get_next_line.c

/* ************************************************************************** */
/*                                                                            */
/*                                                        :::      ::::::::   */
/*   get_next_line.c                                    :+:      :+:    :+:   */
/*                                                    +:+ +:+         +:+     */
/*   By: marvin <marvin@student.42.fr>              +#+  +:+       +#+        */
/*                                                +#+#+#+#+#+   +#+           */
/*   Created: 2022/10/10 23:00:23 by marvin            #+#    #+#             */
/*   Updated: 2022/10/30 22:01:58 by larcrist         ###   ########.fr       */
/*                                                                            */
/* ************************************************************************** */

#include "get_next_line.h"

static int			ft_found_error(int fd);
static void			ft_free(char **str);
static char			*ft_slice(char **str);
static char			*ft_substr(char const *str, unsigned int start, size_t len);

char	*get_next_line(int fd)
{
	int			size;
	char		*buffer;
	char		*support;
	static char	*string;

	if (ft_found_error(fd))
		return (NULL);
	buffer = malloc(sizeof(char) * (BUFFER_SIZE + 1));
	size = read(fd, buffer, BUFFER_SIZE);
	while (size > 0)
	{
		buffer[size] = '\0';
		if (!string)
			string = ft_strdup(buffer);
		else
		{
			support = ft_strjoin(string, buffer);
			ft_free(&string);
			string = support;
		}
		if (ft_strchr(string, '\n'))
			break ;
		size = read(fd, buffer, BUFFER_SIZE);
	}
	return (ft_free(&buffer), ft_slice(&string));
}

//finds an error in input
static int	ft_found_error(int fd)
{
	if (fd == -1 || BUFFER_SIZE <= 0)
		return (1);
	return (0);
}

//de-allocate the memory
static	void	ft_free(char **str)
{
	if (str[0])
	{
		free(str[0]);
		str[0] = NULL;
	}
}

//slice the string into pieces
static char	*ft_slice(char **str)
{
	int		index;
	char	*ret;
	char	*sup;

	index = 0;
	if (!str[0])
		return (NULL);
	while (str[0][index] != '\n' && str[0][index] != '\0')
		index++;
	ret = ft_substr(str[0], 0, index + 1);
	sup = ft_strdup(str[0]);
	ft_free(str);
	str[0] = ft_substr(sup, index + 1, ft_strlen(sup));
	ft_free(&sup);
	if (!ft_strchr(ret, '\n'))
	{
		if (!ft_strlen(ret))
			ft_free(&ret);
		ft_free(str);
	}
	return (ret);
}

//returns a substring from a string
static char	*ft_substr(char const *s, unsigned int start, size_t len)
{
	char	*str;

	if (!s)
		return (NULL);
	if (ft_strlen(s) < start)
	{
		str = (char *)malloc(sizeof(*s));
		str[0] = '\0';
		return (str);
	}
	if (ft_strlen(s) < start)
		len = 0;
	if (ft_strlen(s + start) < len)
		len = ft_strlen(s + start);
	str = (char *)malloc(len + 1);
	if (!str)
	{
		return (NULL);
	}
	ft_strlcpy(str, s + start, len + 1);
	return (str);
}