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/* Create a pipe, with specific opening flags.
Copyright (C) 2009-2024 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/>. */
#include <config.h>
/* Specification. */
#include <unistd.h>
#include <errno.h>
#include <fcntl.h>
#include "binary-io.h"
#if GNULIB_defined_O_NONBLOCK
# include "nonblocking.h"
#endif
#if defined _WIN32 && ! defined __CYGWIN__
/* Native Windows API. */
# include <io.h>
#endif
int
pipe2 (int fd[2], int flags)
{
/* Mingw _pipe() corrupts fd on failure; also, if we succeed at
creating the pipe but later fail at changing fcntl, we want
to leave fd unchanged: http://austingroupbugs.net/view.php?id=467 */
int tmp[2];
tmp[0] = fd[0];
tmp[1] = fd[1];
#if HAVE_PIPE2
# undef pipe2
/* Try the system call first, if it exists. (We may be running with a glibc
that has the function but with an older kernel that lacks it.) */
{
/* Cache the information whether the system call really exists. */
static int have_pipe2_really; /* 0 = unknown, 1 = yes, -1 = no */
if (have_pipe2_really >= 0)
{
int result = pipe2 (fd, flags);
if (!(result < 0 && errno == ENOSYS))
{
have_pipe2_really = 1;
return result;
}
have_pipe2_really = -1;
}
}
#endif
/* Check the supported flags. */
if ((flags & ~(O_CLOEXEC | O_NONBLOCK | O_BINARY | O_TEXT)) != 0)
{
errno = EINVAL;
return -1;
}
#if defined _WIN32 && ! defined __CYGWIN__
/* Native Windows API. */
if (_pipe (fd, 4096, flags & ~O_NONBLOCK) < 0)
{
fd[0] = tmp[0];
fd[1] = tmp[1];
return -1;
}
/* O_NONBLOCK handling.
On native Windows platforms, O_NONBLOCK is defined by gnulib. Use the
functions defined by the gnulib module 'nonblocking'. */
# if GNULIB_defined_O_NONBLOCK
if (flags & O_NONBLOCK)
{
if (set_nonblocking_flag (fd[0], true) != 0
|| set_nonblocking_flag (fd[1], true) != 0)
goto fail;
}
# else
{
static_assert (O_NONBLOCK == 0);
}
# endif
return 0;
#else
/* Unix API. */
if (pipe (fd) < 0)
return -1;
/* POSIX <https://pubs.opengroup.org/onlinepubs/9699919799/functions/pipe.html>
says that initially, the O_NONBLOCK and FD_CLOEXEC flags are cleared on
both fd[0] and fd[1]. */
/* O_NONBLOCK handling.
On Unix platforms, O_NONBLOCK is defined by the system. Use fcntl(). */
if (flags & O_NONBLOCK)
{
int fcntl_flags;
if ((fcntl_flags = fcntl (fd[1], F_GETFL, 0)) < 0
|| fcntl (fd[1], F_SETFL, fcntl_flags | O_NONBLOCK) == -1
|| (fcntl_flags = fcntl (fd[0], F_GETFL, 0)) < 0
|| fcntl (fd[0], F_SETFL, fcntl_flags | O_NONBLOCK) == -1)
goto fail;
}
if (flags & O_CLOEXEC)
{
int fcntl_flags;
if ((fcntl_flags = fcntl (fd[1], F_GETFD, 0)) < 0
|| fcntl (fd[1], F_SETFD, fcntl_flags | FD_CLOEXEC) == -1
|| (fcntl_flags = fcntl (fd[0], F_GETFD, 0)) < 0
|| fcntl (fd[0], F_SETFD, fcntl_flags | FD_CLOEXEC) == -1)
goto fail;
}
# if O_BINARY
if (flags & O_BINARY)
{
set_binary_mode (fd[1], O_BINARY);
set_binary_mode (fd[0], O_BINARY);
}
else if (flags & O_TEXT)
{
set_binary_mode (fd[1], O_TEXT);
set_binary_mode (fd[0], O_TEXT);
}
# endif
return 0;
#endif
#if GNULIB_defined_O_NONBLOCK || !(defined _WIN32 && ! defined __CYGWIN__)
fail:
{
int saved_errno = errno;
close (fd[0]);
close (fd[1]);
fd[0] = tmp[0];
fd[1] = tmp[1];
errno = saved_errno;
return -1;
}
#endif
}
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