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v0.5.1
https://github.com/python/cpython
09 December 2020, 11:06:31 UTC
Revision 00833d507b999bfdf858ac8b76d5c5a1fd93ec45 authored by cvs2svn on 13 April 2001, 19:41:28 UTC, committed by cvs2svn on 13 April 2001, 19:41:28 UTC 
This commit was manufactured by cvs2svn to create tag 'r21c1'.
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Tip revision: 00833d507b999bfdf858ac8b76d5c5a1fd93ec45 authored by cvs2svn on 13 April 2001, 19:41:28 UTC
This commit was manufactured by cvs2svn to create tag 'r21c1'.
Tip revision: 00833d5
dup2.c 
/*
 * 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;
}
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