first
        current = nd;
    } else {
        // Current's next node is the one we created
        current->next = nd;
        // Our new node will have as previous the current one
        nd->previous = current;
        // Create is always appending at the end
        nd->index = ++(nd->previous->index);
        // Set our current node to nd
        current = nd;
    }

    return nd;
}

node *
create_nodes(int nodes_count)
{
    // Counter for our loop
    int counter;
    // Return the head of our struct
    node *head;
    // Create our nodes
    for(counter = 0; counter < nodes_count; counter++)
    {
        if ( counter == 0 )
        {
            // if it's the first store it as head
            head = create_node();
        } else {
            create_node();
        }
    }
    return head;
}

int main(int argc, char const *argv[]) {
    sqlite3 *db;

    int nodesCount = 0, c = 0;
    char *zErrMsg = 0;
    int rc;

    scanf(" %d", &nodesCount);

    node *head = create_nodes(nodesCount);

    rc = sqlite3_open("nodes", &db);

    sqlite3_exec(db, CREATE_TABLE("nodes", idx integer(4), test varchar(250)), NULL, 0, &zErrMsg);

    if ( rc ) {
        fprintf(stderr, "Can't open database: %s\n", sqlite3_errmsg(db));
        sqlite3_close(db);
        return(1);
    }

    while( c != ESCAPE ) {

        char *tmp, *tmp2, *tmp3;

        if( c == 'n' )
            head = head->next;

        if( c == 'p' )
            head = head->previous;


        tmp = (char *)malloc(sizeof(char)*4096);
        tmp2 = (char *)malloc(sizeof(char)*4096);
        tmp3 = (char *)malloc(sizeof(char)*4096);

        if ( head->previous != NULL ) {
          asprintf(&tmp, "Previous: %d", head->previous->index);
        }

        asprintf(&tmp2, "Current: %d", head->index);

        if ( head->next != NULL ) {
            asprintf(&tmp3, "Next: %d", head->next->index);
        }

        printf("%s - %s - %s\n", tmp, tmp2, tmp3);
        free(tmp);
        free(tmp2);
        free(tmp3);

        char *create_statement;
        create_statement = (char *)malloc(sizeof(char)*4096);
        INSERT_INTO(create_statement, "nodes", "idx, test", "%d, %d", head->index, c);
        sqlite3_exec(db, create_statement, NULL, 0, &zErrMsg);
        free(create_statement);

        if ( rc ) {
            fprintf(stderr, "Can't open database: %s\n", sqlite3_errmsg(db));
            sqlite3_close(db);
            return(1);
        }
        scanf(" %c", &c);
    }

    sqlite3_close(db);

    free(head);

    return 0;
}