ft_strlcat.c

/* ************************************************************************** */
/*                                                                            */
/*                                                        :::      ::::::::   */
/*   ft_strlcat.c                                       :+:      :+:    :+:   */
/*                                                    +:+ +:+         +:+     */
/*   By: mmaurer <mmaurer@student.42wolfsburg.de>   +#+  +:+       +#+        */
/*                                                +#+#+#+#+#+   +#+           */
/*   Created: 2021/08/25 18:03:42 by mmaurer           #+#    #+#             */
/*   Updated: 2021/09/07 22:20:50 by mmaurer          ###   ########.fr       */
/*                                                                            */
/* ************************************************************************** */

#include "libft.h"

/*	size_t strlcat(char *dest, const char *src, size_t size);
* This function appends the null-terminated string src to the string dest,
* copying at most size-strlen(dest)-1 from src, and adds a terminating
* null byte to the result, unless size is less than strlen(dest). This
* function fixes the buffer overrun problem of strcat(), but the caller must
* still handle the possibility of data loss if size is too small. The
* function returns the length of the string  strlcat() tried to create;
* if the return value is greater than or equal to size, data loss occurred.
1.	First, it checks that the size of the destination buffer is not zero. If it
	is, then it returns the length of the source string.
2.	Next, it checks that the size of the destination buffer is not equal to or
	greater than the size of the source string. If it is, then it returns the
	length of the source string.
3.	Finally, it copies the source string to the destination buffer, and returns
	the length of the source string.
*/
size_t	ft_strlcat(char *dest, const char *src, size_t size)
{
	char		*d;
	const char	*s;
	size_t		n;
	size_t		dlen;

	d = dest;
	s = src;
	n = size;
	while (n-- != 0 && *d != '\0')
		d++;
	dlen = d - dest;
	n = size - dlen;
	if (n == 0)
		return (dlen + ft_strlen(s));
	while (*s != '\0')
	{
		if (n != 1)
		{
			*d++ = *s;
			n--;
		}
		s++;
	}
	*d = '\0';
	return (dlen + (s - src));
}