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/* cloexec.c - set or clear the close-on-exec descriptor flag
Copyright (C) 1991, 2004-2006, 2009-2021 Free Software Foundation, Inc.
This program 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 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 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/>.
The code is taken from glibc/manual/llio.texi */
#include <config.h>
#include "cloexec.h"
#include <errno.h>
#include <fcntl.h>
#include <unistd.h>
/* Set the 'FD_CLOEXEC' flag of DESC if VALUE is true,
or clear the flag if VALUE is false.
Return 0 on success, or -1 on error with 'errno' set.
Note that on MingW, this function does NOT protect DESC from being
inherited into spawned children. Instead, either use dup_cloexec
followed by closing the original DESC, or use interfaces such as
open or pipe2 that accept flags like O_CLOEXEC to create DESC
non-inheritable in the first place. */
int
set_cloexec_flag (int desc, bool value)
{
#ifdef F_SETFD
int flags = fcntl (desc, F_GETFD, 0);
if (0 <= flags)
{
int newflags = (value ? flags | FD_CLOEXEC : flags & ~FD_CLOEXEC);
if (flags == newflags
|| fcntl (desc, F_SETFD, newflags) != -1)
return 0;
}
return -1;
#else /* !F_SETFD */
/* Use dup2 to reject invalid file descriptors; the cloexec flag
will be unaffected. */
if (desc < 0)
{
errno = EBADF;
return -1;
}
if (dup2 (desc, desc) < 0)
/* errno is EBADF here. */
return -1;
/* There is nothing we can do on this kind of platform. Punt. */
return 0;
#endif /* !F_SETFD */
}
/* Duplicates a file handle FD, while marking the copy to be closed
prior to exec or spawn. Returns -1 and sets errno if FD could not
be duplicated. */
int
dup_cloexec (int fd)
{
return fcntl (fd, F_DUPFD_CLOEXEC, 0);
}
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