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84 lines
2.3 KiB
C
84 lines
2.3 KiB
C
/* cloexec.c - set or clear the close-on-exec descriptor flag
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Copyright (C) 1991, 2004-2006, 2009-2021 Free Software Foundation, Inc.
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <https://www.gnu.org/licenses/>.
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The code is taken from glibc/manual/llio.texi */
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#include <config.h>
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#include "cloexec.h"
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#include <errno.h>
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#include <fcntl.h>
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#include <unistd.h>
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/* Set the 'FD_CLOEXEC' flag of DESC if VALUE is true,
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or clear the flag if VALUE is false.
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Return 0 on success, or -1 on error with 'errno' set.
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Note that on MingW, this function does NOT protect DESC from being
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inherited into spawned children. Instead, either use dup_cloexec
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followed by closing the original DESC, or use interfaces such as
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open or pipe2 that accept flags like O_CLOEXEC to create DESC
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non-inheritable in the first place. */
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int
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set_cloexec_flag (int desc, bool value)
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{
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#ifdef F_SETFD
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int flags = fcntl (desc, F_GETFD, 0);
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if (0 <= flags)
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{
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int newflags = (value ? flags | FD_CLOEXEC : flags & ~FD_CLOEXEC);
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if (flags == newflags
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|| fcntl (desc, F_SETFD, newflags) != -1)
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return 0;
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}
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return -1;
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#else /* !F_SETFD */
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/* Use dup2 to reject invalid file descriptors; the cloexec flag
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will be unaffected. */
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if (desc < 0)
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{
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errno = EBADF;
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return -1;
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}
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if (dup2 (desc, desc) < 0)
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/* errno is EBADF here. */
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return -1;
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/* There is nothing we can do on this kind of platform. Punt. */
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return 0;
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#endif /* !F_SETFD */
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}
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/* Duplicates a file handle FD, while marking the copy to be closed
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prior to exec or spawn. Returns -1 and sets errno if FD could not
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be duplicated. */
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int
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dup_cloexec (int fd)
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{
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return fcntl (fd, F_DUPFD_CLOEXEC, 0);
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}
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