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/* Duplicate an open file descriptor to a specified file descriptor.
Copyright (C) 1999, 2004-2007, 2009-2023 Free Software Foundation, Inc.
This file is free software: you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as
published by the Free Software Foundation; either version 2.1 of the
License, or (at your option) any later version.
This file 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 Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>. */
/* written by Paul Eggert */
#include <config.h>
/* Specification. */
#include <unistd.h>
#include <errno.h>
#include <fcntl.h>
#undef dup2
#if defined _WIN32 && ! defined __CYGWIN__
/* Get declarations of the native Windows API functions. */
# define WIN32_LEAN_AND_MEAN
# include <windows.h>
# if HAVE_MSVC_INVALID_PARAMETER_HANDLER
# include "msvc-inval.h"
# endif
/* Get _get_osfhandle. */
# if GNULIB_MSVC_NOTHROW
# include "msvc-nothrow.h"
# else
# include <io.h>
# endif
# if HAVE_MSVC_INVALID_PARAMETER_HANDLER
static int
dup2_nothrow (int fd, int desired_fd)
{
int result;
TRY_MSVC_INVAL
{
result = _dup2 (fd, desired_fd);
}
CATCH_MSVC_INVAL
{
errno = EBADF;
result = -1;
}
DONE_MSVC_INVAL;
return result;
}
# else
# define dup2_nothrow _dup2
# endif
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:
https://bugs.winehq.org/show_bug.cgi?id=21289 */
if (desired_fd < 0)
{
errno = EBADF;
return -1;
}
result = dup2_nothrow (fd, desired_fd);
if (result == 0)
result = desired_fd;
return result;
}
# define dup2 ms_windows_dup2
#elif defined __KLIBC__
# include <InnoTekLIBC/backend.h>
static int
klibc_dup2dirfd (int fd, int desired_fd)
{
int tempfd;
int dupfd;
tempfd = open ("NUL", O_RDONLY);
if (tempfd == -1)
return -1;
if (tempfd == desired_fd)
{
close (tempfd);
char path[_MAX_PATH];
if (__libc_Back_ioFHToPath (fd, path, sizeof (path)))
return -1;
return open(path, O_RDONLY);
}
dupfd = klibc_dup2dirfd (fd, desired_fd);
close (tempfd);
return dupfd;
}
static int
klibc_dup2 (int fd, int desired_fd)
{
int dupfd;
struct stat sbuf;
dupfd = dup2 (fd, desired_fd);
if (dupfd == -1 && errno == ENOTSUP \
&& !fstat (fd, &sbuf) && S_ISDIR (sbuf.st_mode))
{
close (desired_fd);
return klibc_dup2dirfd (fd, desired_fd);
}
return dupfd;
}
# define dup2 klibc_dup2
#endif
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 Cygwin 1.7.17, dup2 (1, -1) dumps core.
On Cygwin 1.7.25, dup2 (1, 256) can dump core.
On Haiku, dup2 (fd, fd) mistakenly clears FD_CLOEXEC. */
# if HAVE_SETDTABLESIZE
setdtablesize (desired_fd + 1);
# endif
if (desired_fd < 0)
fd = desired_fd;
if (fd == desired_fd)
return fcntl (fd, F_GETFL) == -1 ? -1 : fd;
#endif
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 REPLACE_FCHDIR
if (fd != desired_fd && result != -1)
result = _gl_register_dup (fd, result);
#endif
return result;
}
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