1 /* closexec.c - set or clear the close-on-exec descriptor flag
3 Copyright (C) 1991, 2004, 2005, 2006, 2009 Free Software
6 This program is free software: you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 3 of the License, or
9 (at your option) any later version.
11 This program is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with this program. If not, see <http://www.gnu.org/licenses/>.
19 The code is taken from glibc/manual/llio.texi */
29 #if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
30 /* Native Woe32 API. */
31 # define WIN32_LEAN_AND_MEAN
37 /* Set the `FD_CLOEXEC' flag of DESC if VALUE is true,
38 or clear the flag if VALUE is false.
39 Return 0 on success, or -1 on error with `errno' set.
41 Note that on MingW, this function does NOT protect DESC from being
42 inherited into spawned children. Instead, either use dup_cloexec
43 followed by closing the original DESC, or use interfaces such as
44 open or pipe2 that accept flags like O_CLOEXEC to create DESC
45 non-inheritable in the first place. */
48 set_cloexec_flag (int desc, bool value)
50 #if defined F_GETFD && defined F_SETFD
52 int flags = fcntl (desc, F_GETFD, 0);
56 int newflags = (value ? flags | FD_CLOEXEC : flags & ~FD_CLOEXEC);
59 || fcntl (desc, F_SETFD, newflags) != -1)
72 return dup2 (desc, desc) == desc ? 0 : -1;
78 /* Duplicates a file handle FD, while marking the copy to be closed
79 prior to exec or spawn. Returns -1 and sets errno if FD could not
82 int dup_cloexec (int fd)
86 #if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
88 /* Native Woe32 API. */
89 HANDLE curr_process = GetCurrentProcess ();
90 HANDLE old_handle = (HANDLE) _get_osfhandle (fd);
93 if (old_handle == INVALID_HANDLE_VALUE)
95 /* fd is closed, or is open to no handle at all.
96 We cannot duplicate fd in this case, because _open_osfhandle
97 fails for an INVALID_HANDLE_VALUE argument. */
102 if (!DuplicateHandle (curr_process, /* SourceProcessHandle */
103 old_handle, /* SourceHandle */
104 curr_process, /* TargetProcessHandle */
105 (PHANDLE) &new_handle, /* TargetHandle */
106 (DWORD) 0, /* DesiredAccess */
107 FALSE, /* InheritHandle */
108 DUPLICATE_SAME_ACCESS)) /* Options */
114 nfd = _open_osfhandle ((long) new_handle, O_BINARY | O_NOINHERIT);
117 CloseHandle (new_handle);
124 result = _gl_register_dup (fd, nfd);
132 # ifdef F_DUPFD_CLOEXEC
133 nfd = fcntl (fd, F_DUPFD_CLOEXEC, 0);
136 result = _gl_register_dup (fd, nfd);
139 # else /* !F_DUPFD_CLOEXEC */
141 if (0 <= nfd && set_cloexec_flag (nfd, true))
143 int saved_errno = errno;
148 # endif /* !F_DUPFD_CLOEXEC */