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be6b16d9 | 1 | /* Test case for cache invalidation after concurrent write (bug 24882). |
2b778ceb | 2 | Copyright (C) 2019-2021 Free Software Foundation, Inc. |
be6b16d9 FW |
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 License as | |
7 | published by the Free Software Foundation; either version 2.1 of the | |
8 | 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; see the file COPYING.LIB. If | |
17 | not, see <http://www.gnu.org/licenses/>. */ | |
18 | ||
19 | /* This test writes an entry to the utmpx file, reads it (so that it | |
20 | is cached) in process1, and overwrites the same entry in process2 | |
21 | with something that does not match the search criteria. At this | |
22 | point, the cache of the first process is stale, and when process1 | |
23 | attempts to write a new record which would have gone to the same | |
24 | place (as indicated by the cache), it needs to realize that it has | |
25 | to pick a different slot because the old slot is now used for | |
26 | something else. */ | |
27 | ||
28 | #include <errno.h> | |
29 | #include <stdlib.h> | |
30 | #include <string.h> | |
31 | #include <support/check.h> | |
32 | #include <support/namespace.h> | |
33 | #include <support/support.h> | |
34 | #include <support/temp_file.h> | |
35 | #include <support/xthread.h> | |
36 | #include <support/xunistd.h> | |
37 | #include <utmp.h> | |
38 | #include <utmpx.h> | |
39 | ||
40 | /* Set to the path of the utmp file. */ | |
41 | static char *utmp_file; | |
42 | ||
43 | /* Used to synchronize the subprocesses. The barrier itself is | |
44 | allocated in shared memory. */ | |
45 | static pthread_barrier_t *barrier; | |
46 | ||
47 | /* setutxent with error checking. */ | |
48 | static void | |
49 | xsetutxent (void) | |
50 | { | |
51 | errno = 0; | |
52 | setutxent (); | |
53 | TEST_COMPARE (errno, 0); | |
54 | } | |
55 | ||
56 | /* getutxent with error checking. */ | |
57 | static struct utmpx * | |
58 | xgetutxent (void) | |
59 | { | |
60 | errno = 0; | |
61 | struct utmpx *result = getutxent (); | |
62 | if (result == NULL) | |
63 | FAIL_EXIT1 ("getutxent: %m"); | |
64 | return result; | |
65 | } | |
66 | ||
67 | static void | |
68 | put_entry (const char *id, pid_t pid, const char *user, const char *line) | |
69 | { | |
70 | struct utmpx ut = | |
71 | { | |
72 | .ut_type = LOGIN_PROCESS, | |
73 | .ut_pid = pid, | |
74 | .ut_host = "localhost", | |
75 | }; | |
76 | strcpy (ut.ut_id, id); | |
77 | strncpy (ut.ut_user, user, sizeof (ut.ut_user)); | |
78 | strncpy (ut.ut_line, line, sizeof (ut.ut_line)); | |
79 | TEST_VERIFY (pututxline (&ut) != NULL); | |
80 | } | |
81 | ||
82 | /* Use two cooperating subprocesses to avoid issues related to | |
83 | unlock-on-close semantics of POSIX advisory locks. */ | |
84 | ||
85 | static __attribute__ ((noreturn)) void | |
86 | process1 (void) | |
87 | { | |
88 | TEST_COMPARE (utmpname (utmp_file), 0); | |
89 | ||
90 | /* Create an entry. */ | |
91 | xsetutxent (); | |
92 | put_entry ("1", 101, "root", "process1"); | |
93 | ||
94 | /* Retrieve the entry. This will fill the internal cache. */ | |
95 | { | |
96 | errno = 0; | |
97 | setutxent (); | |
98 | TEST_COMPARE (errno, 0); | |
