1 /* Test that dup_safer leaves standard fds alone.
2 Copyright (C) 2009-2021 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 <fcntl.h>
24 #include <errno.h>
25 #include <stdbool.h>
26 #include <stdio.h>
27 #include <unistd.h>
28
29 #include "binary-io.h"
30 #include "cloexec.h"
31
32 #if defined _WIN32 && ! defined __CYGWIN__
33 /* Get declarations of the native Windows API functions. */
34 # define WIN32_LEAN_AND_MEAN
35 # include <windows.h>
36 /* Get _get_osfhandle. */
37 # if GNULIB_MSVC_NOTHROW
38 # include "msvc-nothrow.h"
39 # else
40 # include <io.h>
41 # endif
42 #endif
43
44 #if !O_BINARY
45 # define set_binary_mode(f,m) zero ()
46 static int zero (void) { return 0; }
47 #endif
48
49 /* This test intentionally closes stderr. So, we arrange to have fd 10
50 (outside the range of interesting fd's during the test) set up to
51 duplicate the original stderr. */
52
53 #define BACKUP_STDERR_FILENO 10
54 #define ASSERT_STREAM myerr
55 #include "macros.h"
56
57 static FILE *myerr;
58
59 /* Return true if FD is open. */
60 static bool
61 is_open (int fd)
62 {
63 #if defined _WIN32 && ! defined __CYGWIN__
64 /* On native Windows, the initial state of unassigned standard file
65 descriptors is that they are open but point to an
66 INVALID_HANDLE_VALUE, and there is no fcntl. */
67 return (HANDLE) _get_osfhandle (fd) != INVALID_HANDLE_VALUE;
68 #else
69 # ifndef F_GETFL
70 # error Please port fcntl to your platform
71 # endif
72 return 0 <= fcntl (fd, F_GETFL);
73 #endif
74 }
75
76 /* Return true if FD is open and inheritable across exec/spawn. */
77 static bool
78 is_inheritable (int fd)
79 {
80 #if defined _WIN32 && ! defined __CYGWIN__
81 /* On native Windows, the initial state of unassigned standard file
82 descriptors is that they are open but point to an
83 INVALID_HANDLE_VALUE, and there is no fcntl. */
84 HANDLE h = (HANDLE) _get_osfhandle (fd);
85 DWORD flags;
86 if (h == INVALID_HANDLE_VALUE || GetHandleInformation (h, &flags) == 0)
87 return 0;
88 return (flags & HANDLE_FLAG_INHERIT) != 0;
89 #else
90 # ifndef F_GETFD
91 # error Please port fcntl to your platform
92 # endif
93 int i = fcntl (fd, F_GETFD);
94 return 0 <= i && (i & FD_CLOEXEC) == 0;
95 #endif
96 }
97
98 /* Return true if FD is open in the given MODE, which is either
99 O_TEXT or O_BINARY. */
100 static bool
101 is_mode (int fd, int mode)
102 {
103 int value = set_binary_mode (fd, O_BINARY);
104 set_binary_mode (fd, value);
105 return mode == value;
106 }
107
108 #define witness "test-dup-safer.txt"
109
110 int
111 main (void)
112 {
113 int i;
114 int fd;
115 int bad_fd = getdtablesize ();
116
117 /* We close fd 2 later, so save it in fd 10. */
118 if (dup2 (STDERR_FILENO, BACKUP_STDERR_FILENO) != BACKUP_STDERR_FILENO
119 || (myerr = fdopen (BACKUP_STDERR_FILENO, "w")) == NULL)
120 return 2;
121
122 /* Create file for later checks. */
123 fd = creat (witness, 0600);
124 ASSERT (STDERR_FILENO < fd);
125
126 /* Four iterations, with progressively more standard descriptors
127 closed. */
128 for (i = -1; i <= STDERR_FILENO; i++)
129 {
130 if (0 <= i)
131 ASSERT (close (i) == 0);
132
133 /* Detect errors. */
134 errno = 0;
135 ASSERT (dup (-1) == -1);
136 ASSERT (errno == EBADF);
137 errno = 0;
138 ASSERT (dup (bad_fd) == -1);
139 ASSERT (errno == EBADF);
140 close (fd + 1);
141 errno = 0;
142 ASSERT (dup (fd + 1) == -1);
143 ASSERT (errno == EBADF);
144
145 /* Preserve text vs. binary. */
146 set_binary_mode (fd, O_BINARY);
147 ASSERT (dup (fd) == fd + 1);
148 ASSERT (is_open (fd + 1));
149 ASSERT (is_inheritable (fd + 1));
150 ASSERT (is_mode (fd + 1, O_BINARY));
151
152 ASSERT (close (fd + 1) == 0);
153 set_binary_mode (fd, O_TEXT);
154 ASSERT (dup (fd) == fd + 1);
155 ASSERT (is_open (fd + 1));
156 ASSERT (is_inheritable (fd + 1));
157 ASSERT (is_mode (fd + 1, O_TEXT));
158
159 /* Create cloexec copy. */
160 ASSERT (close (fd + 1) == 0);
161 ASSERT (fd_safer_flag (dup_cloexec (fd), O_CLOEXEC) == fd + 1);
162 ASSERT (set_cloexec_flag (fd + 1, true) == 0);
163 ASSERT (is_open (fd + 1));
164 ASSERT (!is_inheritable (fd + 1));
165 ASSERT (close (fd) == 0);
166
167 /* dup always creates inheritable copies. Also, check that
168 earliest slot past std fds is used. */
169 ASSERT (dup (fd + 1) == fd);
170 ASSERT (is_open (fd));
171 ASSERT (is_inheritable (fd));
172 ASSERT (close (fd + 1) == 0);
173 }
174
175 /* Cleanup. */
176 ASSERT (close (fd) == 0);
177 ASSERT (unlink (witness) == 0);
178
179 return 0;
180 }