1 /* Tests for support_open_dev_null_range.
2 Copyright (C) 2021 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library 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 GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <https://www.gnu.org/licenses/>. */
18
19 #include <errno.h>
20 #include <dirent.h>
21 #include <fcntl.h>
22 #include <limits.h>
23 #include <support/check.h>
24 #include <support/support.h>
25 #include <support/xunistd.h>
26 #include <sys/resource.h>
27 #include <stdlib.h>
28
29 #ifndef PATH_MAX
30 # define PATH_MAX 1024
31 #endif
32
33 #include <stdio.h>
34
35 static void
check_path(int fd)36 check_path (int fd)
37 {
38 char *proc_fd_path = xasprintf ("/proc/self/fd/%d", fd);
39 char file_path[PATH_MAX];
40 ssize_t file_path_length
41 = readlink (proc_fd_path, file_path, sizeof (file_path));
42 free (proc_fd_path);
43 if (file_path_length < 0)
44 FAIL_EXIT1 ("readlink (%s, %p, %zu)", proc_fd_path, file_path,
45 sizeof (file_path));
46 file_path[file_path_length] = '\0';
47 TEST_COMPARE_STRING (file_path, "/dev/null");
48 }
49
50 static int
number_of_opened_files(void)51 number_of_opened_files (void)
52 {
53 DIR *fds = opendir ("/proc/self/fd");
54 if (fds == NULL)
55 FAIL_EXIT1 ("opendir (\"/proc/self/fd\"): %m");
56
57 int r = 0;
58 while (true)
59 {
60 errno = 0;
61 struct dirent64 *e = readdir64 (fds);
62 if (e == NULL)
63 {
64 if (errno != 0)
65 FAIL_EXIT1 ("readdir: %m");
66 break;
67 }
68
69 if (e->d_name[0] == '.')
70 continue;
71
72 char *endptr;
73 long int fd = strtol (e->d_name, &endptr, 10);
74 if (*endptr != '\0' || fd < 0 || fd > INT_MAX)
75 FAIL_EXIT1 ("readdir: invalid file descriptor name: /proc/self/fd/%s",
76 e->d_name);
77
78 /* Skip the descriptor which is used to enumerate the
79 descriptors. */
80 if (fd == dirfd (fds))
81 continue;
82
83 r = r + 1;
84 }
85
86 closedir (fds);
87
88 return r;
89 }
90
91 static int
do_test(void)92 do_test (void)
93 {
94 const int nfds1 = 8;
95 int lowfd = support_open_dev_null_range (nfds1, O_RDONLY, 0600);
96 for (int i = 0; i < nfds1; i++)
97 {
98 TEST_VERIFY (fcntl (lowfd + i, F_GETFL) > -1);
99 check_path (lowfd + i);
100 }
101
102 /* create some gaps. */
103 xclose (lowfd + 1);
104 xclose (lowfd + 5);
105 xclose (lowfd + 6);
106
107 const int nfds2 = 16;
108 int lowfd2 = support_open_dev_null_range (nfds2, O_RDONLY, 0600);
109 for (int i = 0; i < nfds2; i++)
110 {
111 TEST_VERIFY (fcntl (lowfd2 + i, F_GETFL) > -1);
112 check_path (lowfd2 + i);
113 }
114
115 /* Decrease the maximum number of files. */
116 {
117 struct rlimit rl;
118 if (getrlimit (RLIMIT_NOFILE, &rl) == -1)
119 FAIL_EXIT1 ("getrlimit (RLIMIT_NOFILE): %m");
120
121 rl.rlim_cur = number_of_opened_files ();
122
123 if (setrlimit (RLIMIT_NOFILE, &rl) == 1)
124 FAIL_EXIT1 ("setrlimit (RLIMIT_NOFILE): %m");
125 }
126
127 const int nfds3 = 16;
128 int lowfd3 = support_open_dev_null_range (nfds3, O_RDONLY, 0600);
129 for (int i = 0; i < nfds3; i++)
130 {
131 TEST_VERIFY (fcntl (lowfd3 + i, F_GETFL) > -1);
132 check_path (lowfd3 + i);
133 }
134
135 /* create a lot of gaps to trigger the range extension. */
136 xclose (lowfd3 + 1);
137 xclose (lowfd3 + 3);
138 xclose (lowfd3 + 5);
139 xclose (lowfd3 + 7);
140 xclose (lowfd3 + 9);
141 xclose (lowfd3 + 11);
142 xclose (lowfd3 + 13);
143
144 const int nfds4 = 16;
145 int lowfd4 = support_open_dev_null_range (nfds4, O_RDONLY, 0600);
146 for (int i = 0; i < nfds4; i++)
147 {
148 TEST_VERIFY (fcntl (lowfd4 + i, F_GETFL) > -1);
149 check_path (lowfd4 + i);
150 }
151
152 return 0;
153 }
154
155 #include <support/test-driver.c>
156