Hi I need to make an implementation for double linked list in C. However when I try any, I get a Segmentaiton Fault error in my terminal. Here is the skeleton code, I need to have a method that does not cause this error.

#include
	#include
	#include
	#include "dlist.h"
	// Prepend a value in front of the double list.
	int dlist_prepend(struct dlist** headp, struct dlist** endp, int value)
	{
	// Error handling.
	if (headp == NULL || endp == NULL) {
	return 0;
	}
	if (*headp == NULL) {
	// The list is empty.
	assert (*endp == NULL);
	*headp = (struct dlist*) malloc(sizeof(struct dlist));
	(*headp)->value = value;
	(*headp)->prev = NULL;
	(*headp)->next = NULL;
	*endp = *headp;
	} else {
	// Add your code here.
	}
	return 1;
	}
	// Append a value in the end of the double list.
	int dlist_append(struct dlist** headp, struct dlist** endp, int value)
	{
	// Error handling.
	if (headp == NULL || endp == NULL) {
	return 0;
	}
	if (*headp == NULL) {
	// The list is empty.
	assert (*endp == NULL);
	*headp = (struct dlist*) malloc(sizeof(struct dlist));
	(*headp)->value = value;
	(*headp)->prev = NULL;
	(*headp)->next = NULL;
	*endp = *headp;
	} else {
	// Add your code here.
	}
	return 0;
	}