get_next_line/get_next_line.c

/* ************************************************************************** */
/*                                                                            */
/*                                                        :::      ::::::::   */
/*   get_next_line.c                                    :+:      :+:    :+:   */
/*                                                    +:+ +:+         +:+     */
/*   By: kcolin <marvin@42.fr>                      +#+  +:+       +#+        */
/*                                                +#+#+#+#+#+   +#+           */
/*   Created: 2024/10/23 20:32:46 by kcolin            #+#    #+#             */
/*   Updated: 2024/10/31 17:30:56 by kcolin           ###   ########.fr       */
/*                                                                            */
/* ************************************************************************** */

#include "get_next_line.h"
#include <stdlib.h>

char	*ft_strchr(const char *s, int c)
{
	size_t	i;

	i = 0;
	while (s[i] != '\0')
	{
		if (s[i] == (char)c)
			return ((char *)s + i);
		i++;
	}
	if ((char)c == '\0')
		return ((char *)s + i);
	return (0);
}

size_t	ft_strlen(const char *s)
{
	size_t	i;

	i = 0;
	while (s[i] != '\0')
		i++;
	return (i);
}

size_t	ft_strlcpy(char *dst, const char *src, size_t size)
{
	size_t	i;

	i = 0;
	while (src[i] != 0)
	{
		if (i < size)
			dst[i] = src[i];
		i++;
	}
	if (size > 0)
	{
		if (size - 1 > i)
			dst[i] = '\0';
		else
			dst[size - 1] = '\0';
	}
	return (i);
}

size_t	ft_strlcat(char *dst, const char *src, size_t size)
{
	size_t	dst_len;
	size_t	src_len;
	size_t	i;

	dst_len = 0;
	while (dst[dst_len] != '\0')
		dst_len++;
	src_len = 0;
	while (src[src_len] != '\0')
		src_len++;
	if (size <= dst_len)
		return (size + src_len);
	i = 0;
	while (src[i] != '\0' && i < size - dst_len - 1)
	{
		dst[dst_len + i] = src[i];
		i++;
	}
	dst[dst_len + i] = '\0';
	return (dst_len + src_len);
}

char	*ft_strjoin_free_s1(char const *s1, char const *s2)
{
	char	*out;
	size_t	len;

	len = ft_strlen(s1) + ft_strlen(s2) + 1;
	out = malloc(len);
	if (out == NULL)
		return (NULL);
	ft_strlcpy(out, s1, len);
	ft_strlcat(out, s2, len);
	free((void *)s1);
	return (out);
}

char	*shorten_buffer(char *buffer)
{
	char	*outbuf;
	char	*addr_of_newline;
	size_t	index_after_newline;
	size_t	outlen;

	addr_of_newline = ft_strchr(buffer, '\n');
	if (addr_of_newline == NULL)
	{
		outbuf = malloc(1 * sizeof(char));
		if (outbuf == NULL)
		{
			free(buffer);
			return (NULL);
		}
		outbuf[0] = '\0';
	}
	else
	{
		index_after_newline = addr_of_newline + 1 - buffer;
		outlen = ft_strlen(buffer + index_after_newline) + 1;
		outbuf = malloc(outlen * sizeof(char));
		if (outbuf == NULL)
		{
			free(buffer);
			return (NULL);
		}
		ft_strlcpy(outbuf, buffer + index_after_newline, outlen);
	}
	free(buffer);
	return (outbuf);
}

char	*get_next_line(int fd)
{
	static char	*buffer = NULL;
	char		*read_buffer;
	int			num_bytes_read;
	char		*outbuf;

	if (buffer == NULL)
	{
		buffer = malloc(1 * sizeof(char));
		if (buffer == NULL)
			return (NULL);
		buffer[0] = '\0';
	}
	read_buffer = malloc((BUFFER_SIZE + 1) * sizeof(char));
	if (read_buffer == NULL)
		return (NULL);
	num_bytes_read = 1;
	while (num_bytes_read != 0)
	{
		// DONE: if newline found,
		if (ft_strchr(buffer, '\n'))
		{
			// DONE: copy string until newline to new buffer,
			outbuf = malloc((ft_strchr(buffer, '\n') - buffer + 2));
			if (outbuf == NULL)
			{
				free(read_buffer);
				free(buffer);
				buffer = NULL;
				return (NULL);
			}
			ft_strlcpy(outbuf, buffer, ft_strchr(buffer, '\n') - buffer + 2);
			// DONE: shorten current buffer,
			// buffer += ft_strchr(buffer, '\n') - buffer + 1;
			buffer = shorten_buffer(buffer);
			// DONE: and return.
			free(read_buffer);
			return (outbuf);
		}
		num_bytes_read = read(fd, read_buffer, BUFFER_SIZE);
		if (num_bytes_read < 0)
		{
			free(read_buffer);
			free(buffer);
			buffer = NULL;
			return (NULL);
		}
		read_buffer[num_bytes_read] = '\0';
		// DONE: join with big buffer
		buffer = ft_strjoin_free_s1(buffer, read_buffer);
		if (buffer == NULL)
		{
			free(read_buffer);
			return (NULL);
		}
	}
	free(read_buffer);
	outbuf = buffer;
	if (ft_strlen(buffer) == 0)
	{
		free(buffer);
		outbuf = NULL;
	}
	buffer = NULL;
	return (outbuf);
}