1#include <unistd.h>
 2#include <errno.h>
 3#include <fcntl.h>
 4#include "syscall.h"
 5
 6int dup2(int old, int new)
 7{
 8	int r;
 9#ifdef SYS_dup2
10	while ((r=__syscall(SYS_dup2, old, new))==-EBUSY);
11#else
12	if (old==new) {
13		r = __syscall(SYS_fcntl, old, F_GETFD);
14		if (r >= 0) return old;
15	} else {
16		while ((r=__syscall(SYS_dup3, old, new, 0))==-EBUSY);
17	}
18#endif
19	return __syscall_ret(r);
20}