linereader.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "linereader.h"

#define read_buf_size 1024

linereader linereader_create(int fd) {
    linereader reader = (linereader)calloc(1, sizeof(struct _linereader));
    reader->fd = fd;
    reader->read_buffer = (char *)calloc(read_buf_size, sizeof(char));
    reader->read_left_buffer = (char *)calloc(read_buf_size, sizeof(char));
    reader->line_buffer = NULL;
    return reader;
}

void linereader_free(linereader reader) {
    free(reader->read_buffer);
    free(reader->read_left_buffer);
    free(reader->line_buffer);
    free(reader);
}
static int linereader_readbuffer(linereader reader) {
    if (reader->read_left_count) {
        memcpy(reader->read_buffer, reader->read_left_buffer, reader->read_left_count);
        return reader->read_left_count;
    }

    int size = read(reader->fd, reader->read_buffer, read_buf_size);
    return size;
}
int linereader_readline(linereader reader) {
    int bytes_count;
    int line_size = 0;

    if (reader->line_buffer) {
        free(reader->line_buffer);
        reader->line_buffer = NULL;
    }

    int read_count = 0;

    while ((bytes_count = linereader_readbuffer(reader)) != 0) {
        read_count ++;
        char *read_buffer = reader->read_buffer;
        int br_index = -1;

        for (int i = 0; i < bytes_count; i++) {
            if (read_buffer[i] == '\n') {
                br_index = i;
                break;
            }
        }

        //if \n finded
        if (br_index != -1) {
            int copy_count = br_index;

            if (copy_count) {
                reader->line_buffer = realloc(reader->line_buffer, sizeof(char) * (line_size + copy_count + 1));
                memcpy(reader->line_buffer + line_size, read_buffer, copy_count);
                reader->line_buffer[line_size + copy_count] = '\0';
                line_size += copy_count;
            }

            //save chars afer \n
            int left_count = bytes_count - br_index - 1;
            memcpy(reader->read_left_buffer, read_buffer + br_index + 1, left_count);
            reader->read_left_count = left_count;
            break;
        } else { //copy read buffer
            int copy_count = bytes_count;
            reader->line_buffer = realloc(reader->line_buffer, sizeof(char) * (line_size + copy_count + 1));
            memcpy(reader->line_buffer + line_size, read_buffer, copy_count);
            reader->line_buffer[line_size + copy_count] = '\0';
            line_size += copy_count;
            reader->read_left_count = 0;
        }
    }

    if (read_count == 0) {
        return -1;
    } else {
        return line_size;
    }
}