1 /* Copy a file descriptor, applying specific flags.
2 Copyright (C) 2009-2013 Free Software Foundation, Inc.
4 This program is free software; you can redistribute it and/or modify
5 it under the terms of the GNU General Public License as published by
6 the Free Software Foundation; either version 2, or (at your option)
9 This program is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 GNU General Public License for more details.
14 You should have received a copy of the GNU General Public License along
15 with this program; if not, see <http://www.gnu.org/licenses/>. */
26 #include "binary-io.h"
29 dup3 (int oldfd, int newfd, int flags)
33 # if HAVE_SETDTABLESIZE
34 /* Avoid a cygwin crasher. */
35 setdtablesize (newfd + 1);
37 /* Try the system call first, if it exists. (We may be running with a glibc
38 that has the function but with an older kernel that lacks it.) */
40 /* Cache the information whether the system call really exists. */
41 static int have_dup3_really; /* 0 = unknown, 1 = yes, -1 = no */
42 if (have_dup3_really >= 0)
44 int result = dup3 (oldfd, newfd, flags);
45 if (!(result < 0 && errno == ENOSYS))
50 result = _gl_register_dup (oldfd, newfd);
54 have_dup3_really = -1;
59 if (newfd < 0 || newfd >= getdtablesize () || fcntl (oldfd, F_GETFD) == -1)
71 /* Check the supported flags.
72 Note that O_NONBLOCK is not supported, because setting it on newfd
73 would implicitly also set it on oldfd. */
74 if ((flags & ~(O_CLOEXEC | O_BINARY | O_TEXT)) != 0)
80 if (flags & O_CLOEXEC)
84 result = fcntl (oldfd, F_DUPFD_CLOEXEC, newfd);
94 else if (dup2 (oldfd, newfd) < 0)
99 set_binary_mode (newfd, O_BINARY);
100 else if (flags & O_TEXT)
101 set_binary_mode (newfd, O_TEXT);