#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <errno.h>

#define MAX_SIZE 1024

int read_line(int fd, char *buffer, int max_size)
{
    int i;
    int n_read;
    char temp;

    for(i = 0; i < max_size; i++)
    {
        if((n_read=read(fd, &temp, 1)) == -1)
    {
        perror("read error");
        exit(1);
    }
        if(n_read == 0)
    {
        return 0;
    }

    if(temp == '\n')
    {
        buffer[i] = ' ';
        return i + 1;
    }
    else
    {
        buffer[i] = temp;
    }
    }

    return i;
}

int main(int argc, char **argv)
{
    int from_fd;
    int to_fd;
    int n_read;
    int n_write;
    char buffer[MAX_SIZE];

    if(argc != 3)
    {
        printf("please input from_file and to_file!\n");
    exit(1);
    }

    if((from_fd = open(argv[1], O_RDONLY)) == -1)
    {
        printf("Open %s Error:%s\n", argv[1], strerror(errno));
    exit(1);
    }

    if((to_fd = open(argv[2], O_RDWR | O_CREAT, 0766)) == -1)
    {
        printf("Open %s Error:%s\n", argv[2], strerror(errno));
    exit(1);
    }

    while((n_read = read_line(from_fd, buffer, sizeof(buffer))) != 0)
    {
        buffer[n_read] = '\0';
    write(to_fd, buffer, strlen(buffer));
    write(to_fd, "\n", 1);
    memset(buffer, 0 ,sizeof(buffer));
    }

    close(from_fd);
    close(to_fd);
    return 0;
}