1/* Duplicate an open file descriptor to a specified file descriptor.
2
3   Copyright (C) 1999, 2004-2007, 2009-2010 Free Software Foundation, Inc.
4
5   This program is free software: you can redistribute it and/or modify
6   it under the terms of the GNU General Public License as published by
7   the Free Software Foundation; either version 3 of the License, or
8   (at your option) any later version.
9
10   This program is distributed in the hope that it will be useful,
11   but WITHOUT ANY WARRANTY; without even the implied warranty of
12   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
13   GNU General Public License for more details.
14
15   You should have received a copy of the GNU General Public License
16   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
17
18/* written by Paul Eggert */
19
20#include <config.h>
21
22/* Specification.  */
23#include <unistd.h>
24
25#include <errno.h>
26#include <fcntl.h>
27
28#if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
29/* Get declarations of the Win32 API functions.  */
30# define WIN32_LEAN_AND_MEAN
31# include <windows.h>
32#endif
33
34#if HAVE_DUP2
35
36# undef dup2
37
38int
39rpl_dup2 (int fd, int desired_fd)
40{
41  int result;
42# if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
43  /* If fd is closed, mingw hangs on dup2 (fd, fd).  If fd is open,
44     dup2 (fd, fd) returns 0, but all further attempts to use fd in
45     future dup2 calls will hang.  */
46  if (fd == desired_fd)
47    {
48      if ((HANDLE) _get_osfhandle (fd) == INVALID_HANDLE_VALUE)
49        {
50          errno = EBADF;
51          return -1;
52        }
53      return fd;
54    }
55  /* Wine 1.0.1 return 0 when desired_fd is negative but not -1:
56     http://bugs.winehq.org/show_bug.cgi?id=21289 */
57  if (desired_fd < 0)
58    {
59      errno = EBADF;
60      return -1;
61    }
62# endif
63  result = dup2 (fd, desired_fd);
64# ifdef __linux__
65  /* Correct a Linux return value.
66     <http://git.kernel.org/?p=linux/kernel/git/stable/linux-2.6.30.y.git;a=commitdiff;h=2b79bc4f7ebbd5af3c8b867968f9f15602d5f802>
67   */
68  if (fd == desired_fd && result == (unsigned int) -EBADF)
69    {
70      errno = EBADF;
71      result = -1;
72    }
73# endif
74  if (result == 0)
75    result = desired_fd;
76  /* Correct a cygwin 1.5.x errno value.  */
77  else if (result == -1 && errno == EMFILE)
78    errno = EBADF;
79# if REPLACE_FCHDIR
80  if (fd != desired_fd && result != -1)
81    result = _gl_register_dup (fd, result);
82# endif
83  return result;
84}
85
86#else /* !HAVE_DUP2 */
87
88/* On older platforms, dup2 did not exist.  */
89
90# ifndef F_DUPFD
91static int
92dupfd (int fd, int desired_fd)
93{
94  int duplicated_fd = dup (fd);
95  if (duplicated_fd < 0 || duplicated_fd == desired_fd)
96    return duplicated_fd;
97  else
98    {
99      int r = dupfd (fd, desired_fd);
100      int e = errno;
101      close (duplicated_fd);
102      errno = e;
103      return r;
104    }
105}
106# endif
107
108int
109dup2 (int fd, int desired_fd)
110{
111  int result = fcntl (fd, F_GETFL) < 0 ? -1 : fd;
112  if (result == -1 || fd == desired_fd)
113    return result;
114  close (desired_fd);
115# ifdef F_DUPFD
116  result = fcntl (fd, F_DUPFD, desired_fd);
117#  if REPLACE_FCHDIR
118  if (0 <= result)
119    result = _gl_register_dup (fd, result);
120#  endif
121# else
122  result = dupfd (fd, desired_fd);
123# endif
124  if (result == -1 && (errno == EMFILE || errno == EINVAL))
125    errno = EBADF;
126  return result;
127}
128#endif /* !HAVE_DUP2 */
129