Построчное считывание файла

#include <semaphore.h>
#include <unistd.h>
#include "fcntl.h"
#include "sys/stat.h"
#include <iostream>
#include <string>
#include <cstring>
 
using namespace std;
 
void processCharacter(char);
void removeFirst(char*);
 
int main(void)
{
  (void)umask(0);
  
  const int buffSize = 10;
  sem_t *mutex = sem_open("mutex", O_CREAT, 0666, 1);
  sem_t *writeCount = sem_open("write_count", O_CREAT, 0666, buffSize);
  sem_t *readCount = sem_open("read_count", O_CREAT, 0666, 0);
  
  char *characters = new char[buffSize];
  int fd;
  while(1)
  {
    sleep(2);
    sem_wait(readCount);
    sem_wait(mutex);
    
    fd = open("data", O_RDONLY, 0666);
    read(fd, characters, buffSize);
    close(fd);
    
    processCharacter(characters[0]);
    removeFirst(characters);
    fd = open("data", O_WRONLY | O_TRUNC, 0666);
    write(fd, characters, strlen(characters));
    close(fd);
    
    sem_post(mutex);
    sem_post(writeCount);
  }
}
void processCharacter(char character)
{
  cout << "Процесс: " << getpid() << " символ-время: " << character << endl;
}
void removeFirst(char *characters)
{
  int i = 1;
  int len = strlen(characters);
  while (i < len)
  {
    characters[i - 1] = characters[i];
    i++;
  }
  characters[i - 1] = '\0';
}