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https://github.com/python/cpython
Revision 96545924780da34afc457bc22a869096af985ebf authored by Zackery Spytz on 30 November 2020, 08:39:12 UTC, committed by GitHub on 30 November 2020, 08:39:12 UTC
1 parent 6cc2c41
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Tip revision: 96545924780da34afc457bc22a869096af985ebf authored by Zackery Spytz on 30 November 2020, 08:39:12 UTC
bpo-42506: Fix unexpected output in test_format (GH-23564)
Tip revision: 9654592
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>
#include <unistd.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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