dup3.c\linux\src - musl - musl - an implementation of the standard library for Linux-based systems

#define _GNU_SOURCE
#include <unistd.h>
#include <errno.h>
#include "syscall.h"
int dup3(int old, int new, int flags) {
 int r;
 while ((r=__syscall(SYS_dup3, old, new, flags))==-EBUSY);
 return __syscall_ret(r);
}