/*
* 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;
}