1 #include <unistd.h>
2 #include <errno.h>
3 #include <fcntl.h>
4 #include "syscall.h"
5 
dup2(int old,int new)6 int 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 }
21