S01_PLIKI_03

/*
Zademonstruj działanie funkcji replikującej deskryptory plików.
*/

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <string.h>

#define BUFFER_SIZE 128

int main(int argc, char *argv[])
{
    char *filename = (char *)malloc(sizeof(strlen(argv[0]) + strlen(".c") + 1));
    filename = strcat(argv[0], ".c");

    int first_fd, second_fd;
    char buffer[BUFFER_SIZE];
    int result;

    if((first_fd = open(filename, O_RDONLY | 0600)) == -1) {
        perror("open");
        return EXIT_FAILURE;
    }

    if((second_fd = dup(first_fd)) == -1) {
        perror("dup2");
        return EXIT_FAILURE;
    }

    printf("Odczytywanie pliku za pomoca skopiowanego deskryptora: \n");

    for(;;) {
        memset(buffer, '\0', BUFFER_SIZE);
        result = read(second_fd, buffer, BUFFER_SIZE-1);
        if(result == -1) {
            perror("read");
            return EXIT_FAILURE;
        }
        else if(result == 0)
            break;
        else
            printf("%s", buffer);
    }

    printf("\n");

    if(close(first_fd) || close(second_fd)) {
        perror("close");
        return EXIT_FAILURE;
    }

    return EXIT_SUCCESS;
}