Plugging properties of clogging function with Fcntl ()

#include <stdio.h> #include <stdlib.h> #include <string.h> #include <sys/types.h> #include <        sys/stat.h> #include <fcntl.h> #include <unistd.h> #define ERR_EXIT (m) do {perror (M);    Exit (Exit_failure); }while (0) void activate_nonblock (int fd), void deactivate_nonblock (int fd), int main (int argc, const char *argv[]) {Activa    Te_nonblock (Stdin_fileno);    Char buffer[1024] = {0};    int ret = read (Stdin_fileno, buffer, 1024);    if (ret = =-1) printf ("read"); return 0;}    void Activate_nonblock (int fd) {int ret;    int flags = FCNTL (FD, F_GETFL);    if (flags = =-1) err_exit ("Fcntl");    Flags |= O_nonblock;    ret = Fcntl (FD, F_SETFL, flags); if (ret = =-1) err_exit ("Fcntl");}    void Deactivate_nonblock (int fd) {int ret;    int flags = FCNTL (FD, F_GETFL);    if (flags = =-1) err_exit ("Fcntl");    Flags &=~O_NONBLOCK;    ret = Fcntl (FD, F_SETFL, flags); if (ret = =-1) err_exit ("Fcntl");}

Plugging properties of clogging function with Fcntl ()