#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <err.h>
#include <fcntl.h>
int
main(int argc, char *argv[])
{
int orgfd, fd1, fd2;
char temp[] = "/tmp/dup2XXXXXXXXX";
if ((orgfd = mkstemp(temp)) < 0)
err(1, "mkstemp");
remove(temp);
if (ftruncate(orgfd, 1024) != 0)
err(1, "ftruncate");
if ((fd1 = dup(orgfd)) < 0)
err(1, "dup");
if (fcntl(fd1, F_SETFD, 1) != 0)
err(1, "fcntl(F_SETFD)");
if ((fd2 = dup2(fd1, fd1 + 1)) < 0)
err(1, "dup2");
if (fd2 != fd1 + 1)
errx(1, "dup2 didn't give us the right fd");
if (fcntl(fd2, F_GETFD) != 0)
errx(1, "dup2 didn't clear close-on-exec");
return 0;
}