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/*
* dup2.C -- A dup2 emulation.
*/
/*
* $Id: dup2.C,v 3.0.1.1 1994/01/24 13:58:37 ram Exp $
*
* Copyright (c) 1991-1993, Raphael Manfredi
*
* You may redistribute only under the terms of the Artistic Licence,
* as specified in the README file that comes with the distribution.
* You may reuse parts of this distribution only within the terms of
* that same Artistic Licence; a copy of which may be found at the root
* of the source tree for dist 3.0.
*
* Original Author: Larry Wall <lwall@netlabs.com>
*
* $Log: dup2.C,v $
* Revision 3.0.1.1 1994/01/24 13:58:37 ram
* patch16: created
*
*/
#include "config.h"
#ifdef I_FCNTL
#include <fcntl.h>
#endif
#include "confmagic.h" /* Remove if not metaconfig -M */
#ifndef HAS_DUP2
/*
* dup2
*
* This routine duplicates file descriptor 'old' into 'new'. After the
* operation, both 'new' and 'old' refer to the same file 'old' was referring
* to in the first place.
*
* Returns 0 if OK, -1 on failure with errno being set to indicate the error.
*
*/
V_FUNC(int dup2, (old, new),
int old /* Opened file descriptor */ NXT_ARG
int new /* File descriptor we'd like to get */)
{
#ifdef HAS_FCNTL
#ifdef F_DUPFD
#define USE_FNCTL
#endif
#endif
#ifdef USE_FCNTL
if (old == new)
return 0;
close(new);
return fcntl(old, F_DUPFD, new);
#else
int fd_used[256]; /* Fixed stack used to record dup'ed files */
int fd_top = 0; /* Top in the fixed stack */
int fd; /* Currently dup'ed file descriptor */
if (old == new)
return 0;
close(new); /* Ensure one free slot */
while ((fd = dup(old)) != new) /* Until dup'ed file matches */
fd_used[fd_top++] = fd; /* Remember we have to close it later */
while (fd_top > 0) /* Close all useless dup'ed slots */
close(fd_used[--fd_top]);
return 0;
#endif
}
#endif
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