1 /* Duplicate an open file descriptor to a specified file descriptor.
2
3 Copyright (C) 1999, 2004-2007, 2009-2019 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 <https://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 HAVE_DUP2
29
30 # undef dup2
31
32 # if defined _WIN32 && ! defined __CYGWIN__
33
34 /* Get declarations of the native Windows API functions. */
35 # define WIN32_LEAN_AND_MEAN
36 # include <windows.h>
37
38 # if HAVE_MSVC_INVALID_PARAMETER_HANDLER
39 # include "msvc-inval.h"
40 # endif
41
42 /* Get _get_osfhandle. */
43 # if GNULIB_MSVC_NOTHROW
44 # include "msvc-nothrow.h"
45 # else
46 # include <io.h>
47 # endif
48
49 # if HAVE_MSVC_INVALID_PARAMETER_HANDLER
50 static int
dup2_nothrow(int fd,int desired_fd)51 dup2_nothrow (int fd, int desired_fd)
52 {
53 int result;
54
55 TRY_MSVC_INVAL
56 {
57 result = dup2 (fd, desired_fd);
58 }
59 CATCH_MSVC_INVAL
60 {
61 errno = EBADF;
62 result = -1;
63 }
64 DONE_MSVC_INVAL;
65
66 return result;
67 }
68 # else
69 # define dup2_nothrow dup2
70 # endif
71
72 static int
ms_windows_dup2(int fd,int desired_fd)73 ms_windows_dup2 (int fd, int desired_fd)
74 {
75 int result;
76
77 /* If fd is closed, mingw hangs on dup2 (fd, fd). If fd is open,
78 dup2 (fd, fd) returns 0, but all further attempts to use fd in
79 future dup2 calls will hang. */
80 if (fd == desired_fd)
81 {
82 if ((HANDLE) _get_osfhandle (fd) == INVALID_HANDLE_VALUE)
83 {
84 errno = EBADF;
85 return -1;
86 }
87 return fd;
88 }
89
90 /* Wine 1.0.1 return 0 when desired_fd is negative but not -1:
91 https://bugs.winehq.org/show_bug.cgi?id=21289 */
92 if (desired_fd < 0)
93 {
94 errno = EBADF;
95 return -1;
96 }
97
98 result = dup2_nothrow (fd, desired_fd);
99
100 if (result == 0)
101 result = desired_fd;
102
103 return result;
104 }
105
106 # define dup2 ms_windows_dup2
107
108 # elif defined __KLIBC__
109
110 # include <InnoTekLIBC/backend.h>
111
112 static int
klibc_dup2dirfd(int fd,int desired_fd)113 klibc_dup2dirfd (int fd, int desired_fd)
114 {
115 int tempfd;
116 int dupfd;
117
118 tempfd = open ("NUL", O_RDONLY);
119 if (tempfd == -1)
120 return -1;
121
122 if (tempfd == desired_fd)
123 {
124 close (tempfd);
125
126 char path[_MAX_PATH];
127 if (__libc_Back_ioFHToPath (fd, path, sizeof (path)))
128 return -1;
129
130 return open(path, O_RDONLY);
131 }
132
133 dupfd = klibc_dup2dirfd (fd, desired_fd);
134
135 close (tempfd);
136
137 return dupfd;
138 }
139
140 static int
klibc_dup2(int fd,int desired_fd)141 klibc_dup2 (int fd, int desired_fd)
142 {
143 int dupfd;
144 struct stat sbuf;
145
146 dupfd = dup2 (fd, desired_fd);
147 if (dupfd == -1 && errno == ENOTSUP \
148 && !fstat (fd, &sbuf) && S_ISDIR (sbuf.st_mode))
149 {
150 close (desired_fd);
151
152 return klibc_dup2dirfd (fd, desired_fd);
153 }
154
155 return dupfd;
156 }
157
158 # define dup2 klibc_dup2
159 # endif
160
161 int
rpl_dup2(int fd,int desired_fd)162 rpl_dup2 (int fd, int desired_fd)
163 {
164 int result;
165
166 # ifdef F_GETFL
167 /* On Linux kernels 2.6.26-2.6.29, dup2 (fd, fd) returns -EBADF.
168 On Cygwin 1.5.x, dup2 (1, 1) returns 0.
169 On Cygwin 1.7.17, dup2 (1, -1) dumps core.
170 On Cygwin 1.7.25, dup2 (1, 256) can dump core.
171 On Haiku, dup2 (fd, fd) mistakenly clears FD_CLOEXEC. */
172 # if HAVE_SETDTABLESIZE
173 setdtablesize (desired_fd + 1);
174 # endif
175 if (desired_fd < 0)
176 fd = desired_fd;
177 if (fd == desired_fd)
178 return fcntl (fd, F_GETFL) == -1 ? -1 : fd;
179 # endif
180
181 result = dup2 (fd, desired_fd);
182
183 /* Correct an errno value on FreeBSD 6.1 and Cygwin 1.5.x. */
184 if (result == -1 && errno == EMFILE)
185 errno = EBADF;
186 # if REPLACE_FCHDIR
187 if (fd != desired_fd && result != -1)
188 result = _gl_register_dup (fd, result);
189 # endif
190 return result;
191 }
192
193 #else /* !HAVE_DUP2 */
194
195 /* On older platforms, dup2 did not exist. */
196
197 # ifndef F_DUPFD
198 static int
dupfd(int fd,int desired_fd)199 dupfd (int fd, int desired_fd)
200 {
201 int duplicated_fd = dup (fd);
202 if (duplicated_fd < 0 || duplicated_fd == desired_fd)
203 return duplicated_fd;
204 else
205 {
206 int r = dupfd (fd, desired_fd);
207 int e = errno;
208 close (duplicated_fd);
209 errno = e;
210 return r;
211 }
212 }
213 # endif
214
215 int
dup2(int fd,int desired_fd)216 dup2 (int fd, int desired_fd)
217 {
218 int result = fcntl (fd, F_GETFL) < 0 ? -1 : fd;
219 if (result == -1 || fd == desired_fd)
220 return result;
221 close (desired_fd);
222 # ifdef F_DUPFD
223 result = fcntl (fd, F_DUPFD, desired_fd);
224 # if REPLACE_FCHDIR
225 if (0 <= result)
226 result = _gl_register_dup (fd, result);
227 # endif
228 # else
229 result = dupfd (fd, desired_fd);
230 # endif
231 if (result == -1 && (errno == EMFILE || errno == EINVAL))
232 errno = EBADF;
233 return result;
234 }
235 #endif /* !HAVE_DUP2 */
236