Аналог команды chmod

#include <stdio.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <stdlib.h>
#include <fcntl.h>
 
#define ANSWER_SIZE 256
 
void add_mode (mode_t * mode, const char* answer, mode_t bit)
{
    if(answer[0]=='y')
    {
        *mode |=bit;
    printf("set\n");
        } else printf("not set\n");
}
 
int main(int argc, char ** argv)
{
    char* answer;
    mode_t mode = 0000;
 
    if(argc<2)
    {
    printf("%s","Too few arguments\n");
    return 1;
    }
 
answer = (char *) malloc (sizeof (char) * ANSWER_SIZE);
if (answer == NULL)
{
    printf("%s", "*malloc() error\n");
        return 1;
}
 
printf("User can read: ");
printf("\nPress y for YES and other for NO\n");
scanf("%s", answer);
add_mode (&mode, answer, S_IRUSR);
 
 
 
printf("User can write: ");
printf("\nPress y for YES and other for NO\n");
scanf("%s", answer);
add_mode(&mode, answer, S_IWUSR);
 
printf("User can execute: ");
printf("\nPress y for YES and other for NO\n");
scanf("%s", answer);
add_mode(&mode, answer, S_IXUSR);
 
printf("Group can read: ");
printf("\nPress y for YES and other for NO\n");
scanf("%s", answer);
add_mode(&mode, answer, S_IRGRP);
 
printf("Group can write: ");
printf("\nPress y for YES and other for NO\n");
scanf("%s", answer);
add_mode(&mode, answer, S_IWGRP);
 
printf("Group can execute: ");
printf("\nPress y for YES and other for NO\n");
scanf("%s", answer);
add_mode(&mode, answer, S_IXGRP);
 
 
printf("World can read: ");
printf("\nPress y for YES and other for NO\n");
scanf("%s", answer);
add_mode(&mode, answer, S_IROTH);
 
printf("World can write: ");
printf("\nPress y for YES and other for NO\n");
scanf("%s", answer);
add_mode(&mode, answer, S_IWOTH);
 
printf("World can execute: ");
printf("\nPress y for YES and other for NO\n");
scanf("%s", answer);
add_mode(&mode, answer, S_IXOTH);
 
printf("SUID: ");
printf("\nPress y for YES and other for NO\n");
scanf("%s", answer);
add_mode(&mode, answer, S_ISUID);
 
printf("SGID: ");
printf("\nPress y for YES and other for NO\n");
scanf("%s", answer);
add_mode(&mode, answer, S_ISGID);
 
printf("Sticky: ");
printf("\nPress y for YES and other for NO\n");
scanf("%s", answer);
add_mode(&mode, answer, S_ISVTX);
 
if (chmod(argv[1], mode) == -1 )
{
printf("%s", "chmod() error\n");
return 1;
}
free (answer);
return 0;
}

 while ((c = getopt_long (argc, argv,
                           "Rcfvr::w::x::X::s::t::u::g::o::a::,::+::=::",
                           long_options, NULL))
         != -1)
    {
      switch (c)
        {
        case 'r':
        case 'w':
        case 'x':
        case 'X':
        case 's':
        case 't':
        case 'u':
        case 'g':
        case 'o':
        case 'a':
        case ',':
        case '+':
        case '=':
          /* Support nonportable uses like "chmodfate -w", but diagnose
             surprises due to umask confusion.  Even though "--", "--r",
             etc., are valid modes, there is no "case '-'" here since
             getopt_long reserves leading "--" for long options.  */
          {
            /* Allocate a mode string (e.g., "-rwx") by concatenating
               the argument containing this option.  If a previous mode
               string was given, concatenate the previous string, a
               comma, and the new string (e.g., "-s,-rwx").  */
 
            char const *arg = argv[optind - 1];
            size_t arg_len = strlen (arg);
            size_t mode_comma_len = mode_len + !!mode_len;
            size_t new_mode_len = mode_comma_len + arg_len;
            if (mode_alloc <= new_mode_len)
              {
                mode_alloc = new_mode_len + 1;
                mode = X2REALLOC (mode, &mode_alloc);
              }
            mode[mode_len] = ',';
            strcpy (mode + mode_comma_len, arg);
            mode_len = new_mode_len;
 
            diagnose_surprises = true;
          }
          break;