1 /* Test duplicating file descriptors.
2 Copyright (C) 2009-2022 Free Software Foundation, Inc.
3
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 3 of the License, or
7 (at your option) any later version.
8
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.
13
14 You should have received a copy of the GNU General Public License
15 along with this program. If not, see <https://www.gnu.org/licenses/>. */
16
17 /* Written by Eric Blake <ebb9@byu.net>, 2009. */
18
19 #include <config.h>
20
21 #include <unistd.h>
22
23 #include "signature.h"
24 SIGNATURE_CHECK (dup2, int, (int, int));
25
26 #include <errno.h>
27 #include <fcntl.h>
28
29 #if HAVE_SYS_RESOURCE_H
30 # include <sys/resource.h>
31 #endif
32
33 #include "binary-io.h"
34
35 #if GNULIB_TEST_CLOEXEC
36 # include "cloexec.h"
37 #endif
38
39 #if defined _WIN32 && ! defined __CYGWIN__
40 /* Get declarations of the native Windows API functions. */
41 # define WIN32_LEAN_AND_MEAN
42 # include <windows.h>
43 /* Get _get_osfhandle. */
44 # if GNULIB_MSVC_NOTHROW
45 # include "msvc-nothrow.h"
46 # else
47 # include <io.h>
48 # endif
49 #endif
50
51 #include "macros.h"
52
53 /* Return non-zero if FD is open. */
54 static int
55 is_open (int fd)
56 {
57 #if defined _WIN32 && ! defined __CYGWIN__
58 /* On native Windows, the initial state of unassigned standard file
59 descriptors is that they are open but point to an
60 INVALID_HANDLE_VALUE, and there is no fcntl. */
61 return (HANDLE) _get_osfhandle (fd) != INVALID_HANDLE_VALUE;
62 #else
63 # ifndef F_GETFL
64 # error Please port fcntl to your platform
65 # endif
66 return 0 <= fcntl (fd, F_GETFL);
67 #endif
68 }
69
70 #if GNULIB_TEST_CLOEXEC
71 /* Return non-zero if FD is open and inheritable across exec/spawn. */
72 static int
73 is_inheritable (int fd)
74 {
75 # if defined _WIN32 && ! defined __CYGWIN__
76 /* On native Windows, the initial state of unassigned standard file
77 descriptors is that they are open but point to an
78 INVALID_HANDLE_VALUE, and there is no fcntl. */
79 HANDLE h = (HANDLE) _get_osfhandle (fd);
80 DWORD flags;
81 if (h == INVALID_HANDLE_VALUE || GetHandleInformation (h, &flags) == 0)
82 return 0;
83 return (flags & HANDLE_FLAG_INHERIT) != 0;
84 # else
85 # ifndef F_GETFD
86 # error Please port fcntl to your platform
87 # endif
88 int i = fcntl (fd, F_GETFD);
89 return 0 <= i && (i & FD_CLOEXEC) == 0;
90 # endif
91 }
92 #endif /* GNULIB_TEST_CLOEXEC */
93
94 #if !O_BINARY
95 # define set_binary_mode(f,m) zero ()
96 static int zero (void) { return 0; }
97 #endif
98
99 /* Return non-zero if FD is open in the given MODE, which is either
100 O_TEXT or O_BINARY. */
101 static int
102 is_mode (int fd, int mode)
103 {
104 int value = set_binary_mode (fd, O_BINARY);
105 set_binary_mode (fd, value);
106 return mode == value;
107 }
108
109 int
110 main (void)
111 {
112 const char *file = "test-dup2.tmp";
113 char buffer[1];
114 int bad_fd = getdtablesize ();
115 int fd = open (file, O_CREAT | O_TRUNC | O_RDWR, 0600);
116
117 /* Assume std descriptors were provided by invoker. */
118 ASSERT (STDERR_FILENO < fd);
119 ASSERT (is_open (fd));
