/*

 * Public domain dup2() lookalike

 * by Curtis Jackson @ AT&T Technologies, Burlington, NC

 * electronic address:  burl!rcj

 *

 * dup2 performs the following functions:

 *

 * Check to make sure that fd1 is a valid open file descriptor.

 * Check to see if fd2 is already open; if so, close it.

 * Duplicate fd1 onto fd2; checking to make sure fd2 is a valid fd.

 * Return fd2 if all went well; return BADEXIT otherwise.

 */

#include <fcntl.h>

#define BADEXIT -1

int

dup2(int fd1, int fd2)

{

	if (fd1 != fd2) {

		if (fcntl(fd1, F_GETFL) < 0)

			return BADEXIT;

		if (fcntl(fd2, F_GETFL) >= 0)

			close(fd2);

		if (fcntl(fd1, F_DUPFD, fd2) < 0)

			return BADEXIT;

	}

	return fd2;

}