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/* Test duplicating file descriptors.
Copyright (C) 2009-2023 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 <https://www.gnu.org/licenses/>. */
/* Written by Eric Blake <ebb9@byu.net>, 2009,
and Bruno Haible <bruno@clisp.org>, 2009. */
#include <config.h>
#include <unistd.h>
#include "signature.h"
SIGNATURE_CHECK (dup3, int, (int, int, int));
#include <errno.h>
#include <fcntl.h>
#if defined _WIN32 && ! defined __CYGWIN__
/* Get declarations of the native Windows API functions. */
# define WIN32_LEAN_AND_MEAN
# include <windows.h>
/* Get _get_osfhandle. */
# if GNULIB_MSVC_NOTHROW
# include "msvc-nothrow.h"
# else
# include <io.h>
# endif
#endif
#include "binary-io.h"
#include "macros.h"
/* Return true if FD is open. */
static bool
is_open (int fd)
{
#if defined _WIN32 && ! defined __CYGWIN__
/* On native Windows, the initial state of unassigned standard file
descriptors is that they are open but point to an
INVALID_HANDLE_VALUE, and there is no fcntl. */
return (HANDLE) _get_osfhandle (fd) != INVALID_HANDLE_VALUE;
#else
# ifndef F_GETFL
# error Please port fcntl to your platform
# endif
return 0 <= fcntl (fd, F_GETFL);
#endif
}
/* Return true if FD is not inherited to child processes. */
static bool
is_cloexec (int fd)
{
#if defined _WIN32 && ! defined __CYGWIN__
HANDLE h = (HANDLE) _get_osfhandle (fd);
DWORD flags;
ASSERT (GetHandleInformation (h, &flags));
return (flags & HANDLE_FLAG_INHERIT) == 0;
#else
int flags;
ASSERT ((flags = fcntl (fd, F_GETFD)) >= 0);
return (flags & FD_CLOEXEC) != 0;
#endif
}
int
main ()
{
int use_cloexec;
int bad_fd = getdtablesize ();
#if O_CLOEXEC
for (use_cloexec = 0; use_cloexec <= 1; use_cloexec++)
#else
use_cloexec = 0;
#endif
{
const char *file = "test-dup3.tmp";
int fd = open (file, O_CREAT | O_TRUNC | O_RDWR, 0600);
int o_flags;
char buffer[1];
o_flags = 0;
#if O_CLOEXEC
if (use_cloexec)
o_flags |= O_CLOEXEC;
#endif
/* Assume std descriptors were provided by invoker. */
ASSERT (STDERR_FILENO < fd);
ASSERT (is_open (fd));
/* Ignore any other fd's leaked into this process. */
close (fd + 1);
close (fd + 2);
ASSERT (!is_open (fd + 1));
ASSERT (!is_open (fd + 2));
/* Assigning to self is invalid. */
errno = 0;
ASSERT (dup3 (fd, fd, o_flags) == -1);
ASSERT (errno == EINVAL);
ASSERT (is_open (fd));
/* If the source is not open, then the destination is unaffected. */
errno = 0;
ASSERT (dup3 (fd + 1, fd + 2, o_flags) == -1);
ASSERT (errno == EBADF);
ASSERT (!is_open (fd + 2));
errno = 0;
ASSERT (dup3 (fd + 1, fd, o_flags) == -1);
ASSERT (errno == EBADF);
ASSERT (is_open (fd));
/* The destination must be valid. */
errno = 0;
ASSERT (dup3 (fd, -2, o_flags) == -1);
ASSERT (errno == EBADF);
if (bad_fd > 256)
{
ASSERT (dup3 (fd, 255, 0) == 255);
ASSERT (dup3 (fd, 256, 0) == 256);
ASSERT (close (255) == 0);
ASSERT (close (256) == 0);
}
ASSERT (dup3 (fd, bad_fd - 1, 0) == bad_fd - 1);
ASSERT (close (bad_fd - 1) == 0);
errno = 0;
ASSERT (dup3 (fd, bad_fd, o_flags) == -1);
ASSERT (errno == EBADF);
/* Using dup3 can skip fds. */
ASSERT (dup3 (fd, fd + 2, o_flags) == fd + 2);
ASSERT (is_open (fd));
ASSERT (!is_open (fd + 1));
ASSERT (is_open (fd + 2));
if (use_cloexec)
ASSERT (is_cloexec (fd + 2));
else
ASSERT (!is_cloexec (fd + 2));
/* Verify that dup3 closes the previous occupant of a fd. */
ASSERT (open ("/dev/null", O_WRONLY, 0600) == fd + 1);
ASSERT (dup3 (fd + 1, fd, o_flags) == fd);
ASSERT (close (fd + 1) == 0);
ASSERT (write (fd, "1", 1) == 1);
ASSERT (dup3 (fd + 2, fd, o_flags) == fd);
ASSERT (lseek (fd, 0, SEEK_END) == 0);
ASSERT (write (fd + 2, "2", 1) == 1);
ASSERT (lseek (fd, 0, SEEK_SET) == 0);
ASSERT (read (fd, buffer, 1) == 1);
ASSERT (*buffer == '2');
/* Clean up. */
ASSERT (close (fd + 2) == 0);
ASSERT (close (fd) == 0);
ASSERT (unlink (file) == 0);
}
return 0;
}
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