120 /* Ignore any other fd's leaked into this process. */
121 close (fd + 1);
122 close (fd + 2);
123 ASSERT (!is_open (fd + 1));
124 ASSERT (!is_open (fd + 2));
125
126 /* Assigning to self must be a no-op. */
127 ASSERT (dup2 (fd, fd) == fd);
128 ASSERT (is_open (fd));
129
130 /* The source must be valid. */
131 errno = 0;
132 ASSERT (dup2 (-1, fd) == -1);
133 ASSERT (errno == EBADF);
134 close (99);
135 errno = 0;
136 ASSERT (dup2 (99, fd) == -1);
137 ASSERT (errno == EBADF);
138 errno = 0;
139 ASSERT (dup2 (AT_FDCWD, fd) == -1);
140 ASSERT (errno == EBADF);
141 ASSERT (is_open (fd));
142
143 /* If the source is not open, then the destination is unaffected. */
144 errno = 0;
145 ASSERT (dup2 (fd + 1, fd + 1) == -1);
146 ASSERT (errno == EBADF);
147 ASSERT (!is_open (fd + 1));
148 errno = 0;
149 ASSERT (dup2 (fd + 1, fd) == -1);
150 ASSERT (errno == EBADF);
151 ASSERT (is_open (fd));
152
153 /* The destination must be valid. */
154 errno = 0;
155 ASSERT (dup2 (fd, -2) == -1);
156 ASSERT (errno == EBADF);
157 if (bad_fd > 256)
158 {
159 ASSERT (dup2 (fd, 255) == 255);
160 ASSERT (dup2 (fd, 256) == 256);
161 ASSERT (close (255) == 0);
162 ASSERT (close (256) == 0);
163 }
164 ASSERT (dup2 (fd, bad_fd - 1) == bad_fd - 1);
165 ASSERT (close (bad_fd - 1) == 0);
166 errno = 0;
167 ASSERT (dup2 (fd, bad_fd) == -1);
168 ASSERT (errno == EBADF);
169
170 /* Using dup2 can skip fds. */
171 ASSERT (dup2 (fd, fd + 2) == fd + 2);
172 ASSERT (is_open (fd));
173 ASSERT (!is_open (fd + 1));
174 ASSERT (is_open (fd + 2));
175
176 /* Verify that dup2 closes the previous occupant of a fd. */
177 ASSERT (open ("/dev/null", O_WRONLY, 0600) == fd + 1);
178 ASSERT (dup2 (fd + 1, fd) == fd);
179 ASSERT (close (fd + 1) == 0);
180 ASSERT (write (fd, "1", 1) == 1);
181 ASSERT (dup2 (fd + 2, fd) == fd);
182 ASSERT (lseek (fd, 0, SEEK_END) == 0);
183 ASSERT (write (fd + 2, "2", 1) == 1);
184 ASSERT (lseek (fd, 0, SEEK_SET) == 0);
185 ASSERT (read (fd, buffer, 1) == 1);
186 ASSERT (*buffer == '2');
187
188 #if GNULIB_TEST_CLOEXEC
189 /* Any new fd created by dup2 must not be cloexec. */
190 ASSERT (close (fd + 2) == 0);
191 ASSERT (dup_cloexec (fd) == fd + 1);
192 ASSERT (!is_inheritable (fd + 1));
193 ASSERT (dup2 (fd + 1, fd + 1) == fd + 1);
194 ASSERT (!is_inheritable (fd + 1));
195 ASSERT (dup2 (fd + 1, fd + 2) == fd + 2);
196 ASSERT (!is_inheritable (fd + 1));
197 ASSERT (is_inheritable (fd + 2));
198 errno = 0;
199 ASSERT (dup2 (fd + 1, -1) == -1);
200 ASSERT (errno == EBADF);
201 ASSERT (!is_inheritable (fd + 1));
202 #endif
203
204 /* On systems that distinguish between text and binary mode, dup2
205 reuses the mode of the source. */
206 set_binary_mode (fd, O_BINARY);
207 ASSERT (is_mode (fd, O_BINARY));
208 ASSERT (dup2 (fd, fd + 1) == fd + 1);
209 ASSERT (is_mode (fd + 1, O_BINARY));
210 set_binary_mode (fd, O_TEXT);
211 ASSERT (is_mode (fd, O_TEXT));
212 ASSERT (dup2 (fd, fd + 1) == fd + 1);
213 ASSERT (is_mode (fd + 1, O_TEXT));
214
215 /* Clean up. */
216 ASSERT (close (fd + 2) == 0);
217 ASSERT (close (fd + 1) == 0);
218 ASSERT (close (fd) == 0);
219 ASSERT (unlink (file) == 0);
220
221 return 0;
222 }