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https://github.com/python/cpython
Revision 7a240aef1526e56943381dca3fbda139962500f2 authored by Zackery Spytz on 28 November 2020, 21:46:30 UTC, committed by GitHub on 28 November 2020, 21:46:30 UTC
Commit 035deee265c7fb227ddc87222fa48761231d8bd7 converted the
_posixsubprocess module to multiphase initialization, but the news entry
mentions the _posixshmem module.
1 parent fa840cc
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Tip revision: 7a240aef1526e56943381dca3fbda139962500f2 authored by Zackery Spytz on 28 November 2020, 21:46:30 UTC
Fix an error in the news entry for _posixsubprocess multiphase init (GH-23516)
Tip revision: 7a240ae
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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