public domain dup2() should work on most Unix systems

[R. Curtis Jackson]

/*
 * 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.
 */

# define BADEXIT -1

# include <fcntl.h>

extern int errno;

dup2(fd1, fd2)
int 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);
}

-- 
The MAD Programmer -- 919-228-3313 (Cornet 291)
alias: Curtis Jackson	...![ ihnp4 ulysses cbosgd mgnetp ]!burl!rcj
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