C - linked list

我有三个文件-String（用于获取字符并将它们组装成字符串（作为指针，但不是数组））、LinkedList文件和main（测试文件）。字符串部分运行良好，经过测试。但我被困在了LinkedList上。

---->我知道问题出在addString（）方法中，这是逻辑中的一个问题，因为我在它的末尾放了一个打印检查，但我从来没有做到。但我似乎没有发现任何逻辑问题。。。以下是LinkedList的代码：

#include <stdio.h>
#include <stdlib.h>
#include "LinkedList.h"
struct node
{
    struct node *next;
    struct node *previous;
    struct string *str;
};
static struct node *head;
static struct node *tail;
int count = 0;
void initList()
{
    head = NULL;
    tail = NULL;
}
void addString(struct string *str_)
{
    struct node *current = malloc(sizeof(struct node));
    if (head = NULL)
    {
        head = current;
        tail = current;
        current->next = tail;
        current->previous = head;
        current->str = str_;
    }
    else
    {
        current->previous = tail;
        tail->next = current;
        tail = current;
        current->str = str_;
    }
    puts("nA string has been added!");
}
void deleteString(int index)
{
    struct node *currentNode;
    currentNode = head;
    int i = 0;
    if(index == 0)
    {
        head->str = NULL;
        head->next = head;
        // delete first node and relocate "head" to next node
    }
    while(currentNode != NULL)
    {
        if(i == index)
        {
            currentNode->str = NULL;
            currentNode->previous->next = currentNode->next;
            currentNode->next->previous = currentNode->previous;
        }
        else
        {
            currentNode = currentNode->next;
            i++;
        }
        // 1.loop through and starting from 0 as first (head) element
        // 2.when index is reached - delete it and replace the connections
    }
}
void printAll()
{
    struct node *currentNode;
    currentNode = head; 
    while(currentNode !=NULL)
    {
        printf("%s", currentNode->str);
        currentNode = currentNode->next;
    }// need to iterate through list
}

这是测试文件：

#include <stdio.h>
#include <stdlib.h>
#include "String.h"
#include "LinkedList.h"
int main(int argc, char** argv) {
    initList();
    char* c;
    c = getChars();
    struct string *strp1;
    strp1 = malloc(sizeof(struct string));
    strp1 = make_string(c);
    addString(strp1);
    printAll();
    printf("%s", *strp1);
    puts("nsome text");
    return (EXIT_SUCCESS);
}