int getgrgid_r(gid_t, struct group *, char *, size_t, struct group **);
int getgrnam_r(const char *, struct group *, char *, size_t, struct group **);
int getgrgid_r(gid_t, struct group *, char *, size_t, struct group **);
int getgrnam_r(const char *, struct group *, char *, size_t, struct group **);