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dup2.c
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dup2.c
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/* dup2.c: Duplicate an open file descriptor to a specified file descriptor
Copyright (C) 1999, 2004-2007, 2009-2012 Free Software Foundation, Inc.
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/> */
/* written by Paul Eggert */
#include <config.h>
/* Specification: */
#include <unistd.h>
#include <errno.h>
#include <fcntl.h>
#include "dup.h"
#if HAVE_DUP2
# undef dup2
# if (defined(_WIN32) || defined(__WIN32__)) && ! defined(__CYGWIN__)
/* Get declarations of the native Windows API functions: */
# define WIN32_LEAN_AND_MEAN
# include <windows.h>
# include "msvc-inval.h"
/* Get _get_osfhandle: */
# include "msvc-nothrow.h"
static int
ms_windows_dup2(int fd, int desired_fd)
{
int result;
/* If fd is closed, mingw hangs on dup2 (fd, fd). If fd is open,
* dup2 (fd, fd) returns 0, but all further attempts to use fd in
* future dup2 calls will hang. */
if (fd == desired_fd)
{
if ((HANDLE) _get_osfhandle (fd) == INVALID_HANDLE_VALUE)
{
errno = EBADF;
return -1;
}
return fd;
}
/* Wine 1.0.1 return 0 when desired_fd is negative but not -1:
* http://bugs.winehq.org/show_bug.cgi?id=21289 */
if (desired_fd < 0)
{
errno = EBADF;
return -1;
}
TRY_MSVC_INVAL
{
result = dup2 (fd, desired_fd);
}
CATCH_MSVC_INVAL
{
errno = EBADF;
result = -1;
}
DONE_MSVC_INVAL;
if (result == 0)
result = desired_fd;
return result;
}
# define dup2 ms_windows_dup2
# endif /* (_WIN32 || __WIN32__) && !__CYGWIN__ */
int
rpl_dup2(int fd, int desired_fd)
{
int result;
# ifdef F_GETFL
/* On Linux kernels 2.6.26-2.6.29, dup2(fd, fd) returns -EBADF.
* On Cygwin 1.5.x, dup2(1, 1) returns 0.
* On Haiku, dup2(fd, fd) mistakenly clears FD_CLOEXEC: */
if (fd == desired_fd)
return ((fcntl(fd, F_GETFL) == -1) ? -1 : fd);
# endif /* F_GETFL */
result = dup2 (fd, desired_fd);
/* Correct an errno value on FreeBSD 6.1 and Cygwin 1.5.x: */
if ((result == -1) && (errno == EMFILE))
errno = EBADF;
# if defined(REPLACE_FCHDIR) && REPLACE_FCHDIR
if ((fd != desired_fd) && (result != -1))
result = _gl_register_dup(fd, result);
# endif /* REPLACE_FCHDIR */
return result;
}
#else /* !HAVE_DUP2 */
/* On older platforms, dup2 did not exist: */
# if !defined(dupfd) && (!defined(F_DUPFD) || !defined(HAVE_DUPFD))
static int
dupfd(int fd, int desired_fd)
{
int duplicated_fd;
duplicated_fd = dup(fd);
if ((duplicated_fd < 0) || (duplicated_fd == desired_fd)) {
return duplicated_fd;
} else {
int r = dupfd(fd, desired_fd);
int e = errno;
close(duplicated_fd);
errno = e;
return r;
}
}
# endif /* !dupfd && (!F_DUPFD || !HAVE_DUPFD) */
int
dup2(int fd, int desired_fd)
{
int result = ((fcntl(fd, F_GETFL) < 0) ? -1 : fd);
if ((result == -1) || (fd == desired_fd))
return result;
close(desired_fd);
# ifdef F_DUPFD
result = fcntl(fd, F_DUPFD, desired_fd);
# if REPLACE_FCHDIR
if (0 <= result)
result = _gl_register_dup(fd, result);
# endif
# else
result = dupfd(fd, desired_fd);
# endif
if ((result == -1) && ((errno == EMFILE) || (errno == EINVAL)))
errno = EBADF;
return result;
}
#endif /* !HAVE_DUP2 */
/* EOF */