C stack implementation

stack.c

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

#define _E(msg, args...) \
do{ \
       printf( "[ERROR][%s][%d]: ", __FUNCTION__, __LINE__); \
    printf( (msg), ##args); \
}while(0)

struct stack
{
	char *data;
	int max_size;
	int top;
};

int stack_init(struct stack *stack, size_t size)
{
	if (size == 0)
		{
			_E("Size cannot be zero\n");
			return 1;
		}

	char *new_data = malloc(sizeof(char) * size);
	if (new_data == NULL)
		{
			_E("Failed to allocate buffer for a new"
			        " stack\n");
			return 2;
		}

	stack->data = new_data;
	stack->max_size = size;
	stack->top = -1;

	return 0;
}

void stack_deinit(struct stack *stack)
{
	free(stack->data);
}

int stack_push(struct stack *stack, char val)
{
	if (stack->top == stack->max_size - 1)
		{
			_E("Stack is full\n");
			return 1;
		}

	stack->data[++(stack->top)] = val;
	return 0;
}

int stack_pop(struct stack *stack)
{
	if (stack->top == -1)
		{
			_E("Stack is empty\n");
			return 1;
		}
	--stack->top;
	return 0;
}

int stack_is_empty(struct stack *stack)
{
	int ret = stack->top == -1 ? 1 : 0;
	return ret;
}

char stack_get_top_value(struct stack *stack)
{
	if (stack_is_empty(stack))
		{
			_E("Stack is empty\n");
			return 1;
		}
	return stack->data[stack->top];
}

int main(void)
{
	struct stack my_stack;
	if (stack_init(&my_stack, 2))
		{
			fprintf(stderr, "stack_init() failed. Exiting\n");
			exit(EXIT_FAILURE);
		}

	printf("Stack size: %d\n", my_stack.max_size);
	printf("Is stack empty: %s\n", stack_is_empty(&my_stack) ? "yes" :
	                                                           "no");

	puts("Push 100");
	stack_push(&my_stack, 100);
	printf("Is stack empty: %s\n", stack_is_empty(&my_stack) ? "yes" :
	                                                           "no");
	printf("Stack top: %d\n", stack_get_top_value(&my_stack));

	puts("Push 101");
	stack_push(&my_stack, 101);
	printf("Stack top: %d\n", stack_get_top_value(&my_stack));

	puts("Push 102");
	stack_push(&my_stack, 102);

	puts("Remove element");
	stack_pop(&my_stack);
	printf("Stack top: %d\n", stack_get_top_value(&my_stack));

	puts("Push 103");
	stack_push(&my_stack, 103);

	printf("Stack top: %d\n", stack_get_top_value(&my_stack));
	stack_deinit(&my_stack);

	exit(0);
}