99 | struct utmpx ut = | |
100 | { | |
101 | .ut_type = LOGIN_PROCESS, | |
102 | .ut_line = "process1", | |
103 | }; | |
104 | struct utmpx *result = getutxline (&ut); | |
105 | if (result == NULL) | |
106 | FAIL_EXIT1 ("getutxline (\"process1\"): %m"); | |
107 | TEST_COMPARE (result->ut_pid, 101); | |
108 | } | |
109 | ||
110 | /* Signal the other process to overwrite the entry. */ | |
111 | xpthread_barrier_wait (barrier); | |
112 | ||
113 | /* Wait for the other process to complete the write operation. */ | |
114 | xpthread_barrier_wait (barrier); | |
115 | ||
116 | /* Add another entry. Note: This time, there is no setutxent call. */ | |
117 | put_entry ("1", 103, "root", "process1"); | |
118 | ||
119 | _exit (0); | |
120 | } | |
121 | ||
122 | static void | |
123 | process2 (void *closure) | |
124 | { | |
125 | /* Wait for the first process to write its entry. */ | |
126 | xpthread_barrier_wait (barrier); | |
127 | ||
128 | /* Truncate the file. The glibc interface does not support | |
129 | re-purposing records, but an external expiration mechanism may | |
130 | trigger this. */ | |
131 | TEST_COMPARE (truncate64 (utmp_file, 0), 0); | |
132 | ||
133 | /* Write the replacement entry. */ | |
134 | TEST_COMPARE (utmpname (utmp_file), 0); | |
135 | xsetutxent (); | |
136 | put_entry ("2", 102, "user", "process2"); | |
137 | ||
138 | /* Signal the other process that the entry has been replaced. */ | |
139 | xpthread_barrier_wait (barrier); | |
140 | } | |
141 | ||
142 | static int | |
143 | do_test (void) | |
144 | { | |
145 | xclose (create_temp_file ("tst-tumpx-cache-write-", &utmp_file)); | |
146 | { | |
147 | pthread_barrierattr_t attr; | |
148 | xpthread_barrierattr_init (&attr); | |
149 | xpthread_barrierattr_setpshared (&attr, PTHREAD_SCOPE_PROCESS); | |
150 | barrier = support_shared_allocate (sizeof (*barrier)); | |
151 | xpthread_barrier_init (barrier, &attr, 2); | |
152 | } | |
153 | ||
154 | /* Run both subprocesses in parallel. */ | |
155 | { | |
156 | pid_t pid1 = xfork (); | |
157 | if (pid1 == 0) | |
158 | process1 (); | |
159 | support_isolate_in_subprocess (process2, NULL); | |
160 | int status; | |
161 | xwaitpid (pid1, &status, 0); | |
162 | TEST_COMPARE (status, 0); | |
163 | } | |
164 | ||
165 | /* Check that the utmpx database contains the expected records. */ | |
166 | { | |
167 | TEST_COMPARE (utmpname (utmp_file), 0); | |
168 | xsetutxent (); | |
169 | ||
170 | struct utmpx *ut = xgetutxent (); | |
171 | TEST_COMPARE_STRING (ut->ut_id, "2"); | |
172 | TEST_COMPARE (ut->ut_pid, 102); | |
173 | TEST_COMPARE_STRING (ut->ut_user, "user"); | |
174 | TEST_COMPARE_STRING (ut->ut_line, "process2"); | |
175 | ||
176 | ut = xgetutxent (); | |
177 | TEST_COMPARE_STRING (ut->ut_id, "1"); | |
178 | TEST_COMPARE (ut->ut_pid, 103); | |
179 | TEST_COMPARE_STRING (ut->ut_user, "root"); | |
180 | TEST_COMPARE_STRING (ut->ut_line, "process1"); | |
181 | ||
182 | if (getutxent () != NULL) | |
183 | FAIL_EXIT1 ("additional utmpx entry"); | |
184 | } | |
185 | ||
186 | xpthread_barrier_destroy (barrier); | |
187 | support_shared_free (barrier); | |
188 | free (utmp_file); | |
189 | ||
190 | return 0; | |
191 | } | |
192 | ||
193 | #include <support/test-driver.c> |