get_next_line.c

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/* ************************************************************************** */
/*                                                                            */
/*                                                        :::      ::::::::   */
/*   get_next_line.c                                    :+:      :+:    :+:   */
/*                                                    +:+ +:+         +:+     */
/*   By: kfujita <kfujita@student.42tokyo.jp>       +#+  +:+       +#+        */
/*                                                +#+#+#+#+#+   +#+           */
/*   Created: 2023/02/06 18:17:29 by kfujita           #+#    #+#             */
/*   Updated: 2023/02/07 01:00:36 by kfujita          ###   ########.fr       */
/*                                                                            */
/* ************************************************************************** */
 
#include "get_next_line.h"
#include "../ft_mem/ft_mem.h"
#include "../ft_vect/ft_vect.h"
 
// - read
#include <unistd.h>
 
// - ssize_t
#include <sys/types.h>
 
// - free
#include <stdlib.h>
 
static const t_gnl_state    g_gnl_state_init_val = {
    // fd
    0,
    // buf
    NULL,
    // len
    0,
    // cap
    0
};
 
t_gnl_state gen_gnl_state(int fd, ssize_t cap)
{
    t_gnl_state state;
 
    state = g_gnl_state_init_val;
    state.buf = ft_calloc(cap, sizeof(char));
    if (state.buf != NULL)
        state.cap = cap;
    state.fd = fd;
    return (state);
}
 
void    dispose_gnl_state(t_gnl_state *state)
{
    free(state->buf);
    *state = g_gnl_state_init_val;
}
 
// `\n` found: TRUE
//  not found: FALSE
static bool check_and_update_state(t_vect *ret, t_gnl_state *state)
{
    char    *lf_ptr;
    size_t  append_len;
 
    if (state->len == 0)
        return (false);
    lf_ptr = (char *)ft_memchr(state->buf, '\n', state->len);
    if (lf_ptr == NULL)
        append_len = state->len;
    else
        append_len = lf_ptr - state->buf + 1;
    vect_append_str(ret, state->buf, append_len);
    if (lf_ptr != NULL)
    {
        ft_memmove(state->buf, state->buf + append_len,
            state->len - append_len);
        state->len -= append_len;
    }
    else
        state->len = 0;
    return (lf_ptr != NULL);
}
 
char    *get_next_line(t_gnl_state *state)
{
    t_vect  ret;
    ssize_t read_result;
 
    if (state == NULL || state->buf == NULL || state->cap == 0)
        return (NULL);
    ret = vect_init(0, sizeof(char));
    if (check_and_update_state(&ret, state))
        return (ret.p);
    while (true)
    {
        read_result = read(state->fd, state->buf, state->cap);
        if (read_result <= 0)
        {
            dispose_gnl_state(state);
            if (ret.len == 0)
                vect_dispose(&ret);
            return (ret.p);
        }
        state->len = read_result;
        if (check_and_update_state(&ret, state))
            return (ret.p);
    }
}